drivers/platform/x86/intel_scu_ipcutil.c

   1 /*
   2  * intel_scu_ipc.c: Driver for the Intel SCU IPC mechanism
   3  *
   4  * (C) Copyright 2008-2010 Intel Corporation
   5  * Author: Sreedhara DS (sreedhara.ds@intel.com)
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License
   9  * as published by the Free Software Foundation; version 2
  10  * of the License.
  11  *
  12  * This driver provides ioctl interfaces to call intel scu ipc driver api
  13  */
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/errno.h>
  18 #include <linux/types.h>
  19 #include <linux/fs.h>
  20 #include <linux/fcntl.h>
  21 #include <linux/sched.h>
  22 #include <linux/uaccess.h>
  23 #include <linux/slab.h>
  24 #include <linux/init.h>
  25 #include <asm/intel_scu_ipc.h>
  26
  27 static int major;
  28
  29 /* ioctl commnds */
  30 #define INTE_SCU_IPC_REGISTER_READ      0
  31 #define INTE_SCU_IPC_REGISTER_WRITE     1
  32 #define INTE_SCU_IPC_REGISTER_UPDATE    2
  33
  34 struct scu_ipc_data {
  35         u32     count;  /* No. of registers */
  36         u16     addr[5]; /* Register addresses */
  37         u8      data[5]; /* Register data */
  38         u8      mask; /* Valid for read-modify-write */
  39 };
  40
  41 /**
  42  *      scu_reg_access          -       implement register access ioctls
  43  *      @cmd: command we are doing (read/write/update)
  44  *      @data: kernel copy of ioctl data
  45  *
  46  *      Allow the user to perform register accesses on the SCU via the
  47  *      kernel interface
  48  */
  49
  50 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  51 {
  52         unsigned int count = data->count;
  53
  54         if (count == 0 || count == 3 || count > 4)
  55                 return -EINVAL;
  56
  57         switch (cmd) {
  58         case INTE_SCU_IPC_REGISTER_READ:
  59                 return intel_scu_ipc_readv(data->addr, data->data, count);
  60         case INTE_SCU_IPC_REGISTER_WRITE:
  61                 return intel_scu_ipc_writev(data->addr, data->data, count);
  62         case INTE_SCU_IPC_REGISTER_UPDATE:
  63                 return intel_scu_ipc_update_register(data->addr[0],
  64                                                     data->data[0], data->mask);
  65         default:
  66                 return -ENOTTY;
  67         }
  68 }
  69
  70 /**
  71  *      scu_ipc_ioctl           -       control ioctls for the SCU
  72  *      @fp: file handle of the SCU device
  73  *      @cmd: ioctl coce
  74  *      @arg: pointer to user passed structure
  75  *
  76  *      Support the I/O and firmware flashing interfaces of the SCU
  77  */
  78 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  79                                                         unsigned long arg)
  80 {
  81         int ret;
  82         struct scu_ipc_data  data;
  83         void __user *argp = (void __user *)arg;
  84
  85         if (!capable(CAP_SYS_RAWIO))
  86                 return -EPERM;
  87
  88         if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  89                 return -EFAULT;
  90         ret = scu_reg_access(cmd, &data);
  91         if (ret < 0)
  92                 return ret;
  93         if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  94                 return -EFAULT;
  95         return 0;
  96 }
  97
  98 static const struct file_operations scu_ipc_fops = {
  99         .unlocked_ioctl = scu_ipc_ioctl,
 100 };
 101
 102 static int __init ipc_module_init(void)
 103 {
 104         major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
 105         if (major < 0)
 106                 return major;
 107
 108         return 0;
 109 }
 110
 111 static void __exit ipc_module_exit(void)
 112 {
 113         unregister_chrdev(major, "intel_mid_scu");
 114 }
 115
 116 module_init(ipc_module_init);
 117 module_exit(ipc_module_exit);
 118
 119 MODULE_LICENSE("GPL v2");
 120 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
 121 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");