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1da177e4 LT |
1 | /* |
2 | * Sky CPU State Driver | |
3 | * | |
4 | * Copyright (C) 2002 Brian Waite | |
5 | * | |
6 | * This driver allows use of the CPU state bits | |
7 | * It exports the /dev/sky_cpustate and also | |
8 | * /proc/sky_cpustate pseudo-file for status information. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or | |
11 | * modify it under the terms of the GNU General Public License | |
12 | * as published by the Free Software Foundation; either version | |
13 | * 2 of the License, or (at your option) any later version. | |
14 | * | |
15 | */ | |
16 | ||
1da177e4 LT |
17 | #include <linux/module.h> |
18 | #include <linux/kernel.h> | |
19 | #include <linux/spinlock.h> | |
20 | #include <linux/miscdevice.h> | |
1da177e4 | 21 | #include <linux/proc_fs.h> |
d052d1be | 22 | #include <linux/platform_device.h> |
1da177e4 LT |
23 | #include <asm/uaccess.h> |
24 | #include <linux/hdpu_features.h> | |
d2ceb47a | 25 | #include <asm/io.h> |
1da177e4 LT |
26 | |
27 | #define SKY_CPUSTATE_VERSION "1.1" | |
28 | ||
3ae5eaec RK |
29 | static int hdpu_cpustate_probe(struct platform_device *pdev); |
30 | static int hdpu_cpustate_remove(struct platform_device *pdev); | |
1da177e4 LT |
31 | |
32 | struct cpustate_t cpustate; | |
33 | ||
34 | static int cpustate_get_ref(int excl) | |
35 | { | |
36 | ||
37 | int retval = -EBUSY; | |
38 | ||
39 | spin_lock(&cpustate.lock); | |
40 | ||
41 | if (cpustate.excl) | |
42 | goto out_busy; | |
43 | ||
44 | if (excl) { | |
45 | if (cpustate.open_count) | |
46 | goto out_busy; | |
47 | cpustate.excl = 1; | |
48 | } | |
49 | ||
50 | cpustate.open_count++; | |
51 | retval = 0; | |
52 | ||
53 | out_busy: | |
54 | spin_unlock(&cpustate.lock); | |
55 | return retval; | |
56 | } | |
57 | ||
58 | static int cpustate_free_ref(void) | |
59 | { | |
60 | ||
61 | spin_lock(&cpustate.lock); | |
62 | ||
63 | cpustate.excl = 0; | |
64 | cpustate.open_count--; | |
65 | ||
66 | spin_unlock(&cpustate.lock); | |
67 | return 0; | |
68 | } | |
69 | ||
70 | unsigned char cpustate_get_state(void) | |
71 | { | |
72 | ||
73 | return cpustate.cached_val; | |
74 | } | |
75 | ||
76 | void cpustate_set_state(unsigned char new_state) | |
77 | { | |
78 | unsigned int state = (new_state << 21); | |
79 | ||
80 | #ifdef DEBUG_CPUSTATE | |
81 | printk("CPUSTATE -> 0x%x\n", new_state); | |
82 | #endif | |
83 | spin_lock(&cpustate.lock); | |
84 | cpustate.cached_val = new_state; | |
85 | writel((0xff << 21), cpustate.clr_addr); | |
86 | writel(state, cpustate.set_addr); | |
87 | spin_unlock(&cpustate.lock); | |
88 | } | |
89 | ||
90 | /* | |
91 | * Now all the various file operations that we export. | |
92 | */ | |
93 | ||
94 | static ssize_t cpustate_read(struct file *file, char *buf, | |
95 | size_t count, loff_t * ppos) | |
96 | { | |
97 | unsigned char data; | |
98 | ||
99 | if (count < 0) | |
100 | return -EFAULT; | |
101 | if (count == 0) | |
102 | return 0; | |
103 | ||
104 | data = cpustate_get_state(); | |
105 | if (copy_to_user(buf, &data, sizeof(unsigned char))) | |
106 | return -EFAULT; | |
107 | return sizeof(unsigned char); | |
108 | } | |
109 | ||
110 | static ssize_t cpustate_write(struct file *file, const char *buf, | |
111 | size_t count, loff_t * ppos) | |
112 | { | |
113 | unsigned char data; | |
114 | ||
115 | if (count < 0) | |
116 | return -EFAULT; | |
117 | ||
118 | if (count == 0) | |
119 | return 0; | |
120 | ||
121 | if (copy_from_user((unsigned char *)&data, buf, sizeof(unsigned char))) | |
122 | return -EFAULT; | |
123 | ||
124 | cpustate_set_state(data); | |
125 | return sizeof(unsigned char); | |
126 | } | |
127 | ||
128 | static int cpustate_open(struct inode *inode, struct file *file) | |
129 | { | |
130 | return cpustate_get_ref((file->f_flags & O_EXCL)); | |
131 | } | |
132 | ||
