1/*
2 * R-Mobile TPU PWM driver
3 *
4 * Copyright (C) 2012 Renesas Solutions Corp.
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License
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/clk.h>
17#include <linux/err.h>
18#include <linux/io.h>
19#include <linux/init.h>
20#include <linux/ioport.h>
21#include <linux/module.h>
22#include <linux/mutex.h>
23#include <linux/of.h>
24#include <linux/platform_device.h>
25#include <linux/pm_runtime.h>
26#include <linux/pwm.h>
27#include <linux/slab.h>
28#include <linux/spinlock.h>
29
30#define TPU_CHANNEL_MAX		4
31
32#define TPU_TSTR		0x00	/* Timer start register (shared) */
33
34#define TPU_TCRn		0x00	/* Timer control register */
35#define TPU_TCR_CCLR_NONE	(0 << 5)
36#define TPU_TCR_CCLR_TGRA	(1 << 5)
37#define TPU_TCR_CCLR_TGRB	(2 << 5)
38#define TPU_TCR_CCLR_TGRC	(5 << 5)
39#define TPU_TCR_CCLR_TGRD	(6 << 5)
40#define TPU_TCR_CKEG_RISING	(0 << 3)
41#define TPU_TCR_CKEG_FALLING	(1 << 3)
42#define TPU_TCR_CKEG_BOTH	(2 << 3)
43#define TPU_TMDRn		0x04	/* Timer mode register */
44#define TPU_TMDR_BFWT		(1 << 6)
45#define TPU_TMDR_BFB		(1 << 5)
46#define TPU_TMDR_BFA		(1 << 4)
47#define TPU_TMDR_MD_NORMAL	(0 << 0)
48#define TPU_TMDR_MD_PWM		(2 << 0)
49#define TPU_TIORn		0x08	/* Timer I/O control register */
50#define TPU_TIOR_IOA_0		(0 << 0)
51#define TPU_TIOR_IOA_0_CLR	(1 << 0)
52#define TPU_TIOR_IOA_0_SET	(2 << 0)
53#define TPU_TIOR_IOA_0_TOGGLE	(3 << 0)
54#define TPU_TIOR_IOA_1		(4 << 0)
55#define TPU_TIOR_IOA_1_CLR	(5 << 0)
56#define TPU_TIOR_IOA_1_SET	(6 << 0)
57#define TPU_TIOR_IOA_1_TOGGLE	(7 << 0)
58#define TPU_TIERn		0x0c	/* Timer interrupt enable register */
59#define TPU_TSRn		0x10	/* Timer status register */
60#define TPU_TCNTn		0x14	/* Timer counter */
61#define TPU_TGRAn		0x18	/* Timer general register A */
62#define TPU_TGRBn		0x1c	/* Timer general register B */
63#define TPU_TGRCn		0x20	/* Timer general register C */
64#define TPU_TGRDn		0x24	/* Timer general register D */
65
66#define TPU_CHANNEL_OFFSET	0x10
67#define TPU_CHANNEL_SIZE	0x40
68
69enum tpu_pin_state {
70	TPU_PIN_INACTIVE,		/* Pin is driven inactive */
71	TPU_PIN_PWM,			/* Pin is driven by PWM */
72	TPU_PIN_ACTIVE,			/* Pin is driven active */
73};
74
75struct tpu_device;
76
77struct tpu_pwm_device {
78	bool timer_on;			/* Whether the timer is running */
79
80	struct tpu_device *tpu;
81	unsigned int channel;		/* Channel number in the TPU */
82
83	enum pwm_polarity polarity;
84	unsigned int prescaler;
85	u16 period;
86	u16 duty;
87};
88
89struct tpu_device {
90	struct platform_device *pdev;
91	struct pwm_chip chip;
92	spinlock_t lock;
93
94	void __iomem *base;
95	struct clk *clk;
96};
97
98#define to_tpu_device(c)	container_of(c, struct tpu_device, chip)
99
100static void tpu_pwm_write(struct tpu_pwm_device *pwm, int reg_nr, u16 value)
101{
102	void __iomem *base = pwm->tpu->base + TPU_CHANNEL_OFFSET
103			   + pwm->channel * TPU_CHANNEL_SIZE;
104
105	iowrite16(value, base + reg_nr);
106}
107
108static void tpu_pwm_set_pin(struct tpu_pwm_device *pwm,
109			    enum tpu_pin_state state)
110{
111	static const char * const states[] = { "inactive", "PWM", "active" };
112
113	dev_dbg(&pwm->tpu->pdev->dev, "%u: configuring pin as %s\n",
114		pwm->channel, states[state]);
115
116	switch (state) {
117	case TPU_PIN_INACTIVE:
118		tpu_pwm_write(pwm, TPU_TIORn,
119			      pwm->polarity == PWM_POLARITY_INVERSED ?
