summaryrefslogtreecommitdiffstats
path: root/drivers/pwm/pwm-stmpe.c
blob: 3439f1e902cb0e5dbfba93f1bbd88d0a1785c4fa (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
/*
 * Copyright (C) 2016 Linaro Ltd.
 *
 * Author: Linus Walleij <linus.walleij@linaro.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2, as
 * published by the Free Software Foundation.
 *
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/mfd/stmpe.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>

#define STMPE24XX_PWMCS		0x30
#define PWMCS_EN_PWM0		BIT(0)
#define PWMCS_EN_PWM1		BIT(1)
#define PWMCS_EN_PWM2		BIT(2)
#define STMPE24XX_PWMIC0	0x38
#define STMPE24XX_PWMIC1	0x39
#define STMPE24XX_PWMIC2	0x3a

#define STMPE_PWM_24XX_PINBASE	21

struct stmpe_pwm {
	struct stmpe *stmpe;
	struct pwm_chip chip;
	u8 last_duty;
};

static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
{
	return container_of(chip, struct stmpe_pwm, chip);
}

static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
	u8 value;
	int ret;

	ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
	if (ret < 0) {
		dev_err(chip->dev, "error reading PWM#%u control\n",
			pwm->hwpwm);
		return ret;
	}

	value = ret | BIT(pwm->hwpwm);

	ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
	if (ret) {
		dev_err(chip->dev, "error writing PWM#%u control\n",
			pwm->hwpwm);
		return ret;
	}

	return 0;
}

static void stmpe_24xx_pwm_disable(struct pwm_chip *chip,
				   struct pwm_device *pwm)
{
	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
	u8 value;
	int ret;

	ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
	if (ret < 0) {
		dev_err(chip->dev, "error reading PWM#%u control\n",
			pwm->hwpwm);
		return;
	}

	value = ret & ~BIT(pwm->hwpwm);

	ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
	if (ret) {
		dev_err(chip->dev, "error writing PWM#%u control\n",
			pwm->hwpwm);
		return;
	}
}

/* STMPE 24xx PWM instructions */
#define SMAX		0x007f
#define SMIN		0x00ff
#define GTS		0x0000
#define LOAD		BIT(14) /* Only available on 2403 */
#define RAMPUP		0x0000
#define RAMPDOWN	BIT(7)
#define PRESCALE_512	BIT(14)
#define STEPTIME_1	BIT(8)
#define BRANCH		(BIT(15) | BIT(13))

static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
				 int duty_ns, int period_ns)
{
	struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
	unsigned int i, pin;
	u16 program[3] = {
		SMAX,
		GTS,
		GTS,
	};
	u8 offset;
	int ret;

	/* Make sure we are disabled */
	if (pwm_is_enabled(pwm)) {
		stmpe_24xx_pwm_disable(chip, pwm);
	} else {
		/* Connect the PWM to the pin */
		pin = pwm->hwpwm;

		/* On STMPE2401 and 2403 pins 21,22,23 are used */
		if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
		    stmpe_pwm->stmpe->partnum == STMPE2403)
			pin += STMPE_PWM_24XX_PINBASE;

		ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
					STMPE_BLOCK_PWM);
		if (ret) {
			dev_err(chip->dev, "unable to connect PWM#%u to pin\n",
				pwm->hwpwm);
			return ret;
		}
	}

	/* STMPE24XX */
	switch (pwm->hwpwm) {
	case 0:
		offset = STMPE24XX_PWMIC0;
		break;

	case 1:
		offset = STMPE24XX_PWMIC1;
		break;

	case 2:
		offset = STMPE24XX_PWMIC2;
		break;

	default:
		/* Should not happen as npwm is 3 */
		return -ENODEV;
	}

	dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n",
		pwm->hwpwm, duty_ns, period_ns);

	if (duty_ns == 0) {
		if (stmpe_pwm->stmpe->partnum == STMPE2401)
			program[0] = SMAX; /* off all the time */

		if (stmpe_pwm->stmpe->partnum == STMPE2403)
			program[0] = LOAD | 0xff; /* LOAD 0xff */

		stmpe_pwm->last_duty = 0x00;
	} else if (duty_ns == period_ns) {
		if (stmpe_pwm->stmpe->partnum == STMPE2401)
			program[0] = SMIN; /* on all the time */

		if (stmpe_pwm->stmpe->partnum == STMPE2403)
			program[0] = LOAD | 0x00; /* LOAD 0x00 */

		stmpe_pwm->last_duty = 0xff;
	} else {
		u8 value, last = stmpe_pwm->last_duty;
		unsigned long duty;