133 | static int cpustate_release(struct inode *inode, struct file *file) | |
134 | { | |
135 | return cpustate_free_ref(); | |
136 | } | |
137 | ||
138 | /* | |
139 | * Info exported via "/proc/sky_cpustate". | |
140 | */ | |
141 | static int cpustate_read_proc(char *page, char **start, off_t off, | |
142 | int count, int *eof, void *data) | |
143 | { | |
144 | char *p = page; | |
145 | int len = 0; | |
146 | ||
147 | p += sprintf(p, "CPU State: %04x\n", cpustate_get_state()); | |
148 | len = p - page; | |
149 | ||
150 | if (len <= off + count) | |
151 | *eof = 1; | |
152 | *start = page + off; | |
153 | len -= off; | |
154 | if (len > count) | |
155 | len = count; | |
156 | if (len < 0) | |
157 | len = 0; | |
158 | return len; | |
159 | } | |
160 | ||
3ae5eaec | 161 | static struct platform_driver hdpu_cpustate_driver = { |
1da177e4 LT |
162 | .probe = hdpu_cpustate_probe, |
163 | .remove = hdpu_cpustate_remove, | |
3ae5eaec RK |
164 | .driver = { |
165 | .name = HDPU_CPUSTATE_NAME, | |
166 | }, | |
1da177e4 LT |
167 | }; |
168 | ||
169 | /* | |
170 | * The various file operations we support. | |
171 | */ | |
d54b1fdb | 172 | static const struct file_operations cpustate_fops = { |
8b70da1a CG |
173 | .owner = THIS_MODULE, |
174 | .open = cpustate_open, | |
175 | .release = cpustate_release, | |
176 | .read = cpustate_read, | |
177 | .write = cpustate_write, | |
178 | .llseek = no_llseek, | |
1da177e4 LT |
179 | }; |
180 | ||
181 | static struct miscdevice cpustate_dev = { | |
8b70da1a CG |
182 | .minor = MISC_DYNAMIC_MINOR, |
183 | .name = "sky_cpustate", | |
184 | .fops = &cpustate_fops, | |
1da177e4 LT |
185 | }; |
186 | ||
3ae5eaec | 187 | static int hdpu_cpustate_probe(struct platform_device *pdev) |
1da177e4 | 188 | { |
1da177e4 | 189 | struct resource *res; |
1ac19f4c CL |
190 | struct proc_dir_entry *proc_de; |
191 | int ret; | |
1da177e4 LT |
192 | |
193 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
7472fd36 CG |
194 | if (!res) { |
195 | printk(KERN_ERR "sky_cpustate: " | |
196 | "Invalid memory resource.\n"); | |
197 | return -EINVAL; | |
198 | } | |
1da177e4 LT |
199 | cpustate.set_addr = (unsigned long *)res->start; |
200 | cpustate.clr_addr = (unsigned long *)res->end - 1; | |
201 | ||
1ac19f4c CL |
202 | ret = misc_register(&cpustate_dev); |
203 | if (ret) { | |
a4e32b5f CG |
204 | printk(KERN_WARNING "sky_cpustate: " |
205 | "Unable to register misc device.\n"); | |
1ac19f4c CL |
206 | cpustate.set_addr = NULL; |
207 | cpustate.clr_addr = NULL; | |
208 | return ret; | |
209 | } | |
210 | ||
211 | proc_de = create_proc_read_entry("sky_cpustate", 0, 0, | |
a4e32b5f | 212 | cpustate_read_proc, NULL); |
1ac19f4c | 213 | if (proc_de == NULL) |
a4e32b5f CG |
214 | printk(KERN_WARNING "sky_cpustate: " |
215 | "Unable to create proc dir entry\n"); | |
1da177e4 LT |
216 | |
217 | printk(KERN_INFO "Sky CPU State Driver v" SKY_CPUSTATE_VERSION "\n"); | |
218 | return 0; | |
219 | } | |
1ac19f4c | 220 | |
3ae5eaec | 221 | static int hdpu_cpustate_remove(struct platform_device *pdev) |
1da177e4 | 222 | { |
1ac19f4c CL |
223 | cpustate.set_addr = NULL; |
224 | cpustate.clr_addr = NULL; | |
1da177e4 LT |
225 | |
226 | remove_proc_entry("sky_cpustate", NULL); | |
227 | misc_deregister(&cpustate_dev); | |
1da177e4 | 228 | |
a4e32b5f | 229 | return 0; |
1da177e4 LT |
230 | } |
231 | ||
232 | static int __init cpustate_init(void) | |
233 | { | |
a4e32b5f | 234 | return platform_driver_register(&hdpu_cpustate_driver); |
1da177e4 LT |
235 | } |
236 | ||
237 | static void __exit cpustate_exit(void) | |
238 | { | |
3ae5eaec | 239 | platform_driver_unregister(&hdpu_cpustate_driver); |
1da177e4 LT |
240 | } |
241 | ||
242 | module_init(cpustate_init); | |
243 | module_exit(cpustate_exit); | |
244 | ||
245 | MODULE_AUTHOR("Brian Waite"); | |
246 | MODULE_LICENSE("GPL"); |