1 /* arch/arm/plat-s3c24xx/pwm.c
2 *
3 * Copyright (c) 2007 Ben Dooks
4 * Copyright (c) 2008 Simtec Electronics
5 * Ben Dooks <ben@simtec.co.uk>, <ben-linux@fluff.org>
6 *
7 * S3C24XX PWM device core
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License.
12 */
13
14 #include <linux/module.h>
15 #include <linux/kernel.h>
16 #include <linux/platform_device.h>
17 #include <linux/err.h>
18 #include <linux/clk.h>
19 #include <linux/io.h>
20 #include <linux/pwm.h>
21
22 #include <mach/irqs.h>
23
24 #include <plat/devs.h>
25 #include <plat/regs-timer.h>
26
27 struct pwm_device {
28 struct list_head list;
29 struct platform_device *pdev;
30
31 struct clk *clk_div;
32 struct clk *clk;
33 const char *label;
34
35 unsigned int period_ns;
36 unsigned int duty_ns;
37
38 unsigned char tcon_base;
39 unsigned char running;
40 unsigned char use_count;
41 unsigned char pwm_id;
42 };
43
44 #define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
45
46 static struct clk *clk_scaler[2];
47
48 /* Standard setup for a timer block. */
49
50 #define TIMER_RESOURCE_SIZE (1)
51
52 #define TIMER_RESOURCE(_tmr, _irq) \
53 (struct resource [TIMER_RESOURCE_SIZE]) { \
54 [0] = { \
55 .start = _irq, \
56 .end = _irq, \
57 .flags = IORESOURCE_IRQ \
58 } \
59 }
60
61 #define DEFINE_S3C_TIMER(_tmr_no, _irq) \
62 .name = "s3c24xx-pwm", \
63 .id = _tmr_no, \
64 .num_resources = TIMER_RESOURCE_SIZE, \
65 .resource = TIMER_RESOURCE(_tmr_no, _irq), \
66
67 /* since we already have an static mapping for the timer, we do not
68 * bother setting any IO resource for the base.
69 */
70
71 struct platform_device s3c_device_timer[] = {
72 [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
73 [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
74 [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
75 [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
76 [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
77 };
78
pwm_is_tdiv(struct pwm_device * pwm)79 static inline int pwm_is_tdiv(struct pwm_device *pwm)
80 {
81 return clk_get_parent(pwm->clk) == pwm->clk_div;
82 }
83
84 static DEFINE_MUTEX(pwm_lock);
85 static LIST_HEAD(pwm_list);
86
pwm_request(int pwm_id,const char * label)87 struct pwm_device *pwm_request(int pwm_id, const char *label)
88 {
89 struct pwm_device *pwm;
90 int found = 0;
91
92 mutex_lock(&pwm_lock);
93
94 list_for_each_entry(pwm, &pwm_list, list) {
95 if (pwm->pwm_id == pwm_id) {
96 found = 1;
97 break;
98 }
99 }
100
101 if (found) {
102 if (pwm->use_count == 0) {
103 pwm->use_count = 1;
104 pwm->label = label;
105 } else
106 pwm = ERR_PTR(-EBUSY);
107 } else
108 pwm = ERR_PTR(-ENOENT);
109
110 mutex_unlock(&pwm_lock);
111 return pwm;
112 }
113
114 EXPORT_SYMBOL(pwm_request);
115
116
pwm_free(struct pwm_device * pwm)117 void pwm_free(struct pwm_device *pwm)
118 {
119 mutex_lock(&pwm_lock);
120
121 if (pwm->use_count) {
122 pwm->use_count--;
123 pwm->label = NULL;
124 } else
125 printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
126
127 mutex_unlock(&pwm_lock);
128 }
129
130 EXPORT_SYMBOL(pwm_free);
131
132 #define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
133 #define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
134 #define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
135 #define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
136
pwm_enable(struct pwm_device * pwm)137 int pwm_enable(struct pwm_device *pwm)
138 {
139 unsigned long flags;
140 unsigned long tcon;
141
142 local_irq_save(flags);
143
144 tcon = __raw_readl(S3C2410_TCON);
145 tcon |= pwm_tcon_start(pwm);
146 __raw_writel(tcon, S3C2410_TCON);
147
148 local_irq_restore(flags);
149
150 pwm->running = 1;
151 return 0;
152 }
153
154 EXPORT_SYMBOL(pwm_enable);
155
pwm_disable(struct pwm_device * pwm)156 void pwm_disable(struct pwm_device *pwm)
157 {
158 unsigned long flags;
159 unsigned long tcon;
160
161 local_irq_save(flags);
162
163 tcon = __raw_readl(S3C2410_TCON);
164 tcon &= ~pwm_tcon_start(pwm);
165 __raw_writel(tcon, S3C2410_TCON);
166
167 local_irq_restore(flags);
168
169 pwm->running = 0;
170 }
171
172 EXPORT_SYMBOL(pwm_disable);
173
pwm_calc_tin(struct pwm_device * pwm,unsigned long freq)174 static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
175 {
176 unsigned long tin_parent_rate;
177 unsigned int div;
178
179 tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
180 pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
181
182 for (div = 2; div <= 16; div *= 2) {
183 if ((tin_parent_rate / (div << 16)) < freq)
184 return tin_parent_rate / div;
185 }
186
187 return tin_parent_rate / 16;
188 }
189
190 #define NS_IN_HZ (1000000000UL)
191
pwm_config(struct pwm_device * pwm,int duty_ns,int period_ns)192 int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
193 {
194 unsigned long tin_rate;
195 unsigned long tin_ns;
196 unsigned long period;
197 unsigned long flags;
198 unsigned long tcon;
199 unsigned long tcnt;
200 long tcmp;
201
202 /* We currently avoid using 64bit arithmetic by using the
203 * fact that anything faster than 1Hz is easily representable
