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authorDavid Brownell <david-b@pacbell.net>2008-02-08 07:21:21 -0500
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2008-02-08 12:22:38 -0500
commit9a1e8eb1f0b76b5e72a2343ad881c81b08dd6410 (patch)
treef844d0e1316b49fd66cf773009ba2c3d46fcd18f /drivers/misc/atmel_pwm.c
parentc8cece84c9f36410de5164735e909603426e4d5f (diff)
Basic PWM driver for AVR32 and AT91
PWM device setup, and a simple PWM driver exposing a programming interface giving access to each channel's full capabilities. Note that this doesn't support starting several channels in synch. [hskinnemoen@atmel.com: allocate platform device dynamically] [hskinnemoen@atmel.com: Kconfig fix] Signed-off-by: David Brownell <dbrownell@users.sourceforge.net> Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com> Cc: Andrew Victor <linux@maxim.org.za> Cc: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/misc/atmel_pwm.c')
-rw-r--r--drivers/misc/atmel_pwm.c409
1 files changed, 409 insertions, 0 deletions
diff --git a/drivers/misc/atmel_pwm.c b/drivers/misc/atmel_pwm.c
new file mode 100644
index 000000000000..f8d3b9a76cbd
--- /dev/null
+++ b/drivers/misc/atmel_pwm.c
@@ -0,0 +1,409 @@
1#include <linux/module.h>
2#include <linux/clk.h>
3#include <linux/err.h>
4#include <linux/io.h>
5#include <linux/interrupt.h>
6#include <linux/platform_device.h>
7#include <linux/atmel_pwm.h>
8
9
10/*
11 * This is a simple driver for the PWM controller found in various newer
12 * Atmel SOCs, including the AVR32 series and the AT91sam9263.
13 *
14 * Chips with current Linux ports have only 4 PWM channels, out of max 32.
15 * AT32UC3A and AT32UC3B chips have 7 channels (but currently no Linux).
16 * Docs are inconsistent about the width of the channel counter registers;
17 * it's at least 16 bits, but several places say 20 bits.
18 */
19#define PWM_NCHAN 4 /* max 32 */
20
21struct pwm {
22 spinlock_t lock;
23 struct platform_device *pdev;
24 u32 mask;
25 int irq;
26 void __iomem *base;
27 struct clk *clk;
28 struct pwm_channel *channel[PWM_NCHAN];
29 void (*handler[PWM_NCHAN])(struct pwm_channel *);
30};
31
32
33/* global PWM controller registers */
34#define PWM_MR 0x00
35#define PWM_ENA 0x04
36#define PWM_DIS 0x08
37#define PWM_SR 0x0c
38#define PWM_IER 0x10
39#define PWM_IDR 0x14
40#define PWM_IMR 0x18
41#define PWM_ISR 0x1c
42
43static inline void pwm_writel(const struct pwm *p, unsigned offset, u32 val)
44{
45 __raw_writel(val, p->base + offset);
46}
47
48static inline u32 pwm_readl(const struct pwm *p, unsigned offset)
49{
50 return __raw_readl(p->base + offset);
51}
52
53static inline void __iomem *pwmc_regs(const struct pwm *p, int index)
54{
55 return p->base + 0x200 + index * 0x20;
56}
57
58static struct pwm *pwm;
59
60static void pwm_dumpregs(struct pwm_channel *ch, char *tag)
61{
62 struct device *dev = &pwm->pdev->dev;
63
64 dev_dbg(dev, "%s: mr %08x, sr %08x, imr %08x\n",
65 tag,
66 pwm_readl(pwm, PWM_MR),
67 pwm_readl(pwm, PWM_SR),
68 pwm_readl(pwm, PWM_IMR));
69 dev_dbg(dev,
70 "pwm ch%d - mr %08x, dty %u, prd %u, cnt %u\n",
71 ch->index,
72 pwm_channel_readl(ch, PWM_CMR),
73 pwm_channel_readl(ch, PWM_CDTY),
74 pwm_channel_readl(ch, PWM_CPRD),
75 pwm_channel_readl(ch, PWM_CCNT));
76}
77
78
79/**
80 * pwm_channel_alloc - allocate an unused PWM channel
81 * @index: identifies the channel
82 * @ch: structure to be initialized
83 *
84 * Drivers allocate PWM channels according to the board's wiring, and
85 * matching board-specific setup code. Returns zero or negative errno.