120			      TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
121		break;
122	case TPU_PIN_PWM:
123		tpu_pwm_write(pwm, TPU_TIORn,
124			      pwm->polarity == PWM_POLARITY_INVERSED ?
125			      TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
126		break;
127	case TPU_PIN_ACTIVE:
128		tpu_pwm_write(pwm, TPU_TIORn,
129			      pwm->polarity == PWM_POLARITY_INVERSED ?
130			      TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
131		break;
132	}
133}
134
135static void tpu_pwm_start_stop(struct tpu_pwm_device *pwm, int start)
136{
137	unsigned long flags;
138	u16 value;
139
140	spin_lock_irqsave(&pwm->tpu->lock, flags);
141	value = ioread16(pwm->tpu->base + TPU_TSTR);
142
143	if (start)
144		value |= 1 << pwm->channel;
145	else
146		value &= ~(1 << pwm->channel);
147
148	iowrite16(value, pwm->tpu->base + TPU_TSTR);
149	spin_unlock_irqrestore(&pwm->tpu->lock, flags);
150}
151
152static int tpu_pwm_timer_start(struct tpu_pwm_device *pwm)
153{
154	int ret;
155
156	if (!pwm->timer_on) {
157		/* Wake up device and enable clock. */
158		pm_runtime_get_sync(&pwm->tpu->pdev->dev);
159		ret = clk_prepare_enable(pwm->tpu->clk);
160		if (ret) {
161			dev_err(&pwm->tpu->pdev->dev, "cannot enable clock\n");
162			return ret;
163		}
164		pwm->timer_on = true;
165	}
166
167	/*
168	 * Make sure the channel is stopped, as we need to reconfigure it
169	 * completely. First drive the pin to the inactive state to avoid
170	 * glitches.
171	 */
172	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
173	tpu_pwm_start_stop(pwm, false);
174
175	/*
176	 * - Clear TCNT on TGRB match
177	 * - Count on rising edge
178	 * - Set prescaler
179	 * - Output 0 until TGRA, output 1 until TGRB (active low polarity)
180	 * - Output 1 until TGRA, output 0 until TGRB (active high polarity
181	 * - PWM mode
182	 */
183	tpu_pwm_write(pwm, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING |
184		      pwm->prescaler);
185	tpu_pwm_write(pwm, TPU_TMDRn, TPU_TMDR_MD_PWM);
186	tpu_pwm_set_pin(pwm, TPU_PIN_PWM);
187	tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
188	tpu_pwm_write(pwm, TPU_TGRBn, pwm->period);
189
190	dev_dbg(&pwm->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
191		pwm->channel, pwm->duty, pwm->period);
192
193	/* Start the channel. */
194	tpu_pwm_start_stop(pwm, true);
195
196	return 0;
197}
198
199static void tpu_pwm_timer_stop(struct tpu_pwm_device *pwm)
200{
201	if (!pwm->timer_on)
202		return;
203
204	/* Disable channel. */
205	tpu_pwm_start_stop(pwm, false);
206
207	/* Stop clock and mark device as idle. */
208	clk_disable_unprepare(pwm->tpu->clk);
209	pm_runtime_put(&pwm->tpu->pdev->dev);
210
211	pwm->timer_on = false;
212}
213
214/* -----------------------------------------------------------------------------
215 * PWM API
216 */
217
218static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *_pwm)
219{
220	struct tpu_device *tpu = to_tpu_device(chip);
221	struct tpu_pwm_device *pwm;
222
223	if (_pwm->hwpwm >= TPU_CHANNEL_MAX)
224		return -EINVAL;
225
226	pwm = kzalloc(sizeof(*pwm), GFP_KERNEL);
227	if (pwm == NULL)
228		return -ENOMEM;
229
230	pwm->tpu = tpu;
231	pwm->channel = _pwm->hwpwm;
232	pwm->polarity = PWM_POLARITY_NORMAL;
233	pwm->prescaler = 0;
234	pwm->period = 0;