204 * by 32bits. */
205
206 if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
207 return -ERANGE;
208
209 if (duty_ns > period_ns)
210 return -EINVAL;
211
212 if (period_ns == pwm->period_ns &&
213 duty_ns == pwm->duty_ns)
214 return 0;
215
216 /* The TCMP and TCNT can be read without a lock, they're not
217 * shared between the timers. */
218
219 tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
220 tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
221
222 period = NS_IN_HZ / period_ns;
223
224 pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
225 duty_ns, period_ns, period);
226
227 /* Check to see if we are changing the clock rate of the PWM */
228
229 if (pwm->period_ns != period_ns) {
230 if (pwm_is_tdiv(pwm)) {
231 tin_rate = pwm_calc_tin(pwm, period);
232 clk_set_rate(pwm->clk_div, tin_rate);
233 } else
234 tin_rate = clk_get_rate(pwm->clk);
235
236 pwm->period_ns = period_ns;
237
238 pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
239
240 tin_ns = NS_IN_HZ / tin_rate;
241 tcnt = period_ns / tin_ns;
242 } else
243 tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
244
245 /* Note, counters count down */
246
247 tcmp = duty_ns / tin_ns;
248 tcmp = tcnt - tcmp;
249
250 pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
251
252 if (tcmp < 0)
253 tcmp = 0;
254
255 /* Update the PWM register block. */
256
257 local_irq_save(flags);
258
259 __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
260 __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
261
262 tcon = __raw_readl(S3C2410_TCON);
263 tcon |= pwm_tcon_manulupdate(pwm);
264 tcon |= pwm_tcon_autoreload(pwm);
265 __raw_writel(tcon, S3C2410_TCON);
266
267 tcon &= ~pwm_tcon_manulupdate(pwm);
268 __raw_writel(tcon, S3C2410_TCON);
269
270 local_irq_restore(flags);
271
272 return 0;
273 }
274
275 EXPORT_SYMBOL(pwm_config);
276
pwm_register(struct pwm_device * pwm)277 static int pwm_register(struct pwm_device *pwm)
278 {
279 pwm->duty_ns = -1;
280 pwm->period_ns = -1;
281
282 mutex_lock(&pwm_lock);
283 list_add_tail(&pwm->list, &pwm_list);
284 mutex_unlock(&pwm_lock);
285
286 return 0;
287 }
288
s3c_pwm_probe(struct platform_device * pdev)289 static int s3c_pwm_probe(struct platform_device *pdev)
290 {
291 struct device *dev = &pdev->dev;
292 struct pwm_device *pwm;
293 unsigned long flags;
294 unsigned long tcon;
295 unsigned int id = pdev->id;
296 int ret;
297
298 if (id == 4) {
299 dev_err(dev, "TIMER4 is currently not supported\n");
300 return -ENXIO;
301 }
302
303 pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
304 if (pwm == NULL) {
305 dev_err(dev, "failed to allocate pwm_device\n");
306 return -ENOMEM;
307 }
308
309 pwm->pdev = pdev;
310 pwm->pwm_id = id;
311
312 /* calculate base of control bits in TCON */
313 pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
314
315 pwm->clk = clk_get(dev, "pwm-tin");
316 if (IS_ERR(pwm->clk)) {
317 dev_err(dev, "failed to get pwm tin clk\n");
318 ret = PTR_ERR(pwm->clk);
319 goto err_alloc;
320 }
321
322 pwm->clk_div = clk_get(dev, "pwm-tdiv");
323 if (IS_ERR(pwm->clk_div)) {
324 dev_err(dev, "failed to get pwm tdiv clk\n");
325 ret = PTR_ERR(pwm->clk_div);
326 goto err_clk_tin;
327 }
328
329 local_irq_save(flags);
330
331 tcon = __raw_readl(S3C2410_TCON);
332 tcon |= pwm_tcon_invert(pwm);
333 __raw_writel(tcon, S3C2410_TCON);
334
335 local_irq_restore(flags);
336
337
338 ret = pwm_register(pwm);
339 if (ret) {
340 dev_err(dev, "failed to register pwm\n");
341 goto err_clk_tdiv;
342 }
343
344 pwm_dbg(pwm, "config bits %02x\n",
345 (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
346
347 dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
348 clk_get_rate(pwm->clk),
349 clk_get_rate(pwm->clk_div),
350 pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
351
352 platform_set_drvdata(pdev, pwm);
353 return 0;
354
355 err_clk_tdiv:
356 clk_put(pwm->clk_div);
357
358 err_clk_tin:
359 clk_put(pwm->clk);
360
361 err_alloc:
362 kfree(pwm);
363 return ret;
364 }
365
s3c_pwm_remove(struct platform_device * pdev)366 static int s3c_pwm_remove(struct platform_device *pdev)
367 {
368 struct pwm_device *pwm = platform_get_drvdata(pdev);
369
370 clk_put(pwm->clk_div);
371 clk_put(pwm->clk);
372 kfree(pwm);
373
374 return 0;
375 }
376
377 static struct platform_driver s3c_pwm_driver = {
378 .driver = {
379 .name = "s3c24xx-pwm",
380 .owner = THIS_MODULE,
381 },
382 .probe = s3c_pwm_probe,
383 .remove = __devexit_p(s3c_pwm_remove),
384 };
385
pwm_init(void)386 static int __init pwm_init(void)
387 {
388 int ret;
389
390 clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
391 clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
392
393 if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
394 printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
395 return -EINVAL;
396 }
397
398 ret = platform_driver_register(&s3c_pwm_driver);
399 if (ret)
400 printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
401
402 return ret;
403 }
404
405 arch_initcall(pwm_init);
406