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
28 struct stmpe_pwm {
29 struct stmpe *stmpe;
30 struct pwm_chip chip;
31 u8 last_duty;
32 };
33
to_stmpe_pwm(struct pwm_chip * chip)34 static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
35 {
36 return container_of(chip, struct stmpe_pwm, chip);
37 }
38
stmpe_24xx_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)39 static 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_err(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_err(chip->dev, "error writing PWM#%u control\n",
57 pwm->hwpwm);
58 return ret;
59 }
60
61 return 0;
62 }
63
stmpe_24xx_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)64 static void 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_err(chip->dev, "error reading PWM#%u control\n",
74 pwm->hwpwm);
75 return;
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_err(chip->dev, "error writing PWM#%u control\n",
83 pwm->hwpwm);
84 return;
85 }
86 }
87
88 /* STMPE 24xx PWM instructions */
89 #define SMAX 0x007f
90 #define SMIN 0x00ff
91 #define GTS 0x0000
92 #define LOAD BIT(14) /* Only available on 2403 */
93 #define RAMPUP 0x0000
94 #define RAMPDOWN BIT(7)
95 #define PRESCALE_512 BIT(14)
96 #define STEPTIME_1 BIT(8)
97 #define BRANCH (BIT(15) | BIT(13))
98
stmpe_24xx_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns)99 static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
100 int duty_ns, int period_ns)
101 {
102 struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
103 unsigned int i, pin;
104 u16 program[3] = {
105 SMAX,
106 GTS,
107 GTS,
108 };
109 u8 offset;
110 int ret;
111
112 /* Make sure we are disabled */
113 if (pwm_is_enabled(pwm)) {
114 stmpe_24xx_pwm_disable(chip, pwm);
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(chip->dev, "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(chip->dev, "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(chip->dev,
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_err(chip->dev, "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_err(chip->dev, "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(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
258
259 return 0;
260 }
261
stmpe_24xx_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)262 static 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 stmpe_24xx_pwm_disable(chip, pwm);
273
274 return 0;
275 }
276
277 err = stmpe_24xx_pwm_config(pwm->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
287 static const struct pwm_ops stmpe_24xx_pwm_ops = {
288 .apply = stmpe_24xx_pwm_apply,
289 .owner = THIS_MODULE,
290 };
291
stmpe_pwm_probe(struct platform_device * pdev)292 static 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
330 static struct platform_driver stmpe_pwm_driver = {
331 .driver = {
332 .name = "stmpe-pwm",
333 },
334 };
335 builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);
336