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
41 struct berlin_pwm_channel {
42 u32 enable;
43 u32 ctrl;
44 u32 duty;
45 u32 tcnt;
46 };
47
48 struct berlin_pwm_chip {
49 struct pwm_chip chip;
50 struct clk *clk;
51 void __iomem *base;
52 };
53
to_berlin_pwm_chip(struct pwm_chip * chip)54 static 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
berlin_pwm_readl(struct berlin_pwm_chip * chip,unsigned int channel,unsigned long offset)59 static 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
berlin_pwm_writel(struct berlin_pwm_chip * chip,unsigned int channel,u32 value,unsigned long offset)65 static 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
berlin_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)72 static 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
berlin_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)83 static 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 pwm_set_chip_data(pwm, NULL);
88 kfree(channel);
89 }
90
berlin_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm_dev,int duty_ns,int period_ns)91 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm_dev,
92 int duty_ns, int period_ns)
93 {
94 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
95 bool prescale_4096 = false;
96 u32 value, duty, period;
97 u64 cycles;
98
99 cycles = clk_get_rate(pwm->clk);
100 cycles *= period_ns;
101 do_div(cycles, NSEC_PER_SEC);
102
103 if (cycles > BERLIN_PWM_MAX_TCNT) {
104 prescale_4096 = true;
105 cycles >>= 12; // Prescaled by 4096
106
107 if (cycles > BERLIN_PWM_MAX_TCNT)
108 return -ERANGE;
109 }
110
111 period = cycles;
112 cycles *= duty_ns;
113 do_div(cycles, period_ns);
114 duty = cycles;
115
116 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
117 if (prescale_4096)
118 value |= BERLIN_PWM_PRESCALE_4096;
119 else
120 value &= ~BERLIN_PWM_PRESCALE_4096;
121 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
122
123 berlin_pwm_writel(pwm, pwm_dev->hwpwm, duty, BERLIN_PWM_DUTY);
124 berlin_pwm_writel(pwm, pwm_dev->hwpwm, period, BERLIN_PWM_TCNT);
125
126 return 0;
127 }
128
berlin_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm_dev,enum pwm_polarity polarity)129 static int berlin_pwm_set_polarity(struct pwm_chip *chip,
130 struct pwm_device *pwm_dev,
131 enum pwm_polarity polarity)
132 {
133 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
134 u32 value;
135
136 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_CONTROL);
137
138 if (polarity == PWM_POLARITY_NORMAL)
139 value &= ~BERLIN_PWM_INVERT_POLARITY;
140 else
141 value |= BERLIN_PWM_INVERT_POLARITY;
142
143 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_CONTROL);
144
145 return 0;
146 }
147
berlin_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm_dev)148 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm_dev)
149 {
150 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
151 u32 value;
152
153 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
154 value |= BERLIN_PWM_ENABLE;
155 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
156
157 return 0;
158 }
159
berlin_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm_dev)160 static void berlin_pwm_disable(struct pwm_chip *chip,
161 struct pwm_device *pwm_dev)
162 {
163 struct berlin_pwm_chip *pwm = to_berlin_pwm_chip(chip);
164 u32 value;
165
166 value = berlin_pwm_readl(pwm, pwm_dev->hwpwm, BERLIN_PWM_EN);
167 value &= ~BERLIN_PWM_ENABLE;
168 berlin_pwm_writel(pwm, pwm_dev->hwpwm, value, BERLIN_PWM_EN);
169 }
170
171 static const struct pwm_ops berlin_pwm_ops = {
172 .request = berlin_pwm_request,
173 .free = berlin_pwm_free,
174 .config = berlin_pwm_config,
175 .set_polarity = berlin_pwm_set_polarity,