235	pwm->duty = 0;
236
237	pwm->timer_on = false;
238
239	pwm_set_chip_data(_pwm, pwm);
240
241	return 0;
242}
243
244static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *_pwm)
245{
246	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
247
248	tpu_pwm_timer_stop(pwm);
249	kfree(pwm);
250}
251
252static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *_pwm,
253			  int duty_ns, int period_ns)
254{
255	static const unsigned int prescalers[] = { 1, 4, 16, 64 };
256	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
257	struct tpu_device *tpu = to_tpu_device(chip);
258	unsigned int prescaler;
259	bool duty_only = false;
260	u32 clk_rate;
261	u32 period;
262	u32 duty;
263	int ret;
264
265	/*
266	 * Pick a prescaler to avoid overflowing the counter.
267	 * TODO: Pick the highest acceptable prescaler.
268	 */
269	clk_rate = clk_get_rate(tpu->clk);
270
271	for (prescaler = 0; prescaler < ARRAY_SIZE(prescalers); ++prescaler) {
272		period = clk_rate / prescalers[prescaler]
273		       / (NSEC_PER_SEC / period_ns);
274		if (period <= 0xffff)
275			break;
276	}
277
278	if (prescaler == ARRAY_SIZE(prescalers) || period == 0) {
279		dev_err(&tpu->pdev->dev, "clock rate mismatch\n");
280		return -ENOTSUPP;
281	}
282
283	if (duty_ns) {
284		duty = clk_rate / prescalers[prescaler]
285		     / (NSEC_PER_SEC / duty_ns);
286		if (duty > period)
287			return -EINVAL;
288	} else {
289		duty = 0;
290	}
291
292	dev_dbg(&tpu->pdev->dev,
293		"rate %u, prescaler %u, period %u, duty %u\n",
294		clk_rate, prescalers[prescaler], period, duty);
295
296	if (pwm->prescaler == prescaler && pwm->period == period)
297		duty_only = true;
298
299	pwm->prescaler = prescaler;
300	pwm->period = period;
301	pwm->duty = duty;
302
303	/* If the channel is disabled we're done. */
304	if (!pwm_is_enabled(_pwm))
305		return 0;
306
307	if (duty_only && pwm->timer_on) {
308		/*
309		 * If only the duty cycle changed and the timer is already
310		 * running, there's no need to reconfigure it completely, Just
311		 * modify the duty cycle.
312		 */
313		tpu_pwm_write(pwm, TPU_TGRAn, pwm->duty);
314		dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", pwm->channel,
315			pwm->duty);
316	} else {
317		/* Otherwise perform a full reconfiguration. */
318		ret = tpu_pwm_timer_start(pwm);
319		if (ret < 0)
320			return ret;
321	}
322
323	if (duty == 0 || duty == period) {
324		/*
325		 * To avoid running the timer when not strictly required, handle
326		 * 0% and 100% duty cycles as fixed levels and stop the timer.
327		 */
328		tpu_pwm_set_pin(pwm, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
329		tpu_pwm_timer_stop(pwm);
330	}
331
332	return 0;
333}
334
335static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *_pwm,
336				enum pwm_polarity polarity)
337{
338	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
339
340	pwm->polarity = polarity;
341
342	return 0;
343}
344
345static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *_pwm)
346{
347	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
348	int ret;
349
350	ret = tpu_pwm_timer_start(pwm);
351	if (ret < 0)
352		return ret;
353
354	/*
355	 * To avoid running the timer when not strictly required, handle 0% and
356	 * 100% duty cycles as fixed levels and stop the timer.
