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 kfree(channel);
88 }
89
berlin_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm_dev,int duty_ns,int period_ns)90 static 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
berlin_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm_dev,enum pwm_polarity polarity)128 static 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
berlin_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm_dev)147 static 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
berlin_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm_dev)159 static 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
170 static 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
180 static const struct of_device_id berlin_pwm_match[] = {
181 { .compatible = "marvell,berlin-pwm" },
182 { },
183 };
184 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
185
berlin_pwm_probe(struct platform_device * pdev)186 static 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
berlin_pwm_remove(struct platform_device * pdev)228 static 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
berlin_pwm_suspend(struct device * dev)240 static 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
berlin_pwm_resume(struct device * dev)263 static 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
290 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
291 berlin_pwm_resume);
292
293 static 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 };
302 module_platform_driver(berlin_pwm_driver);
303
304 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
305 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
306 MODULE_LICENSE("GPL v2");
307