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
27 struct pwm_imx1_chip {
28 struct clk *clk_ipg;
29 struct clk *clk_per;
30 void __iomem *mmio_base;
31 };
32
to_pwm_imx1_chip(struct pwm_chip * chip)33 static inline struct pwm_imx1_chip *to_pwm_imx1_chip(struct pwm_chip *chip)
34 {
35 return pwmchip_get_drvdata(chip);
36 }
37
pwm_imx1_clk_prepare_enable(struct pwm_chip * chip)38 static int pwm_imx1_clk_prepare_enable(struct pwm_chip *chip)
39 {
40 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
41 int ret;
42
43 ret = clk_prepare_enable(imx->clk_ipg);
44 if (ret)
45 return ret;
46
47 ret = clk_prepare_enable(imx->clk_per);
48 if (ret) {
49 clk_disable_unprepare(imx->clk_ipg);
50 return ret;
51 }
52
53 return 0;
54 }
55
pwm_imx1_clk_disable_unprepare(struct pwm_chip * chip)56 static void pwm_imx1_clk_disable_unprepare(struct pwm_chip *chip)
57 {
58 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
59
60 clk_disable_unprepare(imx->clk_per);
61 clk_disable_unprepare(imx->clk_ipg);
62 }
63
pwm_imx1_config(struct pwm_chip * chip,struct pwm_device * pwm,u64 duty_ns,u64 period_ns)64 static int pwm_imx1_config(struct pwm_chip *chip,
65 struct pwm_device *pwm, u64 duty_ns, u64 period_ns)
66 {
67 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
68 u32 max, p;
69
70 /*
71 * The PWM subsystem allows for exact frequencies. However,
72 * I cannot connect a scope on my device to the PWM line and
73 * thus cannot provide the program the PWM controller
74 * exactly. Instead, I'm relying on the fact that the
75 * Bootloader (u-boot or WinCE+haret) has programmed the PWM
76 * function group already. So I'll just modify the PWM sample
77 * register to follow the ratio of duty_ns vs. period_ns
78 * accordingly.
79 *
80 * This is good enough for programming the brightness of
81 * the LCD backlight.
82 *
83 * The real implementation would divide PERCLK[0] first by
84 * both the prescaler (/1 .. /128) and then by CLKSEL
85 * (/2 .. /16).
86 */
87 max = readl(imx->mmio_base + MX1_PWMP);
88 p = mul_u64_u64_div_u64(max, duty_ns, period_ns);
89
90 writel(max - p, imx->mmio_base + MX1_PWMS);
91
92 return 0;
93 }
94
pwm_imx1_enable(struct pwm_chip * chip,struct pwm_device * pwm)95 static int pwm_imx1_enable(struct pwm_chip *chip, struct pwm_device *pwm)
96 {
97 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
98 u32 value;
99 int ret;
100
101 ret = pwm_imx1_clk_prepare_enable(chip);
102 if (ret < 0)
103 return ret;
104
105 value = readl(imx->mmio_base + MX1_PWMC);
106 value |= MX1_PWMC_EN;
107 writel(value, imx->mmio_base + MX1_PWMC);
108
109 return 0;
110 }
111
pwm_imx1_disable(struct pwm_chip * chip,struct pwm_device * pwm)112 static void pwm_imx1_disable(struct pwm_chip *chip, struct pwm_device *pwm)
113 {
114 struct pwm_imx1_chip *imx = to_pwm_imx1_chip(chip);
115 u32 value;
116
117 value = readl(imx->mmio_base + MX1_PWMC);
118 value &= ~MX1_PWMC_EN;
119 writel(value, imx->mmio_base + MX1_PWMC);
120
121 pwm_imx1_clk_disable_unprepare(chip);
122 }
123
pwm_imx1_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)124 static int pwm_imx1_apply(struct pwm_chip *chip, struct pwm_device *pwm,
125 const struct pwm_state *state)
126 {
127 int err;
128
129 if (state->polarity != PWM_POLARITY_NORMAL)
130 return -EINVAL;
131
132 if (!state->enabled) {
133 if (pwm->state.enabled)
134 pwm_imx1_disable(chip, pwm);
135
136 return 0;
137 }
138
139 err = pwm_imx1_config(chip, pwm, state->duty_cycle, state->period);
140 if (err)
141 return err;
142
143 if (!pwm->state.enabled)
144 return pwm_imx1_enable(chip, pwm);
145
146 return 0;
147 }
148
149 static const struct pwm_ops pwm_imx1_ops = {
150 .apply = pwm_imx1_apply,
151 };
152
153 static const struct of_device_id pwm_imx1_dt_ids[] = {
154 { .compatible = "fsl,imx1-pwm", },
155 { /* sentinel */ }
156 };
157 MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids);
158
pwm_imx1_probe(struct platform_device * pdev)159 static int pwm_imx1_probe(struct platform_device *pdev)
160 {
161 struct pwm_chip *chip;
162 struct pwm_imx1_chip *imx;
163
164 chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*imx));
165 if (IS_ERR(chip))
166 return PTR_ERR(chip);
167 imx = to_pwm_imx1_chip(chip);
168
169 imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
170 if (IS_ERR(imx->clk_ipg))
171 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
172 "getting ipg clock failed\n");
173
174 imx->clk_per = devm_clk_get(&pdev->dev, "per");
175 if (IS_ERR(imx->clk_per))
176 return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
177 "failed to get peripheral clock\n");
178
179 chip->ops = &pwm_imx1_ops;
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, chip);
186 }
187
188 static 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 };
195 module_platform_driver(pwm_imx1_driver);
196
197 MODULE_DESCRIPTION("i.MX1 and i.MX21 Pulse Width Modulator driver");
198 MODULE_LICENSE("GPL v2");
199 MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");
200