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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * R-Mobile TPU PWM driver
4 *
5 * Copyright (C) 2012 Renesas Solutions Corp.
6 */
7
8#include <linux/clk.h>
9#include <linux/err.h>
10#include <linux/io.h>
11#include <linux/init.h>
12#include <linux/ioport.h>
13#include <linux/module.h>
14#include <linux/of.h>
15#include <linux/platform_device.h>
16#include <linux/pm_runtime.h>
17#include <linux/pwm.h>
18#include <linux/slab.h>
19#include <linux/spinlock.h>
20
21#define TPU_CHANNEL_MAX 4
22
23#define TPU_TSTR 0x00 /* Timer start register (shared) */
24
25#define TPU_TCRn 0x00 /* Timer control register */
26#define TPU_TCR_CCLR_NONE (0 << 5)
27#define TPU_TCR_CCLR_TGRA (1 << 5)
28#define TPU_TCR_CCLR_TGRB (2 << 5)
29#define TPU_TCR_CCLR_TGRC (5 << 5)
30#define TPU_TCR_CCLR_TGRD (6 << 5)
31#define TPU_TCR_CKEG_RISING (0 << 3)
32#define TPU_TCR_CKEG_FALLING (1 << 3)
33#define TPU_TCR_CKEG_BOTH (2 << 3)
34#define TPU_TMDRn 0x04 /* Timer mode register */
35#define TPU_TMDR_BFWT (1 << 6)
36#define TPU_TMDR_BFB (1 << 5)
37#define TPU_TMDR_BFA (1 << 4)
38#define TPU_TMDR_MD_NORMAL (0 << 0)
39#define TPU_TMDR_MD_PWM (2 << 0)
40#define TPU_TIORn 0x08 /* Timer I/O control register */
41#define TPU_TIOR_IOA_0 (0 << 0)
42#define TPU_TIOR_IOA_0_CLR (1 << 0)
43#define TPU_TIOR_IOA_0_SET (2 << 0)
44#define TPU_TIOR_IOA_0_TOGGLE (3 << 0)
45#define TPU_TIOR_IOA_1 (4 << 0)
46#define TPU_TIOR_IOA_1_CLR (5 << 0)
47#define TPU_TIOR_IOA_1_SET (6 << 0)
48#define TPU_TIOR_IOA_1_TOGGLE (7 << 0)
49#define TPU_TIERn 0x0c /* Timer interrupt enable register */
50#define TPU_TSRn 0x10 /* Timer status register */
51#define TPU_TCNTn 0x14 /* Timer counter */
52#define TPU_TGRAn 0x18 /* Timer general register A */
53#define TPU_TGRBn 0x1c /* Timer general register B */
54#define TPU_TGRCn 0x20 /* Timer general register C */
55#define TPU_TGRDn 0x24 /* Timer general register D */
56
57#define TPU_CHANNEL_OFFSET 0x10
58#define TPU_CHANNEL_SIZE 0x40
59
60enum tpu_pin_state {
61 TPU_PIN_INACTIVE, /* Pin is driven inactive */
62 TPU_PIN_PWM, /* Pin is driven by PWM */
63 TPU_PIN_ACTIVE, /* Pin is driven active */
64};
65
66struct tpu_device;
67
68struct tpu_pwm_device {
69 bool timer_on; /* Whether the timer is running */
70
71 struct tpu_device *tpu;
72 unsigned int channel; /* Channel number in the TPU */
73
74 enum pwm_polarity polarity;
75 unsigned int prescaler;
76 u16 period;
77 u16 duty;
78};
79
80struct tpu_device {
81 struct platform_device *pdev;
82 struct pwm_chip chip;
83 spinlock_t lock;
84
85 void __iomem *base;
86 struct clk *clk;
87 struct tpu_pwm_device tpd[TPU_CHANNEL_MAX];
88};
89
90#define to_tpu_device(c) container_of(c, struct tpu_device, chip)
91
92static void tpu_pwm_write(struct tpu_pwm_device *tpd, int reg_nr, u16 value)
93{
94 void __iomem *base = tpd->tpu->base + TPU_CHANNEL_OFFSET
95 + tpd->channel * TPU_CHANNEL_SIZE;
96
97 iowrite16(value, base + reg_nr);
98}
99
100static void tpu_pwm_set_pin(struct tpu_pwm_device *tpd,
101 enum tpu_pin_state state)
102{
103 static const char * const states[] = { "inactive", "PWM", "active" };
104
105 dev_dbg(&tpd->tpu->pdev->dev, "%u: configuring pin as %s\n",
106 tpd->channel, states[state]);
107
108 switch (state) {
109 case TPU_PIN_INACTIVE:
110 tpu_pwm_write(tpd, TPU_TIORn,
111 tpd->polarity == PWM_POLARITY_INVERSED ?
