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