1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) ST-Ericsson SA 2010
4 *
5 * Author: Arun R Murthy <arun.murthy@stericsson.com>
6 * Datasheet: https://web.archive.org/web/20130614115108/http://www.stericsson.com/developers/CD00291561_UM1031_AB8500_user_manual-rev5_CTDS_public.pdf
7 */
8 #include <linux/err.h>
9 #include <linux/platform_device.h>
10 #include <linux/slab.h>
11 #include <linux/pwm.h>
12 #include <linux/mfd/abx500.h>
13 #include <linux/mfd/abx500/ab8500.h>
14 #include <linux/module.h>
15
16 /*
17 * PWM Out generators
18 * Bank: 0x10
19 */
20 #define AB8500_PWM_OUT_CTRL1_REG 0x60
21 #define AB8500_PWM_OUT_CTRL2_REG 0x61
22 #define AB8500_PWM_OUT_CTRL7_REG 0x66
23
24 #define AB8500_PWM_CLKRATE 9600000
25
26 struct ab8500_pwm_chip {
27 unsigned int hwid;
28 };
29
ab8500_pwm_from_chip(struct pwm_chip * chip)30 static struct ab8500_pwm_chip *ab8500_pwm_from_chip(struct pwm_chip *chip)
31 {
32 return pwmchip_get_drvdata(chip);
33 }
34
ab8500_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)35 static int ab8500_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
36 const struct pwm_state *state)
37 {
38 int ret;
39 u8 reg;
40 u8 higher_val, lower_val;
41 unsigned int duty_steps, div;
42 struct ab8500_pwm_chip *ab8500 = ab8500_pwm_from_chip(chip);
43
44 if (state->polarity != PWM_POLARITY_NORMAL)
45 return -EINVAL;
46
47 if (state->enabled) {
48 /*
49 * A time quantum is
50 * q = (32 - FreqPWMOutx[3:0]) / AB8500_PWM_CLKRATE
51 * The period is always 1024 q, duty_cycle is between 1q and 1024q.
52 *
53 * FreqPWMOutx[3:0] | output frequency | output frequency | 1024q = period
54 * | (from manual) | (1 / 1024q) | = 1 / freq
55 * -----------------+------------------+------------------+--------------
56 * b0000 | 293 Hz | 292.968750 Hz | 3413333.33 ns
57 * b0001 | 302 Hz | 302.419355 Hz | 3306666.66 ns
58 * b0010 | 312 Hz | 312.500000 Hz | 3200000 ns
59 * b0011 | 323 Hz | 323.275862 Hz | 3093333.33 ns
60 * b0100 | 334 Hz | 334.821429 Hz | 2986666.66 ns
61 * b0101 | 347 Hz | 347.222222 Hz | 2880000 ns
62 * b0110 | 360 Hz | 360.576923 Hz | 2773333.33 ns
63 * b0111 | 375 Hz | 375.000000 Hz | 2666666.66 ns
64 * b1000 | 390 Hz | 390.625000 Hz | 2560000 ns
65 * b1001 | 407 Hz | 407.608696 Hz | 2453333.33 ns
66 * b1010 | 426 Hz | 426.136364 Hz | 2346666.66 ns
67 * b1011 | 446 Hz | 446.428571 Hz | 2240000 ns
68 * b1100 | 468 Hz | 468.750000 Hz | 2133333.33 ns
69 * b1101 | 493 Hz | 493.421053 Hz | 2026666.66 ns
70 * b1110 | 520 Hz | 520.833333 Hz | 1920000 ns
71 * b1111 | 551 Hz | 551.470588 Hz | 1813333.33 ns
72 *
73 *
74 * AB8500_PWM_CLKRATE is a multiple of 1024, so the division by
75 * 1024 can be done in this factor without loss of precision.
76 */
77 div = min_t(u64, mul_u64_u64_div_u64(state->period,
78 AB8500_PWM_CLKRATE >> 10,
79 NSEC_PER_SEC), 32); /* 32 - FreqPWMOutx[3:0] */
80 if (div <= 16)
81 /* requested period < 3413333.33 */
82 return -EINVAL;
83
84 duty_steps = max_t(u64, mul_u64_u64_div_u64(state->duty_cycle,
85 AB8500_PWM_CLKRATE,
86 (u64)NSEC_PER_SEC * div), 1024);
87 }
88
89 /*
90 * The hardware doesn't support duty_steps = 0 explicitly, but emits low
91 * when disabled.
92 */
93 if (!state->enabled || duty_steps == 0) {
94 ret = abx500_mask_and_set_register_interruptible(pwmchip_parent(chip),
95 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
96 1 << ab8500->hwid, 0);
97
98 if (ret < 0)
99 dev_err(pwmchip_parent(chip), "%s: Failed to disable PWM, Error %d\n",
100 pwm->label, ret);
101 return ret;
102 }
103
104 /*
105 * The lower 8 bits of duty_steps is written to ...
