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};
32
33static inline struct pwm_imx1_chip *to_pwm_imx1_chip(struct pwm_chip *chip)
34{
35 return pwmchip_get_drvdata(chip);
36}
37
38static 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(clk: imx->clk_ipg);
44 if (ret)
45 return ret;
46
47 ret = clk_prepare_enable(clk: imx->clk_per);
48 if (ret) {
49 clk_disable_unprepare(clk: imx->clk_ipg);
50 return ret;
51 }
52
53 return 0;
54}
55
56static 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(clk: imx->clk_per);
61 clk_disable_unprepare(clk: imx->clk_ipg);
62}
63
64static 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(addr: imx->mmio_base + MX1_PWMP);
88 p = mul_u64_u64_div_u64(a: max, mul: duty_ns, div: period_ns);
89
90 writel(val: max - p, addr: imx->mmio_base + MX1_PWMS);
91
92 return 0;
93}
94
95static 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(addr: imx->mmio_base + MX1_PWMC);
106 value |= MX1_PWMC_EN;
107 writel(val: value, addr: imx->mmio_base + MX1_PWMC);
108
109 return 0;
110}
111
112static 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(addr: imx->mmio_base + MX1_PWMC);
118 value &= ~MX1_PWMC_EN;
119 writel(val: value, addr: imx->mmio_base + MX1_PWMC);
120
121 pwm_imx1_clk_disable_unprepare(chip);
122}
123
124static 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, duty_ns: state->duty_cycle, period_ns: 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
149static const struct pwm_ops pwm_imx1_ops = {
150 .apply = pwm_imx1_apply,
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_chip *chip;
162 struct pwm_imx1_chip *imx;
163
164 chip = devm_pwmchip_alloc(parent: &pdev->dev, npwm: 1, sizeof_priv: sizeof(*imx));
165 if (IS_ERR(ptr: chip))
166 return PTR_ERR(ptr: chip);
167 imx = to_pwm_imx1_chip(chip);
168
169 imx->clk_ipg = devm_clk_get(dev: &pdev->dev, id: "ipg");
170 if (IS_ERR(ptr: imx->clk_ipg))
171 return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: imx->clk_ipg),
172 fmt: "getting ipg clock failed\n");
173
174 imx->clk_per = devm_clk_get(dev: &pdev->dev, id: "per");
175 if (IS_ERR(ptr: imx->clk_per))
176 return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: imx->clk_per),
177 fmt: "failed to get peripheral clock\n");
178
179 chip->ops = &pwm_imx1_ops;
180
181 imx->mmio_base = devm_platform_ioremap_resource(pdev, index: 0);
182 if (IS_ERR(ptr: imx->mmio_base))
183 return PTR_ERR(ptr: imx->mmio_base);
184
185 return devm_pwmchip_add(&pdev->dev, 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>");
199

source code of linux/drivers/pwm/pwm-imx1.c