arm/common/bL_switcher_dummy_if.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * arch/arm/common/bL_switcher_dummy_if.c -- b.L switcher dummy interface
0004  *
0005  * Created by:  Nicolas Pitre, November 2012
0006  * Copyright:   (C) 2012-2013  Linaro Limited
0007  *
0008  * Dummy interface to user space for debugging purpose only.
0009  */
0010
0011 #include <linux/init.h>
0012 #include <linux/module.h>
0013 #include <linux/fs.h>
0014 #include <linux/miscdevice.h>
0015 #include <linux/uaccess.h>
0016 #include <asm/bL_switcher.h>
0017
0018 static ssize_t bL_switcher_write(struct file *file, const char __user *buf,
0019             size_t len, loff_t *pos)
0020 {
0021     unsigned char val[3];
0022     unsigned int cpu, cluster;
0023     int ret;
0024
0025     pr_debug("%s\n", __func__);
0026
0027     if (len < 3)
0028         return -EINVAL;
0029
0030     if (copy_from_user(val, buf, 3))
0031         return -EFAULT;
0032
0033     /* format: <cpu#>,<cluster#> */
0034     if (val[0] < '0' || val[0] > '9' ||
0035         val[1] != ',' ||
0036         val[2] < '0' || val[2] > '1')
0037         return -EINVAL;
0038
0039     cpu = val[0] - '0';
0040     cluster = val[2] - '0';
0041     ret = bL_switch_request(cpu, cluster);
0042
0043     return ret ? : len;
0044 }
0045
0046 static const struct file_operations bL_switcher_fops = {
0047     .write      = bL_switcher_write,
0048     .owner  = THIS_MODULE,
0049 };
0050
0051 static struct miscdevice bL_switcher_device = {
0052     MISC_DYNAMIC_MINOR,
0053     "b.L_switcher",
0054     &bL_switcher_fops
0055 };
0056 module_misc_device(bL_switcher_device);
0057
0058 MODULE_AUTHOR("Nicolas Pitre <nico@linaro.org>");
0059 MODULE_LICENSE("GPL v2");
0060 MODULE_DESCRIPTION("big.LITTLE switcher dummy user interface");