drivers/platform/x86/intel_scu_ipcutil.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Driver for the Intel SCU IPC mechanism
   4  *
   5  * (C) Copyright 2008-2010 Intel Corporation
   6  * Author: Sreedhara DS (sreedhara.ds@intel.com)
   7  *
   8  * This driver provides IOCTL interfaces to call Intel SCU IPC driver API.
   9  */
  10
  11 #include <linux/errno.h>
  12 #include <linux/fcntl.h>
  13 #include <linux/fs.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/sched.h>
  17 #include <linux/slab.h>
  18 #include <linux/types.h>
  19 #include <linux/uaccess.h>
  20
  21 #include <asm/intel_scu_ipc.h>
  22
  23 static int major;
  24
  25 /* IOCTL commands */
  26 #define INTE_SCU_IPC_REGISTER_READ      0
  27 #define INTE_SCU_IPC_REGISTER_WRITE     1
  28 #define INTE_SCU_IPC_REGISTER_UPDATE    2
  29
  30 struct scu_ipc_data {
  31         u32     count;  /* No. of registers */
  32         u16     addr[5]; /* Register addresses */
  33         u8      data[5]; /* Register data */
  34         u8      mask; /* Valid for read-modify-write */
  35 };
  36
  37 /**
  38  *      scu_reg_access          -       implement register access ioctls
  39  *      @cmd: command we are doing (read/write/update)
  40  *      @data: kernel copy of ioctl data
  41  *
  42  *      Allow the user to perform register accesses on the SCU via the
  43  *      kernel interface
  44  */
  45
  46 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  47 {
  48         unsigned int count = data->count;
  49
  50         if (count == 0 || count == 3 || count > 4)
  51                 return -EINVAL;
  52
  53         switch (cmd) {
  54         case INTE_SCU_IPC_REGISTER_READ:
  55                 return intel_scu_ipc_readv(data->addr, data->data, count);
  56         case INTE_SCU_IPC_REGISTER_WRITE:
  57                 return intel_scu_ipc_writev(data->addr, data->data, count);
  58         case INTE_SCU_IPC_REGISTER_UPDATE:
  59                 return intel_scu_ipc_update_register(data->addr[0],
  60                                                     data->data[0], data->mask);
  61         default:
  62                 return -ENOTTY;
  63         }
  64 }
  65
  66 /**
  67  *      scu_ipc_ioctl           -       control ioctls for the SCU
  68  *      @fp: file handle of the SCU device
  69  *      @cmd: ioctl coce
  70  *      @arg: pointer to user passed structure
  71  *
  72  *      Support the I/O and firmware flashing interfaces of the SCU
  73  */
  74 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  75                                                         unsigned long arg)
  76 {
  77         int ret;
  78         struct scu_ipc_data  data;
  79         void __user *argp = (void __user *)arg;
  80
  81         if (!capable(CAP_SYS_RAWIO))
  82                 return -EPERM;
  83
  84         if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  85                 return -EFAULT;
  86         ret = scu_reg_access(cmd, &data);
  87         if (ret < 0)
  88                 return ret;
  89         if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  90                 return -EFAULT;
  91         return 0;
  92 }
  93
  94 static const struct file_operations scu_ipc_fops = {
  95         .unlocked_ioctl = scu_ipc_ioctl,
  96 };
  97
  98 static int __init ipc_module_init(void)
  99 {
 100         major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
 101         if (major < 0)
 102                 return major;
 103
 104         return 0;
 105 }
 106
 107 static void __exit ipc_module_exit(void)
 108 {
 109         unregister_chrdev(major, "intel_mid_scu");
 110 }
 111
 112 module_init(ipc_module_init);
 113 module_exit(ipc_module_exit);
 114
 115 MODULE_LICENSE("GPL v2");
 116 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
 117 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");