text: /*
   * st_spi_fsm.c	- ST Fast Sequence Mode (FSM) Serial Flash Controller
   *
   * Author: Angus Clark <angus.clark@st.com>
   *
   * Copyright (C) 2010-2014 STMicroelectronics Limited
   *
   * JEDEC probe based on drivers/mtd/devices/m25p80.c
   *
   * This code is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   *
   */
  #include <linux/kernel.h>
  #include <linux/module.h>
  #include <linux/regmap.h>
  #include <linux/platform_device.h>
  #include <linux/mfd/syscon.h>
  #include <linux/mtd/mtd.h>
  #include <linux/mtd/partitions.h>
  #include <linux/mtd/spi-nor.h>
  #include <linux/sched.h>
  #include <linux/delay.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/clk.h>
  
  #include "serial_flash_cmds.h"
  
  /*
   * FSM SPI Controller Registers
   */
  #define SPI_CLOCKDIV			0x0010
  #define SPI_MODESELECT			0x0018
  #define SPI_CONFIGDATA			0x0020
  #define SPI_STA_MODE_CHANGE		0x0028
  #define SPI_FAST_SEQ_TRANSFER_SIZE	0x0100
  #define SPI_FAST_SEQ_ADD1		0x0104
  #define SPI_FAST_SEQ_ADD2		0x0108
  #define SPI_FAST_SEQ_ADD_CFG		0x010c
  #define SPI_FAST_SEQ_OPC1		0x0110
  #define SPI_FAST_SEQ_OPC2		0x0114
  #define SPI_FAST_SEQ_OPC3		0x0118
  #define SPI_FAST_SEQ_OPC4		0x011c
  #define SPI_FAST_SEQ_OPC5		0x0120
  #define SPI_MODE_BITS			0x0124
  #define SPI_DUMMY_BITS			0x0128
  #define SPI_FAST_SEQ_FLASH_STA_DATA	0x012c
  #define SPI_FAST_SEQ_1			0x0130
  #define SPI_FAST_SEQ_2			0x0134
  #define SPI_FAST_SEQ_3			0x0138
  #define SPI_FAST_SEQ_4			0x013c
  #define SPI_FAST_SEQ_CFG		0x0140
  #define SPI_FAST_SEQ_STA		0x0144
  #define SPI_QUAD_BOOT_SEQ_INIT_1	0x0148
  #define SPI_QUAD_BOOT_SEQ_INIT_2	0x014c
  #define SPI_QUAD_BOOT_READ_SEQ_1	0x0150
  #define SPI_QUAD_BOOT_READ_SEQ_2	0x0154
  #define SPI_PROGRAM_ERASE_TIME		0x0158
  #define SPI_MULT_PAGE_REPEAT_SEQ_1	0x015c
  #define SPI_MULT_PAGE_REPEAT_SEQ_2	0x0160
  #define SPI_STATUS_WR_TIME_REG		0x0164
  #define SPI_FAST_SEQ_DATA_REG		0x0300
  
  /*
   * Register: SPI_MODESELECT
   */
  #define SPI_MODESELECT_CONTIG		0x01
  #define SPI_MODESELECT_FASTREAD		0x02
  #define SPI_MODESELECT_DUALIO		0x04
  #define SPI_MODESELECT_FSM		0x08
  #define SPI_MODESELECT_QUADBOOT		0x10
  
  /*
   * Register: SPI_CONFIGDATA
   */
  #define SPI_CFG_DEVICE_ST		0x1
  #define SPI_CFG_DEVICE_ATMEL		0x4
  #define SPI_CFG_MIN_CS_HIGH(x)		(((x) & 0xfff) << 4)
  #define SPI_CFG_CS_SETUPHOLD(x)		(((x) & 0xff) << 16)
  #define SPI_CFG_DATA_HOLD(x)		(((x) & 0xff) << 24)
  
  #define SPI_CFG_DEFAULT_MIN_CS_HIGH    SPI_CFG_MIN_CS_HIGH(0x0AA)
  #define SPI_CFG_DEFAULT_CS_SETUPHOLD   SPI_CFG_CS_SETUPHOLD(0xA0)
  #define SPI_CFG_DEFAULT_DATA_HOLD      SPI_CFG_DATA_HOLD(0x00)
  
  /*
   * Register: SPI_FAST_SEQ_TRANSFER_SIZE
   */
  #define TRANSFER_SIZE(x)		((x) * 8)
  
  /*
   * Register: SPI_FAST_SEQ_ADD_CFG
   */
  #define ADR_CFG_CYCLES_ADD1(x)		((x) << 0)
  #define ADR_CFG_PADS_1_ADD1		(0x0 << 6)
  #define ADR_CFG_PADS_2_ADD1		(0x1 << 6)
  #define ADR_CFG_PADS_4_ADD1		(0x3 << 6)
  #define ADR_CFG_CSDEASSERT_ADD1		(1   << 8)
  #define ADR_CFG_CYCLES_ADD2(x)		((x) << (0+16))
  #define ADR_CFG_PADS_1_ADD2		(0x0 << (6+16))
  #define ADR_CFG_PADS_2_ADD2		(0x1 << (6+16))
  #define ADR_CFG_PADS_4_ADD2		(0x3 << (6+16))
  #define ADR_CFG_CSDEASSERT_ADD2		(1   << (8+16))
  
  /*
   * Register: SPI_FAST_SEQ_n
   */
  #define SEQ_OPC_OPCODE(x)		((x) << 0)
  #define SEQ_OPC_CYCLES(x)		((x) << 8)
  #define SEQ_OPC_PADS_1			(0x0 << 14)
  #define SEQ_OPC_PADS_2			(0x1 << 14)
  #define SEQ_OPC_PADS_4			(0x3 << 14)
  #define SEQ_OPC_CSDEASSERT		(1   << 16)
  
  /*
   * Register: SPI_FAST_SEQ_CFG
   */
  #define SEQ_CFG_STARTSEQ		(1 << 0)
  #define SEQ_CFG_SWRESET			(1 << 5)
  #define SEQ_CFG_CSDEASSERT		(1 << 6)
  #define SEQ_CFG_READNOTWRITE		(1 << 7)
  #define SEQ_CFG_ERASE			(1 << 8)
  #define SEQ_CFG_PADS_1			(0x0 << 16)
  #define SEQ_CFG_PADS_2			(0x1 << 16)
  #define SEQ_CFG_PADS_4			(0x3 << 16)
  
  /*
   * Register: SPI_MODE_BITS
   */
  #define MODE_DATA(x)			(x & 0xff)
  #define MODE_CYCLES(x)			((x & 0x3f) << 16)
  #define MODE_PADS_1			(0x0 << 22)
  #define MODE_PADS_2			(0x1 << 22)
  #define MODE_PADS_4			(0x3 << 22)
  #define DUMMY_CSDEASSERT		(1   << 24)
  
  /*
   * Register: SPI_DUMMY_BITS
   */
  #define DUMMY_CYCLES(x)			((x & 0x3f) << 16)
  #define DUMMY_PADS_1			(0x0 << 22)
  #define DUMMY_PADS_2			(0x1 << 22)
  #define DUMMY_PADS_4			(0x3 << 22)
  #define DUMMY_CSDEASSERT		(1   << 24)
  
  /*
   * Register: SPI_FAST_SEQ_FLASH_STA_DATA
   */
  #define STA_DATA_BYTE1(x)		((x & 0xff) << 0)
  #define STA_DATA_BYTE2(x)		((x & 0xff) << 8)
  #define STA_PADS_1			(0x0 << 16)
  #define STA_PADS_2			(0x1 << 16)
  #define STA_PADS_4			(0x3 << 16)
  #define STA_CSDEASSERT			(0x1 << 20)
  #define STA_RDNOTWR			(0x1 << 21)
  
  /*
   * FSM SPI Instruction Opcodes
   */
  #define STFSM_OPC_CMD			0x1
  #define STFSM_OPC_ADD			0x2
  #define STFSM_OPC_STA			0x3
  #define STFSM_OPC_MODE			0x4
  #define STFSM_OPC_DUMMY		0x5
  #define STFSM_OPC_DATA			0x6
  #define STFSM_OPC_WAIT			0x7
  #define STFSM_OPC_JUMP			0x8
  #define STFSM_OPC_GOTO			0x9
  #define STFSM_OPC_STOP			0xF
  
  /*
   * FSM SPI Instructions (== opcode + operand).
   */
  #define STFSM_INSTR(cmd, op)		((cmd) | ((op) << 4))
  
  #define STFSM_INST_CMD1			STFSM_INSTR(STFSM_OPC_CMD,	1)
  #define STFSM_INST_CMD2			STFSM_INSTR(STFSM_OPC_CMD,	2)
  #define STFSM_INST_CMD3			STFSM_INSTR(STFSM_OPC_CMD,	3)
  #define STFSM_INST_CMD4			STFSM_INSTR(STFSM_OPC_CMD,	4)
  #define STFSM_INST_CMD5			STFSM_INSTR(STFSM_OPC_CMD,	5)
  #define STFSM_INST_ADD1			STFSM_INSTR(STFSM_OPC_ADD,	1)
  #define STFSM_INST_ADD2			STFSM_INSTR(STFSM_OPC_ADD,	2)
  
  #define STFSM_INST_DATA_WRITE		STFSM_INSTR(STFSM_OPC_DATA,	1)
  #define STFSM_INST_DATA_READ		STFSM_INSTR(STFSM_OPC_DATA,	2)
  
  #define STFSM_INST_STA_RD1		STFSM_INSTR(STFSM_OPC_STA,	0x1)
  #define STFSM_INST_STA_WR1		STFSM_INSTR(STFSM_OPC_STA,	0x1)
  #define STFSM_INST_STA_RD2		STFSM_INSTR(STFSM_OPC_STA,	0x2)
  #define STFSM_INST_STA_WR1_2		STFSM_INSTR(STFSM_OPC_STA,	0x3)
  
  #define STFSM_INST_MODE			STFSM_INSTR(STFSM_OPC_MODE,	0)
  #define STFSM_INST_DUMMY		STFSM_INSTR(STFSM_OPC_DUMMY,	0)
  #define STFSM_INST_WAIT			STFSM_INSTR(STFSM_OPC_WAIT,	0)
  #define STFSM_INST_STOP			STFSM_INSTR(STFSM_OPC_STOP,	0)
  
  #define STFSM_DEFAULT_EMI_FREQ 100000000UL                        /* 100 MHz */
  #define STFSM_DEFAULT_WR_TIME  (STFSM_DEFAULT_EMI_FREQ * (15/1000)) /* 15ms */
  
  #define STFSM_FLASH_SAFE_FREQ  10000000UL                         /* 10 MHz */
  
  #define STFSM_MAX_WAIT_SEQ_MS  1000     /* FSM execution time */
  
  /* S25FLxxxS commands */
  #define S25FL_CMD_WRITE4_1_1_4 0x34
  #define S25FL_CMD_SE4          0xdc
  #define S25FL_CMD_CLSR         0x30
  #define S25FL_CMD_DYBWR                0xe1
  #define S25FL_CMD_DYBRD                0xe0
  #define S25FL_CMD_WRITE4       0x12    /* Note, opcode clashes with
  					* 'SPINOR_OP_WRITE_1_4_4'
  					* as found on N25Qxxx devices! */
  