176 .enable = berlin_pwm_enable,
177 .disable = berlin_pwm_disable,
178 .owner = THIS_MODULE,
179 };
180
181 static const struct of_device_id berlin_pwm_match[] = {
182 { .compatible = "marvell,berlin-pwm" },
183 { },
184 };
185 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
186
berlin_pwm_probe(struct platform_device * pdev)187 static int berlin_pwm_probe(struct platform_device *pdev)
188 {
189 struct berlin_pwm_chip *pwm;
190 struct resource *res;
191 int ret;
192
193 pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
194 if (!pwm)
195 return -ENOMEM;
196
197 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
198 pwm->base = devm_ioremap_resource(&pdev->dev, res);
199 if (IS_ERR(pwm->base))
200 return PTR_ERR(pwm->base);
201
202 pwm->clk = devm_clk_get(&pdev->dev, NULL);
203 if (IS_ERR(pwm->clk))
204 return PTR_ERR(pwm->clk);
205
206 ret = clk_prepare_enable(pwm->clk);
207 if (ret)
208 return ret;
209
210 pwm->chip.dev = &pdev->dev;
211 pwm->chip.ops = &berlin_pwm_ops;
212 pwm->chip.base = -1;
213 pwm->chip.npwm = 4;
214 pwm->chip.of_xlate = of_pwm_xlate_with_flags;
215 pwm->chip.of_pwm_n_cells = 3;
216
217 ret = pwmchip_add(&pwm->chip);
218 if (ret < 0) {
219 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
220 clk_disable_unprepare(pwm->clk);
221 return ret;
222 }
223
224 platform_set_drvdata(pdev, pwm);
225
226 return 0;
227 }
228
berlin_pwm_remove(struct platform_device * pdev)229 static int berlin_pwm_remove(struct platform_device *pdev)
230 {
231 struct berlin_pwm_chip *pwm = platform_get_drvdata(pdev);
232 int ret;
233
234 ret = pwmchip_remove(&pwm->chip);
235 clk_disable_unprepare(pwm->clk);
236
237 return ret;
238 }
239
240 #ifdef CONFIG_PM_SLEEP
berlin_pwm_suspend(struct device * dev)241 static int berlin_pwm_suspend(struct device *dev)
242 {
243 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
244 unsigned int i;
245
246 for (i = 0; i < pwm->chip.npwm; i++) {
247 struct berlin_pwm_channel *channel;
248
249 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
250 if (!channel)
251 continue;
252
253 channel->enable = berlin_pwm_readl(pwm, i, BERLIN_PWM_ENABLE);
254 channel->ctrl = berlin_pwm_readl(pwm, i, BERLIN_PWM_CONTROL);
255 channel->duty = berlin_pwm_readl(pwm, i, BERLIN_PWM_DUTY);
256 channel->tcnt = berlin_pwm_readl(pwm, i, BERLIN_PWM_TCNT);
257 }
258
259 clk_disable_unprepare(pwm->clk);
260
261 return 0;
262 }
263
berlin_pwm_resume(struct device * dev)264 static int berlin_pwm_resume(struct device *dev)
265 {
266 struct berlin_pwm_chip *pwm = dev_get_drvdata(dev);
267 unsigned int i;
268 int ret;
269
270 ret = clk_prepare_enable(pwm->clk);
271 if (ret)
272 return ret;
273
274 for (i = 0; i < pwm->chip.npwm; i++) {
275 struct berlin_pwm_channel *channel;
276
277 channel = pwm_get_chip_data(&pwm->chip.pwms[i]);
278 if (!channel)
279 continue;
280
281 berlin_pwm_writel(pwm, i, channel->ctrl, BERLIN_PWM_CONTROL);
282 berlin_pwm_writel(pwm, i, channel->duty, BERLIN_PWM_DUTY);
283 berlin_pwm_writel(pwm, i, channel->tcnt, BERLIN_PWM_TCNT);
284 berlin_pwm_writel(pwm, i, channel->enable, BERLIN_PWM_ENABLE);
285 }
286
287 return 0;
288 }
289 #endif
290
291 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
292 berlin_pwm_resume);
293
294 static struct platform_driver berlin_pwm_driver = {
295 .probe = berlin_pwm_probe,
296 .remove = berlin_pwm_remove,
297 .driver = {
298 .name = "berlin-pwm",
299 .of_match_table = berlin_pwm_match,
300 .pm = &berlin_pwm_pm_ops,
301 },
302 };
303 module_platform_driver(berlin_pwm_driver);
304
305 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
306 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
307 MODULE_LICENSE("GPL v2");
308