106 * AB8500_PWM_OUT_CTRL1_REG[0:7]
107 */
108 lower_val = (duty_steps - 1) & 0x00ff;
109 /*
110 * The two remaining high bits to
111 * AB8500_PWM_OUT_CTRL2_REG[0:1]; together with FreqPWMOutx.
112 */
113 higher_val = ((duty_steps - 1) & 0x0300) >> 8 | (32 - div) << 4;
114
115 reg = AB8500_PWM_OUT_CTRL1_REG + (ab8500->hwid * 2);
116
117 ret = abx500_set_register_interruptible(pwmchip_parent(chip), AB8500_MISC,
118 reg, lower_val);
119 if (ret < 0)
120 return ret;
121
122 ret = abx500_set_register_interruptible(pwmchip_parent(chip), AB8500_MISC,
123 (reg + 1), higher_val);
124 if (ret < 0)
125 return ret;
126
127 /* enable */
128 ret = abx500_mask_and_set_register_interruptible(pwmchip_parent(chip),
129 AB8500_MISC, AB8500_PWM_OUT_CTRL7_REG,
130 1 << ab8500->hwid, 1 << ab8500->hwid);
131 if (ret < 0)
132 dev_err(pwmchip_parent(chip), "%s: Failed to enable PWM, Error %d\n",
133 pwm->label, ret);
134
135 return ret;
136 }
137
ab8500_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)138 static int ab8500_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
139 struct pwm_state *state)
140 {
141 u8 ctrl7, lower_val, higher_val;
142 int ret;
143 struct ab8500_pwm_chip *ab8500 = ab8500_pwm_from_chip(chip);
144 unsigned int div, duty_steps;
145
146 ret = abx500_get_register_interruptible(pwmchip_parent(chip), AB8500_MISC,
147 AB8500_PWM_OUT_CTRL7_REG,
148 &ctrl7);
149 if (ret)
150 return ret;
151
152 state->polarity = PWM_POLARITY_NORMAL;
153
154 if (!(ctrl7 & 1 << ab8500->hwid)) {
155 state->enabled = false;
156 return 0;
157 }
158
159 ret = abx500_get_register_interruptible(pwmchip_parent(chip), AB8500_MISC,
160 AB8500_PWM_OUT_CTRL1_REG + (ab8500->hwid * 2),
161 &lower_val);
162 if (ret)
163 return ret;
164
165 ret = abx500_get_register_interruptible(pwmchip_parent(chip), AB8500_MISC,
166 AB8500_PWM_OUT_CTRL2_REG + (ab8500->hwid * 2),
167 &higher_val);
168 if (ret)
169 return ret;
170
171 div = 32 - ((higher_val & 0xf0) >> 4);
172 duty_steps = ((higher_val & 3) << 8 | lower_val) + 1;
173
174 state->period = DIV64_U64_ROUND_UP((u64)div << 10, AB8500_PWM_CLKRATE);
175 state->duty_cycle = DIV64_U64_ROUND_UP((u64)div * duty_steps, AB8500_PWM_CLKRATE);
176
177 return 0;
178 }
179
180 static const struct pwm_ops ab8500_pwm_ops = {
181 .apply = ab8500_pwm_apply,
182 .get_state = ab8500_pwm_get_state,
183 };
184
ab8500_pwm_probe(struct platform_device * pdev)185 static int ab8500_pwm_probe(struct platform_device *pdev)
186 {
187 struct pwm_chip *chip;
188 struct ab8500_pwm_chip *ab8500;
189 int err;
190
191 if (pdev->id < 1 || pdev->id > 31)
192 return dev_err_probe(&pdev->dev, -EINVAL, "Invalid device id %d\n", pdev->id);
193
194 /*
195 * Nothing to be done in probe, this is required to get the
196 * device which is required for ab8500 read and write
197 */
198 chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*ab8500));
199 if (IS_ERR(chip))
200 return PTR_ERR(chip);
201
202 ab8500 = ab8500_pwm_from_chip(chip);
203
204 chip->ops = &ab8500_pwm_ops;
205 ab8500->hwid = pdev->id - 1;
206
207 err = devm_pwmchip_add(&pdev->dev, chip);
208 if (err < 0)
209 return dev_err_probe(&pdev->dev, err, "Failed to add pwm chip\n");
210
211 dev_dbg(&pdev->dev, "pwm probe successful\n");
212
213 return 0;
214 }
215
216 static struct platform_driver ab8500_pwm_driver = {
217 .driver = {
218 .name = "ab8500-pwm",
219 },
220 .probe = ab8500_pwm_probe,
221 };
222 module_platform_driver(ab8500_pwm_driver);
223
224 MODULE_AUTHOR("Arun MURTHY <arun.murthy@stericsson.com>");
225 MODULE_DESCRIPTION("AB8500 Pulse Width Modulation Driver");
226 MODULE_ALIAS("platform:ab8500-pwm");
227 MODULE_LICENSE("GPL v2");
228