  /* Status register */
  #define FLASH_STATUS_BUSY      0x01
  #define FLASH_STATUS_WEL       0x02
  #define FLASH_STATUS_BP0       0x04
  #define FLASH_STATUS_BP1       0x08
  #define FLASH_STATUS_BP2       0x10
  #define FLASH_STATUS_SRWP0     0x80
  #define FLASH_STATUS_TIMEOUT   0xff
  /* S25FL Error Flags */
  #define S25FL_STATUS_E_ERR     0x20
  #define S25FL_STATUS_P_ERR     0x40
  
  #define N25Q_CMD_WRVCR         0x81
  #define N25Q_CMD_RDVCR         0x85
  #define N25Q_CMD_RDVECR        0x65
  #define N25Q_CMD_RDNVCR        0xb5
  #define N25Q_CMD_WRNVCR        0xb1
  
  #define FLASH_PAGESIZE         256			/* In Bytes    */
  #define FLASH_PAGESIZE_32      (FLASH_PAGESIZE / 4)	/* In uint32_t */
  #define FLASH_MAX_BUSY_WAIT    (300 * HZ)	/* Maximum 'CHIPERASE' time */
  
  /*
   * Flags to tweak operation of default read/write/erase routines
   */
  #define CFG_READ_TOGGLE_32BIT_ADDR     0x00000001
  #define CFG_WRITE_TOGGLE_32BIT_ADDR    0x00000002
  #define CFG_ERASESEC_TOGGLE_32BIT_ADDR 0x00000008
  #define CFG_S25FL_CHECK_ERROR_FLAGS    0x00000010
  
  struct stfsm_seq {
  	uint32_t data_size;
  	uint32_t addr1;
  	uint32_t addr2;
  	uint32_t addr_cfg;
  	uint32_t seq_opc[5];
  	uint32_t mode;
  	uint32_t dummy;
  	uint32_t status;
  	uint8_t  seq[16];
  	uint32_t seq_cfg;
  } __packed __aligned(4);
  
  struct stfsm {
  	struct device		*dev;
  	void __iomem		*base;
  	struct resource		*region;
  	struct mtd_info		mtd;
  	struct mutex		lock;
  	struct flash_info       *info;
  	struct clk              *clk;
  
  	uint32_t                configuration;
  	uint32_t                fifo_dir_delay;
  	bool                    booted_from_spi;
  	bool                    reset_signal;
  	bool                    reset_por;
  
  	struct stfsm_seq stfsm_seq_read;
  	struct stfsm_seq stfsm_seq_write;
  	struct stfsm_seq stfsm_seq_en_32bit_addr;
  };
  
  /* Parameters to configure a READ or WRITE FSM sequence */
  struct seq_rw_config {
  	uint32_t        flags;          /* flags to support config */
  	uint8_t         cmd;            /* FLASH command */
  	int             write;          /* Write Sequence */
  	uint8_t         addr_pads;      /* No. of addr pads (MODE & DUMMY) */
  	uint8_t         data_pads;      /* No. of data pads */
  	uint8_t         mode_data;      /* MODE data */
  	uint8_t         mode_cycles;    /* No. of MODE cycles */
  	uint8_t         dummy_cycles;   /* No. of DUMMY cycles */
  };
  
  /* SPI Flash Device Table */
  struct flash_info {
  	char            *name;
  	/*
  	 * JEDEC id zero means "no ID" (most older chips); otherwise it has
  	 * a high byte of zero plus three data bytes: the manufacturer id,
  	 * then a two byte device id.
  	 */
  	u32             jedec_id;
  	u16             ext_id;
  	/*
  	 * The size listed here is what works with SPINOR_OP_SE, which isn't
  	 * necessarily called a "sector" by the vendor.
  	 */
  	unsigned        sector_size;
  	u16             n_sectors;
  	u32             flags;
  	/*
  	 * Note, where FAST_READ is supported, freq_max specifies the
  	 * FAST_READ frequency, not the READ frequency.
  	 */
  	u32             max_freq;
  	int             (*config)(struct stfsm *);
  };
  
  static int stfsm_n25q_config(struct stfsm *fsm);
  static int stfsm_mx25_config(struct stfsm *fsm);
  static int stfsm_s25fl_config(struct stfsm *fsm);
  static int stfsm_w25q_config(struct stfsm *fsm);
  
  static struct flash_info flash_types[] = {
  	/*
  	 * ST Microelectronics/Numonyx --
  	 * (newer production versions may have feature updates
  	 * (eg faster operating frequency)
  	 */
  #define M25P_FLAG (FLASH_FLAG_READ_WRITE | FLASH_FLAG_READ_FAST)
  	{ "m25p40",  0x202013, 0,  64 * 1024,   8, M25P_FLAG, 25, NULL },
  	{ "m25p80",  0x202014, 0,  64 * 1024,  16, M25P_FLAG, 25, NULL },
  	{ "m25p16",  0x202015, 0,  64 * 1024,  32, M25P_FLAG, 25, NULL },
  	{ "m25p32",  0x202016, 0,  64 * 1024,  64, M25P_FLAG, 50, NULL },
  	{ "m25p64",  0x202017, 0,  64 * 1024, 128, M25P_FLAG, 50, NULL },
  	{ "m25p128", 0x202018, 0, 256 * 1024,  64, M25P_FLAG, 50, NULL },
  
  #define M25PX_FLAG (FLASH_FLAG_READ_WRITE      |	\
  		    FLASH_FLAG_READ_FAST        |	\
  		    FLASH_FLAG_READ_1_1_2       |	\
  		    FLASH_FLAG_WRITE_1_1_2)
  	{ "m25px32", 0x207116, 0,  64 * 1024,  64, M25PX_FLAG, 75, NULL },
  	{ "m25px64", 0x207117, 0,  64 * 1024, 128, M25PX_FLAG, 75, NULL },
  
  	/* Macronix MX25xxx
  	 *     - Support for 'FLASH_FLAG_WRITE_1_4_4' is omitted for devices
  	 *       where operating frequency must be reduced.
  	 */
  #define MX25_FLAG (FLASH_FLAG_READ_WRITE       |	\
  		   FLASH_FLAG_READ_FAST         |	\
  		   FLASH_FLAG_READ_1_1_2        |	\
  		   FLASH_FLAG_READ_1_2_2        |	\
  		   FLASH_FLAG_READ_1_1_4        |	\
  		   FLASH_FLAG_SE_4K             |	\
  		   FLASH_FLAG_SE_32K)
  	{ "mx25l3255e",  0xc29e16, 0, 64 * 1024, 64,
  	  (MX25_FLAG | FLASH_FLAG_WRITE_1_4_4), 86,
  	  stfsm_mx25_config},
  	{ "mx25l25635e", 0xc22019, 0, 64*1024, 512,
  	  (MX25_FLAG | FLASH_FLAG_32BIT_ADDR | FLASH_FLAG_RESET), 70,
  	  stfsm_mx25_config },
  	{ "mx25l25655e", 0xc22619, 0, 64*1024, 512,
  	  (MX25_FLAG | FLASH_FLAG_32BIT_ADDR | FLASH_FLAG_RESET), 70,
  	  stfsm_mx25_config},
  
  #define N25Q_FLAG (FLASH_FLAG_READ_WRITE       |	\
  		   FLASH_FLAG_READ_FAST         |	\
  		   FLASH_FLAG_READ_1_1_2        |	\
  		   FLASH_FLAG_READ_1_2_2        |	\
  		   FLASH_FLAG_READ_1_1_4        |	\
  		   FLASH_FLAG_READ_1_4_4        |	\
  		   FLASH_FLAG_WRITE_1_1_2       |	\
  		   FLASH_FLAG_WRITE_1_2_2       |	\
  		   FLASH_FLAG_WRITE_1_1_4       |	\
  		   FLASH_FLAG_WRITE_1_4_4)
  	{ "n25q128", 0x20ba18, 0, 64 * 1024,  256, N25Q_FLAG, 108,
  	  stfsm_n25q_config },
  	{ "n25q256", 0x20ba19, 0, 64 * 1024,  512,
  	  N25Q_FLAG | FLASH_FLAG_32BIT_ADDR, 108, stfsm_n25q_config },
  
  	/*
  	 * Spansion S25FLxxxP
  	 *     - 256KiB and 64KiB sector variants (identified by ext. JEDEC)
  	 */
  #define S25FLXXXP_FLAG (FLASH_FLAG_READ_WRITE  |	\
  			FLASH_FLAG_READ_1_1_2   |	\
  			FLASH_FLAG_READ_1_2_2   |	\
  			FLASH_FLAG_READ_1_1_4   |	\
  			FLASH_FLAG_READ_1_4_4   |	\
  			FLASH_FLAG_WRITE_1_1_4  |	\
  			FLASH_FLAG_READ_FAST)
  	{ "s25fl032p",  0x010215, 0x4d00,  64 * 1024,  64, S25FLXXXP_FLAG, 80,
  	  stfsm_s25fl_config},
  	{ "s25fl129p0", 0x012018, 0x4d00, 256 * 1024,  64, S25FLXXXP_FLAG, 80,
  	  stfsm_s25fl_config },
  	{ "s25fl129p1", 0x012018, 0x4d01,  64 * 1024, 256, S25FLXXXP_FLAG, 80,
  	  stfsm_s25fl_config },
  
  	/*
  	 * Spansion S25FLxxxS
  	 *     - 256KiB and 64KiB sector variants (identified by ext. JEDEC)
  	 *     - RESET# signal supported by die but not bristled out on all
  	 *       package types.  The package type is a function of board design,
  	 *       so this information is captured in the board's flags.
  	 *     - Supports 'DYB' sector protection. Depending on variant, sectors
  	 *       may default to locked state on power-on.
  	 */
  #define S25FLXXXS_FLAG (S25FLXXXP_FLAG         |	\
  			FLASH_FLAG_RESET        |	\
  			FLASH_FLAG_DYB_LOCKING)
  	{ "s25fl128s0", 0x012018, 0x0300,  256 * 1024, 64, S25FLXXXS_FLAG, 80,
  	  stfsm_s25fl_config },
  	{ "s25fl128s1", 0x012018, 0x0301,  64 * 1024, 256, S25FLXXXS_FLAG, 80,
  	  stfsm_s25fl_config },
  	{ "s25fl256s0", 0x010219, 0x4d00, 256 * 1024, 128,
  	  S25FLXXXS_FLAG | FLASH_FLAG_32BIT_ADDR, 80, stfsm_s25fl_config },
  	{ "s25fl256s1", 0x010219, 0x4d01,  64 * 1024, 512,
  	  S25FLXXXS_FLAG | FLASH_FLAG_32BIT_ADDR, 80, stfsm_s25fl_config },
  
