text: /* drivers/media/platform/s5p-cec/s5p_cec.c
   *
   * Samsung S5P CEC driver
   *
   * Copyright (c) 2014 Samsung Electronics Co., Ltd.
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This driver is based on the "cec interface driver for exynos soc" by
   * SangPil Moon.
   */
  
  #include <linux/clk.h>
  #include <linux/interrupt.h>
  #include <linux/kernel.h>
  #include <linux/mfd/syscon.h>
  #include <linux/module.h>
  #include <linux/of.h>
  #include <linux/of_platform.h>
  #include <linux/platform_device.h>
  #include <linux/pm_runtime.h>
  #include <linux/timer.h>
  #include <linux/workqueue.h>
  #include <media/cec.h>
  #include <media/cec-notifier.h>
  
  #include "exynos_hdmi_cec.h"
  #include "regs-cec.h"
  #include "s5p_cec.h"
  
  #define CEC_NAME	"s5p-cec"
  
  static int debug;
  module_param(debug, int, 0644);
  MODULE_PARM_DESC(debug, "debug level (0-2)");
  
  static int s5p_cec_adap_enable(struct cec_adapter *adap, bool enable)
  {
  	struct s5p_cec_dev *cec = cec_get_drvdata(adap);
  
  	if (enable) {
  		pm_runtime_get_sync(cec->dev);
  
  		s5p_cec_reset(cec);
  
  		s5p_cec_set_divider(cec);
  		s5p_cec_threshold(cec);
  
  		s5p_cec_unmask_tx_interrupts(cec);
  		s5p_cec_unmask_rx_interrupts(cec);
  		s5p_cec_enable_rx(cec);
  	} else {
  		s5p_cec_mask_tx_interrupts(cec);
  		s5p_cec_mask_rx_interrupts(cec);
  		pm_runtime_disable(cec->dev);
  	}
  
  	return 0;
  }
  
  static int s5p_cec_adap_log_addr(struct cec_adapter *adap, u8 addr)
  {
  	struct s5p_cec_dev *cec = cec_get_drvdata(adap);
  
  	s5p_cec_set_addr(cec, addr);
  	return 0;
  }
  
  static int s5p_cec_adap_transmit(struct cec_adapter *adap, u8 attempts,
  				 u32 signal_free_time, struct cec_msg *msg)
  {
  	struct s5p_cec_dev *cec = cec_get_drvdata(adap);
  
  	/*
  	 * Unclear if 0 retries are allowed by the hardware, so have 1 as
  	 * the minimum.
  	 */
  	s5p_cec_copy_packet(cec, msg->msg, msg->len, max(1, attempts - 1));
  	return 0;
  }
  
  static irqreturn_t s5p_cec_irq_handler(int irq, void *priv)
  {
  	struct s5p_cec_dev *cec = priv;
  	u32 status = 0;
  
  	status = s5p_cec_get_status(cec);
  
  	dev_dbg(cec->dev, "irq received\n");
  
  	if (status & CEC_STATUS_TX_DONE) {
  		if (status & CEC_STATUS_TX_NACK) {
  			dev_dbg(cec->dev, "CEC_STATUS_TX_NACK set\n");
  			cec->tx = STATE_NACK;
  		} else if (status & CEC_STATUS_TX_ERROR) {
  			dev_dbg(cec->dev, "CEC_STATUS_TX_ERROR set\n");
  			cec->tx = STATE_ERROR;
  		} else {
  			dev_dbg(cec->dev, "CEC_STATUS_TX_DONE\n");
  			cec->tx = STATE_DONE;
  		}
  		s5p_clr_pending_tx(cec);
  	}
  
  	if (status & CEC_STATUS_RX_DONE) {
  		if (status & CEC_STATUS_RX_ERROR) {
  			dev_dbg(cec->dev, "CEC_STATUS_RX_ERROR set\n");
  			s5p_cec_rx_reset(cec);
  			s5p_cec_enable_rx(cec);
  		} else {
  			dev_dbg(cec->dev, "CEC_STATUS_RX_DONE set\n");
  			if (cec->rx != STATE_IDLE)
  				dev_dbg(cec->dev, "Buffer overrun (worker did not process previous message)\n");
  			cec->rx = STATE_BUSY;
  			cec->msg.len = status >> 24;
  			cec->msg.rx_status = CEC_RX_STATUS_OK;
  			s5p_cec_get_rx_buf(cec, cec->msg.len,
  					cec->msg.msg);
  			cec->rx = STATE_DONE;
  			s5p_cec_enable_rx(cec);
  		}
  		/* Clear interrupt pending bit */
  		s5p_clr_pending_rx(cec);
  	}
  	return IRQ_WAKE_THREAD;
  }
  
  static irqreturn_t s5p_cec_irq_handler_thread(int irq, void *priv)
  {
  	struct s5p_cec_dev *cec = priv;
  
  	dev_dbg(cec->dev, "irq processing thread\n");
  	switch (cec->tx) {
  	case STATE_DONE:
  		cec_transmit_done(cec->adap, CEC_TX_STATUS_OK, 0, 0, 0, 0);
  		cec->tx = STATE_IDLE;
  		break;
  	case STATE_NACK:
  		cec_transmit_done(cec->adap,
  			CEC_TX_STATUS_MAX_RETRIES | CEC_TX_STATUS_NACK,
  			0, 1, 0, 0);
  		cec->tx = STATE_IDLE;
  		break;
  	case STATE_ERROR:
  		cec_transmit_done(cec->adap,
  			CEC_TX_STATUS_MAX_RETRIES | CEC_TX_STATUS_ERROR,
  			0, 0, 0, 1);
  		cec->tx = STATE_IDLE;
  		break;
  	case STATE_BUSY:
  		dev_err(cec->dev, "state set to busy, this should not occur here\n");
  		break;
  	default:
  		break;
  	}
  
