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 struct intel_scu_ipc_dev *scu;
  26 static DEFINE_MUTEX(scu_lock);
  27
  28 /* IOCTL commands */
  29 #define INTE_SCU_IPC_REGISTER_READ      0
  30 #define INTE_SCU_IPC_REGISTER_WRITE     1
  31 #define INTE_SCU_IPC_REGISTER_UPDATE    2
  32
  33 struct scu_ipc_data {
  34         u32     count;  /* No. of registers */
  35         u16     addr[5]; /* Register addresses */
  36         u8      data[5]; /* Register data */
  37         u8      mask; /* Valid for read-modify-write */
  38 };
  39
  40 /**
  41  *      scu_reg_access          -       implement register access ioctls
  42  *      @cmd: command we are doing (read/write/update)
  43  *      @data: kernel copy of ioctl data
  44  *
  45  *      Allow the user to perform register accesses on the SCU via the
  46  *      kernel interface
  47  */
  48
  49 static int scu_reg_access(u32 cmd, struct scu_ipc_data  *data)
  50 {
  51         unsigned int count = data->count;
  52
  53         if (count == 0 || count == 3 || count > 4)
  54                 return -EINVAL;
  55
  56         switch (cmd) {
  57         case INTE_SCU_IPC_REGISTER_READ:
  58                 return intel_scu_ipc_dev_readv(scu, data->addr, data->data, count);
  59         case INTE_SCU_IPC_REGISTER_WRITE:
  60                 return intel_scu_ipc_dev_writev(scu, data->addr, data->data, count);
  61         case INTE_SCU_IPC_REGISTER_UPDATE:
  62                 return intel_scu_ipc_dev_update(scu, data->addr[0], data->data[0],
  63                                                 data->mask);
  64         default:
  65                 return -ENOTTY;
  66         }
  67 }
  68
  69 /**
  70  *      scu_ipc_ioctl           -       control ioctls for the SCU
  71  *      @fp: file handle of the SCU device
  72  *      @cmd: ioctl coce
  73  *      @arg: pointer to user passed structure
  74  *
  75  *      Support the I/O and firmware flashing interfaces of the SCU
  76  */
  77 static long scu_ipc_ioctl(struct file *fp, unsigned int cmd,
  78                                                         unsigned long arg)
  79 {
  80         int ret;
  81         struct scu_ipc_data  data;
  82         void __user *argp = (void __user *)arg;
  83
  84         if (!capable(CAP_SYS_RAWIO))
  85                 return -EPERM;
  86
  87         if (copy_from_user(&data, argp, sizeof(struct scu_ipc_data)))
  88                 return -EFAULT;
  89         ret = scu_reg_access(cmd, &data);
  90         if (ret < 0)
  91                 return ret;
  92         if (copy_to_user(argp, &data, sizeof(struct scu_ipc_data)))
  93                 return -EFAULT;
  94         return 0;
  95 }
  96
  97 static int scu_ipc_open(struct inode *inode, struct file *file)
  98 {
  99         int ret = 0;
 100
 101         /* Only single open at the time */
 102         mutex_lock(&scu_lock);
 103         if (scu) {
 104                 ret = -EBUSY;
 105                 goto unlock;
 106         }
 107
 108         scu = intel_scu_ipc_dev_get();
 109         if (!scu)
 110                 ret = -ENODEV;
 111
 112 unlock:
 113         mutex_unlock(&scu_lock);
 114         return ret;
 115 }
 116
 117 static int scu_ipc_release(struct inode *inode, struct file *file)
 118 {
 119         mutex_lock(&scu_lock);
 120         intel_scu_ipc_dev_put(scu);
 121         scu = NULL;
 122         mutex_unlock(&scu_lock);
 123
 124         return 0;
 125 }
 126
 127 static const struct file_operations scu_ipc_fops = {
 128         .unlocked_ioctl = scu_ipc_ioctl,
 129         .open = scu_ipc_open,
 130         .release = scu_ipc_release,
 131 };
 132
 133 static int __init ipc_module_init(void)
 134 {
 135         major = register_chrdev(0, "intel_mid_scu", &scu_ipc_fops);
 136         if (major < 0)
 137                 return major;
 138
 139         return 0;
 140 }
 141
 142 static void __exit ipc_module_exit(void)
 143 {
 144         unregister_chrdev(major, "intel_mid_scu");
 145 }
 146
 147 module_init(ipc_module_init);
 148 module_exit(ipc_module_exit);
 149
 150 MODULE_LICENSE("GPL v2");
 151 MODULE_DESCRIPTION("Utility driver for intel scu ipc");
 152 MODULE_AUTHOR("Sreedhara <sreedhara.ds@intel.com>");