1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Linaro Ltd.
4 *
5 * Author: Linus Walleij <linus.walleij@linaro.org>
6 */
7
8#include <linux/bitops.h>
9#include <linux/delay.h>
10#include <linux/err.h>
11#include <linux/mfd/stmpe.h>
12#include <linux/module.h>
13#include <linux/of.h>
14#include <linux/platform_device.h>
15#include <linux/pwm.h>
16#include <linux/slab.h>
17
18#define STMPE24XX_PWMCS		0x30
19#define PWMCS_EN_PWM0		BIT(0)
20#define PWMCS_EN_PWM1		BIT(1)
21#define PWMCS_EN_PWM2		BIT(2)
22#define STMPE24XX_PWMIC0	0x38
23#define STMPE24XX_PWMIC1	0x39
24#define STMPE24XX_PWMIC2	0x3a
25
26#define STMPE_PWM_24XX_PINBASE	21
27
28struct stmpe_pwm {
29	struct stmpe *stmpe;
30	u8 last_duty;
31};
32
33static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
34{
35	return pwmchip_get_drvdata(chip);
36}
37
38static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
39{
40	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
41	u8 value;
42	int ret;
43
44	ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
45	if (ret < 0) {
46		dev_dbg(pwmchip_parent(chip), "error reading PWM#%u control\n",
47			pwm->hwpwm);
48		return ret;
49	}
50
51	value = ret | BIT(pwm->hwpwm);
52
53	ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
54	if (ret) {
55		dev_dbg(pwmchip_parent(chip), "error writing PWM#%u control\n",
56			pwm->hwpwm);
57		return ret;
58	}
59
60	return 0;
61}
62
63static int stmpe_24xx_pwm_disable(struct pwm_chip *chip,
64				  struct pwm_device *pwm)
65{
66	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
67	u8 value;
68	int ret;
69
70	ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
71	if (ret < 0) {
72		dev_dbg(pwmchip_parent(chip), "error reading PWM#%u control\n",
73			pwm->hwpwm);
74		return ret;
75	}
76
77	value = ret & ~BIT(pwm->hwpwm);
78
79	ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
80	if (ret)
81		dev_dbg(pwmchip_parent(chip), "error writing PWM#%u control\n",
82			pwm->hwpwm);
83	return ret;
84}
85
86/* STMPE 24xx PWM instructions */
87#define SMAX		0x007f
88#define SMIN		0x00ff
89#define GTS		0x0000
90#define LOAD		BIT(14) /* Only available on 2403 */
91#define RAMPUP		0x0000
92#define RAMPDOWN	BIT(7)
93#define PRESCALE_512	BIT(14)
94#define STEPTIME_1	BIT(8)
95#define BRANCH		(BIT(15) | BIT(13))
96
97static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
98				 int duty_ns, int period_ns)
99{
100	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
101	unsigned int i, pin;
102	u16 program[3] = {
103		SMAX,
104		GTS,
105		GTS,
106	};
107	u8 offset;
108	int ret;
109
110	/* Make sure we are disabled */
111	if (pwm_is_enabled(pwm)) {
112		ret = stmpe_24xx_pwm_disable(chip, pwm);
113		if (ret)
114			return ret;
115	} else {
116		/* Connect the PWM to the pin */
117		pin = pwm->hwpwm;
118
119		/* On STMPE2401 and 2403 pins 21,22,23 are used */
120		if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
121		    stmpe_pwm->stmpe->partnum == STMPE2403)
122			pin += STMPE_PWM_24XX_PINBASE;
123
124		ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
125					STMPE_BLOCK_PWM);
126		if (ret) {
127			dev_err(pwmchip_parent(chip), "unable to connect PWM#%u to pin\n",
128				pwm->hwpwm);
129			return ret;
130		}
131	}
132
133	/* STMPE24XX */
134	switch (pwm->hwpwm) {
135	case 0:
136		offset = STMPE24XX_PWMIC0;
137		break;
138
139	case 1:
140		offset = STMPE24XX_PWMIC1;
141		break;
142
143	case 2:
144		offset = STMPE24XX_PWMIC2;
145		break;
146
147	default:
148		/* Should not happen as npwm is 3 */
149		return -ENODEV;
150	}
151
152	dev_dbg(pwmchip_parent(chip), "PWM#%u: config duty %d ns, period %d ns\n",
153		pwm->hwpwm, duty_ns, period_ns);
154
155	if (duty_ns == 0) {
156		if (stmpe_pwm->stmpe->partnum == STMPE2401)
157			program[0] = SMAX; /* off all the time */
158
159		if (stmpe_pwm->stmpe->partnum == STMPE2403)
160			program[0] = LOAD | 0xff; /* LOAD 0xff */
161
162		stmpe_pwm->last_duty = 0x00;
163	} else if (duty_ns == period_ns) {
164		if (stmpe_pwm->stmpe->partnum == STMPE2401)
165			program[0] = SMIN; /* on all the time */
166
167		if (stmpe_pwm->stmpe->partnum == STMPE2403)
168			program[0] = LOAD | 0x00; /* LOAD 0x00 */
169
170		stmpe_pwm->last_duty = 0xff;
171	} else {
172		u8 value, last = stmpe_pwm->last_duty;
173		unsigned long duty;
174
175		/*
176		 * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
177		 * (means a period of 30517 ns) then this is compared to the
178		 * counter from the ramp, if this is >= PWM counter the output
179		 * is high. With LOAD we can define how much of the cycle it
180		 * is on.