  	/* Winbond -- w25x "blocks" are 64K, "sectors" are 4KiB */
  #define W25X_FLAG (FLASH_FLAG_READ_WRITE       |	\
  		   FLASH_FLAG_READ_FAST         |	\
  		   FLASH_FLAG_READ_1_1_2        |	\
  		   FLASH_FLAG_WRITE_1_1_2)
  	{ "w25x40",  0xef3013, 0,  64 * 1024,   8, W25X_FLAG, 75, NULL },
  	{ "w25x80",  0xef3014, 0,  64 * 1024,  16, W25X_FLAG, 75, NULL },
  	{ "w25x16",  0xef3015, 0,  64 * 1024,  32, W25X_FLAG, 75, NULL },
  	{ "w25x32",  0xef3016, 0,  64 * 1024,  64, W25X_FLAG, 75, NULL },
  	{ "w25x64",  0xef3017, 0,  64 * 1024, 128, W25X_FLAG, 75, NULL },
  
  	/* Winbond -- w25q "blocks" are 64K, "sectors" are 4KiB */
  #define W25Q_FLAG (FLASH_FLAG_READ_WRITE       |	\
  		   FLASH_FLAG_READ_FAST         |	\
  		   FLASH_FLAG_READ_1_1_2        |	\
  		   FLASH_FLAG_READ_1_2_2        |	\
  		   FLASH_FLAG_READ_1_1_4        |	\
  		   FLASH_FLAG_READ_1_4_4        |	\
  		   FLASH_FLAG_WRITE_1_1_4)
  	{ "w25q80",  0xef4014, 0,  64 * 1024,  16, W25Q_FLAG, 80,
  	  stfsm_w25q_config },
  	{ "w25q16",  0xef4015, 0,  64 * 1024,  32, W25Q_FLAG, 80,
  	  stfsm_w25q_config },
  	{ "w25q32",  0xef4016, 0,  64 * 1024,  64, W25Q_FLAG, 80,
  	  stfsm_w25q_config },
  	{ "w25q64",  0xef4017, 0,  64 * 1024, 128, W25Q_FLAG, 80,
  	  stfsm_w25q_config },
  
  	/* Sentinel */
  	{ NULL, 0x000000, 0, 0, 0, 0, 0, NULL },
  };
  
  /*
   * FSM message sequence configurations:
   *
   * All configs are presented in order of preference
   */
  
  /* Default READ configurations, in order of preference */
  static struct seq_rw_config default_read_configs[] = {
  	{FLASH_FLAG_READ_1_4_4, SPINOR_OP_READ_1_4_4,	0, 4, 4, 0x00, 2, 4},
  	{FLASH_FLAG_READ_1_1_4, SPINOR_OP_READ_1_1_4,	0, 1, 4, 0x00, 4, 0},
  	{FLASH_FLAG_READ_1_2_2, SPINOR_OP_READ_1_2_2,	0, 2, 2, 0x00, 4, 0},
  	{FLASH_FLAG_READ_1_1_2, SPINOR_OP_READ_1_1_2,	0, 1, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_FAST,	SPINOR_OP_READ_FAST,	0, 1, 1, 0x00, 0, 8},
  	{FLASH_FLAG_READ_WRITE, SPINOR_OP_READ,		0, 1, 1, 0x00, 0, 0},
  	{0x00,			0,			0, 0, 0, 0x00, 0, 0},
  };
  
  /* Default WRITE configurations */
  static struct seq_rw_config default_write_configs[] = {
  	{FLASH_FLAG_WRITE_1_4_4, SPINOR_OP_WRITE_1_4_4, 1, 4, 4, 0x00, 0, 0},
  	{FLASH_FLAG_WRITE_1_1_4, SPINOR_OP_WRITE_1_1_4, 1, 1, 4, 0x00, 0, 0},
  	{FLASH_FLAG_WRITE_1_2_2, SPINOR_OP_WRITE_1_2_2, 1, 2, 2, 0x00, 0, 0},
  	{FLASH_FLAG_WRITE_1_1_2, SPINOR_OP_WRITE_1_1_2, 1, 1, 2, 0x00, 0, 0},
  	{FLASH_FLAG_READ_WRITE,  SPINOR_OP_WRITE,       1, 1, 1, 0x00, 0, 0},
  	{0x00,			 0,			0, 0, 0, 0x00, 0, 0},
  };
  
  /*
   * [N25Qxxx] Configuration
   */
  #define N25Q_VCR_DUMMY_CYCLES(x)	(((x) & 0xf) << 4)
  #define N25Q_VCR_XIP_DISABLED		((uint8_t)0x1 << 3)
  #define N25Q_VCR_WRAP_CONT		0x3
  
  /* N25Q 3-byte Address READ configurations
   *	- 'FAST' variants configured for 8 dummy cycles.
   *
   * Note, the number of dummy cycles used for 'FAST' READ operations is
   * configurable and would normally be tuned according to the READ command and
   * operating frequency.  However, this applies universally to all 'FAST' READ
   * commands, including those used by the SPIBoot controller, and remains in
   * force until the device is power-cycled.  Since the SPIBoot controller is
   * hard-wired to use 8 dummy cycles, we must configure the device to also use 8
   * cycles.
   */
  static struct seq_rw_config n25q_read3_configs[] = {
  	{FLASH_FLAG_READ_1_4_4, SPINOR_OP_READ_1_4_4,	0, 4, 4, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_1_4, SPINOR_OP_READ_1_1_4,	0, 1, 4, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_2_2, SPINOR_OP_READ_1_2_2,	0, 2, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_1_2, SPINOR_OP_READ_1_1_2,	0, 1, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_FAST,	SPINOR_OP_READ_FAST,	0, 1, 1, 0x00, 0, 8},
  	{FLASH_FLAG_READ_WRITE, SPINOR_OP_READ,	        0, 1, 1, 0x00, 0, 0},
  	{0x00,			0,			0, 0, 0, 0x00, 0, 0},
  };
  
  /* N25Q 4-byte Address READ configurations
   *	- use special 4-byte address READ commands (reduces overheads, and
   *        reduces risk of hitting watchdog reset issues).
   *	- 'FAST' variants configured for 8 dummy cycles (see note above.)
   */
  static struct seq_rw_config n25q_read4_configs[] = {
  	{FLASH_FLAG_READ_1_4_4, SPINOR_OP_READ4_1_4_4,	0, 4, 4, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_1_4, SPINOR_OP_READ4_1_1_4,	0, 1, 4, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_2_2, SPINOR_OP_READ4_1_2_2,	0, 2, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_1_2, SPINOR_OP_READ4_1_1_2,	0, 1, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_FAST,	SPINOR_OP_READ4_FAST,	0, 1, 1, 0x00, 0, 8},
  	{FLASH_FLAG_READ_WRITE, SPINOR_OP_READ4,	0, 1, 1, 0x00, 0, 0},
  	{0x00,			0,			0, 0, 0, 0x00, 0, 0},
  };
  
  /*
   * [MX25xxx] Configuration
   */
  #define MX25_STATUS_QE			(0x1 << 6)
  
  static int stfsm_mx25_en_32bit_addr_seq(struct stfsm_seq *seq)
  {
  	seq->seq_opc[0] = (SEQ_OPC_PADS_1 |
  			   SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(SPINOR_OP_EN4B) |
  			   SEQ_OPC_CSDEASSERT);
  
  	seq->seq[0] = STFSM_INST_CMD1;
  	seq->seq[1] = STFSM_INST_WAIT;
  	seq->seq[2] = STFSM_INST_STOP;
  
  	seq->seq_cfg = (SEQ_CFG_PADS_1 |
  			SEQ_CFG_ERASE |
  			SEQ_CFG_READNOTWRITE |
  			SEQ_CFG_CSDEASSERT |
  			SEQ_CFG_STARTSEQ);
  
  	return 0;
  }
  
  /*
   * [S25FLxxx] Configuration
   */
  #define STFSM_S25FL_CONFIG_QE		(0x1 << 1)
  
  /*
   * S25FLxxxS devices provide three ways of supporting 32-bit addressing: Bank
   * Register, Extended Address Modes, and a 32-bit address command set.  The
   * 32-bit address command set is used here, since it avoids any problems with
   * entering a state that is incompatible with the SPIBoot Controller.
   */
  static struct seq_rw_config stfsm_s25fl_read4_configs[] = {
  	{FLASH_FLAG_READ_1_4_4,  SPINOR_OP_READ4_1_4_4,  0, 4, 4, 0x00, 2, 4},
  	{FLASH_FLAG_READ_1_1_4,  SPINOR_OP_READ4_1_1_4,  0, 1, 4, 0x00, 0, 8},
  	{FLASH_FLAG_READ_1_2_2,  SPINOR_OP_READ4_1_2_2,  0, 2, 2, 0x00, 4, 0},
  	{FLASH_FLAG_READ_1_1_2,  SPINOR_OP_READ4_1_1_2,  0, 1, 2, 0x00, 0, 8},
  	{FLASH_FLAG_READ_FAST,   SPINOR_OP_READ4_FAST,   0, 1, 1, 0x00, 0, 8},
  	{FLASH_FLAG_READ_WRITE,  SPINOR_OP_READ4,        0, 1, 1, 0x00, 0, 0},
  	{0x00,                   0,                      0, 0, 0, 0x00, 0, 0},
  };
  
  static struct seq_rw_config stfsm_s25fl_write4_configs[] = {
  	{FLASH_FLAG_WRITE_1_1_4, S25FL_CMD_WRITE4_1_1_4, 1, 1, 4, 0x00, 0, 0},
  	{FLASH_FLAG_READ_WRITE,  S25FL_CMD_WRITE4,       1, 1, 1, 0x00, 0, 0},
  	{0x00,                   0,                      0, 0, 0, 0x00, 0, 0},
  };
  
  /*
   * [W25Qxxx] Configuration
   */
  #define W25Q_STATUS_QE			(0x1 << 1)
  
  static struct stfsm_seq stfsm_seq_read_jedec = {
  	.data_size = TRANSFER_SIZE(8),
  	.seq_opc[0] = (SEQ_OPC_PADS_1 |
  		       SEQ_OPC_CYCLES(8) |
  		       SEQ_OPC_OPCODE(SPINOR_OP_RDID)),
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_DATA_READ,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  static struct stfsm_seq stfsm_seq_read_status_fifo = {
  	.data_size = TRANSFER_SIZE(4),
  	.seq_opc[0] = (SEQ_OPC_PADS_1 |
  		       SEQ_OPC_CYCLES(8) |
  		       SEQ_OPC_OPCODE(SPINOR_OP_RDSR)),
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_DATA_READ,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  static struct stfsm_seq stfsm_seq_erase_sector = {
  	/* 'addr_cfg' configured during initialisation */
  	.seq_opc = {
  		(SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		 SEQ_OPC_OPCODE(SPINOR_OP_WREN) | SEQ_OPC_CSDEASSERT),
  
  		(SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		 SEQ_OPC_OPCODE(SPINOR_OP_SE)),
  	},
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_CMD2,
  		STFSM_INST_ADD1,
  		STFSM_INST_ADD2,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  static struct stfsm_seq stfsm_seq_erase_chip = {
  	.seq_opc = {
  		(SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		 SEQ_OPC_OPCODE(SPINOR_OP_WREN) | SEQ_OPC_CSDEASSERT),
  
