Root/arch/arm/plat-samsung/pwm.c

1/* arch/arm/plat-s3c/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 * S3C series 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/slab.h>
18#include <linux/err.h>
19#include <linux/clk.h>
20#include <linux/io.h>
21#include <linux/pwm.h>
22
23#include <mach/irqs.h>
24#include <mach/map.h>
25
26#include <plat/devs.h>
27#include <plat/regs-timer.h>
28
29struct pwm_device {
30    struct list_head list;
31    struct platform_device *pdev;
32
33    struct clk *clk_div;
34    struct clk *clk;
35    const char *label;
36
37    unsigned int period_ns;
38    unsigned int duty_ns;
39
40    unsigned char tcon_base;
41    unsigned char running;
42    unsigned char use_count;
43    unsigned char pwm_id;
44};
45
46#define pwm_dbg(_pwm, msg...) dev_dbg(&(_pwm)->pdev->dev, msg)
47
48static struct clk *clk_scaler[2];
49
50/* Standard setup for a timer block. */
51
52#define TIMER_RESOURCE_SIZE (1)
53
54#define TIMER_RESOURCE(_tmr, _irq) \
55    (struct resource [TIMER_RESOURCE_SIZE]) { \
56        [0] = { \
57            .start = _irq, \
58            .end = _irq, \
59            .flags = IORESOURCE_IRQ \
60        } \
61    }
62
63#define DEFINE_S3C_TIMER(_tmr_no, _irq) \
64    .name = "s3c24xx-pwm", \
65    .id = _tmr_no, \
66    .num_resources = TIMER_RESOURCE_SIZE, \
67    .resource = TIMER_RESOURCE(_tmr_no, _irq), \
68
69/* since we already have an static mapping for the timer, we do not
70 * bother setting any IO resource for the base.
71 */
72
73struct platform_device s3c_device_timer[] = {
74    [0] = { DEFINE_S3C_TIMER(0, IRQ_TIMER0) },
75    [1] = { DEFINE_S3C_TIMER(1, IRQ_TIMER1) },
76    [2] = { DEFINE_S3C_TIMER(2, IRQ_TIMER2) },
77    [3] = { DEFINE_S3C_TIMER(3, IRQ_TIMER3) },
78    [4] = { DEFINE_S3C_TIMER(4, IRQ_TIMER4) },
79};
80
81static inline int pwm_is_tdiv(struct pwm_device *pwm)
82{
83    return clk_get_parent(pwm->clk) == pwm->clk_div;
84}
85
86static DEFINE_MUTEX(pwm_lock);
87static LIST_HEAD(pwm_list);
88
89struct pwm_device *pwm_request(int pwm_id, const char *label)
90{
91    struct pwm_device *pwm;
92    int found = 0;
93
94    mutex_lock(&pwm_lock);
95
96    list_for_each_entry(pwm, &pwm_list, list) {
97        if (pwm->pwm_id == pwm_id) {
98            found = 1;
99            break;
100        }
101    }
102
103    if (found) {
104        if (pwm->use_count == 0) {
105            pwm->use_count = 1;
106            pwm->label = label;
107        } else
108            pwm = ERR_PTR(-EBUSY);
109    } else
110        pwm = ERR_PTR(-ENOENT);
111
112    mutex_unlock(&pwm_lock);
113    return pwm;
114}
115
116EXPORT_SYMBOL(pwm_request);
117
118
119void pwm_free(struct pwm_device *pwm)
120{
121    mutex_lock(&pwm_lock);
122
123    if (pwm->use_count) {
124        pwm->use_count--;
125        pwm->label = NULL;
126    } else
127        printk(KERN_ERR "PWM%d device already freed\n", pwm->pwm_id);
128
129    mutex_unlock(&pwm_lock);
130}
131
132EXPORT_SYMBOL(pwm_free);
133
134#define pwm_tcon_start(pwm) (1 << (pwm->tcon_base + 0))
135#define pwm_tcon_invert(pwm) (1 << (pwm->tcon_base + 2))
136#define pwm_tcon_autoreload(pwm) (1 << (pwm->tcon_base + 3))
137#define pwm_tcon_manulupdate(pwm) (1 << (pwm->tcon_base + 1))
138
139int pwm_enable(struct pwm_device *pwm)
140{
141    unsigned long flags;
142    unsigned long tcon;
143
144    local_irq_save(flags);
145
146    tcon = __raw_readl(S3C2410_TCON);
147    tcon |= pwm_tcon_start(pwm);
148    __raw_writel(tcon, S3C2410_TCON);
149
150    local_irq_restore(flags);
151
152    pwm->running = 1;
153    return 0;
154}
155
156EXPORT_SYMBOL(pwm_enable);
157
158void pwm_disable(struct pwm_device *pwm)
159{
160    unsigned long flags;
161    unsigned long tcon;
162
163    local_irq_save(flags);
164
165    tcon = __raw_readl(S3C2410_TCON);
