linux/arch/arm/common/bL_switcher_dummy_if.c
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   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
  18static 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
  46static const struct file_operations bL_switcher_fops = {
  47        .write          = bL_switcher_write,
  48        .owner  = THIS_MODULE,
  49};
  50
  51static struct miscdevice bL_switcher_device = {
  52        MISC_DYNAMIC_MINOR,
  53        "b.L_switcher",
  54        &bL_switcher_fops
  55};
  56module_misc_device(bL_switcher_device);
  57
  58MODULE_AUTHOR("Nicolas Pitre <nico@linaro.org>");
  59MODULE_LICENSE("GPL v2");
  60MODULE_DESCRIPTION("big.LITTLE switcher dummy user interface");
  61