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1 | /* |
2 | * arch/arm/mach-vt8500/pwm.c | |
3 | * | |
4 | * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> | |
5 | * | |
6 | * This software is licensed under the terms of the GNU General Public | |
7 | * License version 2, as published by the Free Software Foundation, and | |
8 | * may be copied, distributed, and modified under those terms. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | */ | |
15 | ||
16 | #include <linux/module.h> | |
17 | #include <linux/kernel.h> | |
18 | #include <linux/platform_device.h> | |
19 | #include <linux/slab.h> | |
20 | #include <linux/err.h> | |
21 | #include <linux/io.h> | |
22 | #include <linux/pwm.h> | |
23 | #include <linux/delay.h> | |
24 | ||
25 | #include <asm/div64.h> | |
26 | ||
27 | #define VT8500_NR_PWMS 4 | |
28 | ||
29 | static DEFINE_MUTEX(pwm_lock); | |
30 | static LIST_HEAD(pwm_list); | |
31 | ||
32 | struct pwm_device { | |
33 | struct list_head node; | |
34 | struct platform_device *pdev; | |
35 | ||
36 | const char *label; | |
37 | ||
38 | void __iomem *regbase; | |
39 | ||
40 | unsigned int use_count; | |
41 | unsigned int pwm_id; | |
42 | }; | |
43 | ||
44 | #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) | |
45 | static inline void pwm_busy_wait(void __iomem *reg, u8 bitmask) | |
46 | { | |
47 | int loops = msecs_to_loops(10); | |
48 | while ((readb(reg) & bitmask) && --loops) | |
49 | cpu_relax(); | |
50 | ||
51 | if (unlikely(!loops)) | |
52 | pr_warning("Waiting for status bits 0x%x to clear timed out\n", | |
53 | bitmask); | |
54 | } | |
55 | ||
56 | int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns) | |
57 | { | |
58 | unsigned long long c; | |
59 | unsigned long period_cycles, prescale, pv, dc; | |
60 | ||
61 | if (pwm == NULL || period_ns == 0 || duty_ns > period_ns) | |
62 | return -EINVAL; | |
63 | ||
64 | c = 25000000/2; /* wild guess --- need to implement clocks */ | |
65 | c = c * period_ns; | |
66 | do_div(c, 1000000000); | |
67 | period_cycles = c; | |
68 | ||
69 | if (period_cycles < 1) | |
70 | period_cycles = 1; | |
71 | prescale = (period_cycles - 1) / 4096; | |
72 | pv = period_cycles / (prescale + 1) - 1; | |
73 | if (pv > 4095) | |
74 | pv = 4095; | |
75 | ||
76 | if (prescale > 1023) | |
77 | return -EINVAL; | |
78 | ||
79 | c = (unsigned long long)pv * duty_ns; | |
80 | do_div(c, period_ns); | |
81 | dc = c; | |
82 | ||
83 | pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 1)); | |
84 | writel(prescale, pwm->regbase + 0x4 + (pwm->pwm_id << 4)); | |
85 | ||
86 | pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 2)); | |
87 | writel(pv, pwm->regbase + 0x8 + (pwm->pwm_id << 4)); | |
88 | ||
89 | pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 3)); | |
90 | writel(dc, pwm->regbase + 0xc + (pwm->pwm_id << 4)); | |
91 | ||
92 | return 0; | |
93 | } | |
94 | EXPORT_SYMBOL(pwm_config); | |
95 | ||
96 | int pwm_enable(struct pwm_device *pwm) | |
97 | { | |
98 | pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0)); | |
99 | writel(5, pwm->regbase + (pwm->pwm_id << 4)); | |
100 | return 0; | |
101 | } | |
102 | EXPORT_SYMBOL(pwm_enable); | |
103 | ||
104 | void pwm_disable(struct pwm_device *pwm) | |
105 | { | |
106 | pwm_busy_wait(pwm->regbase + 0x40 + pwm->pwm_id, (1 << 0)); | |
107 | writel(0, pwm->regbase + (pwm->pwm_id << 4)); | |
108 | } | |
109 | EXPORT_SYMBOL(pwm_disable); | |
110 | ||
111 | struct pwm_device *pwm_request(int pwm_id, const char *label) | |
112 | { | |
113 | struct pwm_device *pwm; | |
114 | int found = 0; | |
115 | ||
116 | mutex_lock(&pwm_lock); | |
117 | ||
118 | list_for_each_entry(pwm, &pwm_list, node) { | |
119 | if (pwm->pwm_id == pwm_id) { | |
120 | found = 1; | |
121 | break; | |
122 | } | |
123 | } | |
124 | ||
125 | if (found) { | |
126 | if (pwm->use_count == 0) { | |
127 | pwm->use_count++; | |
