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