112 TPU_TIOR_IOA_1 : TPU_TIOR_IOA_0);
113 break;
114 case TPU_PIN_PWM:
115 tpu_pwm_write(tpd, TPU_TIORn,
116 tpd->polarity == PWM_POLARITY_INVERSED ?
117 TPU_TIOR_IOA_0_SET : TPU_TIOR_IOA_1_CLR);
118 break;
119 case TPU_PIN_ACTIVE:
120 tpu_pwm_write(tpd, TPU_TIORn,
121 tpd->polarity == PWM_POLARITY_INVERSED ?
122 TPU_TIOR_IOA_0 : TPU_TIOR_IOA_1);
123 break;
124 }
125}
126
127static void tpu_pwm_start_stop(struct tpu_pwm_device *tpd, int start)
128{
129 unsigned long flags;
130 u16 value;
131
132 spin_lock_irqsave(&tpd->tpu->lock, flags);
133 value = ioread16(tpd->tpu->base + TPU_TSTR);
134
135 if (start)
136 value |= 1 << tpd->channel;
137 else
138 value &= ~(1 << tpd->channel);
139
140 iowrite16(value, tpd->tpu->base + TPU_TSTR);
141 spin_unlock_irqrestore(&tpd->tpu->lock, flags);
142}
143
144static int tpu_pwm_timer_start(struct tpu_pwm_device *tpd)
145{
146 int ret;
147
148 if (!tpd->timer_on) {
149 /* Wake up device and enable clock. */
150 pm_runtime_get_sync(&tpd->tpu->pdev->dev);
151 ret = clk_prepare_enable(tpd->tpu->clk);
152 if (ret) {
153 dev_err(&tpd->tpu->pdev->dev, "cannot enable clock\n");
154 return ret;
155 }
156 tpd->timer_on = true;
157 }
158
159 /*
160 * Make sure the channel is stopped, as we need to reconfigure it
161 * completely. First drive the pin to the inactive state to avoid
162 * glitches.
163 */
164 tpu_pwm_set_pin(tpd, TPU_PIN_INACTIVE);
165 tpu_pwm_start_stop(tpd, false);
166
167 /*
168 * - Clear TCNT on TGRB match
169 * - Count on rising edge
170 * - Set prescaler
171 * - Output 0 until TGRA, output 1 until TGRB (active low polarity)
172 * - Output 1 until TGRA, output 0 until TGRB (active high polarity
173 * - PWM mode
174 */
175 tpu_pwm_write(tpd, TPU_TCRn, TPU_TCR_CCLR_TGRB | TPU_TCR_CKEG_RISING |
176 tpd->prescaler);
177 tpu_pwm_write(tpd, TPU_TMDRn, TPU_TMDR_MD_PWM);
178 tpu_pwm_set_pin(tpd, TPU_PIN_PWM);
179 tpu_pwm_write(tpd, TPU_TGRAn, tpd->duty);
180 tpu_pwm_write(tpd, TPU_TGRBn, tpd->period);
181
182 dev_dbg(&tpd->tpu->pdev->dev, "%u: TGRA 0x%04x TGRB 0x%04x\n",
183 tpd->channel, tpd->duty, tpd->period);
184
185 /* Start the channel. */
186 tpu_pwm_start_stop(tpd, true);
187
188 return 0;
189}
190
191static void tpu_pwm_timer_stop(struct tpu_pwm_device *tpd)
192{
193 if (!tpd->timer_on)
194 return;
195
196 /* Disable channel. */
197 tpu_pwm_start_stop(tpd, false);
198
199 /* Stop clock and mark device as idle. */
200 clk_disable_unprepare(tpd->tpu->clk);
201 pm_runtime_put(&tpd->tpu->pdev->dev);
202
203 tpd->timer_on = false;
204}
205
206/* -----------------------------------------------------------------------------
207 * PWM API
208 */
209
210static int tpu_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
211{
212 struct tpu_device *tpu = to_tpu_device(chip);
213 struct tpu_pwm_device *tpd;
214
215 if (pwm->hwpwm >= TPU_CHANNEL_MAX)
216 return -EINVAL;
217
218 tpd = &tpu->tpd[pwm->hwpwm];
219
220 tpd->tpu = tpu;
221 tpd->channel = pwm->hwpwm;
222 tpd->polarity = PWM_POLARITY_NORMAL;
223 tpd->prescaler = 0;
224 tpd->period = 0;
225 tpd->duty = 0;
226
227 tpd->timer_on = false;
228
229 return 0;
230}
231
232static void tpu_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
233{
234 struct tpu_device *tpu = to_tpu_device(chip);
235 struct tpu_pwm_device *tpd = &tpu->tpd[pwm->hwpwm];
236
237 tpu_pwm_timer_stop(tpd);
238}
239
240static int tpu_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
241 u64 duty_ns, u64 period_ns, bool enabled)
242{
243 struct tpu_device *tpu = to_tpu_device(chip);
244 struct tpu_pwm_device *tpd = &tpu->tpd[pwm->hwpwm];
245 unsigned int prescaler;
246 bool duty_only = false;
247 u32 clk_rate;
248 u64 period;
249 u32 duty;
250 int ret;
251
252 clk_rate = clk_get_rate(tpu->clk);
253 if (unlikely(clk_rate > NSEC_PER_SEC)) {
254 /*
255 * This won't happen in the nearer future, so this is only a
256 * safeguard to prevent the following calculation from
257 * overflowing. With this clk_rate * period_ns / NSEC_PER_SEC is
258 * not greater than period_ns and so fits into an u64.