357	 */
358	if (pwm->duty == 0 || pwm->duty == pwm->period) {
359		tpu_pwm_set_pin(pwm, pwm->duty ?
360				TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
361		tpu_pwm_timer_stop(pwm);
362	}
363
364	return 0;
365}
366
367static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *_pwm)
368{
369	struct tpu_pwm_device *pwm = pwm_get_chip_data(_pwm);
370
371	/* The timer must be running to modify the pin output configuration. */
372	tpu_pwm_timer_start(pwm);
373	tpu_pwm_set_pin(pwm, TPU_PIN_INACTIVE);
374	tpu_pwm_timer_stop(pwm);
375}
376
377static const struct pwm_ops tpu_pwm_ops = {
378	.request = tpu_pwm_request,
379	.free = tpu_pwm_free,
380	.config = tpu_pwm_config,
381	.set_polarity = tpu_pwm_set_polarity,
382	.enable = tpu_pwm_enable,
383	.disable = tpu_pwm_disable,
384	.owner = THIS_MODULE,
385};
386
387/* -----------------------------------------------------------------------------
388 * Probe and remove
389 */
390
391static int tpu_probe(struct platform_device *pdev)
392{
393	struct tpu_device *tpu;
394	struct resource *res;
395	int ret;
396
397	tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
398	if (tpu == NULL)
399		return -ENOMEM;
400
401	spin_lock_init(&tpu->lock);
402	tpu->pdev = pdev;
403
404	/* Map memory, get clock and pin control. */
405	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
406	tpu->base = devm_ioremap_resource(&pdev->dev, res);
407	if (IS_ERR(tpu->base))
408		return PTR_ERR(tpu->base);
409
410	tpu->clk = devm_clk_get(&pdev->dev, NULL);
411	if (IS_ERR(tpu->clk)) {
412		dev_err(&pdev->dev, "cannot get clock\n");
413		return PTR_ERR(tpu->clk);
414	}
415
416	/* Initialize and register the device. */
417	platform_set_drvdata(pdev, tpu);
418
419	tpu->chip.dev = &pdev->dev;
420	tpu->chip.ops = &tpu_pwm_ops;
421	tpu->chip.of_xlate = of_pwm_xlate_with_flags;
422	tpu->chip.of_pwm_n_cells = 3;
423	tpu->chip.base = -1;
424	tpu->chip.npwm = TPU_CHANNEL_MAX;
425
426	ret = pwmchip_add(&tpu->chip);
427	if (ret < 0) {
428		dev_err(&pdev->dev, "failed to register PWM chip\n");
429		return ret;
430	}
431
432	dev_info(&pdev->dev, "TPU PWM %d registered\n", tpu->pdev->id);
433
434	pm_runtime_enable(&pdev->dev);
435
436	return 0;
437}
438
439static int tpu_remove(struct platform_device *pdev)
440{
441	struct tpu_device *tpu = platform_get_drvdata(pdev);
442	int ret;
443
444	ret = pwmchip_remove(&tpu->chip);
445	if (ret)
446		return ret;
447
448	pm_runtime_disable(&pdev->dev);
449
450	return 0;
451}
452
453#ifdef CONFIG_OF
454static const struct of_device_id tpu_of_table[] = {
455	{ .compatible = "renesas,tpu-r8a73a4", },
456	{ .compatible = "renesas,tpu-r8a7740", },
457	{ .compatible = "renesas,tpu-r8a7790", },
458	{ .compatible = "renesas,tpu-sh7372", },
459	{ .compatible = "renesas,tpu", },
460	{ },
461};
462
463MODULE_DEVICE_TABLE(of, tpu_of_table);
464#endif
465
466static struct platform_driver tpu_driver = {
467	.probe		= tpu_probe,
468	.remove		= tpu_remove,
469	.driver		= {
470		.name	= "renesas-tpu-pwm",
471		.of_match_table = of_match_ptr(tpu_of_table),
472	}
473};
474
475module_platform_driver(tpu_driver);
476
477MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
478MODULE_DESCRIPTION("Renesas TPU PWM Driver");
479MODULE_LICENSE("GPL v2");
480MODULE_ALIAS("platform:renesas-tpu-pwm");
481