arch/arm/common/bL_switcher_dummy_if.c

   1 /*
   2  * arch/arm/common/bL_switcher_dummy_if.c -- b.L switcher dummy interface
   3  *
   4  * Created by:  Nicolas Pitre, November 2012
   5  * Copyright:   (C) 2012-2013  Linaro Limited
   6  *
   7  * Dummy interface to user space for debugging purpose only.
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/fs.h>
  17 #include <linux/miscdevice.h>
  18 #include <linux/uaccess.h>
  19 #include <asm/bL_switcher.h>
  20
  21 static ssize_t bL_switcher_write(struct file *file, const char __user *buf,
  22                         size_t len, loff_t *pos)
  23 {
  24         unsigned char val[3];
  25         unsigned int cpu, cluster;
  26         int ret;
  27
  28         pr_debug("%s\n", __func__);
  29
  30         if (len < 3)
  31                 return -EINVAL;
  32
  33         if (copy_from_user(val, buf, 3))
  34                 return -EFAULT;
  35
  36         /* format: <cpu#>,<cluster#> */
  37         if (val[0] < '0' || val[0] > '9' ||
  38             val[1] != ',' ||
  39             val[2] < '0' || val[2] > '1')
  40                 return -EINVAL;
  41
  42         cpu = val[0] - '0';
  43         cluster = val[2] - '0';
  44         ret = bL_switch_request(cpu, cluster);
  45
  46         return ret ? : len;
  47 }
  48
  49 static const struct file_operations bL_switcher_fops = {
  50         .write          = bL_switcher_write,
  51         .owner  = THIS_MODULE,
  52 };
  53
  54 static struct miscdevice bL_switcher_device = {
  55         MISC_DYNAMIC_MINOR,
  56         "b.L_switcher",
  57         &bL_switcher_fops
  58 };
  59 module_misc_device(bL_switcher_device);
  60
  61 MODULE_AUTHOR("Nicolas Pitre <nico@linaro.org>");
  62 MODULE_LICENSE("GPL v2");
  63 MODULE_DESCRIPTION("big.LITTLE switcher dummy user interface");