86 */
87int pwm_channel_alloc(int index, struct pwm_channel *ch)
88{
89 unsigned long flags;
90 int status = 0;
91
92 /* insist on PWM init, with this signal pinned out */
93 if (!pwm || !(pwm->mask & 1 << index))
94 return -ENODEV;
95
96 if (index < 0 || index >= PWM_NCHAN || !ch)
97 return -EINVAL;
98 memset(ch, 0, sizeof *ch);
99
100 spin_lock_irqsave(&pwm->lock, flags);
101 if (pwm->channel[index])
102 status = -EBUSY;
103 else {
104 clk_enable(pwm->clk);
105
106 ch->regs = pwmc_regs(pwm, index);
107 ch->index = index;
108
109 /* REVISIT: ap7000 seems to go 2x as fast as we expect!! */
110 ch->mck = clk_get_rate(pwm->clk);
111
112 pwm->channel[index] = ch;
113 pwm->handler[index] = NULL;
114
115 /* channel and irq are always disabled when we return */
116 pwm_writel(pwm, PWM_DIS, 1 << index);
117 pwm_writel(pwm, PWM_IDR, 1 << index);
118 }
119 spin_unlock_irqrestore(&pwm->lock, flags);
120 return status;
121}
122EXPORT_SYMBOL(pwm_channel_alloc);
123
124static int pwmcheck(struct pwm_channel *ch)
125{
126 int index;
127
128 if (!pwm)
129 return -ENODEV;
130 if (!ch)
131 return -EINVAL;
132 index = ch->index;
133 if (index < 0 || index >= PWM_NCHAN || pwm->channel[index] != ch)
134 return -EINVAL;
135
136 return index;
137}
138
139/**
140 * pwm_channel_free - release a previously allocated channel
141 * @ch: the channel being released
142 *
143 * The channel is completely shut down (counter and IRQ disabled),
144 * and made available for re-use. Returns zero, or negative errno.
145 */
146int pwm_channel_free(struct pwm_channel *ch)
147{
148 unsigned long flags;
149 int t;
150
151 spin_lock_irqsave(&pwm->lock, flags);
152 t = pwmcheck(ch);
153 if (t >= 0) {
154 pwm->channel[t] = NULL;
155 pwm->handler[t] = NULL;
156
157 /* channel and irq are always disabled when we return */
158 pwm_writel(pwm, PWM_DIS, 1 << t);
159 pwm_writel(pwm, PWM_IDR, 1 << t);
160
161 clk_disable(pwm->clk);
162 t = 0;
163 }
164 spin_unlock_irqrestore(&pwm->lock, flags);
165 return t;
166}
167EXPORT_SYMBOL(pwm_channel_free);
168
169int __pwm_channel_onoff(struct pwm_channel *ch, int enabled)
170{
171 unsigned long flags;
172 int t;
173
174 /* OMITTED FUNCTIONALITY: starting several channels in synch */
175
176 spin_lock_irqsave(&pwm->lock, flags);
177 t = pwmcheck(ch);
178 if (t >= 0) {
179 pwm_writel(pwm, enabled ? PWM_ENA : PWM_DIS, 1 << t);
180 t = 0;
181 pwm_dumpregs(ch, enabled ? "enable" : "disable");
182 }
183 spin_unlock_irqrestore(&pwm->lock, flags);
184
185 return t;
186}
187EXPORT_SYMBOL(__pwm_channel_onoff);
188
189/**
190 * pwm_clk_alloc - allocate and configure CLKA or CLKB
191 * @prescale: from 0..10, the power of two used to divide MCK
192 * @div: from 1..255, the linear divisor to use
193 *
194 * Returns PWM_CPR_CLKA, PWM_CPR_CLKB, or negative errno. The allocated
195 * clock will run with a period of (2^prescale * div) / MCK, or twice as
196 * long if center aligned PWM output is used. The clock must later be
197 * deconfigured using pwm_clk_free().
198 */
199int pwm_clk_alloc(unsigned prescale, unsigned div)
200{
201 unsigned long flags;
202 u32 mr;
203 u32 val = (prescale << 8) | div;
204 int ret = -EBUSY;
205
206 if (prescale >= 10 || div == 0 || div > 255)
207 return -EINVAL;
208
209 spin_lock_irqsave(&pwm->lock, flags);
210 mr = pwm_readl(pwm, PWM_MR);
211 if ((mr & 0xffff) == 0) {
212 mr |= val;
213 ret = PWM_CPR_CLKA;
214 }
215 if ((mr & (0xffff << 16)) == 0) {
216 mr |= val << 16;
217 ret = PWM_CPR_CLKB;
218 }
219 if (ret > 0)
220 pwm_writel(pwm, PWM_MR, mr);
221 spin_unlock_irqrestore(&pwm->lock, flags);
222 return ret;
223}
224EXPORT_SYMBOL(pwm_clk_alloc);
225
226/**
227 * pwm_clk_free - deconfigure and release CLKA or CLKB
228 *
229 * Reverses the effect of pwm_clk_alloc().
230 */
231void pwm_clk_free(unsigned clk)
232{
233 unsigned long flags;
234 u32 mr;
235
236 spin_lock_irqsave(&pwm->lock, flags);
237 mr = pwm_readl(pwm, PWM_MR);
238 if (clk == PWM_CPR_CLKA)
239 pwm_writel(pwm, PWM_MR, mr & ~(0xffff << 0));
240 if (clk == PWM_CPR_CLKB)
241 pwm_writel(pwm, PWM_MR, mr & ~(0xffff << 16));
242 spin_unlock_irqrestore(&pwm->lock, flags);
243}
244EXPORT_SYMBOL(pwm_clk_free);
245
246/**
247 * pwm_channel_handler - manage channel's IRQ handler
248 * @ch: the channel
249 * @handler: the handler to use, possibly NULL
250 *
251 * If the handler is non-null, the handler will be called after every
252 * period of this PWM channel. If the handler is null, this channel
253 * won't generate an IRQ.
