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 | |
33 | static inline struct pwm_imx1_chip *to_pwm_imx1_chip(struct pwm_chip *chip) |
34 | { |
35 | return pwmchip_get_drvdata(chip); |
36 | } |
37 | |
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(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 | |
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(clk: imx->clk_per); |
61 | clk_disable_unprepare(clk: imx->clk_ipg); |
62 | } |
63 | |
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(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 | |
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(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 | |
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(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 | |
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, 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 | |
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 | |
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(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 | |
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_LICENSE("GPL v2" ); |
198 | MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>" ); |
199 | |