  		(SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		 SEQ_OPC_OPCODE(SPINOR_OP_CHIP_ERASE) | SEQ_OPC_CSDEASSERT),
  	},
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_CMD2,
  		STFSM_INST_WAIT,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_ERASE |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  static struct stfsm_seq stfsm_seq_write_status = {
  	.seq_opc[0] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		       SEQ_OPC_OPCODE(SPINOR_OP_WREN) | SEQ_OPC_CSDEASSERT),
  	.seq_opc[1] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  		       SEQ_OPC_OPCODE(SPINOR_OP_WRSR)),
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_CMD2,
  		STFSM_INST_STA_WR1,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  /* Dummy sequence to read one byte of data from flash into the FIFO */
  static const struct stfsm_seq stfsm_seq_load_fifo_byte = {
  	.data_size = TRANSFER_SIZE(1),
  	.seq_opc[0] = (SEQ_OPC_PADS_1 |
  		       SEQ_OPC_CYCLES(8) |
  		       SEQ_OPC_OPCODE(SPINOR_OP_RDID)),
  	.seq = {
  		STFSM_INST_CMD1,
  		STFSM_INST_DATA_READ,
  		STFSM_INST_STOP,
  	},
  	.seq_cfg = (SEQ_CFG_PADS_1 |
  		    SEQ_CFG_READNOTWRITE |
  		    SEQ_CFG_CSDEASSERT |
  		    SEQ_CFG_STARTSEQ),
  };
  
  static int stfsm_n25q_en_32bit_addr_seq(struct stfsm_seq *seq)
  {
  	seq->seq_opc[0] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(SPINOR_OP_EN4B));
  	seq->seq_opc[1] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(SPINOR_OP_WREN) |
  			   SEQ_OPC_CSDEASSERT);
  
  	seq->seq[0] = STFSM_INST_CMD2;
  	seq->seq[1] = STFSM_INST_CMD1;
  	seq->seq[2] = STFSM_INST_WAIT;
  	seq->seq[3] = STFSM_INST_STOP;
  
  	seq->seq_cfg = (SEQ_CFG_PADS_1 |
  			SEQ_CFG_ERASE |
  			SEQ_CFG_READNOTWRITE |
  			SEQ_CFG_CSDEASSERT |
  			SEQ_CFG_STARTSEQ);
  
  	return 0;
  }
  
  static inline int stfsm_is_idle(struct stfsm *fsm)
  {
  	return readl(fsm->base + SPI_FAST_SEQ_STA) & 0x10;
  }
  
  static inline uint32_t stfsm_fifo_available(struct stfsm *fsm)
  {
  	return (readl(fsm->base + SPI_FAST_SEQ_STA) >> 5) & 0x7f;
  }
  
  static inline void stfsm_load_seq(struct stfsm *fsm,
  				  const struct stfsm_seq *seq)
  {
  	void __iomem *dst = fsm->base + SPI_FAST_SEQ_TRANSFER_SIZE;
  	const uint32_t *src = (const uint32_t *)seq;
  	int words = sizeof(*seq) / sizeof(*src);
  
  	BUG_ON(!stfsm_is_idle(fsm));
  
  	while (words--) {
  		writel(*src, dst);
  		src++;
  		dst += 4;
  	}
  }
  
  static void stfsm_wait_seq(struct stfsm *fsm)
  {
  	unsigned long deadline;
  	int timeout = 0;
  
  	deadline = jiffies + msecs_to_jiffies(STFSM_MAX_WAIT_SEQ_MS);
  
  	while (!timeout) {
  		if (time_after_eq(jiffies, deadline))
  			timeout = 1;
  
  		if (stfsm_is_idle(fsm))
  			return;
  
  		cond_resched();
  	}
  
  	dev_err(fsm->dev, "timeout on sequence completion\n");
  }
  
  static void stfsm_read_fifo(struct stfsm *fsm, uint32_t *buf, uint32_t size)
  {
  	uint32_t remaining = size >> 2;
  	uint32_t avail;
  	uint32_t words;
  
  	dev_dbg(fsm->dev, "Reading %d bytes from FIFO\n", size);
  
  	BUG_ON((((uintptr_t)buf) & 0x3) || (size & 0x3));
  
  	while (remaining) {
  		for (;;) {
  			avail = stfsm_fifo_available(fsm);
  			if (avail)
  				break;
  			udelay(1);
  		}
  		words = min(avail, remaining);
  		remaining -= words;
  
  		readsl(fsm->base + SPI_FAST_SEQ_DATA_REG, buf, words);
  		buf += words;
  	}
  }
  
  /*
   * Clear the data FIFO
   *
   * Typically, this is only required during driver initialisation, where no
   * assumptions can be made regarding the state of the FIFO.
   *
   * The process of clearing the FIFO is complicated by fact that while it is
   * possible for the FIFO to contain an arbitrary number of bytes [1], the
   * SPI_FAST_SEQ_STA register only reports the number of complete 32-bit words
   * present.  Furthermore, data can only be drained from the FIFO by reading
   * complete 32-bit words.
   *
   * With this in mind, a two stage process is used to the clear the FIFO:
   *
   *     1. Read any complete 32-bit words from the FIFO, as reported by the
   *        SPI_FAST_SEQ_STA register.
   *
   *     2. Mop up any remaining bytes.  At this point, it is not known if there
   *        are 0, 1, 2, or 3 bytes in the FIFO.  To handle all cases, a dummy FSM
   *        sequence is used to load one byte at a time, until a complete 32-bit
   *        word is formed; at most, 4 bytes will need to be loaded.
   *
   * [1] It is theoretically possible for the FIFO to contain an arbitrary number
   *     of bits.  However, since there are no known use-cases that leave
   *     incomplete bytes in the FIFO, only words and bytes are considered here.
   */
  static void stfsm_clear_fifo(struct stfsm *fsm)
  {
  	const struct stfsm_seq *seq = &stfsm_seq_load_fifo_byte;
  	uint32_t words, i;
  
  	/* 1. Clear any 32-bit words */
  	words = stfsm_fifo_available(fsm);
  	if (words) {
  		for (i = 0; i < words; i++)
  			readl(fsm->base + SPI_FAST_SEQ_DATA_REG);
  		dev_dbg(fsm->dev, "cleared %d words from FIFO\n", words);
  	}
  
  	/*
  	 * 2. Clear any remaining bytes
  	 *    - Load the FIFO, one byte at a time, until a complete 32-bit word
  	 *      is available.
  	 */
  	for (i = 0, words = 0; i < 4 && !words; i++) {
  		stfsm_load_seq(fsm, seq);
  		stfsm_wait_seq(fsm);
  		words = stfsm_fifo_available(fsm);
  	}
  
  	/*    - A single word must be available now */
  	if (words != 1) {
  		dev_err(fsm->dev, "failed to clear bytes from the data FIFO\n");
  		return;
  	}
  
  	/*    - Read the 32-bit word */
  	readl(fsm->base + SPI_FAST_SEQ_DATA_REG);
  
  	dev_dbg(fsm->dev, "cleared %d byte(s) from the data FIFO\n", 4 - i);
  }
  
  static int stfsm_write_fifo(struct stfsm *fsm, const uint32_t *buf,
  			    uint32_t size)
  {
  	uint32_t words = size >> 2;
  
  	dev_dbg(fsm->dev, "writing %d bytes to FIFO\n", size);
  
  	BUG_ON((((uintptr_t)buf) & 0x3) || (size & 0x3));
  
  	writesl(fsm->base + SPI_FAST_SEQ_DATA_REG, buf, words);
  
  	return size;
  }
  
  static int stfsm_enter_32bit_addr(struct stfsm *fsm, int enter)
  {
  	struct stfsm_seq *seq = &fsm->stfsm_seq_en_32bit_addr;
  	uint32_t cmd = enter ? SPINOR_OP_EN4B : SPINOR_OP_EX4B;
  
  	seq->seq_opc[0] = (SEQ_OPC_PADS_1 |
  			   SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(cmd) |
  			   SEQ_OPC_CSDEASSERT);
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_wait_seq(fsm);
  
  	return 0;
  }
  
  static uint8_t stfsm_wait_busy(struct stfsm *fsm)
  {
  	struct stfsm_seq *seq = &stfsm_seq_read_status_fifo;
  	unsigned long deadline;
  	uint32_t status;
  	int timeout = 0;
  
  	/* Use RDRS1 */
  	seq->seq_opc[0] = (SEQ_OPC_PADS_1 |
  			   SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(SPINOR_OP_RDSR));
  
  	/* Load read_status sequence */
  	stfsm_load_seq(fsm, seq);
  
  	/*
  	 * Repeat until busy bit is deasserted, or timeout, or error (S25FLxxxS)
  	 */
  	deadline = jiffies + FLASH_MAX_BUSY_WAIT;
  	while (!timeout) {
  		if (time_after_eq(jiffies, deadline))
  			timeout = 1;
  
  		stfsm_wait_seq(fsm);
  
  		stfsm_read_fifo(fsm, &status, 4);
  
  		if ((status & FLASH_STATUS_BUSY) == 0)
  			return 0;
  
  		if ((fsm->configuration & CFG_S25FL_CHECK_ERROR_FLAGS) &&
  		    ((status & S25FL_STATUS_P_ERR) ||
  		     (status & S25FL_STATUS_E_ERR)))
  			return (uint8_t)(status & 0xff);
  
  		if (!timeout)
  			/* Restart */
  			writel(seq->seq_cfg, fsm->base + SPI_FAST_SEQ_CFG);
  
  		cond_resched();
  	}
  
  	dev_err(fsm->dev, "timeout on wait_busy\n");
  
  	return FLASH_STATUS_TIMEOUT;
  }
  
  static int stfsm_read_status(struct stfsm *fsm, uint8_t cmd,
  			     uint8_t *data, int bytes)
  {
  	struct stfsm_seq *seq = &stfsm_seq_read_status_fifo;
  	uint32_t tmp;
  	uint8_t *t = (uint8_t *)&tmp;
  	int i;
  
  	dev_dbg(fsm->dev, "read 'status' register [0x%02x], %d byte(s)\n",
  		cmd, bytes);
  
  	BUG_ON(bytes != 1 && bytes != 2);
  
  	seq->seq_opc[0] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(cmd)),
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_read_fifo(fsm, &tmp, 4);
  
  	for (i = 0; i < bytes; i++)
  		data[i] = t[i];
  
  	stfsm_wait_seq(fsm);
  
  	return 0;
  }
  
  static int stfsm_write_status(struct stfsm *fsm, uint8_t cmd,
  			    uint16_t data, int bytes, int wait_busy)
  {
  	struct stfsm_seq *seq = &stfsm_seq_write_status;
  
  	dev_dbg(fsm->dev,
  		"write 'status' register [0x%02x], %d byte(s), 0x%04x\n"
  		" %s wait-busy\n", cmd, bytes, data, wait_busy ? "with" : "no");
  
