xref: /openbmc/linux/drivers/pwm/pwm-crc.c (revision 92f2de28)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2015 Intel Corporation. All rights reserved.
4  *
5  * Author: Shobhit Kumar <shobhit.kumar@intel.com>
6  */
7 
8 #include <linux/platform_device.h>
9 #include <linux/regmap.h>
10 #include <linux/mfd/intel_soc_pmic.h>
11 #include <linux/pwm.h>
12 
13 #define PWM0_CLK_DIV		0x4B
14 #define  PWM_OUTPUT_ENABLE	BIT(7)
15 #define  PWM_DIV_CLK_0		0x00 /* DIVIDECLK = BASECLK */
16 #define  PWM_DIV_CLK_100	0x63 /* DIVIDECLK = BASECLK/100 */
17 #define  PWM_DIV_CLK_128	0x7F /* DIVIDECLK = BASECLK/128 */
18 
19 #define PWM0_DUTY_CYCLE		0x4E
20 #define BACKLIGHT_EN		0x51
21 
22 #define PWM_MAX_LEVEL		0xFF
23 
24 #define PWM_BASE_CLK_MHZ	6	/* 6 MHz */
25 #define PWM_MAX_PERIOD_NS	5461334	/* 183 Hz */
26 
27 /**
28  * struct crystalcove_pwm - Crystal Cove PWM controller
29  * @chip: the abstract pwm_chip structure.
30  * @regmap: the regmap from the parent device.
31  */
32 struct crystalcove_pwm {
33 	struct pwm_chip chip;
34 	struct regmap *regmap;
35 };
36 
to_crc_pwm(struct pwm_chip * chip)37 static inline struct crystalcove_pwm *to_crc_pwm(struct pwm_chip *chip)
38 {
39 	return container_of(chip, struct crystalcove_pwm, chip);
40 }
41 
crc_pwm_calc_clk_div(int period_ns)42 static int crc_pwm_calc_clk_div(int period_ns)
43 {
44 	int clk_div;
45 
46 	clk_div = PWM_BASE_CLK_MHZ * period_ns / (256 * NSEC_PER_USEC);
47 	/* clk_div 1 - 128, maps to register values 0-127 */
48 	if (clk_div > 0)
49 		clk_div--;
50 
51 	return clk_div;
52 }
53 
crc_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)54 static int crc_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
55 			 const struct pwm_state *state)
56 {
57 	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
58 	struct device *dev = crc_pwm->chip.dev;
59 	int err;
60 
61 	if (state->period > PWM_MAX_PERIOD_NS) {
62 		dev_err(dev, "un-supported period_ns\n");
63 		return -EINVAL;
64 	}
65 
66 	if (state->polarity != PWM_POLARITY_NORMAL)
67 		return -EINVAL;
68 
69 	if (pwm_is_enabled(pwm) && !state->enabled) {
70 		err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 0);
71 		if (err) {
72 			dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
73 			return err;
74 		}
75 	}
76 
77 	if (pwm_get_duty_cycle(pwm) != state->duty_cycle ||
78 	    pwm_get_period(pwm) != state->period) {
79 		u64 level = state->duty_cycle * PWM_MAX_LEVEL;
80 
81 		do_div(level, state->period);
82 
83 		err = regmap_write(crc_pwm->regmap, PWM0_DUTY_CYCLE, level);
84 		if (err) {
85 			dev_err(dev, "Error writing PWM0_DUTY_CYCLE %d\n", err);
86 			return err;
87 		}
88 	}
89 
90 	if (pwm_is_enabled(pwm) && state->enabled &&
91 	    pwm_get_period(pwm) != state->period) {
92 		/* changing the clk divisor, clear PWM_OUTPUT_ENABLE first */
93 		err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV, 0);
94 		if (err) {
95 			dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
96 			return err;
97 		}
98 	}
99 
100 	if (pwm_get_period(pwm) != state->period ||
101 	    pwm_is_enabled(pwm) != state->enabled) {
102 		int clk_div = crc_pwm_calc_clk_div(state->period);
103 		int pwm_output_enable = state->enabled ? PWM_OUTPUT_ENABLE : 0;
104 
105 		err = regmap_write(crc_pwm->regmap, PWM0_CLK_DIV,
106 				   clk_div | pwm_output_enable);
107 		if (err) {
108 			dev_err(dev, "Error writing PWM0_CLK_DIV %d\n", err);
109 			return err;
110 		}
111 	}
112 
113 	if (!pwm_is_enabled(pwm) && state->enabled) {
114 		err = regmap_write(crc_pwm->regmap, BACKLIGHT_EN, 1);
115 		if (err) {
116 			dev_err(dev, "Error writing BACKLIGHT_EN %d\n", err);
117 			return err;
118 		}
119 	}
120 
121 	return 0;
122 }
123 
crc_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)124 static int crc_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
125 			     struct pwm_state *state)
126 {
127 	struct crystalcove_pwm *crc_pwm = to_crc_pwm(chip);
128 	struct device *dev = crc_pwm->chip.dev;
129 	unsigned int clk_div, clk_div_reg, duty_cycle_reg;
130 	int error;
131 
132 	error = regmap_read(crc_pwm->regmap, PWM0_CLK_DIV, &clk_div_reg);
133 	if (error) {
134 		dev_err(dev, "Error reading PWM0_CLK_DIV %d\n", error);
135 		return error;
136 	}
137 
138 	error = regmap_read(crc_pwm->regmap, PWM0_DUTY_CYCLE, &duty_cycle_reg);
139 	if (error) {
140 		dev_err(dev, "Error reading PWM0_DUTY_CYCLE %d\n", error);
141 		return error;
142 	}
143 
144 	clk_div = (clk_div_reg & ~PWM_OUTPUT_ENABLE) + 1;
145 
146 	state->period =
147 		DIV_ROUND_UP(clk_div * NSEC_PER_USEC * 256, PWM_BASE_CLK_MHZ);
148 	state->duty_cycle =
149 		DIV_ROUND_UP_ULL(duty_cycle_reg * state->period, PWM_MAX_LEVEL);
150 	state->polarity = PWM_POLARITY_NORMAL;
151 	state->enabled = !!(clk_div_reg & PWM_OUTPUT_ENABLE);
152 
153 	return 0;
154 }
155 
156 static const struct pwm_ops crc_pwm_ops = {
157 	.apply = crc_pwm_apply,
158 	.get_state = crc_pwm_get_state,
159 };
160 
crystalcove_pwm_probe(struct platform_device * pdev)161 static int crystalcove_pwm_probe(struct platform_device *pdev)
162 {
163 	struct crystalcove_pwm *pwm;
164 	struct device *dev = pdev->dev.parent;
165 	struct intel_soc_pmic *pmic = dev_get_drvdata(dev);
166 
167 	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
168 	if (!pwm)
169 		return -ENOMEM;
170 
171 	pwm->chip.dev = &pdev->dev;
172 	pwm->chip.ops = &crc_pwm_ops;
173 	pwm->chip.npwm = 1;
174 
175 	/* get the PMIC regmap */
176 	pwm->regmap = pmic->regmap;
177 
178 	return devm_pwmchip_add(&pdev->dev, &pwm->chip);
179 }
180 
181 static struct platform_driver crystalcove_pwm_driver = {
182 	.probe = crystalcove_pwm_probe,
183 	.driver = {
184 		.name = "crystal_cove_pwm",
185 	},
186 };
187 
188 builtin_platform_driver(crystalcove_pwm_driver);
189