166    tcon &= ~pwm_tcon_start(pwm);
167    __raw_writel(tcon, S3C2410_TCON);
168
169    local_irq_restore(flags);
170
171    pwm->running = 0;
172}
173
174EXPORT_SYMBOL(pwm_disable);
175
176static unsigned long pwm_calc_tin(struct pwm_device *pwm, unsigned long freq)
177{
178    unsigned long tin_parent_rate;
179    unsigned int div;
180
181    tin_parent_rate = clk_get_rate(clk_get_parent(pwm->clk_div));
182    pwm_dbg(pwm, "tin parent at %lu\n", tin_parent_rate);
183
184    for (div = 2; div <= 16; div *= 2) {
185        if ((tin_parent_rate / (div << 16)) < freq)
186            return tin_parent_rate / div;
187    }
188
189    return tin_parent_rate / 16;
190}
191
192#define NS_IN_HZ (1000000000UL)
193
194int pwm_config(struct pwm_device *pwm, int duty_ns, int period_ns)
195{
196    unsigned long tin_rate;
197    unsigned long tin_ns;
198    unsigned long period;
199    unsigned long flags;
200    unsigned long tcon;
201    unsigned long tcnt;
202    long tcmp;
203
204    /* We currently avoid using 64bit arithmetic by using the
205     * fact that anything faster than 1Hz is easily representable
206     * by 32bits. */
207
208    if (period_ns > NS_IN_HZ || duty_ns > NS_IN_HZ)
209        return -ERANGE;
210
211    if (duty_ns > period_ns)
212        return -EINVAL;
213
214    if (period_ns == pwm->period_ns &&
215        duty_ns == pwm->duty_ns)
216        return 0;
217
218    /* The TCMP and TCNT can be read without a lock, they're not
219     * shared between the timers. */
220
221    tcmp = __raw_readl(S3C2410_TCMPB(pwm->pwm_id));
222    tcnt = __raw_readl(S3C2410_TCNTB(pwm->pwm_id));
223
224    period = NS_IN_HZ / period_ns;
225
226    pwm_dbg(pwm, "duty_ns=%d, period_ns=%d (%lu)\n",
227        duty_ns, period_ns, period);
228
229    /* Check to see if we are changing the clock rate of the PWM */
230
231    if (pwm->period_ns != period_ns) {
232        if (pwm_is_tdiv(pwm)) {
233            tin_rate = pwm_calc_tin(pwm, period);
234            clk_set_rate(pwm->clk_div, tin_rate);
235        } else
236            tin_rate = clk_get_rate(pwm->clk);
237
238        pwm->period_ns = period_ns;
239
240        pwm_dbg(pwm, "tin_rate=%lu\n", tin_rate);
241
242        tin_ns = NS_IN_HZ / tin_rate;
243        tcnt = period_ns / tin_ns;
244    } else
245        tin_ns = NS_IN_HZ / clk_get_rate(pwm->clk);
246
247    /* Note, counters count down */
248
249    tcmp = duty_ns / tin_ns;
250    tcmp = tcnt - tcmp;
251    /* the pwm hw only checks the compare register after a decrement,
252       so the pin never toggles if tcmp = tcnt */
253    if (tcmp == tcnt)
254        tcmp--;
255
256    pwm_dbg(pwm, "tin_ns=%lu, tcmp=%ld/%lu\n", tin_ns, tcmp, tcnt);
257
258    if (tcmp < 0)
259        tcmp = 0;
260
261    /* Update the PWM register block. */
262
263    local_irq_save(flags);
264
265    __raw_writel(tcmp, S3C2410_TCMPB(pwm->pwm_id));
266    __raw_writel(tcnt, S3C2410_TCNTB(pwm->pwm_id));
267
268    tcon = __raw_readl(S3C2410_TCON);
269    tcon |= pwm_tcon_manulupdate(pwm);
270    tcon |= pwm_tcon_autoreload(pwm);
271    __raw_writel(tcon, S3C2410_TCON);
272
273    tcon &= ~pwm_tcon_manulupdate(pwm);
274    __raw_writel(tcon, S3C2410_TCON);
275
276    local_irq_restore(flags);
277
278    return 0;
279}
280
281EXPORT_SYMBOL(pwm_config);
282
283static int pwm_register(struct pwm_device *pwm)
284{
285    pwm->duty_ns = -1;
286    pwm->period_ns = -1;
287
288    mutex_lock(&pwm_lock);
289    list_add_tail(&pwm->list, &pwm_list);
290    mutex_unlock(&pwm_lock);
291
292    return 0;
293}
294
295static int s3c_pwm_probe(struct platform_device *pdev)
296{
297    struct device *dev = &pdev->dev;
298    struct pwm_device *pwm;
299    unsigned long flags;
300    unsigned long tcon;
301    unsigned int id = pdev->id;
302    int ret;
303