  	BUG_ON(bytes != 1 && bytes != 2);
  
  	seq->seq_opc[1] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(cmd));
  
  	seq->status = (uint32_t)data | STA_PADS_1 | STA_CSDEASSERT;
  	seq->seq[2] = (bytes == 1) ? STFSM_INST_STA_WR1 : STFSM_INST_STA_WR1_2;
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_wait_seq(fsm);
  
  	if (wait_busy)
  		stfsm_wait_busy(fsm);
  
  	return 0;
  }
  
  /*
   * SoC reset on 'boot-from-spi' systems
   *
   * Certain modes of operation cause the Flash device to enter a particular state
   * for a period of time (e.g. 'Erase Sector', 'Quad Enable', and 'Enter 32-bit
   * Addr' commands).  On boot-from-spi systems, it is important to consider what
   * happens if a warm reset occurs during this period.  The SPIBoot controller
   * assumes that Flash device is in its default reset state, 24-bit address mode,
   * and ready to accept commands.  This can be achieved using some form of
   * on-board logic/controller to force a device POR in response to a SoC-level
   * reset or by making use of the device reset signal if available (limited
   * number of devices only).
   *
   * Failure to take such precautions can cause problems following a warm reset.
   * For some operations (e.g. ERASE), there is little that can be done.  For
   * other modes of operation (e.g. 32-bit addressing), options are often
   * available that can help minimise the window in which a reset could cause a
   * problem.
   *
   */
  static bool stfsm_can_handle_soc_reset(struct stfsm *fsm)
  {
  	/* Reset signal is available on the board and supported by the device */
  	if (fsm->reset_signal && fsm->info->flags & FLASH_FLAG_RESET)
  		return true;
  
  	/* Board-level logic forces a power-on-reset */
  	if (fsm->reset_por)
  		return true;
  
  	/* Reset is not properly handled and may result in failure to reboot */
  	return false;
  }
  
  /* Configure 'addr_cfg' according to addressing mode */
  static void stfsm_prepare_erasesec_seq(struct stfsm *fsm,
  				       struct stfsm_seq *seq)
  {
  	int addr1_cycles = fsm->info->flags & FLASH_FLAG_32BIT_ADDR ? 16 : 8;
  
  	seq->addr_cfg = (ADR_CFG_CYCLES_ADD1(addr1_cycles) |
  			 ADR_CFG_PADS_1_ADD1 |
  			 ADR_CFG_CYCLES_ADD2(16) |
  			 ADR_CFG_PADS_1_ADD2 |
  			 ADR_CFG_CSDEASSERT_ADD2);
  }
  
  /* Search for preferred configuration based on available flags */
  static struct seq_rw_config *
  stfsm_search_seq_rw_configs(struct stfsm *fsm,
  			    struct seq_rw_config cfgs[])
  {
  	struct seq_rw_config *config;
  	int flags = fsm->info->flags;
  
  	for (config = cfgs; config->cmd != 0; config++)
  		if ((config->flags & flags) == config->flags)
  			return config;
  
  	return NULL;
  }
  
  /* Prepare a READ/WRITE sequence according to configuration parameters */
  static void stfsm_prepare_rw_seq(struct stfsm *fsm,
  				 struct stfsm_seq *seq,
  				 struct seq_rw_config *cfg)
  {
  	int addr1_cycles, addr2_cycles;
  	int i = 0;
  
  	memset(seq, 0, sizeof(*seq));
  
  	/* Add READ/WRITE OPC  */
  	seq->seq_opc[i++] = (SEQ_OPC_PADS_1 |
  			     SEQ_OPC_CYCLES(8) |
  			     SEQ_OPC_OPCODE(cfg->cmd));
  
  	/* Add WREN OPC for a WRITE sequence */
  	if (cfg->write)
  		seq->seq_opc[i++] = (SEQ_OPC_PADS_1 |
  				     SEQ_OPC_CYCLES(8) |
  				     SEQ_OPC_OPCODE(SPINOR_OP_WREN) |
  				     SEQ_OPC_CSDEASSERT);
  
  	/* Address configuration (24 or 32-bit addresses) */
  	addr1_cycles  = (fsm->info->flags & FLASH_FLAG_32BIT_ADDR) ? 16 : 8;
  	addr1_cycles /= cfg->addr_pads;
  	addr2_cycles  = 16 / cfg->addr_pads;
  	seq->addr_cfg = ((addr1_cycles & 0x3f) << 0 |	/* ADD1 cycles */
  			 (cfg->addr_pads - 1) << 6 |	/* ADD1 pads */
  			 (addr2_cycles & 0x3f) << 16 |	/* ADD2 cycles */
  			 ((cfg->addr_pads - 1) << 22));	/* ADD2 pads */
  
  	/* Data/Sequence configuration */
  	seq->seq_cfg = ((cfg->data_pads - 1) << 16 |
  			SEQ_CFG_STARTSEQ |
  			SEQ_CFG_CSDEASSERT);
  	if (!cfg->write)
  		seq->seq_cfg |= SEQ_CFG_READNOTWRITE;
  
  	/* Mode configuration (no. of pads taken from addr cfg) */
  	seq->mode = ((cfg->mode_data & 0xff) << 0 |	/* data */
  		     (cfg->mode_cycles & 0x3f) << 16 |	/* cycles */
  		     (cfg->addr_pads - 1) << 22);	/* pads */
  
  	/* Dummy configuration (no. of pads taken from addr cfg) */
  	seq->dummy = ((cfg->dummy_cycles & 0x3f) << 16 |	/* cycles */
  		      (cfg->addr_pads - 1) << 22);		/* pads */
  
  
  	/* Instruction sequence */
  	i = 0;
  	if (cfg->write)
  		seq->seq[i++] = STFSM_INST_CMD2;
  
  	seq->seq[i++] = STFSM_INST_CMD1;
  
  	seq->seq[i++] = STFSM_INST_ADD1;
  	seq->seq[i++] = STFSM_INST_ADD2;
  
  	if (cfg->mode_cycles)
  		seq->seq[i++] = STFSM_INST_MODE;
  
  	if (cfg->dummy_cycles)
  		seq->seq[i++] = STFSM_INST_DUMMY;
  
  	seq->seq[i++] =
  		cfg->write ? STFSM_INST_DATA_WRITE : STFSM_INST_DATA_READ;
  	seq->seq[i++] = STFSM_INST_STOP;
  }
  
  static int stfsm_search_prepare_rw_seq(struct stfsm *fsm,
  				       struct stfsm_seq *seq,
  				       struct seq_rw_config *cfgs)
  {
  	struct seq_rw_config *config;
  
  	config = stfsm_search_seq_rw_configs(fsm, cfgs);
  	if (!config) {
  		dev_err(fsm->dev, "failed to find suitable config\n");
  		return -EINVAL;
  	}
  
  	stfsm_prepare_rw_seq(fsm, seq, config);
  
  	return 0;
  }
  
  /* Prepare a READ/WRITE/ERASE 'default' sequences */
  static int stfsm_prepare_rwe_seqs_default(struct stfsm *fsm)
  {
  	uint32_t flags = fsm->info->flags;
  	int ret;
  
  	/* Configure 'READ' sequence */
  	ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_read,
  					  default_read_configs);
  	if (ret) {
  		dev_err(fsm->dev,
  			"failed to prep READ sequence with flags [0x%08x]\n",
  			flags);
  		return ret;
  	}
  
  	/* Configure 'WRITE' sequence */
  	ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_write,
  					  default_write_configs);
  	if (ret) {
  		dev_err(fsm->dev,
  			"failed to prep WRITE sequence with flags [0x%08x]\n",
  			flags);
  		return ret;
  	}
  
  	/* Configure 'ERASE_SECTOR' sequence */
  	stfsm_prepare_erasesec_seq(fsm, &stfsm_seq_erase_sector);
  
  	return 0;
  }
  
  static int stfsm_mx25_config(struct stfsm *fsm)
  {
  	uint32_t flags = fsm->info->flags;
  	uint32_t data_pads;
  	uint8_t sta;
  	int ret;
  	bool soc_reset;
  
  	/*
  	 * Use default READ/WRITE sequences
  	 */
  	ret = stfsm_prepare_rwe_seqs_default(fsm);
  	if (ret)
  		return ret;
  
  	/*
  	 * Configure 32-bit Address Support
  	 */
  	if (flags & FLASH_FLAG_32BIT_ADDR) {
  		/* Configure 'enter_32bitaddr' FSM sequence */
  		stfsm_mx25_en_32bit_addr_seq(&fsm->stfsm_seq_en_32bit_addr);
  
  		soc_reset = stfsm_can_handle_soc_reset(fsm);
  		if (soc_reset || !fsm->booted_from_spi)
  			/* If we can handle SoC resets, we enable 32-bit address
  			 * mode pervasively */
  			stfsm_enter_32bit_addr(fsm, 1);
  
  		else
  			/* Else, enable/disable 32-bit addressing before/after
  			 * each operation */
  			fsm->configuration = (CFG_READ_TOGGLE_32BIT_ADDR |
  					      CFG_WRITE_TOGGLE_32BIT_ADDR |
  					      CFG_ERASESEC_TOGGLE_32BIT_ADDR);
  	}
  
  	/* Check status of 'QE' bit, update if required. */
  	stfsm_read_status(fsm, SPINOR_OP_RDSR, &sta, 1);
  	data_pads = ((fsm->stfsm_seq_read.seq_cfg >> 16) & 0x3) + 1;
  	if (data_pads == 4) {
  		if (!(sta & MX25_STATUS_QE)) {
  			/* Set 'QE' */
  			sta |= MX25_STATUS_QE;
  
  			stfsm_write_status(fsm, SPINOR_OP_WRSR, sta, 1, 1);
  		}
  	} else {
  		if (sta & MX25_STATUS_QE) {
  			/* Clear 'QE' */
  			sta &= ~MX25_STATUS_QE;
  
  			stfsm_write_status(fsm, SPINOR_OP_WRSR, sta, 1, 1);
  		}
  	}
  
  	return 0;
  }
  
  static int stfsm_n25q_config(struct stfsm *fsm)
  {
  	uint32_t flags = fsm->info->flags;
  	uint8_t vcr;
  	int ret = 0;
  	bool soc_reset;
  
  	/* Configure 'READ' sequence */
  	if (flags & FLASH_FLAG_32BIT_ADDR)
  		ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_read,
  						  n25q_read4_configs);
  	else
  		ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_read,
  						  n25q_read3_configs);
  	if (ret) {
  		dev_err(fsm->dev,
  			"failed to prepare READ sequence with flags [0x%08x]\n",
  			flags);
  		return ret;
  	}
  
  	/* Configure 'WRITE' sequence (default configs) */
  	ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_write,
  					  default_write_configs);
  	if (ret) {
  		dev_err(fsm->dev,
  			"preparing WRITE sequence using flags [0x%08x] failed\n",
  			flags);
  		return ret;
  	}
  
  	/* * Configure 'ERASE_SECTOR' sequence */
  	stfsm_prepare_erasesec_seq(fsm, &stfsm_seq_erase_sector);
  