181		 *
182		 * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
183		 */
184
185		/* Scale to 0..0xff */
186		duty = duty_ns * 256;
187		duty = DIV_ROUND_CLOSEST(duty, period_ns);
188		value = duty;
189
190		if (value == last) {
191			/* Run the old program */
192			if (pwm_is_enabled(pwm))
193				stmpe_24xx_pwm_enable(chip, pwm);
194
195			return 0;
196		} else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
197			/* STMPE2403 can simply set the right PWM value */
198			program[0] = LOAD | value;
199			program[1] = 0x0000;
200		} else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
201			/* STMPE2401 need a complex program */
202			u16 incdec = 0x0000;
203
204			if (last < value)
205				/* Count up */
206				incdec = RAMPUP | (value - last);
207			else
208				/* Count down */
209				incdec = RAMPDOWN | (last - value);
210
211			/* Step to desired value, smoothly */
212			program[0] = PRESCALE_512 | STEPTIME_1 | incdec;
213
214			/* Loop eternally to 0x00 */
215			program[1] = BRANCH;
216		}
217
218		dev_dbg(pwmchip_parent(chip),
219			"PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
220			pwm->hwpwm, value, last, program[0], program[1],
221			program[2]);
222		stmpe_pwm->last_duty = value;
223	}
224
225	/*
226	 * We can write programs of up to 64 16-bit words into this channel.
227	 */
228	for (i = 0; i < ARRAY_SIZE(program); i++) {
229		u8 value;
230
231		value = (program[i] >> 8) & 0xff;
232
233		ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
234		if (ret) {
235			dev_dbg(pwmchip_parent(chip), "error writing register %02x: %d\n",
236				offset, ret);
237			return ret;
238		}
239
240		value = program[i] & 0xff;
241
242		ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
243		if (ret) {
244			dev_dbg(pwmchip_parent(chip), "error writing register %02x: %d\n",
245				offset, ret);
246			return ret;
247		}
248	}
249
250	/* If we were enabled, re-enable this PWM */
251	if (pwm_is_enabled(pwm))
252		stmpe_24xx_pwm_enable(chip, pwm);
253
254	/* Sleep for 200ms so we're sure it will take effect */
255	msleep(200);
256
257	dev_dbg(pwmchip_parent(chip), "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
258
259	return 0;
260}
261
262static int stmpe_24xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
263				const struct pwm_state *state)
264{
265	int err;
266
267	if (state->polarity != PWM_POLARITY_NORMAL)
268		return -EINVAL;
269
270	if (!state->enabled) {
271		if (pwm->state.enabled)
272			return stmpe_24xx_pwm_disable(chip, pwm);
273
274		return 0;
275	}
276
277	err = stmpe_24xx_pwm_config(chip, pwm, state->duty_cycle, state->period);
278	if (err)
279		return err;
280
281	if (!pwm->state.enabled)
282		err = stmpe_24xx_pwm_enable(chip, pwm);
283
284	return err;
285}
286
287static const struct pwm_ops stmpe_24xx_pwm_ops = {
288	.apply = stmpe_24xx_pwm_apply,
289};
290
291static int __init stmpe_pwm_probe(struct platform_device *pdev)
292{
293	struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
294	struct pwm_chip *chip;
295	struct stmpe_pwm *stmpe_pwm;
296	int ret;
297
298	switch (stmpe->partnum) {
299	case STMPE2401:
300	case STMPE2403:
301		break;
302	case STMPE1601:
303		return dev_err_probe(&pdev->dev, -ENODEV,
304				     "STMPE1601 not yet supported\n");
305	default:
306		return dev_err_probe(&pdev->dev, -ENODEV,
307				     "Unknown STMPE PWM\n");
308	}
309
310	chip = devm_pwmchip_alloc(&pdev->dev, 3, sizeof(*stmpe_pwm));
311	if (IS_ERR(chip))
312		return PTR_ERR(chip);
313	stmpe_pwm = to_stmpe_pwm(chip);
314
315	stmpe_pwm->stmpe = stmpe;
316
317	chip->ops = &stmpe_24xx_pwm_ops;
318
319	ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
320	if (ret)
321		return ret;
322
323	ret = pwmchip_add(chip);
324	if (ret) {
325		stmpe_disable(stmpe, STMPE_BLOCK_PWM);
326		return ret;
327	}
328
329	return 0;
330}
331
332static struct platform_driver stmpe_pwm_driver = {
333	.driver = {
334		.name = "stmpe-pwm",
335	},
336};
337builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);
338