1/*
  2 * Marvell Berlin PWM driver
  3 *
  4 * Copyright (C) 2015 Marvell Technology Group Ltd.
  5 *
  6 * Author: Antoine Tenart <antoine.tenart@free-electrons.com>
  7 *
  8 * This file is licensed under the terms of the GNU General Public
  9 * License version 2. This program is licensed "as is" without any
 10 * warranty of any kind, whether express or implied.
 11 */
 12
 13#include <linux/clk.h>
 14#include <linux/io.h>
 15#include <linux/kernel.h>
 16#include <linux/module.h>
 17#include <linux/platform_device.h>
 18#include <linux/pwm.h>
 19
 20#define BERLIN_PWM_EN			0x0
 21#define  BERLIN_PWM_ENABLE		BIT(0)
 22#define BERLIN_PWM_CONTROL		0x4
 23#define  BERLIN_PWM_PRESCALE_MASK	0x7
 24#define  BERLIN_PWM_PRESCALE_MAX	4096
 25#define  BERLIN_PWM_INVERT_POLARITY	BIT(3)
 26#define BERLIN_PWM_DUTY			0x8
 27#define BERLIN_PWM_TCNT			0xc
 28#define  BERLIN_PWM_MAX_TCNT		65535
 29
 30struct berlin_pwm_chip {
 31	struct pwm_chip chip;
 32	struct clk *clk;
 33	void __iomem *base;
 34};
 35
 36static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
 37{
 38	return container_of(chip, struct berlin_pwm_chip, chip);
 39}
 40
 41static const u32 prescaler_table[] = {
 42	1, 4, 8, 16, 64, 256, 1024, 4096
 43};
 44
 45static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip,
 46				   unsigned int channel, unsigned long offset)
 47{
 48	return readl_relaxed(chip->base + channel * 0x10 + offset);
 49}
 50
 51static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,
 52				     unsigned int channel, u32 value,
 53				     unsigned long offset)
 54{
 55	writel_relaxed(value, chip->base + channel * 0x10 + offset);
 56}
 57
 58static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
 59			     int duty_ns, int period_ns)
 60{
 61	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
 62	unsigned int prescale;
 63	u32 value, duty, period;
 64	u64 cycles, tmp;
 65
 66	cycles = clk_get_rate(pwm->clk);
 67	cycles *= period_ns;
 68	do_div(cycles, NSEC_PER_SEC);
 69
 70	for (prescale = 0; prescale < ARRAY_SIZE(prescaler_table); prescale++) {
 71		tmp = cycles;
 72		do_div(tmp, prescaler_table[prescale]);
 73
 74		if (tmp <= BERLIN_PWM_MAX_TCNT)
 75			break;
 76	}
 77
 78	if (tmp > BERLIN_PWM_MAX_TCNT)
 79		return -ERANGE;
 80
 81	period = tmp;
 82	cycles = tmp * duty_ns;
 83	do_div(cycles, period_ns);
 84	duty = cycles;
 85
 86	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
 87	value &= ~BERLIN_PWM_PRESCALE_MASK;
 88	value |= prescale;
 89	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
 90
 91	berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
 92	berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT);
 93
 94	return 0;
 95}
 96
 97static int berlin_pwm_set_polarity(struct pwm_chip *chip,
 98				   struct pwm_device *pwm_dev,
 99				   enum pwm_polarity polarity)
100{
101	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
102	u32 value;
103
104	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
105
106	if (polarity == PWM_POLARITY_NORMAL)
107		value &= ~BERLIN_PWM_INVERT_POLARITY;
108	else
109		value |= BERLIN_PWM_INVERT_POLARITY;
110
111	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
112
113	return 0;
114}
115
116static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
117{
118	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
119	u32 value;
120
121	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
122	value |= BERLIN_PWM_ENABLE;
123	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
124
125	return 0;
126}
127
128static void berlin_pwm_disable(struct pwm_chip *chip,
129			       struct pwm_device *pwm_dev)
130{
131	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
132	u32 value;
133
134	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
135	value &= ~BERLIN_PWM_ENABLE;
136	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
137}
138
139static const struct pwm_ops berlin_pwm_ops = {
140	.config = berlin_pwm_config,
141	.set_polarity = berlin_pwm_set_polarity,
142	.enable = berlin_pwm_enable,
143	.disable = berlin_pwm_disable,
144	.owner = THIS_MODULE,
145};
146
147static const struct of_device_id berlin_pwm_match[] = {
148	{ .compatible = "marvell,berlin-pwm" },
149	{ },
150};
151MODULE_DEVICE_TABLE(of, berlin_pwm_match);
152
153static int berlin_pwm_probe(struct platform_device *pdev)
154{
155	struct berlin_pwm_chip *pwm;
156	struct resource *res;
157	int ret;
158
159	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
160	if (!pwm)
161		return -ENOMEM;
162
163	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
164	pwm->base = devm_ioremap_resource(&pdev->dev, res);
165	if (IS_ERR(pwm->base))
166		return PTR_ERR(pwm->base);
167
168	pwm->clk = devm_clk_get(&pdev->dev, NULL);
169	if (IS_ERR(pwm->clk))
170		return PTR_ERR(pwm->clk);
171
172	ret = clk_prepare_enable(pwm->clk);
173	if (ret)
174		return ret;
175
176	pwm->chip.dev = &pdev->dev;
177	pwm->chip.ops = &berlin_pwm_ops;
178	pwm->chip.base = -1;
179	pwm->chip.npwm = 4;
180	pwm->chip.can_sleep = true;
181	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
182	pwm->chip.of_pwm_n_cells = 3;
183
184	ret = pwmchip_add(&pwm->chip);
185	if (ret < 0) {
186		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
187		clk_disable_unprepare(pwm->clk);
188		return ret;
189	}
190
191	platform_set_drvdata(pdev, pwm);
192
193	return 0;
194}
195
196static int berlin_pwm_remove(struct platform_device *pdev)
197{
198	struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
199	int ret;
200
201	ret = pwmchip_remove(&pwm->chip);
202	clk_disable_unprepare(pwm->clk);
203
204	return ret;
205}
206
207static struct platform_driver berlin_pwm_driver = {
208	.probe = berlin_pwm_probe,
209	.remove = berlin_pwm_remove,
210	.driver = {
211		.name = "berlin-pwm",
212		.of_match_table = berlin_pwm_match,
213	},
214};
215module_platform_driver(berlin_pwm_driver);
216
217MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
218MODULE_DESCRIPTION("Marvell Berlin PWM driver");
219MODULE_LICENSE("GPL v2");