arch/arm/common/bL_switcher_dummy_if.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * arch/arm/common/bL_switcher_dummy_if.c -- b.L switcher dummy interface
   4  *
   5  * Created by:  Nicolas Pitre, November 2012
   6  * Copyright:   (C) 2012-2013  Linaro Limited
   7  *
   8  * Dummy interface to user space for debugging purpose only.
   9  */
  10
  11 #include <linux/init.h>
  12 #include <linux/module.h>
  13 #include <linux/fs.h>
  14 #include <linux/miscdevice.h>
  15 #include <linux/uaccess.h>
  16 #include <asm/bL_switcher.h>
  17
  18 static ssize_t bL_switcher_write(struct file *file, const char __user *buf,
  19                         size_t len, loff_t *pos)
  20 {
  21         unsigned char val[3];
  22         unsigned int cpu, cluster;
  23         int ret;
  24
  25         pr_debug("%s\n", __func__);
  26
  27         if (len < 3)
  28                 return -EINVAL;
  29
  30         if (copy_from_user(val, buf, 3))
  31                 return -EFAULT;
  32
  33         /* format: <cpu#>,<cluster#> */
  34         if (val[0] < '0' || val[0] > '9' ||
  35             val[1] != ',' ||
  36             val[2] < '0' || val[2] > '1')
  37                 return -EINVAL;
  38
  39         cpu = val[0] - '0';
  40         cluster = val[2] - '0';
  41         ret = bL_switch_request(cpu, cluster);
  42
  43         return ret ? : len;
  44 }
  45
  46 static const struct file_operations bL_switcher_fops = {
  47         .write          = bL_switcher_write,
  48         .owner  = THIS_MODULE,
  49 };
  50
  51 static struct miscdevice bL_switcher_device = {
  52         MISC_DYNAMIC_MINOR,
  53         "b.L_switcher",
  54         &bL_switcher_fops
  55 };
  56 module_misc_device(bL_switcher_device);
  57
  58 MODULE_AUTHOR("Nicolas Pitre <nico@linaro.org>");
  59 MODULE_LICENSE("GPL v2");
  60 MODULE_DESCRIPTION("big.LITTLE switcher dummy user interface");