text: /*
   * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
   *
   * (C) Copyright 2008-2010 Intel Corporation
   * Author: Sreedhara DS (sreedhara.ds@intel.com)
   *
   * 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; version 2
   * of the License.
   *
   * This driver provides ioctl interfaces to call intel scu ipc driver api
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/types.h>
  #include <linux/fs.h>
  #include <linux/fcntl.h>
  #include <linux/sched.h>
  #include <linux/uaccess.h>
  #include <linux/slab.h>
  #include <linux/init.h>
  #include <asm/intel_scu_ipc.h>
  
  static int major;
  
  /* ioctl commnds */
  #define	INTE_SCU_IPC_REGISTER_READ	0
  #define INTE_SCU_IPC_REGISTER_WRITE	1
  #define INTE_SCU_IPC_REGISTER_UPDATE	2
  
  struct scu_ipc_data {
  	u32     count;  /* No. of registers */
  	u16     addr[5]; /* Register addresses */
  	u8      data[5]; /* Register data */
  	u8      mask; /* Valid for read-modify-write */
  };
  
  /**
   *	scu_reg_access		-	implement register access ioctls
   *	@cmd: command we are doing (read/write/update)
   *	@data: kernel copy of ioctl data
   *
   *	Allow the user to perform register accesses on the SCU via the
   *	kernel interface
   */
  
  static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  {
  	unsigned int count = data->count;
  
  	if (count == 0 || count == 3 || count > 4)
  		return -EINVAL;
  
  	switch (cmd) {
  	case INTE_SCU_IPC_REGISTER_READ:
  		return intel_scu_ipc_readv(data->addr, data->data, count);
  	case INTE_SCU_IPC_REGISTER_WRITE:
  		return intel_scu_ipc_writev(data->addr, data->data, count);
  	case INTE_SCU_IPC_REGISTER_UPDATE:
  		return intel_scu_ipc_update_register(data->addr[0],
  						    data->data[0], data->mask);
  	default:
  		return -ENOTTY;
  	}
  }
  
  /**
   *	scu_ipc_ioctl		-	control ioctls for the SCU
   *	@fp: file handle of the SCU device
   *	@cmd: ioctl coce
   *	@arg: pointer to user passed structure
   *
   *	Support the I/O and firmware flashing interfaces of the SCU
   */
  static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  							unsigned long arg)
  {
  	int ret;
  	struct scu_ipc_data  data;
  	void __user *argp = (void __user *)arg;
  
  	if (!capable(CAP_SYS_RAWIO))
  		return -EPERM;
  
  	if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  		return -EFAULT;
  	ret = scu_reg_access(cmd, &data);
  	if (ret < 0)
  		return ret;
  	if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  		return -EFAULT;
  	return 0;
  }
  
  static const struct file_operations scu_ipc_fops = {
  	.unlocked_ioctl = scu_ipc_ioctl,
  };
  
  static int __init ipc_module_init(void)
  {
  	major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
  	if (major < 0)
  		return major;
  
  	return 0;
  }
  
  static void __exit ipc_module_exit(void)
  {
  	unregister_chrdev(major, "intel_mid_scu");
  }
  
  module_init(ipc_module_init);
  module_exit(ipc_module_exit);
  
  MODULE_LICENSE("GPL v2");
  MODULE_DESCRIPTION("Utility driver for intel scu ipc");
  MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");
  