  	/* Configure 32-bit address support */
  	if (flags & FLASH_FLAG_32BIT_ADDR) {
  		stfsm_n25q_en_32bit_addr_seq(&fsm->stfsm_seq_en_32bit_addr);
  
  		soc_reset = stfsm_can_handle_soc_reset(fsm);
  		if (soc_reset || !fsm->booted_from_spi) {
  			/*
  			 * If we can handle SoC resets, we enable 32-bit
  			 * address mode pervasively
  			 */
  			stfsm_enter_32bit_addr(fsm, 1);
  		} else {
  			/*
  			 * If not, enable/disable for WRITE and ERASE
  			 * operations (READ uses special commands)
  			 */
  			fsm->configuration = (CFG_WRITE_TOGGLE_32BIT_ADDR |
  					      CFG_ERASESEC_TOGGLE_32BIT_ADDR);
  		}
  	}
  
  	/*
  	 * Configure device to use 8 dummy cycles
  	 */
  	vcr = (N25Q_VCR_DUMMY_CYCLES(8) | N25Q_VCR_XIP_DISABLED |
  	       N25Q_VCR_WRAP_CONT);
  	stfsm_write_status(fsm, N25Q_CMD_WRVCR, vcr, 1, 0);
  
  	return 0;
  }
  
  static void stfsm_s25fl_prepare_erasesec_seq_32(struct stfsm_seq *seq)
  {
  	seq->seq_opc[1] = (SEQ_OPC_PADS_1 |
  			   SEQ_OPC_CYCLES(8) |
  			   SEQ_OPC_OPCODE(S25FL_CMD_SE4));
  
  	seq->addr_cfg = (ADR_CFG_CYCLES_ADD1(16) |
  			 ADR_CFG_PADS_1_ADD1 |
  			 ADR_CFG_CYCLES_ADD2(16) |
  			 ADR_CFG_PADS_1_ADD2 |
  			 ADR_CFG_CSDEASSERT_ADD2);
  }
  
  static void stfsm_s25fl_read_dyb(struct stfsm *fsm, uint32_t offs, uint8_t *dby)
  {
  	uint32_t tmp;
  	struct stfsm_seq seq = {
  		.data_size = TRANSFER_SIZE(4),
  		.seq_opc[0] = (SEQ_OPC_PADS_1 |
  			       SEQ_OPC_CYCLES(8) |
  			       SEQ_OPC_OPCODE(S25FL_CMD_DYBRD)),
  		.addr_cfg = (ADR_CFG_CYCLES_ADD1(16) |
  			     ADR_CFG_PADS_1_ADD1 |
  			     ADR_CFG_CYCLES_ADD2(16) |
  			     ADR_CFG_PADS_1_ADD2),
  		.addr1 = (offs >> 16) & 0xffff,
  		.addr2 = offs & 0xffff,
  		.seq = {
  			STFSM_INST_CMD1,
  			STFSM_INST_ADD1,
  			STFSM_INST_ADD2,
  			STFSM_INST_DATA_READ,
  			STFSM_INST_STOP,
  		},
  		.seq_cfg = (SEQ_CFG_PADS_1 |
  			    SEQ_CFG_READNOTWRITE |
  			    SEQ_CFG_CSDEASSERT |
  			    SEQ_CFG_STARTSEQ),
  	};
  
  	stfsm_load_seq(fsm, &seq);
  
  	stfsm_read_fifo(fsm, &tmp, 4);
  
  	*dby = (uint8_t)(tmp >> 24);
  
  	stfsm_wait_seq(fsm);
  }
  
  static void stfsm_s25fl_write_dyb(struct stfsm *fsm, uint32_t offs, uint8_t dby)
  {
  	struct stfsm_seq seq = {
  		.seq_opc[0] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			       SEQ_OPC_OPCODE(SPINOR_OP_WREN) |
  			       SEQ_OPC_CSDEASSERT),
  		.seq_opc[1] = (SEQ_OPC_PADS_1 | SEQ_OPC_CYCLES(8) |
  			       SEQ_OPC_OPCODE(S25FL_CMD_DYBWR)),
  		.addr_cfg = (ADR_CFG_CYCLES_ADD1(16) |
  			     ADR_CFG_PADS_1_ADD1 |
  			     ADR_CFG_CYCLES_ADD2(16) |
  			     ADR_CFG_PADS_1_ADD2),
  		.status = (uint32_t)dby | STA_PADS_1 | STA_CSDEASSERT,
  		.addr1 = (offs >> 16) & 0xffff,
  		.addr2 = offs & 0xffff,
  		.seq = {
  			STFSM_INST_CMD1,
  			STFSM_INST_CMD2,
  			STFSM_INST_ADD1,
  			STFSM_INST_ADD2,
  			STFSM_INST_STA_WR1,
  			STFSM_INST_STOP,
  		},
  		.seq_cfg = (SEQ_CFG_PADS_1 |
  			    SEQ_CFG_READNOTWRITE |
  			    SEQ_CFG_CSDEASSERT |
  			    SEQ_CFG_STARTSEQ),
  	};
  
  	stfsm_load_seq(fsm, &seq);
  	stfsm_wait_seq(fsm);
  
  	stfsm_wait_busy(fsm);
  }
  
  static int stfsm_s25fl_clear_status_reg(struct stfsm *fsm)
  {
  	struct stfsm_seq seq = {
  		.seq_opc[0] = (SEQ_OPC_PADS_1 |
  			       SEQ_OPC_CYCLES(8) |
  			       SEQ_OPC_OPCODE(S25FL_CMD_CLSR) |
  			       SEQ_OPC_CSDEASSERT),
  		.seq_opc[1] = (SEQ_OPC_PADS_1 |
  			       SEQ_OPC_CYCLES(8) |
  			       SEQ_OPC_OPCODE(SPINOR_OP_WRDI) |
  			       SEQ_OPC_CSDEASSERT),
  		.seq = {
  			STFSM_INST_CMD1,
  			STFSM_INST_CMD2,
  			STFSM_INST_WAIT,
  			STFSM_INST_STOP,
  		},
  		.seq_cfg = (SEQ_CFG_PADS_1 |
  			    SEQ_CFG_ERASE |
  			    SEQ_CFG_READNOTWRITE |
  			    SEQ_CFG_CSDEASSERT |
  			    SEQ_CFG_STARTSEQ),
  	};
  
  	stfsm_load_seq(fsm, &seq);
  
  	stfsm_wait_seq(fsm);
  
  	return 0;
  }
  
  static int stfsm_s25fl_config(struct stfsm *fsm)
  {
  	struct flash_info *info = fsm->info;
  	uint32_t flags = info->flags;
  	uint32_t data_pads;
  	uint32_t offs;
  	uint16_t sta_wr;
  	uint8_t sr1, cr1, dyb;
  	int update_sr = 0;
  	int ret;
  
  	if (flags & FLASH_FLAG_32BIT_ADDR) {
  		/*
  		 * Prepare Read/Write/Erase sequences according to S25FLxxx
  		 * 32-bit address command set
  		 */
  		ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_read,
  						  stfsm_s25fl_read4_configs);
  		if (ret)
  			return ret;
  
  		ret = stfsm_search_prepare_rw_seq(fsm, &fsm->stfsm_seq_write,
  						  stfsm_s25fl_write4_configs);
  		if (ret)
  			return ret;
  
  		stfsm_s25fl_prepare_erasesec_seq_32(&stfsm_seq_erase_sector);
  
  	} else {
  		/* Use default configurations for 24-bit addressing */
  		ret = stfsm_prepare_rwe_seqs_default(fsm);
  		if (ret)
  			return ret;
  	}
  
  	/*
  	 * For devices that support 'DYB' sector locking, check lock status and
  	 * unlock sectors if necessary (some variants power-on with sectors
  	 * locked by default)
  	 */
  	if (flags & FLASH_FLAG_DYB_LOCKING) {
  		offs = 0;
  		for (offs = 0; offs < info->sector_size * info->n_sectors;) {
  			stfsm_s25fl_read_dyb(fsm, offs, &dyb);
  			if (dyb == 0x00)
  				stfsm_s25fl_write_dyb(fsm, offs, 0xff);
  
  			/* Handle bottom/top 4KiB parameter sectors */
  			if ((offs < info->sector_size * 2) ||
  			    (offs >= (info->sector_size - info->n_sectors * 4)))
  				offs += 0x1000;
  			else
  				offs += 0x10000;
  		}
  	}
  
  	/* Check status of 'QE' bit, update if required. */
  	stfsm_read_status(fsm, SPINOR_OP_RDSR2, &cr1, 1);
  	data_pads = ((fsm->stfsm_seq_read.seq_cfg >> 16) & 0x3) + 1;
  	if (data_pads == 4) {
  		if (!(cr1 & STFSM_S25FL_CONFIG_QE)) {
  			/* Set 'QE' */
  			cr1 |= STFSM_S25FL_CONFIG_QE;
  
  			update_sr = 1;
  		}
  	} else {
  		if (cr1 & STFSM_S25FL_CONFIG_QE) {
  			/* Clear 'QE' */
  			cr1 &= ~STFSM_S25FL_CONFIG_QE;
  
  			update_sr = 1;
  		}
  	}
  	if (update_sr) {
  		stfsm_read_status(fsm, SPINOR_OP_RDSR, &sr1, 1);
  		sta_wr = ((uint16_t)cr1  << 8) | sr1;
  		stfsm_write_status(fsm, SPINOR_OP_WRSR, sta_wr, 2, 1);
  	}
  
  	/*
  	 * S25FLxxx devices support Program and Error error flags.
  	 * Configure driver to check flags and clear if necessary.
  	 */
  	fsm->configuration |= CFG_S25FL_CHECK_ERROR_FLAGS;
  
  	return 0;
  }
  
  static int stfsm_w25q_config(struct stfsm *fsm)
  {
  	uint32_t data_pads;
  	uint8_t sr1, sr2;
  	uint16_t sr_wr;
  	int update_sr = 0;
  	int ret;
  
  	ret = stfsm_prepare_rwe_seqs_default(fsm);
  	if (ret)
  		return ret;
  
  	/* Check status of 'QE' bit, update if required. */
  	stfsm_read_status(fsm, SPINOR_OP_RDSR2, &sr2, 1);
  	data_pads = ((fsm->stfsm_seq_read.seq_cfg >> 16) & 0x3) + 1;
  	if (data_pads == 4) {
  		if (!(sr2 & W25Q_STATUS_QE)) {
  			/* Set 'QE' */
  			sr2 |= W25Q_STATUS_QE;
  			update_sr = 1;
  		}
  	} else {
  		if (sr2 & W25Q_STATUS_QE) {
  			/* Clear 'QE' */
  			sr2 &= ~W25Q_STATUS_QE;
  			update_sr = 1;
  		}
  	}
  	if (update_sr) {
  		/* Write status register */
  		stfsm_read_status(fsm, SPINOR_OP_RDSR, &sr1, 1);
  		sr_wr = ((uint16_t)sr2 << 8) | sr1;
  		stfsm_write_status(fsm, SPINOR_OP_WRSR, sr_wr, 2, 1);
  	}
  
  	return 0;
  }
  
  static int stfsm_read(struct stfsm *fsm, uint8_t *buf, uint32_t size,
  		      uint32_t offset)
  {
  	struct stfsm_seq *seq = &fsm->stfsm_seq_read;
  	uint32_t data_pads;
  	uint32_t read_mask;
  	uint32_t size_ub;
  	uint32_t size_lb;
  	uint32_t size_mop;
  	uint32_t tmp[4];
  	uint32_t page_buf[FLASH_PAGESIZE_32];
  	uint8_t *p;
  
  	dev_dbg(fsm->dev, "reading %d bytes from 0x%08x\n", size, offset);
  
