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