128 | pwm->label = label; | |
129 | } else { | |
130 | pwm = ERR_PTR(-EBUSY); | |
131 | } | |
132 | } else { | |
133 | pwm = ERR_PTR(-ENOENT); | |
134 | } | |
135 | ||
136 | mutex_unlock(&pwm_lock); | |
137 | return pwm; | |
138 | } | |
139 | EXPORT_SYMBOL(pwm_request); | |
140 | ||
141 | void pwm_free(struct pwm_device *pwm) | |
142 | { | |
143 | mutex_lock(&pwm_lock); | |
144 | ||
145 | if (pwm->use_count) { | |
146 | pwm->use_count--; | |
147 | pwm->label = NULL; | |
148 | } else { | |
149 | pr_warning("PWM device already freed\n"); | |
150 | } | |
151 | ||
152 | mutex_unlock(&pwm_lock); | |
153 | } | |
154 | EXPORT_SYMBOL(pwm_free); | |
155 | ||
156 | static inline void __add_pwm(struct pwm_device *pwm) | |
157 | { | |
158 | mutex_lock(&pwm_lock); | |
159 | list_add_tail(&pwm->node, &pwm_list); | |
160 | mutex_unlock(&pwm_lock); | |
161 | } | |
162 | ||
163 | static int __devinit pwm_probe(struct platform_device *pdev) | |
164 | { | |
165 | struct pwm_device *pwms; | |
166 | struct resource *r; | |
167 | int ret = 0; | |
168 | int i; | |
169 | ||
170 | pwms = kzalloc(sizeof(struct pwm_device) * VT8500_NR_PWMS, GFP_KERNEL); | |
171 | if (pwms == NULL) { | |
172 | dev_err(&pdev->dev, "failed to allocate memory\n"); | |
173 | return -ENOMEM; | |
174 | } | |
175 | ||
176 | for (i = 0; i < VT8500_NR_PWMS; i++) { | |
177 | pwms[i].use_count = 0; | |
178 | pwms[i].pwm_id = i; | |
179 | pwms[i].pdev = pdev; | |
180 | } | |
181 | ||
182 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
183 | if (r == NULL) { | |
184 | dev_err(&pdev->dev, "no memory resource defined\n"); | |
185 | ret = -ENODEV; | |
186 | goto err_free; | |
187 | } | |
188 | ||
189 | r = request_mem_region(r->start, resource_size(r), pdev->name); | |
190 | if (r == NULL) { | |
191 | dev_err(&pdev->dev, "failed to request memory resource\n"); | |
192 | ret = -EBUSY; | |
193 | goto err_free; | |
194 | } | |
195 | ||
196 | pwms[0].regbase = ioremap(r->start, resource_size(r)); | |
197 | if (pwms[0].regbase == NULL) { | |
198 | dev_err(&pdev->dev, "failed to ioremap() registers\n"); | |
199 | ret = -ENODEV; | |
200 | goto err_free_mem; | |
201 | } | |
202 | ||
203 | for (i = 1; i < VT8500_NR_PWMS; i++) | |
204 | pwms[i].regbase = pwms[0].regbase; | |
205 | ||
206 | for (i = 0; i < VT8500_NR_PWMS; i++) | |
207 | __add_pwm(&pwms[i]); | |
208 | ||
209 | platform_set_drvdata(pdev, pwms); | |
210 | return 0; | |
211 | ||
212 | err_free_mem: | |
213 | release_mem_region(r->start, resource_size(r)); | |
214 | err_free: | |
215 | kfree(pwms); | |
216 | return ret; | |
217 | } | |
218 | ||
219 | static int __devexit pwm_remove(struct platform_device *pdev) | |
220 | { | |
221 | struct pwm_device *pwms; | |
222 | struct resource *r; | |
223 | int i; | |
224 | ||
225 | pwms = platform_get_drvdata(pdev); | |
226 | if (pwms == NULL) | |
227 | return -ENODEV; | |
228 | ||
229 | mutex_lock(&pwm_lock); | |
230 | ||
231 | for (i = 0; i < VT8500_NR_PWMS; i++) | |
232 | list_del(&pwms[i].node); | |
233 | mutex_unlock(&pwm_lock); | |
234 | ||
235 | iounmap(pwms[0].regbase); | |
236 | ||
237 | r = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
238 | release_mem_region(r->start, resource_size(r)); | |
239 | ||
240 | kfree(pwms); | |
241 | return 0; | |
242 | } | |
243 | ||
244 | static struct platform_driver pwm_driver = { | |
245 | .driver = { | |
246 | .name = "vt8500-pwm", | |
247 | .owner = THIS_MODULE, | |
248 | }, | |
249 | .probe = pwm_probe, | |
250 | .remove = __devexit_p(pwm_remove), | |
251 | }; | |
252 | ||
253 | static int __init pwm_init(void) | |
254 | { | |
255 | return platform_driver_register(&pwm_driver); | |
256 | } | |
257 | arch_initcall(pwm_init); | |
258 | ||
259 | static void __exit pwm_exit(void) | |
260 | { | |
261 | platform_driver_unregister(&pwm_driver); | |
262 | } | |
263 | module_exit(pwm_exit); | |
264 | ||
265 | MODULE_LICENSE("GPL"); |