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#include <linux/slab.h>
20
21#define BERLIN_PWM_EN			0x0
22#define  BERLIN_PWM_ENABLE		BIT(0)
23#define BERLIN_PWM_CONTROL		0x4
24/*
25 * The prescaler claims to support 8 different moduli, configured using the
26 * low three bits of PWM_CONTROL. (Sequentially, they are 1, 4, 8, 16, 64,
27 * 256, 1024, and 4096.)  However, the moduli from 4 to 1024 appear to be
28 * implemented by internally shifting TCNT left without adding additional
29 * bits. So, the max TCNT that actually works for a modulus of 4 is 0x3fff;
30 * for 8, 0x1fff; and so on. This means that those moduli are entirely
31 * useless, as we could just do the shift ourselves. The 4096 modulus is
32 * implemented with a real prescaler, so we do use that, but we treat it
33 * as a flag instead of pretending the modulus is actually configurable.
34 */
35#define  BERLIN_PWM_PRESCALE_4096	0x7
36#define  BERLIN_PWM_INVERT_POLARITY	BIT(3)
37#define BERLIN_PWM_DUTY			0x8
38#define BERLIN_PWM_TCNT			0xc
39#define  BERLIN_PWM_MAX_TCNT		65535
40
41struct berlin_pwm_channel {
42	u32 enable;
43	u32 ctrl;
44	u32 duty;
45	u32 tcnt;
46};
47
48struct berlin_pwm_chip {
49	struct pwm_chip chip;
50	struct clk *clk;
51	void __iomem *base;
52};
53
54static inline struct berlin_pwm_chip *to_berlin_pwm_chip(struct pwm_chip *chip)
55{
56	return container_of(chip, struct berlin_pwm_chip, chip);
57}
58
59static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *chip,
60				   unsigned int channel, unsigned long offset)
61{
62	return readl_relaxed(chip->base + channel * 0x10 + offset);
63}
64
65static inline void berlin_pwm_writel(struct berlin_pwm_chip *chip,
66				     unsigned int channel, u32 value,
67				     unsigned long offset)
68{
69	writel_relaxed(value, chip->base + channel * 0x10 + offset);
70}
71
72static int berlin_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
73{
74	struct berlin_pwm_channel *channel;
75
76	channel = kzalloc(sizeof(*channel), GFP_KERNEL);
77	if (!channel)
78		return -ENOMEM;
79
80	return pwm_set_chip_data(pwm, channel);
81}
82
83static void berlin_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
84{
85	struct berlin_pwm_channel *channel = pwm_get_chip_data(pwm);
86
87	kfree(channel);
88}
89
90static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
91			     int duty_ns, int period_ns)
92{
93	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
94	bool prescale_4096 = false;
95	u32 value, duty, period;
96	u64 cycles;
97
98	cycles = clk_get_rate(pwm->clk);
99	cycles *= period_ns;
100	do_div(cycles, NSEC_PER_SEC);
101
102	if (cycles > BERLIN_PWM_MAX_TCNT) {
103		prescale_4096 = true;
104		cycles >>= 12; // Prescaled by 4096
105
106		if (cycles > BERLIN_PWM_MAX_TCNT)
107			return -ERANGE;
108	}
109
110	period = cycles;
111	cycles *= duty_ns;
112	do_div(cycles, period_ns);
113	duty = cycles;
114
115	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
116	if (prescale_4096)
117		value |= BERLIN_PWM_PRESCALE_4096;
118	else
119		value &= ~BERLIN_PWM_PRESCALE_4096;
120	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
121
122	berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
123	berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT);
124
125	return 0;
126}
127
128static int berlin_pwm_set_polarity(struct pwm_chip *chip,
129				   struct pwm_device *pwm_dev,
130				   enum pwm_polarity polarity)
131{
132	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
133	u32 value;
134
135	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
136
137	if (polarity == PWM_POLARITY_NORMAL)
138		value &= ~BERLIN_PWM_INVERT_POLARITY;
139	else
140		value |= BERLIN_PWM_INVERT_POLARITY;
141
142	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
143
144	return 0;
145}
146
147static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
148{
149	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
150	u32 value;
151
152	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
153	value |= BERLIN_PWM_ENABLE;
154	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
155
156	return 0;
