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");
220