GNU Linux-libre 4.9.328-gnu1
[releases.git] / drivers / pwm / pwm-stmpe.c
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
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
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
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
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
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);