summaryrefslogtreecommitdiff
path: root/drivers/misc/hdpuftrs/hdpu_cpustate.c
blob: 1874b0740f2b12e01208416eae0a058ea52c4480 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
/*
 *	Sky CPU State Driver
 *
 *	Copyright (C) 2002 Brian Waite
 *
 *	This driver allows use of the CPU state bits
 *	It exports the /dev/sky_cpustate and also
 *	/proc/sky_cpustate pseudo-file for status information.
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 *
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/spinlock.h>
#include <linux/miscdevice.h>
#include <linux/proc_fs.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <linux/hdpu_features.h>

#define SKY_CPUSTATE_VERSION		"1.1"

static int hdpu_cpustate_probe(struct platform_device *pdev);
static int hdpu_cpustate_remove(struct platform_device *pdev);

struct cpustate_t cpustate;

static int cpustate_get_ref(int excl)
{

	int retval = -EBUSY;

	spin_lock(&cpustate.lock);

	if (cpustate.excl)
		goto out_busy;

	if (excl) {
		if (cpustate.open_count)
			goto out_busy;
		cpustate.excl = 1;
	}

	cpustate.open_count++;
	retval = 0;

      out_busy:
	spin_unlock(&cpustate.lock);
	return retval;
}

static int cpustate_free_ref(void)
{

	spin_lock(&cpustate.lock);

	cpustate.excl = 0;
	cpustate.open_count--;

	spin_unlock(&cpustate.lock);
	return 0;
}

unsigned char cpustate_get_state(void)
{

	return cpustate.cached_val;
}

void cpustate_set_state(unsigned char new_state)
{
	unsigned int state = (new_state << 21);

#ifdef DEBUG_CPUSTATE
	printk("CPUSTATE -> 0x%x\n", new_state);
#endif
	spin_lock(&cpustate.lock);
	cpustate.cached_val = new_state;
	writel((0xff << 21), cpustate.clr_addr);
	writel(state, cpustate.set_addr);
	spin_unlock(&cpustate.lock);
}

/*
 *	Now all the various file operations that we export.
 */

static ssize_t cpustate_read(struct file *file, char *buf,
			     size_t count, loff_t * ppos)
{
	unsigned char data;

	if (count < 0)
		return -EFAULT;
	if (count == 0)
		return 0;

	data = cpustate_get_state();
	if (copy_to_user(buf, &data, sizeof(unsigned char)))
		return -EFAULT;
	return sizeof(unsigned char);
}

static ssize_t cpustate_write(struct file *file, const char *buf,
			      size_t count, loff_t * ppos)
{
	unsigned char data;

	if (count < 0)
		return -EFAULT;

	if (count == 0)
		return 0;

	if (copy_from_user((unsigned char *)&data, buf, sizeof(unsigned char)))
		return -EFAULT;

	cpustate_set_state(data);
	return sizeof(unsigned char);
}

static int cpustate_open(struct inode *inode, struct file *file)
{
	return cpustate_get_ref((file->f_flags & O_EXCL));
}

static int cpustate_release(struct inode *inode, struct file *file)
{
	return cpustate_free_ref();
}

/*
 *	Info exported via "/proc/sky_cpustate".
 */
static int cpustate_read_proc(char *page, char **start, off_t off,
			      int count, int *eof, void *data)
{
	char *p = page;
	int len = 0;

	p += sprintf(p, "CPU State: %04x\n", cpustate_get_state());
	len = p - page;

	if (len <= off + count)
		*eof = 1;
	*start = page + off;
	len -= off;
	if (len > count)
		len = count;
	if (len < 0)
		len = 0;
	return len;
}

static struct platform_driver hdpu_cpustate_driver = {
	.probe = hdpu_cpustate_probe,
	.remove = hdpu_cpustate_remove,
	.driver = {
		.name = HDPU_CPUSTATE_NAME,
	},
};

/*
 *	The various file operations we support.
 */
static const struct file_operations cpustate_fops = {
      owner:	THIS_MODULE,
      open:	cpustate_open,
      release:	cpustate_release,
      read:	cpustate_read,
      write:	cpustate_write,
      fasync:	NULL,
      poll:	NULL,
      ioctl:	NULL,
      llseek:	no_llseek,
};

static struct miscdevice cpustate_dev = {
	MISC_DYNAMIC_MINOR,
	"sky_cpustate",
	&cpustate_fops,
};

static int hdpu_cpustate_probe(struct platform_device *pdev)
{
	struct resource *res;
	struct proc_dir_entry *proc_de;
	int ret;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	cpustate.set_addr = (unsigned long *)res->start;
	cpustate.clr_addr = (unsigned long *)res->end - 1;

	ret = misc_register(&cpustate_dev);
	if (ret) {
		printk(KERN_WARNING "sky_cpustate: "
		       "Unable to register misc device.\n");
		cpustate.set_addr = NULL;
		cpustate.clr_addr = NULL;
		return ret;
	}

	proc_de = create_proc_read_entry("sky_cpustate", 0, 0,
					 cpustate_read_proc, NULL);
	if (proc_de == NULL)
		printk(KERN_WARNING "sky_cpustate: "
		       "Unable to create proc dir entry\n");

	printk(KERN_INFO "Sky CPU State Driver v" SKY_CPUSTATE_VERSION "\n");
	return 0;
}

static int hdpu_cpustate_remove(struct platform_device *pdev)
{
	cpustate.set_addr = NULL;
	cpustate.clr_addr = NULL;

	remove_proc_entry("sky_cpustate", NULL);
	misc_deregister(&cpustate_dev);

	return 0;
}

static int __init cpustate_init(void)
{
	return platform_driver_register(&hdpu_cpustate_driver);
}

static void __exit cpustate_exit(void)
{
	platform_driver_unregister(&hdpu_cpustate_driver);
}

module_init(cpustate_init);
module_exit(cpustate_exit);

MODULE_AUTHOR("Brian Waite");
MODULE_LICENSE("GPL");