254 */
255int pwm_channel_handler(struct pwm_channel *ch,
256 void (*handler)(struct pwm_channel *ch))
257{
258 unsigned long flags;
259 int t;
260
261 spin_lock_irqsave(&pwm->lock, flags);
262 t = pwmcheck(ch);
263 if (t >= 0) {
264 pwm->handler[t] = handler;
265 pwm_writel(pwm, handler ? PWM_IER : PWM_IDR, 1 << t);
266 t = 0;
267 }
268 spin_unlock_irqrestore(&pwm->lock, flags);
269
270 return t;
271}
272EXPORT_SYMBOL(pwm_channel_handler);
273
274static irqreturn_t pwm_irq(int id, void *_pwm)
275{
276 struct pwm *p = _pwm;
277 irqreturn_t handled = IRQ_NONE;
278 u32 irqstat;
279 int index;
280
281 spin_lock(&p->lock);
282
283 /* ack irqs, then handle them */
284 irqstat = pwm_readl(pwm, PWM_ISR);
285
286 while (irqstat) {
287 struct pwm_channel *ch;
288 void (*handler)(struct pwm_channel *ch);
289
290 index = ffs(irqstat) - 1;
291 irqstat &= ~(1 << index);
292 ch = pwm->channel[index];
293 handler = pwm->handler[index];
294 if (handler && ch) {
295 spin_unlock(&p->lock);
296 handler(ch);
297 spin_lock(&p->lock);
298 handled = IRQ_HANDLED;
299 }
300 }
301
302 spin_unlock(&p->lock);
303 return handled;
304}
305
306static int __init pwm_probe(struct platform_device *pdev)
307{
308 struct resource *r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
309 int irq = platform_get_irq(pdev, 0);
310 u32 *mp = pdev->dev.platform_data;
311 struct pwm *p;
312 int status = -EIO;
313
314 if (pwm)
315 return -EBUSY;
316 if (!r || irq < 0 || !mp || !*mp)
317 return -ENODEV;
318 if (*mp & ~((1<<PWM_NCHAN)-1)) {
319 dev_warn(&pdev->dev, "mask 0x%x ... more than %d channels\n",
320 *mp, PWM_NCHAN);
321 return -EINVAL;
322 }
323
324 p = kzalloc(sizeof(*p), GFP_KERNEL);
325 if (!p)
326 return -ENOMEM;
327
328 spin_lock_init(&p->lock);
329 p->pdev = pdev;
330 p->mask = *mp;
331 p->irq = irq;
332 p->base = ioremap(r->start, r->end - r->start + 1);
333 if (!p->base)
334 goto fail;
335 p->clk = clk_get(&pdev->dev, "mck");
336 if (IS_ERR(p->clk)) {
337 status = PTR_ERR(p->clk);
338 p->clk = NULL;
339 goto fail;
340 }
341
342 status = request_irq(irq, pwm_irq, 0, pdev->name, p);
343 if (status < 0)
344 goto fail;
345
346 pwm = p;
347 platform_set_drvdata(pdev, p);
348
349 return 0;
350
351fail:
352 if (p->clk)
353 clk_put(p->clk);
354 if (p->base)
355 iounmap(p->base);
356
357 kfree(p);
358 return status;
359}
360
361static int __exit pwm_remove(struct platform_device *pdev)
362{
363 struct pwm *p = platform_get_drvdata(pdev);
364
365 if (p != pwm)
366 return -EINVAL;
367
368 clk_enable(pwm->clk);
369 pwm_writel(pwm, PWM_DIS, (1 << PWM_NCHAN) - 1);
370 pwm_writel(pwm, PWM_IDR, (1 << PWM_NCHAN) - 1);
371 clk_disable(pwm->clk);
372
373 pwm = NULL;
374
375 free_irq(p->irq, p);
376 clk_put(p->clk);
377 iounmap(p->base);
378 kfree(p);
379
380 return 0;
381}
382
383static struct platform_driver atmel_pwm_driver = {
384 .driver = {
385 .name = "atmel_pwm",
386 .owner = THIS_MODULE,
387 },
388 .remove = __exit_p(pwm_remove),
389
390 /* NOTE: PWM can keep running in AVR32 "idle" and "frozen" states;
391 * and all AT91sam9263 states, albeit at reduced clock rate if
392 * MCK becomes the slow clock (i.e. what Linux labels STR).
393 */
394};
395
396static int __init pwm_init(void)
397{
398 return platform_driver_probe(&atmel_pwm_driver, pwm_probe);
399}
400module_init(pwm_init);
401
402static void __exit pwm_exit(void)
403{
404 platform_driver_unregister(&atmel_pwm_driver);
405}
406module_exit(pwm_exit);
407
408MODULE_DESCRIPTION("Driver for AT32/AT91 PWM module");
409MODULE_LICENSE("GPL");