  	/* Enter 32-bit address mode, if required */
  	if (fsm->configuration & CFG_READ_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 1);
  
  	/* Must read in multiples of 32 cycles (or 32*pads/8 Bytes) */
  	data_pads = ((seq->seq_cfg >> 16) & 0x3) + 1;
  	read_mask = (data_pads << 2) - 1;
  
  	/* Handle non-aligned buf */
  	p = ((uintptr_t)buf & 0x3) ? (uint8_t *)page_buf : buf;
  
  	/* Handle non-aligned size */
  	size_ub = (size + read_mask) & ~read_mask;
  	size_lb = size & ~read_mask;
  	size_mop = size & read_mask;
  
  	seq->data_size = TRANSFER_SIZE(size_ub);
  	seq->addr1 = (offset >> 16) & 0xffff;
  	seq->addr2 = offset & 0xffff;
  
  	stfsm_load_seq(fsm, seq);
  
  	if (size_lb)
  		stfsm_read_fifo(fsm, (uint32_t *)p, size_lb);
  
  	if (size_mop) {
  		stfsm_read_fifo(fsm, tmp, read_mask + 1);
  		memcpy(p + size_lb, &tmp, size_mop);
  	}
  
  	/* Handle non-aligned buf */
  	if ((uintptr_t)buf & 0x3)
  		memcpy(buf, page_buf, size);
  
  	/* Wait for sequence to finish */
  	stfsm_wait_seq(fsm);
  
  	stfsm_clear_fifo(fsm);
  
  	/* Exit 32-bit address mode, if required */
  	if (fsm->configuration & CFG_READ_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 0);
  
  	return 0;
  }
  
  static int stfsm_write(struct stfsm *fsm, const uint8_t *buf,
  		       uint32_t size, uint32_t offset)
  {
  	struct stfsm_seq *seq = &fsm->stfsm_seq_write;
  	uint32_t data_pads;
  	uint32_t write_mask;
  	uint32_t size_ub;
  	uint32_t size_lb;
  	uint32_t size_mop;
  	uint32_t tmp[4];
  	uint32_t i;
  	uint32_t page_buf[FLASH_PAGESIZE_32];
  	uint8_t *t = (uint8_t *)&tmp;
  	const uint8_t *p;
  	int ret;
  
  	dev_dbg(fsm->dev, "writing %d bytes to 0x%08x\n", size, offset);
  
  	/* Enter 32-bit address mode, if required */
  	if (fsm->configuration & CFG_WRITE_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 1);
  
  	/* Must write in multiples of 32 cycles (or 32*pads/8 bytes) */
  	data_pads = ((seq->seq_cfg >> 16) & 0x3) + 1;
  	write_mask = (data_pads << 2) - 1;
  
  	/* Handle non-aligned buf */
  	if ((uintptr_t)buf & 0x3) {
  		memcpy(page_buf, buf, size);
  		p = (uint8_t *)page_buf;
  	} else {
  		p = buf;
  	}
  
  	/* Handle non-aligned size */
  	size_ub = (size + write_mask) & ~write_mask;
  	size_lb = size & ~write_mask;
  	size_mop = size & write_mask;
  
  	seq->data_size = TRANSFER_SIZE(size_ub);
  	seq->addr1 = (offset >> 16) & 0xffff;
  	seq->addr2 = offset & 0xffff;
  
  	/* Need to set FIFO to write mode, before writing data to FIFO (see
  	 * GNBvb79594)
  	 */
  	writel(0x00040000, fsm->base + SPI_FAST_SEQ_CFG);
  
  	/*
  	 * Before writing data to the FIFO, apply a small delay to allow a
  	 * potential change of FIFO direction to complete.
  	 */
  	if (fsm->fifo_dir_delay == 0)
  		readl(fsm->base + SPI_FAST_SEQ_CFG);
  	else
  		udelay(fsm->fifo_dir_delay);
  
  
  	/* Write data to FIFO, before starting sequence (see GNBvd79593) */
  	if (size_lb) {
  		stfsm_write_fifo(fsm, (uint32_t *)p, size_lb);
  		p += size_lb;
  	}
  
  	/* Handle non-aligned size */
  	if (size_mop) {
  		memset(t, 0xff, write_mask + 1);	/* fill with 0xff's */
  		for (i = 0; i < size_mop; i++)
  			t[i] = *p++;
  
  		stfsm_write_fifo(fsm, tmp, write_mask + 1);
  	}
  
  	/* Start sequence */
  	stfsm_load_seq(fsm, seq);
  
  	/* Wait for sequence to finish */
  	stfsm_wait_seq(fsm);
  
  	/* Wait for completion */
  	ret = stfsm_wait_busy(fsm);
  	if (ret && fsm->configuration & CFG_S25FL_CHECK_ERROR_FLAGS)
  		stfsm_s25fl_clear_status_reg(fsm);
  
  	/* Exit 32-bit address mode, if required */
  	if (fsm->configuration & CFG_WRITE_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 0);
  
  	return 0;
  }
  
  /*
   * Read an address range from the flash chip. The address range
   * may be any size provided it is within the physical boundaries.
   */
  static int stfsm_mtd_read(struct mtd_info *mtd, loff_t from, size_t len,
  			  size_t *retlen, u_char *buf)
  {
  	struct stfsm *fsm = dev_get_drvdata(mtd->dev.parent);
  	uint32_t bytes;
  
  	dev_dbg(fsm->dev, "%s from 0x%08x, len %zd\n",
  		__func__, (u32)from, len);
  
  	mutex_lock(&fsm->lock);
  
  	while (len > 0) {
  		bytes = min_t(size_t, len, FLASH_PAGESIZE);
  
  		stfsm_read(fsm, buf, bytes, from);
  
  		buf += bytes;
  		from += bytes;
  		len -= bytes;
  
  		*retlen += bytes;
  	}
  
  	mutex_unlock(&fsm->lock);
  
  	return 0;
  }
  
  static int stfsm_erase_sector(struct stfsm *fsm, uint32_t offset)
  {
  	struct stfsm_seq *seq = &stfsm_seq_erase_sector;
  	int ret;
  
  	dev_dbg(fsm->dev, "erasing sector at 0x%08x\n", offset);
  
  	/* Enter 32-bit address mode, if required */
  	if (fsm->configuration & CFG_ERASESEC_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 1);
  
  	seq->addr1 = (offset >> 16) & 0xffff;
  	seq->addr2 = offset & 0xffff;
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_wait_seq(fsm);
  
  	/* Wait for completion */
  	ret = stfsm_wait_busy(fsm);
  	if (ret && fsm->configuration & CFG_S25FL_CHECK_ERROR_FLAGS)
  		stfsm_s25fl_clear_status_reg(fsm);
  
  	/* Exit 32-bit address mode, if required */
  	if (fsm->configuration & CFG_ERASESEC_TOGGLE_32BIT_ADDR)
  		stfsm_enter_32bit_addr(fsm, 0);
  
  	return ret;
  }
  
  static int stfsm_erase_chip(struct stfsm *fsm)
  {
  	const struct stfsm_seq *seq = &stfsm_seq_erase_chip;
  
  	dev_dbg(fsm->dev, "erasing chip\n");
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_wait_seq(fsm);
  
  	return stfsm_wait_busy(fsm);
  }
  
  /*
   * Write an address range to the flash chip.  Data must be written in
   * FLASH_PAGESIZE chunks.  The address range may be any size provided
   * it is within the physical boundaries.
   */
  static int stfsm_mtd_write(struct mtd_info *mtd, loff_t to, size_t len,
  			   size_t *retlen, const u_char *buf)
  {
  	struct stfsm *fsm = dev_get_drvdata(mtd->dev.parent);
  
  	u32 page_offs;
  	u32 bytes;
  	uint8_t *b = (uint8_t *)buf;
  	int ret = 0;
  
  	dev_dbg(fsm->dev, "%s to 0x%08x, len %zd\n", __func__, (u32)to, len);
  
  	/* Offset within page */
  	page_offs = to % FLASH_PAGESIZE;
  
  	mutex_lock(&fsm->lock);
  
  	while (len) {
  		/* Write up to page boundary */
  		bytes = min_t(size_t, FLASH_PAGESIZE - page_offs, len);
  
  		ret = stfsm_write(fsm, b, bytes, to);
  		if (ret)
  			goto out1;
  
  		b += bytes;
  		len -= bytes;
  		to += bytes;
  
  		/* We are now page-aligned */
  		page_offs = 0;
  
  		*retlen += bytes;
  
  	}
  
  out1:
  	mutex_unlock(&fsm->lock);
  
  	return ret;
  }
  
  /*
   * Erase an address range on the flash chip. The address range may extend
   * one or more erase sectors.  Return an error is there is a problem erasing.
   */
  static int stfsm_mtd_erase(struct mtd_info *mtd, struct erase_info *instr)
  {
  	struct stfsm *fsm = dev_get_drvdata(mtd->dev.parent);
  	u32 addr, len;
  	int ret;
  
  	dev_dbg(fsm->dev, "%s at 0x%llx, len %lld\n", __func__,
  		(long long)instr->addr, (long long)instr->len);
  
  	addr = instr->addr;
  	len = instr->len;
  
  	mutex_lock(&fsm->lock);
  
  	/* Whole-chip erase? */
  	if (len == mtd->size) {
  		ret = stfsm_erase_chip(fsm);
  		if (ret)
  			goto out1;
  	} else {
  		while (len) {
  			ret = stfsm_erase_sector(fsm, addr);
  			if (ret)
  				goto out1;
  
  			addr += mtd->erasesize;
  			len -= mtd->erasesize;
  		}
  	}
  
  	mutex_unlock(&fsm->lock);
  
  	instr->state = MTD_ERASE_DONE;
  	mtd_erase_callback(instr);
  
  	return 0;
  
  out1:
  	instr->state = MTD_ERASE_FAILED;
  	mutex_unlock(&fsm->lock);
  
  	return ret;
  }
  
  static void stfsm_read_jedec(struct stfsm *fsm, uint8_t *jedec)
  {
  	const struct stfsm_seq *seq = &stfsm_seq_read_jedec;
  	uint32_t tmp[2];
  
  	stfsm_load_seq(fsm, seq);
  
  	stfsm_read_fifo(fsm, tmp, 8);
  
  	memcpy(jedec, tmp, 5);
  
  	stfsm_wait_seq(fsm);
  }
  
  static struct flash_info *stfsm_jedec_probe(struct stfsm *fsm)
  {
  	struct flash_info	*info;
  	u16                     ext_jedec;
  	u32			jedec;
  	u8			id[5];
  
  	stfsm_read_jedec(fsm, id);
  
  	jedec     = id[0] << 16 | id[1] << 8 | id[2];
  	/*
  	 * JEDEC also defines an optional "extended device information"
  	 * string for after vendor-specific data, after the three bytes
  	 * we use here. Supporting some chips might require using it.
  	 */
  	ext_jedec = id[3] << 8  | id[4];
  
  	dev_dbg(fsm->dev, "JEDEC =  0x%08x [%02x %02x %02x %02x %02x]\n",
  		jedec, id[0], id[1], id[2], id[3], id[4]);
  
  	for (info = flash_types; info->name; info++) {
  		if (info->jedec_id == jedec) {
  			if (info->ext_id && info->ext_id != ext_jedec)
  				continue;
  			return info;
  		}
  	}
  	dev_err(fsm->dev, "Unrecognized JEDEC id %06x\n", jedec);
  
  	return NULL;
  }
  
  static int stfsm_set_mode(struct stfsm *fsm, uint32_t mode)
  {
  	int ret, timeout = 10;
  
