1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright 2012 Alexandre Pereira da Silva <aletes.xgr@gmail.com>
4 */
5
6#include <linux/clk.h>
7#include <linux/err.h>
8#include <linux/io.h>
9#include <linux/kernel.h>
10#include <linux/module.h>
11#include <linux/of.h>
12#include <linux/of_address.h>
13#include <linux/platform_device.h>
14#include <linux/pwm.h>
15#include <linux/slab.h>
16
17struct lpc32xx_pwm_chip {
18	struct clk *clk;
19	void __iomem *base;
20};
21
22#define PWM_ENABLE	BIT(31)
23#define PWM_PIN_LEVEL	BIT(30)
24
25static inline struct lpc32xx_pwm_chip *to_lpc32xx_pwm_chip(struct pwm_chip *chip)
26{
27	return pwmchip_get_drvdata(chip);
28}
29
30static int lpc32xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
31			      int duty_ns, int period_ns)
32{
33	struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
34	unsigned long long c;
35	int period_cycles, duty_cycles;
36	u32 val;
37	c = clk_get_rate(lpc32xx->clk);
38
39	/* The highest acceptable divisor is 256, which is represented by 0 */
40	period_cycles = div64_u64(c * period_ns,
41			       (unsigned long long)NSEC_PER_SEC * 256);
42	if (!period_cycles || period_cycles > 256)
43		return -ERANGE;
44	if (period_cycles == 256)
45		period_cycles = 0;
46
47	/* Compute 256 x #duty/period value and care for corner cases */
48	duty_cycles = div64_u64((unsigned long long)(period_ns - duty_ns) * 256,
49				period_ns);
50	if (!duty_cycles)
51		duty_cycles = 1;
52	if (duty_cycles > 255)
53		duty_cycles = 255;
54
55	val = readl(lpc32xx->base);
56	val &= ~0xFFFF;
57	val |= (period_cycles << 8) | duty_cycles;
58	writel(val, lpc32xx->base);
59
60	return 0;
61}
62
63static int lpc32xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
64{
65	struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
66	u32 val;
67	int ret;
68
69	ret = clk_prepare_enable(lpc32xx->clk);
70	if (ret)
71		return ret;
72
73	val = readl(lpc32xx->base);
74	val |= PWM_ENABLE;
75	writel(val, lpc32xx->base);
76
77	return 0;
78}
79
80static void lpc32xx_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
81{
82	struct lpc32xx_pwm_chip *lpc32xx = to_lpc32xx_pwm_chip(chip);
83	u32 val;
84
85	val = readl(lpc32xx->base);
86	val &= ~PWM_ENABLE;
87	writel(val, lpc32xx->base);
88
89	clk_disable_unprepare(lpc32xx->clk);
90}
91
92static int lpc32xx_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
93			     const struct pwm_state *state)
94{
95	int err;
96
97	if (state->polarity != PWM_POLARITY_NORMAL)
98		return -EINVAL;
99
100	if (!state->enabled) {
101		if (pwm->state.enabled)
102			lpc32xx_pwm_disable(chip, pwm);
103
104		return 0;
105	}
106
107	err = lpc32xx_pwm_config(chip, pwm, state->duty_cycle, state->period);
108	if (err)
109		return err;
110
111	if (!pwm->state.enabled)
112		err = lpc32xx_pwm_enable(chip, pwm);
113
114	return err;
115}
116
117static const struct pwm_ops lpc32xx_pwm_ops = {
118	.apply = lpc32xx_pwm_apply,
119};
120
121static int lpc32xx_pwm_probe(struct platform_device *pdev)
122{
123	struct pwm_chip *chip;
124	struct lpc32xx_pwm_chip *lpc32xx;
125	int ret;
126	u32 val;
127
128	chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*lpc32xx));
129	if (IS_ERR(chip))
130		return PTR_ERR(chip);
131	lpc32xx = to_lpc32xx_pwm_chip(chip);
132
133	lpc32xx->base = devm_platform_ioremap_resource(pdev, 0);
134	if (IS_ERR(lpc32xx->base))
135		return PTR_ERR(lpc32xx->base);
136
137	lpc32xx->clk = devm_clk_get(&pdev->dev, NULL);
138	if (IS_ERR(lpc32xx->clk))
139		return PTR_ERR(lpc32xx->clk);
140
141	chip->ops = &lpc32xx_pwm_ops;
142
143	/* If PWM is disabled, configure the output to the default value */
144	val = readl(lpc32xx->base);
145	val &= ~PWM_PIN_LEVEL;
146	writel(val, lpc32xx->base);
147
148	ret = devm_pwmchip_add(&pdev->dev, chip);
149	if (ret < 0) {
150		dev_err(&pdev->dev, "failed to add PWM chip, error %d\n", ret);
151		return ret;
152	}
153
154	return 0;
155}
156
157static const struct of_device_id lpc32xx_pwm_dt_ids[] = {
158	{ .compatible = "nxp,lpc3220-pwm", },
159	{ /* sentinel */ }
160};
161MODULE_DEVICE_TABLE(of, lpc32xx_pwm_dt_ids);
162
163static struct platform_driver lpc32xx_pwm_driver = {
164	.driver = {
165		.name = "lpc32xx-pwm",
166		.of_match_table = lpc32xx_pwm_dt_ids,
167	},
168	.probe = lpc32xx_pwm_probe,
169};
170module_platform_driver(lpc32xx_pwm_driver);
171
172MODULE_ALIAS("platform:lpc32xx-pwm");
173MODULE_AUTHOR("Alexandre Pereira da Silva <aletes.xgr@gmail.com>");
174MODULE_DESCRIPTION("LPC32XX PWM Driver");
175MODULE_LICENSE("GPL v2");
176