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");
61