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(clk: 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, channel: 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, channel: pwm->hwpwm, value, BERLIN_PWM_CONTROL);
106
107 berlin_pwm_writel(bpc, channel: pwm->hwpwm, value: duty, BERLIN_PWM_DUTY);
108 berlin_pwm_writel(bpc, channel: pwm->hwpwm, value: 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, channel: 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, channel: 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, channel: pwm->hwpwm, BERLIN_PWM_EN);
138 value |= BERLIN_PWM_ENABLE;
139 berlin_pwm_writel(bpc, channel: 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, channel: pwm->hwpwm, BERLIN_PWM_EN);
151 value &= ~BERLIN_PWM_ENABLE;
152 berlin_pwm_writel(bpc, channel: 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, polarity: 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, duty_ns: state->duty_cycle, period_ns: 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(parent: &pdev->dev, BERLIN_PWM_NUMPWMS, sizeof_priv: sizeof(*bpc));
205 if (IS_ERR(ptr: chip))
206 return PTR_ERR(ptr: chip);
207 bpc = to_berlin_pwm_chip(chip);
208
209 bpc->base = devm_platform_ioremap_resource(pdev, index: 0);
210 if (IS_ERR(ptr: bpc->base))
211 return PTR_ERR(ptr: bpc->base);
212
213 bpc->clk = devm_clk_get_enabled(dev: &pdev->dev, NULL);
214 if (IS_ERR(ptr: bpc->clk))
215 return PTR_ERR(ptr: 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(dev: &pdev->dev, err: ret, fmt: "failed to add PWM chip\n");
222
223 platform_set_drvdata(pdev, data: 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, channel: i, BERLIN_PWM_EN);
238 channel->ctrl = berlin_pwm_readl(bpc, channel: i, BERLIN_PWM_CONTROL);
239 channel->duty = berlin_pwm_readl(bpc, channel: i, BERLIN_PWM_DUTY);
240 channel->tcnt = berlin_pwm_readl(bpc, channel: i, BERLIN_PWM_TCNT);
241 }
242
243 clk_disable_unprepare(clk: 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(clk: 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, channel: i, value: channel->ctrl, BERLIN_PWM_CONTROL);
263 berlin_pwm_writel(bpc, channel: i, value: channel->duty, BERLIN_PWM_DUTY);
264 berlin_pwm_writel(bpc, channel: i, value: channel->tcnt, BERLIN_PWM_TCNT);
265 berlin_pwm_writel(bpc, channel: i, value: channel->enable, BERLIN_PWM_EN);
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

source code of linux/drivers/pwm/pwm-berlin.c