  	/* Wait for controller to accept mode change */
  	while (--timeout) {
  		ret = readl(fsm->base + SPI_STA_MODE_CHANGE);
  		if (ret & 0x1)
  			break;
  		udelay(1);
  	}
  
  	if (!timeout)
  		return -EBUSY;
  
  	writel(mode, fsm->base + SPI_MODESELECT);
  
  	return 0;
  }
  
  static void stfsm_set_freq(struct stfsm *fsm, uint32_t spi_freq)
  {
  	uint32_t emi_freq;
  	uint32_t clk_div;
  
  	emi_freq = clk_get_rate(fsm->clk);
  
  	/*
  	 * Calculate clk_div - values between 2 and 128
  	 * Multiple of 2, rounded up
  	 */
  	clk_div = 2 * DIV_ROUND_UP(emi_freq, 2 * spi_freq);
  	if (clk_div < 2)
  		clk_div = 2;
  	else if (clk_div > 128)
  		clk_div = 128;
  
  	/*
  	 * Determine a suitable delay for the IP to complete a change of
  	 * direction of the FIFO. The required delay is related to the clock
  	 * divider used. The following heuristics are based on empirical tests,
  	 * using a 100MHz EMI clock.
  	 */
  	if (clk_div <= 4)
  		fsm->fifo_dir_delay = 0;
  	else if (clk_div <= 10)
  		fsm->fifo_dir_delay = 1;
  	else
  		fsm->fifo_dir_delay = DIV_ROUND_UP(clk_div, 10);
  
  	dev_dbg(fsm->dev, "emi_clk = %uHZ, spi_freq = %uHZ, clk_div = %u\n",
  		emi_freq, spi_freq, clk_div);
  
  	writel(clk_div, fsm->base + SPI_CLOCKDIV);
  }
  
  static int stfsm_init(struct stfsm *fsm)
  {
  	int ret;
  
  	/* Perform a soft reset of the FSM controller */
  	writel(SEQ_CFG_SWRESET, fsm->base + SPI_FAST_SEQ_CFG);
  	udelay(1);
  	writel(0, fsm->base + SPI_FAST_SEQ_CFG);
  
  	/* Set clock to 'safe' frequency initially */
  	stfsm_set_freq(fsm, STFSM_FLASH_SAFE_FREQ);
  
  	/* Switch to FSM */
  	ret = stfsm_set_mode(fsm, SPI_MODESELECT_FSM);
  	if (ret)
  		return ret;
  
  	/* Set timing parameters */
  	writel(SPI_CFG_DEVICE_ST            |
  	       SPI_CFG_DEFAULT_MIN_CS_HIGH  |
  	       SPI_CFG_DEFAULT_CS_SETUPHOLD |
  	       SPI_CFG_DEFAULT_DATA_HOLD,
  	       fsm->base + SPI_CONFIGDATA);
  	writel(STFSM_DEFAULT_WR_TIME, fsm->base + SPI_STATUS_WR_TIME_REG);
  
  	/*
  	 * Set the FSM 'WAIT' delay to the minimum workable value.  Note, for
  	 * our purposes, the WAIT instruction is used purely to achieve
  	 * "sequence validity" rather than actually implement a delay.
  	 */
  	writel(0x00000001, fsm->base + SPI_PROGRAM_ERASE_TIME);
  
  	/* Clear FIFO, just in case */
  	stfsm_clear_fifo(fsm);
  
  	return 0;
  }
  
  static void stfsm_fetch_platform_configs(struct platform_device *pdev)
  {
  	struct stfsm *fsm = platform_get_drvdata(pdev);
  	struct device_node *np = pdev->dev.of_node;
  	struct regmap *regmap;
  	uint32_t boot_device_reg;
  	uint32_t boot_device_spi;
  	uint32_t boot_device;     /* Value we read from *boot_device_reg */
  	int ret;
  
  	/* Booting from SPI NOR Flash is the default */
  	fsm->booted_from_spi = true;
  
  	regmap = syscon_regmap_lookup_by_phandle(np, "st,syscfg");
  	if (IS_ERR(regmap))
  		goto boot_device_fail;
  
  	fsm->reset_signal = of_property_read_bool(np, "st,reset-signal");
  
  	fsm->reset_por = of_property_read_bool(np, "st,reset-por");
  
  	/* Where in the syscon the boot device information lives */
  	ret = of_property_read_u32(np, "st,boot-device-reg", &boot_device_reg);
  	if (ret)
  		goto boot_device_fail;
  
  	/* Boot device value when booted from SPI NOR */
  	ret = of_property_read_u32(np, "st,boot-device-spi", &boot_device_spi);
  	if (ret)
  		goto boot_device_fail;
  
  	ret = regmap_read(regmap, boot_device_reg, &boot_device);
  	if (ret)
  		goto boot_device_fail;
  
  	if (boot_device != boot_device_spi)
  		fsm->booted_from_spi = false;
  
  	return;
  
  boot_device_fail:
  	dev_warn(&pdev->dev,
  		 "failed to fetch boot device, assuming boot from SPI\n");
  }
  
  static int stfsm_probe(struct platform_device *pdev)
  {
  	struct device_node *np = pdev->dev.of_node;
  	struct mtd_part_parser_data ppdata;
  	struct flash_info *info;
  	struct resource *res;
  	struct stfsm *fsm;
  	int ret;
  
  	if (!np) {
  		dev_err(&pdev->dev, "No DT found\n");
  		return -EINVAL;
  	}
  	ppdata.of_node = np;
  
  	fsm = devm_kzalloc(&pdev->dev, sizeof(*fsm), GFP_KERNEL);
  	if (!fsm)
  		return -ENOMEM;
  
  	fsm->dev = &pdev->dev;
  
  	platform_set_drvdata(pdev, fsm);
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!res) {
  		dev_err(&pdev->dev, "Resource not found\n");
  		return -ENODEV;
  	}
  
  	fsm->base = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(fsm->base)) {
  		dev_err(&pdev->dev,
  			"Failed to reserve memory region %pR\n", res);
  		return PTR_ERR(fsm->base);
  	}
  
  	fsm->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(fsm->clk)) {
  		dev_err(fsm->dev, "Couldn't find EMI clock.\n");
  		return PTR_ERR(fsm->clk);
  	}
  
  	ret = clk_prepare_enable(fsm->clk);
  	if (ret) {
  		dev_err(fsm->dev, "Failed to enable EMI clock.\n");
  		return ret;
  	}
  
  	mutex_init(&fsm->lock);
  
  	ret = stfsm_init(fsm);
  	if (ret) {
  		dev_err(&pdev->dev, "Failed to initialise FSM Controller\n");
  		return ret;
  	}
  
  	stfsm_fetch_platform_configs(pdev);
  
  	/* Detect SPI FLASH device */
  	info = stfsm_jedec_probe(fsm);
  	if (!info)
  		return -ENODEV;
  	fsm->info = info;
  
  	/* Use device size to determine address width */
  	if (info->sector_size * info->n_sectors > 0x1000000)
  		info->flags |= FLASH_FLAG_32BIT_ADDR;
  
  	/*
  	 * Configure READ/WRITE/ERASE sequences according to platform and
  	 * device flags.
  	 */
  	if (info->config) {
  		ret = info->config(fsm);
  		if (ret)
  			return ret;
  	} else {
  		ret = stfsm_prepare_rwe_seqs_default(fsm);
  		if (ret)
  			return ret;
  	}
  
  	fsm->mtd.name		= info->name;
  	fsm->mtd.dev.parent	= &pdev->dev;
  	fsm->mtd.type		= MTD_NORFLASH;
  	fsm->mtd.writesize	= 4;
  	fsm->mtd.writebufsize	= fsm->mtd.writesize;
  	fsm->mtd.flags		= MTD_CAP_NORFLASH;
  	fsm->mtd.size		= info->sector_size * info->n_sectors;
  	fsm->mtd.erasesize	= info->sector_size;
  
  	fsm->mtd._read  = stfsm_mtd_read;
  	fsm->mtd._write = stfsm_mtd_write;
  	fsm->mtd._erase = stfsm_mtd_erase;
  
  	dev_info(&pdev->dev,
  		"Found serial flash device: %s\n"
  		" size = %llx (%lldMiB) erasesize = 0x%08x (%uKiB)\n",
  		info->name,
  		(long long)fsm->mtd.size, (long long)(fsm->mtd.size >> 20),
  		fsm->mtd.erasesize, (fsm->mtd.erasesize >> 10));
  
  	return mtd_device_parse_register(&fsm->mtd, NULL, &ppdata, NULL, 0);
  }
  
  static int stfsm_remove(struct platform_device *pdev)
  {
  	struct stfsm *fsm = platform_get_drvdata(pdev);
  
  	return mtd_device_unregister(&fsm->mtd);
  }
  
  #ifdef CONFIG_PM_SLEEP
  static int stfsmfsm_suspend(struct device *dev)
  {
  	struct stfsm *fsm = dev_get_drvdata(dev);
  
  	clk_disable_unprepare(fsm->clk);
  
  	return 0;
  }
  
  static int stfsmfsm_resume(struct device *dev)
  {
  	struct stfsm *fsm = dev_get_drvdata(dev);
  
  	clk_prepare_enable(fsm->clk);
  
  	return 0;
  }
  #endif
  
  static SIMPLE_DEV_PM_OPS(stfsm_pm_ops, stfsmfsm_suspend, stfsmfsm_resume);
  
  static const struct of_device_id stfsm_match[] = {
  	{ .compatible = "st,spi-fsm", },
  	{},
  };
  MODULE_DEVICE_TABLE(of, stfsm_match);
  
  static struct platform_driver stfsm_driver = {
  	.probe		= stfsm_probe,
  	.remove		= stfsm_remove,
  	.driver		= {
  		.name	= "st-spi-fsm",
  		.of_match_table = stfsm_match,
  		.pm     = &stfsm_pm_ops,
  	},
  };
  module_platform_driver(stfsm_driver);
  
  MODULE_AUTHOR("Angus Clark <angus.clark@st.com>");
  MODULE_DESCRIPTION("ST SPI FSM driver");
  MODULE_LICENSE("GPL");
  