259 */
260 return -EINVAL;
261 }
262
263 period = mul_u64_u64_div_u64(clk_rate, period_ns, NSEC_PER_SEC);
264
265 /*
266 * Find the minimal prescaler in [0..3] such that
267 *
268 * period >> (2 * prescaler) < 0x10000
269 *
270 * This could be calculated using something like:
271 *
272 * prescaler = max(ilog2(period) / 2, 7) - 7;
273 *
274 * but given there are only four allowed results and that ilog2 isn't
275 * cheap on all platforms using a switch statement is more effective.
276 */
277 switch (period) {
278 case 1 ... 0xffff:
279 prescaler = 0;
280 break;
281
282 case 0x10000 ... 0x3ffff:
283 prescaler = 1;
284 break;
285
286 case 0x40000 ... 0xfffff:
287 prescaler = 2;
288 break;
289
290 case 0x100000 ... 0x3fffff:
291 prescaler = 3;
292 break;
293
294 default:
295 return -EINVAL;
296 }
297
298 period >>= 2 * prescaler;
299
300 if (duty_ns)
301 duty = mul_u64_u64_div_u64(clk_rate, duty_ns,
302 (u64)NSEC_PER_SEC << (2 * prescaler));
303 else
304 duty = 0;
305
306 dev_dbg(&tpu->pdev->dev,
307 "rate %u, prescaler %u, period %u, duty %u\n",
308 clk_rate, 1 << (2 * prescaler), (u32)period, duty);
309
310 if (tpd->prescaler == prescaler && tpd->period == period)
311 duty_only = true;
312
313 tpd->prescaler = prescaler;
314 tpd->period = period;
315 tpd->duty = duty;
316
317 /* If the channel is disabled we're done. */
318 if (!enabled)
319 return 0;
320
321 if (duty_only && tpd->timer_on) {
322 /*
323 * If only the duty cycle changed and the timer is already
324 * running, there's no need to reconfigure it completely, Just
325 * modify the duty cycle.
326 */
327 tpu_pwm_write(tpd, TPU_TGRAn, tpd->duty);
328 dev_dbg(&tpu->pdev->dev, "%u: TGRA 0x%04x\n", tpd->channel,
329 tpd->duty);
330 } else {
331 /* Otherwise perform a full reconfiguration. */
332 ret = tpu_pwm_timer_start(tpd);
333 if (ret < 0)
334 return ret;
335 }
336
337 if (duty == 0 || duty == period) {
338 /*
339 * To avoid running the timer when not strictly required, handle
340 * 0% and 100% duty cycles as fixed levels and stop the timer.
341 */
342 tpu_pwm_set_pin(tpd, duty ? TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
343 tpu_pwm_timer_stop(tpd);
344 }
345
346 return 0;
347}
348
349static int tpu_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
350 enum pwm_polarity polarity)
351{
352 struct tpu_device *tpu = to_tpu_device(chip);
353 struct tpu_pwm_device *tpd = &tpu->tpd[pwm->hwpwm];
354
355 tpd->polarity = polarity;
356
357 return 0;
358}
359
360static int tpu_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
361{
362 struct tpu_device *tpu = to_tpu_device(chip);
363 struct tpu_pwm_device *tpd = &tpu->tpd[pwm->hwpwm];
364 int ret;
365
366 ret = tpu_pwm_timer_start(tpd);
367 if (ret < 0)
368 return ret;
369
370 /*
371 * To avoid running the timer when not strictly required, handle 0% and
372 * 100% duty cycles as fixed levels and stop the timer.