  	switch (cec->rx) {
  	case STATE_DONE:
  		cec_received_msg(cec->adap, &cec->msg);
  		cec->rx = STATE_IDLE;
  		break;
  	default:
  		break;
  	}
  
  	return IRQ_HANDLED;
  }
  
  static const struct cec_adap_ops s5p_cec_adap_ops = {
  	.adap_enable = s5p_cec_adap_enable,
  	.adap_log_addr = s5p_cec_adap_log_addr,
  	.adap_transmit = s5p_cec_adap_transmit,
  };
  
  static int s5p_cec_probe(struct platform_device *pdev)
  {
  	struct device *dev = &pdev->dev;
  	struct device_node *np;
  	struct platform_device *hdmi_dev;
  	struct resource *res;
  	struct s5p_cec_dev *cec;
  	bool needs_hpd = of_property_read_bool(pdev->dev.of_node, "needs-hpd");
  	int ret;
  
  	np = of_parse_phandle(pdev->dev.of_node, "hdmi-phandle", 0);
  
  	if (!np) {
  		dev_err(&pdev->dev, "Failed to find hdmi node in device tree\n");
  		return -ENODEV;
  	}
  	hdmi_dev = of_find_device_by_node(np);
  	if (hdmi_dev == NULL)
  		return -EPROBE_DEFER;
  
  	cec = devm_kzalloc(&pdev->dev, sizeof(*cec), GFP_KERNEL);
  	if (!cec)
  		return -ENOMEM;
  
  	cec->dev = dev;
  
  	cec->irq = platform_get_irq(pdev, 0);
  	if (cec->irq < 0)
  		return cec->irq;
  
  	ret = devm_request_threaded_irq(dev, cec->irq, s5p_cec_irq_handler,
  		s5p_cec_irq_handler_thread, 0, pdev->name, cec);
  	if (ret)
  		return ret;
  
  	cec->clk = devm_clk_get(dev, "hdmicec");
  	if (IS_ERR(cec->clk))
  		return PTR_ERR(cec->clk);
  
  	cec->pmu = syscon_regmap_lookup_by_phandle(dev->of_node,
  						 "samsung,syscon-phandle");
  	if (IS_ERR(cec->pmu))
  		return -EPROBE_DEFER;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	cec->reg = devm_ioremap_resource(dev, res);
  	if (IS_ERR(cec->reg))
  		return PTR_ERR(cec->reg);
  
  	cec->notifier = cec_notifier_get(&hdmi_dev->dev);
  	if (cec->notifier == NULL)
  		return -ENOMEM;
  
  	cec->adap = cec_allocate_adapter(&s5p_cec_adap_ops, cec, CEC_NAME,
  		CEC_CAP_DEFAULTS | (needs_hpd ? CEC_CAP_NEEDS_HPD : 0), 1);
  	ret = PTR_ERR_OR_ZERO(cec->adap);
  	if (ret)
  		return ret;
  
  	ret = cec_register_adapter(cec->adap, &pdev->dev);
  	if (ret)
  		goto err_delete_adapter;
  
  	cec_register_cec_notifier(cec->adap, cec->notifier);
  
  	platform_set_drvdata(pdev, cec);
  	pm_runtime_enable(dev);
  
  	dev_dbg(dev, "successfully probed\n");
  	return 0;
  
  err_delete_adapter:
  	cec_delete_adapter(cec->adap);
  	return ret;
  }
  
  static int s5p_cec_remove(struct platform_device *pdev)
  {
  	struct s5p_cec_dev *cec = platform_get_drvdata(pdev);
  
  	cec_unregister_adapter(cec->adap);
  	cec_notifier_put(cec->notifier);
  	pm_runtime_disable(&pdev->dev);
  	return 0;
  }
  
  static int __maybe_unused s5p_cec_runtime_suspend(struct device *dev)
  {
  	struct s5p_cec_dev *cec = dev_get_drvdata(dev);
  
  	clk_disable_unprepare(cec->clk);
  	return 0;
  }
  
  static int __maybe_unused s5p_cec_runtime_resume(struct device *dev)
  {
  	struct s5p_cec_dev *cec = dev_get_drvdata(dev);
  	int ret;
  
  	ret = clk_prepare_enable(cec->clk);
  	if (ret < 0)
  		return ret;
  	return 0;
  }
  
  static const struct dev_pm_ops s5p_cec_pm_ops = {
  	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
  				pm_runtime_force_resume)
  	SET_RUNTIME_PM_OPS(s5p_cec_runtime_suspend, s5p_cec_runtime_resume,
  			   NULL)
  };
  
  static const struct of_device_id s5p_cec_match[] = {
  	{
  		.compatible	= "samsung,s5p-cec",
  	},
  	{},
  };
  MODULE_DEVICE_TABLE(of, s5p_cec_match);
  
  static struct platform_driver s5p_cec_pdrv = {
  	.probe	= s5p_cec_probe,
  	.remove	= s5p_cec_remove,
  	.driver	= {
  		.name		= CEC_NAME,
  		.of_match_table	= s5p_cec_match,
  		.pm		= &s5p_cec_pm_ops,
  	},
  };
  
  module_platform_driver(s5p_cec_pdrv);
  
  MODULE_AUTHOR("Kamil Debski <kamil@wypas.org>");
  MODULE_LICENSE("GPL");
  MODULE_DESCRIPTION("Samsung S5P CEC driver");
  