157}
158
159static void berlin_pwm_disable(struct pwm_chip *chip,
160			       struct pwm_device *pwm_dev)
161{
162	struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
163	u32 value;
164
165	value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
166	value &= ~BERLIN_PWM_ENABLE;
167	berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
168}
169
170static const struct pwm_ops berlin_pwm_ops = {
171	.request = berlin_pwm_request,
172	.free = berlin_pwm_free,
173	.config = berlin_pwm_config,
174	.set_polarity = berlin_pwm_set_polarity,
175	.enable = berlin_pwm_enable,
176	.disable = berlin_pwm_disable,
177	.owner = THIS_MODULE,
178};
179
180static const struct of_device_id berlin_pwm_match[] = {
181	{ .compatible = "marvell,berlin-pwm" },
182	{ },
183};
184MODULE_DEVICE_TABLE(of, berlin_pwm_match);
185
186static int berlin_pwm_probe(struct platform_device *pdev)
187{
188	struct berlin_pwm_chip *pwm;
189	struct resource *res;
190	int ret;
191
192	pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
193	if (!pwm)
194		return -ENOMEM;
195
196	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
197	pwm->base = devm_ioremap_resource(&pdev->dev, res);
198	if (IS_ERR(pwm->base))
199		return PTR_ERR(pwm->base);
200
201	pwm->clk = devm_clk_get(&pdev->dev, NULL);
202	if (IS_ERR(pwm->clk))
203		return PTR_ERR(pwm->clk);
204
205	ret = clk_prepare_enable(pwm->clk);
206	if (ret)
207		return ret;
208
209	pwm->chip.dev = &pdev->dev;
210	pwm->chip.ops = &berlin_pwm_ops;
211	pwm->chip.base = -1;
212	pwm->chip.npwm = 4;
213	pwm->chip.of_xlate = of_pwm_xlate_with_flags;
214	pwm->chip.of_pwm_n_cells = 3;
215
216	ret = pwmchip_add(&pwm->chip);
217	if (ret < 0) {
218		dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
219		clk_disable_unprepare(pwm->clk);
220		return ret;
221	}
222
223	platform_set_drvdata(pdev, pwm);
224
225	return 0;
226}
227
228static int berlin_pwm_remove(struct platform_device *pdev)
229{
230	struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
231	int ret;
232
233	ret = pwmchip_remove(&pwm->chip);
234	clk_disable_unprepare(pwm->clk);
235
236	return ret;
237}
238
239#ifdef CONFIG_PM_SLEEP
240static int berlin_pwm_suspend(struct device *dev)
241{
242	struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
243	unsigned int i;
244
245	for (i = 0; i < pwm->chip.npwm; i++) {
246		struct berlin_pwm_channel *channel;
247
248		channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
249		if (!channel)
250			continue;
251
252		channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE);
253		channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL);
254		channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY);
255		channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT);
256	}
257
258	clk_disable_unprepare(pwm->clk);
259
260	return 0;
261}
262
263static int berlin_pwm_resume(struct device *dev)
264{
265	struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
266	unsigned int i;
267	int ret;
268
269	ret = clk_prepare_enable(pwm->clk);
270	if (ret)
271		return ret;
272
273	for (i = 0; i < pwm->chip.npwm; i++) {
274		struct berlin_pwm_channel *channel;
275
276		channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
277		if (!channel)
278			continue;
279
280		berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL);
281		berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY);
282		berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT);
283		berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE);
284	}
285
286	return 0;
287}
288#endif
289
290static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
291			 berlin_pwm_resume);
292
293static struct platform_driver berlin_pwm_driver = {
294	.probe = berlin_pwm_probe,
295	.remove = berlin_pwm_remove,
296	.driver = {
297		.name = "berlin-pwm",
298		.of_match_table = berlin_pwm_match,
299		.pm = &berlin_pwm_pm_ops,
300	},
301};
302module_platform_driver(berlin_pwm_driver);
303
304MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
305MODULE_DESCRIPTION("Marvell Berlin PWM driver");
306MODULE_LICENSE("GPL v2");
307