304    if (id == 4) {
305        dev_err(dev, "TIMER4 is currently not supported\n");
306        return -ENXIO;
307    }
308
309    pwm = kzalloc(sizeof(struct pwm_device), GFP_KERNEL);
310    if (pwm == NULL) {
311        dev_err(dev, "failed to allocate pwm_device\n");
312        return -ENOMEM;
313    }
314
315    pwm->pdev = pdev;
316    pwm->pwm_id = id;
317
318    /* calculate base of control bits in TCON */
319    pwm->tcon_base = id == 0 ? 0 : (id * 4) + 4;
320
321    pwm->clk = clk_get(dev, "pwm-tin");
322    if (IS_ERR(pwm->clk)) {
323        dev_err(dev, "failed to get pwm tin clk\n");
324        ret = PTR_ERR(pwm->clk);
325        goto err_alloc;
326    }
327
328    pwm->clk_div = clk_get(dev, "pwm-tdiv");
329    if (IS_ERR(pwm->clk_div)) {
330        dev_err(dev, "failed to get pwm tdiv clk\n");
331        ret = PTR_ERR(pwm->clk_div);
332        goto err_clk_tin;
333    }
334
335    local_irq_save(flags);
336
337    tcon = __raw_readl(S3C2410_TCON);
338    tcon |= pwm_tcon_invert(pwm);
339    __raw_writel(tcon, S3C2410_TCON);
340
341    local_irq_restore(flags);
342
343
344    ret = pwm_register(pwm);
345    if (ret) {
346        dev_err(dev, "failed to register pwm\n");
347        goto err_clk_tdiv;
348    }
349
350    pwm_dbg(pwm, "config bits %02x\n",
351        (__raw_readl(S3C2410_TCON) >> pwm->tcon_base) & 0x0f);
352
353    dev_info(dev, "tin at %lu, tdiv at %lu, tin=%sclk, base %d\n",
354         clk_get_rate(pwm->clk),
355         clk_get_rate(pwm->clk_div),
356         pwm_is_tdiv(pwm) ? "div" : "ext", pwm->tcon_base);
357
358    platform_set_drvdata(pdev, pwm);
359    return 0;
360
361 err_clk_tdiv:
362    clk_put(pwm->clk_div);
363
364 err_clk_tin:
365    clk_put(pwm->clk);
366
367 err_alloc:
368    kfree(pwm);
369    return ret;
370}
371
372static int __devexit s3c_pwm_remove(struct platform_device *pdev)
373{
374    struct pwm_device *pwm = platform_get_drvdata(pdev);
375
376    clk_put(pwm->clk_div);
377    clk_put(pwm->clk);
378    kfree(pwm);
379
380    return 0;
381}
382
383#ifdef CONFIG_PM
384static int s3c_pwm_suspend(struct platform_device *pdev, pm_message_t state)
385{
386    struct pwm_device *pwm = platform_get_drvdata(pdev);
387
388    /* No one preserve these values during suspend so reset them
389     * Otherwise driver leaves PWM unconfigured if same values
390     * passed to pwm_config
391     */
392    pwm->period_ns = 0;
393    pwm->duty_ns = 0;
394
395    return 0;
396}
397
398static int s3c_pwm_resume(struct platform_device *pdev)
399{
400    struct pwm_device *pwm = platform_get_drvdata(pdev);
401    unsigned long tcon;
402
403    /* Restore invertion */
404    tcon = __raw_readl(S3C2410_TCON);
405    tcon |= pwm_tcon_invert(pwm);
406    __raw_writel(tcon, S3C2410_TCON);
407
408    return 0;
409}
410
411#else
412#define s3c_pwm_suspend NULL
413#define s3c_pwm_resume NULL
414#endif
415
416static struct platform_driver s3c_pwm_driver = {
417    .driver = {
418        .name = "s3c24xx-pwm",
419        .owner = THIS_MODULE,
420    },
421    .probe = s3c_pwm_probe,
422    .remove = __devexit_p(s3c_pwm_remove),
423    .suspend = s3c_pwm_suspend,
424    .resume = s3c_pwm_resume,
425};
426
427static int __init pwm_init(void)
428{
429    int ret;
430
431    clk_scaler[0] = clk_get(NULL, "pwm-scaler0");
432    clk_scaler[1] = clk_get(NULL, "pwm-scaler1");
433
434    if (IS_ERR(clk_scaler[0]) || IS_ERR(clk_scaler[1])) {
435        printk(KERN_ERR "%s: failed to get scaler clocks\n", __func__);
436        return -EINVAL;
437    }
438
439    ret = platform_driver_register(&s3c_pwm_driver);
440    if (ret)
441        printk(KERN_ERR "%s: failed to add pwm driver\n", __func__);
442
443    return ret;
444}
445
446arch_initcall(pwm_init);
447

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