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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * simple driver for PWM (Pulse Width Modulator) controller
4 *
5 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
6 */
7
8#include <linux/bitfield.h>
9#include <linux/bitops.h>
10#include <linux/clk.h>
11#include <linux/delay.h>
12#include <linux/err.h>
13#include <linux/io.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/of_device.h>
18#include <linux/platform_device.h>
19#include <linux/pwm.h>
20#include <linux/slab.h>
21
22#define MX1_PWMC 0x00 /* PWM Control Register */
23#define MX1_PWMS 0x04 /* PWM Sample Register */
24#define MX1_PWMP 0x08 /* PWM Period Register */
25
26#define MX1_PWMC_EN BIT(4)
27
28struct pwm_imx1_chip {
29 struct clk *clk_ipg;
30 struct clk *clk_per;
31 void __iomem *mmio_base;
32 struct pwm_chip chip;
33};
34
35#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip)
36
37static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
38{
39 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
40 int ret;
41
42 ret = clk_prepare_enable(imx->clk_ipg);
43 if (ret)
44 return ret;
45
46 ret = clk_prepare_enable(imx->clk_per);
47 if (ret) {
48 clk_disable_unprepare(imx->clk_ipg);
49 return ret;
50 }
51
52 return 0;
53}
54
55static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
56{
57 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
58
59 clk_disable_unprepare(imx->clk_per);
60 clk_disable_unprepare(imx->clk_ipg);
61}
62
63static int pwm_imx1_config(struct pwm_chip *chip,
64 struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
65{
66 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
67 u32 max, p;
68
69 /*
70 * The PWM subsystem allows for exact frequencies. However,
71 * I cannot connect a scope on my device to the PWM line and
72 * thus cannot provide the program the PWM controller
73 * exactly. Instead, I'm relying on the fact that the
74 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
75 * function group already. So I'll just modify the PWM sample
76 * register to follow the ratio of duty_ns vs. period_ns
77 * accordingly.
78 *
79 * This is good enough for programming the brightness of
80 * the LCD backlight.
81 *
82 * The real implementation would divide PERCLK[0] first by
83 * both the prescaler (/1 .. /128) and then by CLKSEL
84 * (/2 .. /16).
85 */
86 max = readl(imx->mmio_base + MX1_PWMP);
87 p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
88
89 writel(max - p, imx->mmio_base + MX1_PWMS);
90
91 return 0;
92}
93
94static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
95{
96 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
97 u32 value;
98 int ret;
99
100 ret = pwm_imx1_clk_prepare_enable(chip);
101 if (ret < 0)
102 return ret;
103
104 value = readl(imx->mmio_base + MX1_PWMC);
105 value |= MX1_PWMC_EN;
106 writel(value, imx->mmio_base + MX1_PWMC);
107
108 return 0;
109}
110
111static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
112{
113 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
114 u32 value;
115
116 value = readl(imx->mmio_base + MX1_PWMC);
117 value &= ~MX1_PWMC_EN;
118 writel(value, imx->mmio_base + MX1_PWMC);
119
120 pwm_imx1_clk_disable_unprepare(chip);
121}
122
123static int pwm_imx1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
124 const struct pwm_state *state)
125{
126 int err;
127
128 if (state->polarity != PWM_POLARITY_NORMAL)
129 return -EINVAL;
130
131 if (!state->enabled) {
132 if (pwm->state.enabled)
133 pwm_imx1_disable(chip, pwm);
134
135 return 0;
136 }
137
138 err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
139 if (err)
140 return err;
141
142 if (!pwm->state.enabled)
143 return pwm_imx1_enable(chip, pwm);
144
145 return 0;
146}
147
148static const struct pwm_ops pwm_imx1_ops = {
149 .apply = pwm_imx1_apply,
150 .owner = THIS_MODULE,
151};
152
153static const struct of_device_id pwm_imx1_dt_ids[] = {
154 { .compatible = "fsl,imx1-pwm", },
155 { /* sentinel */ }
156};
157MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
158
159static int pwm_imx1_probe(struct platform_device *pdev)
160{
161 struct pwm_imx1_chip *imx;
162
163 imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
164 if (!imx)
165 return -ENOMEM;
166
167 imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
168 if (IS_ERR(imx->clk_ipg))
169 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
170 "getting ipg clock failed\n");
171
172 imx->clk_per = devm_clk_get(&pdev->dev, "per");
173 if (IS_ERR(imx->clk_per))
174 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
175 "failed to get peripheral clock\n");
176
177 imx->chip.ops = &pwm_imx1_ops;
178 imx->chip.dev = &pdev->dev;
179 imx->chip.npwm = 1;
180
181 imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
182 if (IS_ERR(imx->mmio_base))
183 return PTR_ERR(imx->mmio_base);
184
185 return devm_pwmchip_add(&pdev->dev, &imx->chip);
186}
187
188static struct platform_driver pwm_imx1_driver = {
189 .driver = {
190 .name = "pwm-imx1",
191 .of_match_table = pwm_imx1_dt_ids,
192 },
193 .probe = pwm_imx1_probe,
194};
195module_platform_driver(pwm_imx1_driver);
196
197MODULE_LICENSE("GPL v2");
198MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * simple driver for PWM (Pulse Width Modulator) controller
4 *
5 * Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
6 */
7
8#include <linux/bitfield.h>
9#include <linux/bitops.h>
10#include <linux/clk.h>
11#include <linux/delay.h>
12#include <linux/err.h>
13#include <linux/io.h>
14#include <linux/kernel.h>
15#include <linux/module.h>
16#include <linux/of.h>
17#include <linux/platform_device.h>
18#include <linux/pwm.h>
19#include <linux/slab.h>
20
21#define MX1_PWMC 0x00 /* PWM Control Register */
22#define MX1_PWMS 0x04 /* PWM Sample Register */
23#define MX1_PWMP 0x08 /* PWM Period Register */
24
25#define MX1_PWMC_EN BIT(4)
26
27struct pwm_imx1_chip {
28 struct clk *clk_ipg;
29 struct clk *clk_per;
30 void __iomem *mmio_base;
31 struct pwm_chip chip;
32};
33
34#define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip)
35
36static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
37{
38 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
39 int ret;
40
41 ret = clk_prepare_enable(imx->clk_ipg);
42 if (ret)
43 return ret;
44
45 ret = clk_prepare_enable(imx->clk_per);
46 if (ret) {
47 clk_disable_unprepare(imx->clk_ipg);
48 return ret;
49 }
50
51 return 0;
52}
53
54static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
55{
56 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
57
58 clk_disable_unprepare(imx->clk_per);
59 clk_disable_unprepare(imx->clk_ipg);
60}
61
62static int pwm_imx1_config(struct pwm_chip *chip,
63 struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
64{
65 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
66 u32 max, p;
67
68 /*
69 * The PWM subsystem allows for exact frequencies. However,
70 * I cannot connect a scope on my device to the PWM line and
71 * thus cannot provide the program the PWM controller
72 * exactly. Instead, I'm relying on the fact that the
73 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
74 * function group already. So I'll just modify the PWM sample
75 * register to follow the ratio of duty_ns vs. period_ns
76 * accordingly.
77 *
78 * This is good enough for programming the brightness of
79 * the LCD backlight.
80 *
81 * The real implementation would divide PERCLK[0] first by
82 * both the prescaler (/1 .. /128) and then by CLKSEL
83 * (/2 .. /16).
84 */
85 max = readl(imx->mmio_base + MX1_PWMP);
86 p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
87
88 writel(max - p, imx->mmio_base + MX1_PWMS);
89
90 return 0;
91}
92
93static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
94{
95 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
96 u32 value;
97 int ret;
98
99 ret = pwm_imx1_clk_prepare_enable(chip);
100 if (ret < 0)
101 return ret;
102
103 value = readl(imx->mmio_base + MX1_PWMC);
104 value |= MX1_PWMC_EN;
105 writel(value, imx->mmio_base + MX1_PWMC);
106
107 return 0;
108}
109
110static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
111{
112 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
113 u32 value;
114
115 value = readl(imx->mmio_base + MX1_PWMC);
116 value &= ~MX1_PWMC_EN;
117 writel(value, imx->mmio_base + MX1_PWMC);
118
119 pwm_imx1_clk_disable_unprepare(chip);
120}
121
122static int pwm_imx1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
123 const struct pwm_state *state)
124{
125 int err;
126
127 if (state->polarity != PWM_POLARITY_NORMAL)
128 return -EINVAL;
129
130 if (!state->enabled) {
131 if (pwm->state.enabled)
132 pwm_imx1_disable(chip, pwm);
133
134 return 0;
135 }
136
137 err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
138 if (err)
139 return err;
140
141 if (!pwm->state.enabled)
142 return pwm_imx1_enable(chip, pwm);
143
144 return 0;
145}
146
147static const struct pwm_ops pwm_imx1_ops = {
148 .apply = pwm_imx1_apply,
149};
150
151static const struct of_device_id pwm_imx1_dt_ids[] = {
152 { .compatible = "fsl,imx1-pwm", },
153 { /* sentinel */ }
154};
155MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
156
157static int pwm_imx1_probe(struct platform_device *pdev)
158{
159 struct pwm_imx1_chip *imx;
160
161 imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
162 if (!imx)
163 return -ENOMEM;
164
165 imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
166 if (IS_ERR(imx->clk_ipg))
167 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
168 "getting ipg clock failed\n");
169
170 imx->clk_per = devm_clk_get(&pdev->dev, "per");
171 if (IS_ERR(imx->clk_per))
172 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
173 "failed to get peripheral clock\n");
174
175 imx->chip.ops = &pwm_imx1_ops;
176 imx->chip.dev = &pdev->dev;
177 imx->chip.npwm = 1;
178
179 imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
180 if (IS_ERR(imx->mmio_base))
181 return PTR_ERR(imx->mmio_base);
182
183 return devm_pwmchip_add(&pdev->dev, &imx->chip);
184}
185
186static struct platform_driver pwm_imx1_driver = {
187 .driver = {
188 .name = "pwm-imx1",
189 .of_match_table = pwm_imx1_dt_ids,
190 },
191 .probe = pwm_imx1_probe,
192};
193module_platform_driver(pwm_imx1_driver);
194
195MODULE_LICENSE("GPL v2");
196MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");