373 */
374 if (tpd->duty == 0 || tpd->duty == tpd->period) {
375 tpu_pwm_set_pin(tpd, tpd->duty ?
376 TPU_PIN_ACTIVE : TPU_PIN_INACTIVE);
377 tpu_pwm_timer_stop(tpd);
378 }
379
380 return 0;
381}
382
383static void tpu_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
384{
385 struct tpu_device *tpu = to_tpu_device(chip);
386 struct tpu_pwm_device *tpd = &tpu->tpd[pwm->hwpwm];
387
388 /* The timer must be running to modify the pin output configuration. */
389 tpu_pwm_timer_start(tpd);
390 tpu_pwm_set_pin(tpd, TPU_PIN_INACTIVE);
391 tpu_pwm_timer_stop(tpd);
392}
393
394static int tpu_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
395 const struct pwm_state *state)
396{
397 int err;
398 bool enabled = pwm->state.enabled;
399
400 if (state->polarity != pwm->state.polarity) {
401 if (enabled) {
402 tpu_pwm_disable(chip, pwm);
403 enabled = false;
404 }
405
406 err = tpu_pwm_set_polarity(chip, pwm, state->polarity);
407 if (err)
408 return err;
409 }
410
411 if (!state->enabled) {
412 if (enabled)
413 tpu_pwm_disable(chip, pwm);
414
415 return 0;
416 }
417
418 err = tpu_pwm_config(chip, pwm,
419 state->duty_cycle, state->period, enabled);
420 if (err)
421 return err;
422
423 if (!enabled)
424 err = tpu_pwm_enable(chip, pwm);
425
426 return err;
427}
428
429static const struct pwm_ops tpu_pwm_ops = {
430 .request = tpu_pwm_request,
431 .free = tpu_pwm_free,
432 .apply = tpu_pwm_apply,
433};
434
435/* -----------------------------------------------------------------------------
436 * Probe and remove
437 */
438
439static int tpu_probe(struct platform_device *pdev)
440{
441 struct tpu_device *tpu;
442 int ret;
443
444 tpu = devm_kzalloc(&pdev->dev, sizeof(*tpu), GFP_KERNEL);
445 if (tpu == NULL)
446 return -ENOMEM;
447
448 spin_lock_init(&tpu->lock);
449 tpu->pdev = pdev;
450
451 /* Map memory, get clock and pin control. */
452 tpu->base = devm_platform_ioremap_resource(pdev, 0);
453 if (IS_ERR(tpu->base))
454 return PTR_ERR(tpu->base);
455
456 tpu->clk = devm_clk_get(&pdev->dev, NULL);
457 if (IS_ERR(tpu->clk))
458 return dev_err_probe(&pdev->dev, PTR_ERR(tpu->clk), "Failed to get clock\n");
459
460 /* Initialize and register the device. */
461 platform_set_drvdata(pdev, tpu);
462
463 tpu->chip.dev = &pdev->dev;
464 tpu->chip.ops = &tpu_pwm_ops;
465 tpu->chip.npwm = TPU_CHANNEL_MAX;
466
467 ret = devm_pm_runtime_enable(&pdev->dev);
468 if (ret < 0)
469 return dev_err_probe(&pdev->dev, ret, "Failed to enable runtime PM\n");
470
471 ret = devm_pwmchip_add(&pdev->dev, &tpu->chip);
472 if (ret < 0)
473 return dev_err_probe(&pdev->dev, ret, "Failed to register PWM chip\n");
474
475 return 0;
476}
477
478#ifdef CONFIG_OF
479static const struct of_device_id tpu_of_table[] = {
480 { .compatible = "renesas,tpu-r8a73a4", },
481 { .compatible = "renesas,tpu-r8a7740", },
482 { .compatible = "renesas,tpu-r8a7790", },
483 { .compatible = "renesas,tpu", },
484 { },
485};
486
487MODULE_DEVICE_TABLE(of, tpu_of_table);
488#endif
489
490static struct platform_driver tpu_driver = {
491 .probe = tpu_probe,
492 .driver = {
493 .name = "renesas-tpu-pwm",
494 .of_match_table = of_match_ptr(tpu_of_table),
495 }
496};
497
498module_platform_driver(tpu_driver);
499
500MODULE_AUTHOR("Laurent Pinchart <laurent.pinchart@ideasonboard.com>");
501MODULE_DESCRIPTION("Renesas TPU PWM Driver");
502MODULE_LICENSE("GPL v2");
503MODULE_ALIAS("platform:renesas-tpu-pwm");