		/*
		 * Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
		 * (means a period of 30517 ns) then this is compared to the
		 * counter from the ramp, if this is >= PWM counter the output
		 * is high. With LOAD we can define how much of the cycle it
		 * is on.
		 *
		 * Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
		 */

		/* Scale to 0..0xff */
		duty = duty_ns * 256;
		duty = DIV_ROUND_CLOSEST(duty, period_ns);
		value = duty;

		if (value == last) {
			/* Run the old program */
			if (pwm_is_enabled(pwm))
				stmpe_24xx_pwm_enable(chip, pwm);

			return 0;
		} else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
			/* STMPE2403 can simply set the right PWM value */
			program[0] = LOAD | value;
			program[1] = 0x0000;
		} else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
			/* STMPE2401 need a complex program */
			u16 incdec = 0x0000;

			if (last < value)
				/* Count up */
				incdec = RAMPUP | (value - last);
			else
				/* Count down */
				incdec = RAMPDOWN | (last - value);

			/* Step to desired value, smoothly */
			program[0] = PRESCALE_512 | STEPTIME_1 | incdec;

			/* Loop eternally to 0x00 */
			program[1] = BRANCH;
		}

		dev_dbg(chip->dev,
			"PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
			pwm->hwpwm, value, last, program[0], program[1],
			program[2]);
		stmpe_pwm->last_duty = value;
	}

	/*
	 * We can write programs of up to 64 16-bit words into this channel.
	 */
	for (i = 0; i < ARRAY_SIZE(program); i++) {
		u8 value;

		value = (program[i] >> 8) & 0xff;

		ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
		if (ret) {
			dev_err(chip->dev, "error writing register %02x: %d\n",
				offset, ret);
			return ret;
		}

		value = program[i] & 0xff;

		ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
		if (ret) {
			dev_err(chip->dev, "error writing register %02x: %d\n",
				offset, ret);
			return ret;
		}
	}

	/* If we were enabled, re-enable this PWM */
	if (pwm_is_enabled(pwm))
		stmpe_24xx_pwm_enable(chip, pwm);

	/* Sleep for 200ms so we're sure it will take effect */
	msleep(200);

	dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);

	return 0;
}

static const struct pwm_ops stmpe_24xx_pwm_ops = {
	.config = stmpe_24xx_pwm_config,
	.enable = stmpe_24xx_pwm_enable,
	.disable = stmpe_24xx_pwm_disable,
	.owner = THIS_MODULE,
};

static int __init stmpe_pwm_probe(struct platform_device *pdev)
{
	struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
	struct stmpe_pwm *pwm;
	int ret;

	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
	if (!pwm)
		return -ENOMEM;

	pwm->stmpe = stmpe;
	pwm->chip.dev = &pdev->dev;
	pwm->chip.base = -1;

	if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) {
		pwm->chip.ops = &stmpe_24xx_pwm_ops;
		pwm->chip.npwm = 3;
	} else {
		if (stmpe->partnum == STMPE1601)
			dev_err(&pdev->dev, "STMPE1601 not yet supported\n");
		else
			dev_err(&pdev->dev, "Unknown STMPE PWM\n");

		return -ENODEV;
	}

	ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
	if (ret)
		return ret;

	ret = pwmchip_add(&pwm->chip);
	if (ret) {
		stmpe_disable(stmpe, STMPE_BLOCK_PWM);
		return ret;
	}

	platform_set_drvdata(pdev, pwm);

	return 0;
}

static struct platform_driver stmpe_pwm_driver = {
	.driver = {
		.name = "stmpe-pwm",
	},
};
builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);