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 | struct pwm_chip chip; |
32 | }; |
33 | |
34 | #define to_pwm_imx1_chip(chip) container_of(chip, struct pwm_imx1_chip, chip) |
35 | |
36 | static 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(clk: imx->clk_ipg); |
42 | if (ret) |
43 | return ret; |
44 | |
45 | ret = clk_prepare_enable(clk: imx->clk_per); |
46 | if (ret) { |
47 | clk_disable_unprepare(clk: imx->clk_ipg); |
48 | return ret; |
49 | } |
50 | |
51 | return 0; |
52 | } |
53 | |
54 | static 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(clk: imx->clk_per); |
59 | clk_disable_unprepare(clk: imx->clk_ipg); |
60 | } |
61 | |
62 | static 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(addr: imx->mmio_base + MX1_PWMP); |
86 | p = mul_u64_u64_div_u64(a: max, mul: duty_ns, div: period_ns); |
87 | |
88 | writel(val: max - p, addr: imx->mmio_base + MX1_PWMS); |
89 | |
90 | return 0; |
91 | } |
92 | |
93 | static 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(addr: imx->mmio_base + MX1_PWMC); |
104 | value |= MX1_PWMC_EN; |
105 | writel(val: value, addr: imx->mmio_base + MX1_PWMC); |
106 | |
107 | return 0; |
108 | } |
109 | |
110 | static 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(addr: imx->mmio_base + MX1_PWMC); |
116 | value &= ~MX1_PWMC_EN; |
117 | writel(val: value, addr: imx->mmio_base + MX1_PWMC); |
118 | |
119 | pwm_imx1_clk_disable_unprepare(chip); |
120 | } |
121 | |
122 | static 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, duty_ns: state->duty_cycle, period_ns: 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 | |
147 | static const struct pwm_ops pwm_imx1_ops = { |
148 | .apply = pwm_imx1_apply, |
149 | .owner = THIS_MODULE, |
150 | }; |
151 | |
152 | static const struct of_device_id pwm_imx1_dt_ids[] = { |
153 | { .compatible = "fsl,imx1-pwm" , }, |
154 | { /* sentinel */ } |
155 | }; |
156 | MODULE_DEVICE_TABLE(of, pwm_imx1_dt_ids); |
157 | |
158 | static int pwm_imx1_probe(struct platform_device *pdev) |
159 | { |
160 | struct pwm_imx1_chip *imx; |
161 | |
162 | imx = devm_kzalloc(dev: &pdev->dev, size: sizeof(*imx), GFP_KERNEL); |
163 | if (!imx) |
164 | return -ENOMEM; |
165 | |
166 | imx->clk_ipg = devm_clk_get(dev: &pdev->dev, id: "ipg" ); |
167 | if (IS_ERR(ptr: imx->clk_ipg)) |
168 | return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: imx->clk_ipg), |
169 | fmt: "getting ipg clock failed\n" ); |
170 | |
171 | imx->clk_per = devm_clk_get(dev: &pdev->dev, id: "per" ); |
172 | if (IS_ERR(ptr: imx->clk_per)) |
173 | return dev_err_probe(dev: &pdev->dev, err: PTR_ERR(ptr: imx->clk_per), |
174 | fmt: "failed to get peripheral clock\n" ); |
175 | |
176 | imx->chip.ops = &pwm_imx1_ops; |
177 | imx->chip.dev = &pdev->dev; |
178 | imx->chip.npwm = 1; |
179 | |
180 | imx->mmio_base = devm_platform_ioremap_resource(pdev, index: 0); |
181 | if (IS_ERR(ptr: imx->mmio_base)) |
182 | return PTR_ERR(ptr: imx->mmio_base); |
183 | |
184 | return devm_pwmchip_add(dev: &pdev->dev, chip: &imx->chip); |
185 | } |
186 | |
187 | static struct platform_driver pwm_imx1_driver = { |
188 | .driver = { |
189 | .name = "pwm-imx1" , |
190 | .of_match_table = pwm_imx1_dt_ids, |
191 | }, |
192 | .probe = pwm_imx1_probe, |
193 | }; |
194 | module_platform_driver(pwm_imx1_driver); |
195 | |
196 | MODULE_LICENSE("GPL v2" ); |
197 | MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>" ); |
198 | |