1/*
  2 * Copyright 2014 Bart Tanghe <bart.tanghe@thomasmore.be>
  3 *
  4 * This program is free software; you can redistribute it and/or modify
  5 * it under the terms of the GNU General Public License as published by
  6 * the Free Software Foundation; version 2.
  7 */
  8
  9#include <linux/clk.h>
 10#include <linux/err.h>
 11#include <linux/io.h>
 12#include <linux/module.h>
 13#include <linux/of.h>
 14#include <linux/platform_device.h>
 15#include <linux/pwm.h>
 16
 17#define PWM_CONTROL		0x000
 18#define PWM_CONTROL_SHIFT(x)	((x) * 8)
 19#define PWM_CONTROL_MASK	0xff
 20#define PWM_MODE		0x80		/* set timer in PWM mode */
 21#define PWM_ENABLE		(1 << 0)
 22#define PWM_POLARITY		(1 << 4)
 23
 24#define PERIOD(x)		(((x) * 0x10) + 0x10)
 25#define DUTY(x)			(((x) * 0x10) + 0x14)
 26
 27#define MIN_PERIOD		108		/* 9.2 MHz max. PWM clock */
 28
 29struct bcm2835_pwm {
 30	struct pwm_chip chip;
 31	struct device *dev;
 32	void __iomem *base;
 33	struct clk *clk;
 34};
 35
 36static inline struct bcm2835_pwm *to_bcm2835_pwm(struct pwm_chip *chip)
 37{
 38	return container_of(chip, struct bcm2835_pwm, chip);
 39}
 40
 41static int bcm2835_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
 42{
 43	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 44	u32 value;
 45
 46	value = readl(pc->base + PWM_CONTROL);
 47	value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
 48	value |= (PWM_MODE << PWM_CONTROL_SHIFT(pwm->hwpwm));
 49	writel(value, pc->base + PWM_CONTROL);
 50
 51	return 0;
 52}
 53
 54static void bcm2835_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
 55{
 56	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 57	u32 value;
 58
 59	value = readl(pc->base + PWM_CONTROL);
 60	value &= ~(PWM_CONTROL_MASK << PWM_CONTROL_SHIFT(pwm->hwpwm));
 61	writel(value, pc->base + PWM_CONTROL);
 62}
 63
 64static int bcm2835_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
 65			      int duty_ns, int period_ns)
 66{
 67	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 68	unsigned long rate = clk_get_rate(pc->clk);
 69	unsigned long scaler;
 70
 71	if (!rate) {
 72		dev_err(pc->dev, "failed to get clock rate\n");
 73		return -EINVAL;
 74	}
 75
 76	scaler = NSEC_PER_SEC / rate;
 77
 78	if (period_ns <= MIN_PERIOD) {
 79		dev_err(pc->dev, "period %d not supported, minimum %d\n",
 80			period_ns, MIN_PERIOD);
 81		return -EINVAL;
 82	}
 83
 84	writel(duty_ns / scaler, pc->base + DUTY(pwm->hwpwm));
 85	writel(period_ns / scaler, pc->base + PERIOD(pwm->hwpwm));
 86
 87	return 0;
 88}
 89
 90static int bcm2835_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
 91{
 92	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
 93	u32 value;
 94
 95	value = readl(pc->base + PWM_CONTROL);
 96	value |= PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm);
 97	writel(value, pc->base + PWM_CONTROL);
 98
 99	return 0;
100}
101
102static void bcm2835_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
103{
104	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
105	u32 value;
106
107	value = readl(pc->base + PWM_CONTROL);
108	value &= ~(PWM_ENABLE << PWM_CONTROL_SHIFT(pwm->hwpwm));
109	writel(value, pc->base + PWM_CONTROL);
110}
111
112static int bcm2835_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
113				enum pwm_polarity polarity)
114{
115	struct bcm2835_pwm *pc = to_bcm2835_pwm(chip);
116	u32 value;
117
118	value = readl(pc->base + PWM_CONTROL);
119
120	if (polarity == PWM_POLARITY_NORMAL)
121		value &= ~(PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm));
122	else
123		value |= PWM_POLARITY << PWM_CONTROL_SHIFT(pwm->hwpwm);
124
125	writel(value, pc->base + PWM_CONTROL);
126
127	return 0;
128}
129
130static const struct pwm_ops bcm2835_pwm_ops = {
131	.request = bcm2835_pwm_request,
132	.free = bcm2835_pwm_free,
133	.config = bcm2835_pwm_config,
134	.enable = bcm2835_pwm_enable,
135	.disable = bcm2835_pwm_disable,
136	.set_polarity = bcm2835_set_polarity,
137	.owner = THIS_MODULE,
138};
139
140static int bcm2835_pwm_probe(struct platform_device *pdev)
141{
142	struct bcm2835_pwm *pc;
143	struct resource *res;
144	int ret;
145
146	pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
147	if (!pc)
148		return -ENOMEM;
149
150	pc->dev = &pdev->dev;
151
152	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
153	pc->base = devm_ioremap_resource(&pdev->dev, res);
154	if (IS_ERR(pc->base))
155		return PTR_ERR(pc->base);
156
157	pc->clk = devm_clk_get(&pdev->dev, NULL);
158	if (IS_ERR(pc->clk)) {
159		dev_err(&pdev->dev, "clock not found: %ld\n", PTR_ERR(pc->clk));
160		return PTR_ERR(pc->clk);
161	}
162
163	ret = clk_prepare_enable(pc->clk);
164	if (ret)
165		return ret;
166
167	pc->chip.dev = &pdev->dev;
168	pc->chip.ops = &bcm2835_pwm_ops;
169	pc->chip.npwm = 2;
170
171	platform_set_drvdata(pdev, pc);
172
173	ret = pwmchip_add(&pc->chip);
174	if (ret < 0)
175		goto add_fail;
176
177	return 0;
178
179add_fail:
180	clk_disable_unprepare(pc->clk);
181	return ret;
182}
183
184static int bcm2835_pwm_remove(struct platform_device *pdev)
185{
186	struct bcm2835_pwm *pc = platform_get_drvdata(pdev);
187
188	clk_disable_unprepare(pc->clk);
189
190	return pwmchip_remove(&pc->chip);
191}
192
193static const struct of_device_id bcm2835_pwm_of_match[] = {
194	{ .compatible = "brcm,bcm2835-pwm", },
195	{ /* sentinel */ }
196};
197MODULE_DEVICE_TABLE(of, bcm2835_pwm_of_match);
198
199static struct platform_driver bcm2835_pwm_driver = {
200	.driver = {
201		.name = "bcm2835-pwm",
202		.of_match_table = bcm2835_pwm_of_match,
203	},
204	.probe = bcm2835_pwm_probe,
205	.remove = bcm2835_pwm_remove,
206};
207module_platform_driver(bcm2835_pwm_driver);
208
209MODULE_AUTHOR("Bart Tanghe <bart.tanghe@thomasmore.be>");
210MODULE_DESCRIPTION("Broadcom BCM2835 PWM driver");
211MODULE_LICENSE("GPL v2");