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 * bpc,unsigned int channel,unsigned long offset)59 static inline u32 berlin_pwm_readl(struct berlin_pwm_chip *bpc,
60 unsigned int channel, unsigned long offset)
61 {
62 return readl_relaxed(bpc->base + channel * 0x10 + offset);
63 }
64
berlin_pwm_writel(struct berlin_pwm_chip * bpc,unsigned int channel,u32 value,unsigned long offset)65 static inline void berlin_pwm_writel(struct berlin_pwm_chip *bpc,
66 unsigned int channel, u32 value,
67 unsigned long offset)
68 {
69 writel_relaxed(value, bpc->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,u64 duty_ns,u64 period_ns)90 static int berlin_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
91 u64 duty_ns, u64 period_ns)
92 {
93 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
94 bool prescale_4096 = false;
95 u32 value, duty, period;
96 u64 cycles;
97
98 cycles = clk_get_rate(bpc->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(bpc, pwm->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(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
121
122 berlin_pwm_writel(bpc, pwm->hwpwm, duty, BERLIN_PWM_DUTY);
123 berlin_pwm_writel(bpc, pwm->hwpwm, period, BERLIN_PWM_TCNT);
124
125 return 0;
126 }
127
berlin_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)128 static int berlin_pwm_set_polarity(struct pwm_chip *chip,
129 struct pwm_device *pwm,
130 enum pwm_polarity polarity)
131 {
132 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
133 u32 value;
134
135 value = berlin_pwm_readl(bpc, pwm->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(bpc, pwm->hwpwm, value, BERLIN_PWM_CONTROL);
143
144 return 0;
145 }
146
berlin_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)147 static int berlin_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
148 {
149 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
150 u32 value;
151
152 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
153 value |= BERLIN_PWM_ENABLE;
154 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
155
156 return 0;
157 }
158
berlin_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)159 static void berlin_pwm_disable(struct pwm_chip *chip,
160 struct pwm_device *pwm)
161 {
162 struct berlin_pwm_chip *bpc = to_berlin_pwm_chip(chip);
163 u32 value;
164
165 value = berlin_pwm_readl(bpc, pwm->hwpwm, BERLIN_PWM_EN);
166 value &= ~BERLIN_PWM_ENABLE;
167 berlin_pwm_writel(bpc, pwm->hwpwm, value, BERLIN_PWM_EN);
168 }
169
berlin_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)170 static int berlin_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
171 const struct pwm_state *state)
172 {
173 int err;
174 bool enabled = pwm->state.enabled;
175
176 if (state->polarity != pwm->state.polarity) {
177 if (enabled) {
178 berlin_pwm_disable(chip, pwm);
179 enabled = false;
180 }
181
182 err = berlin_pwm_set_polarity(chip, pwm, state->polarity);
183 if (err)
184 return err;
185 }
186
187 if (!state->enabled) {
188 if (enabled)
189 berlin_pwm_disable(chip, pwm);
190 return 0;
191 }
192
193 err = berlin_pwm_config(chip, pwm, state->duty_cycle, state->period);
194 if (err)
195 return err;
196
197 if (!enabled)
198 return berlin_pwm_enable(chip, pwm);
199
200 return 0;
201 }
202
203 static const struct pwm_ops berlin_pwm_ops = {
204 .request = berlin_pwm_request,
205 .free = berlin_pwm_free,
206 .apply = berlin_pwm_apply,
207 .owner = THIS_MODULE,
208 };
209
210 static const struct of_device_id berlin_pwm_match[] = {
211 { .compatible = "marvell,berlin-pwm" },
212 { },
213 };
214 MODULE_DEVICE_TABLE(of, berlin_pwm_match);
215
berlin_pwm_probe(struct platform_device * pdev)216 static int berlin_pwm_probe(struct platform_device *pdev)
217 {
218 struct berlin_pwm_chip *bpc;
219 int ret;
220
221 bpc = devm_kzalloc(&pdev->dev, sizeof(*bpc), GFP_KERNEL);
222 if (!bpc)
223 return -ENOMEM;
224
225 bpc->base = devm_platform_ioremap_resource(pdev, 0);
226 if (IS_ERR(bpc->base))
227 return PTR_ERR(bpc->base);
228
229 bpc->clk = devm_clk_get(&pdev->dev, NULL);
230 if (IS_ERR(bpc->clk))
231 return PTR_ERR(bpc->clk);
232
233 ret = clk_prepare_enable(bpc->clk);
234 if (ret)
235 return ret;
236
237 bpc->chip.dev = &pdev->dev;
238 bpc->chip.ops = &berlin_pwm_ops;
239 bpc->chip.npwm = 4;
240
241 ret = pwmchip_add(&bpc->chip);
242 if (ret < 0) {
243 dev_err(&pdev->dev, "failed to add PWM chip: %d\n", ret);
244 clk_disable_unprepare(bpc->clk);
245 return ret;
246 }
247
248 platform_set_drvdata(pdev, bpc);
249
250 return 0;
251 }
252
berlin_pwm_remove(struct platform_device * pdev)253 static int berlin_pwm_remove(struct platform_device *pdev)
254 {
255 struct berlin_pwm_chip *bpc = platform_get_drvdata(pdev);
256
257 pwmchip_remove(&bpc->chip);
258
259 clk_disable_unprepare(bpc->clk);
260
261 return 0;
262 }
263
264 #ifdef CONFIG_PM_SLEEP
berlin_pwm_suspend(struct device * dev)265 static int berlin_pwm_suspend(struct device *dev)
266 {
267 struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
268 unsigned int i;
269
270 for (i = 0; i < bpc->chip.npwm; i++) {
271 struct berlin_pwm_channel *channel;
272
273 channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
274 if (!channel)
275 continue;
276
277 channel->enable = berlin_pwm_readl(bpc, i, BERLIN_PWM_ENABLE);
278 channel->ctrl = berlin_pwm_readl(bpc, i, BERLIN_PWM_CONTROL);
279 channel->duty = berlin_pwm_readl(bpc, i, BERLIN_PWM_DUTY);
280 channel->tcnt = berlin_pwm_readl(bpc, i, BERLIN_PWM_TCNT);
281 }
282
283 clk_disable_unprepare(bpc->clk);
284
285 return 0;
286 }
287
berlin_pwm_resume(struct device * dev)288 static int berlin_pwm_resume(struct device *dev)
289 {
290 struct berlin_pwm_chip *bpc = dev_get_drvdata(dev);
291 unsigned int i;
292 int ret;
293
294 ret = clk_prepare_enable(bpc->clk);
295 if (ret)
296 return ret;
297
298 for (i = 0; i < bpc->chip.npwm; i++) {
299 struct berlin_pwm_channel *channel;
300
301 channel = pwm_get_chip_data(&bpc->chip.pwms[i]);
302 if (!channel)
303 continue;
304
305 berlin_pwm_writel(bpc, i, channel->ctrl, BERLIN_PWM_CONTROL);
306 berlin_pwm_writel(bpc, i, channel->duty, BERLIN_PWM_DUTY);
307 berlin_pwm_writel(bpc, i, channel->tcnt, BERLIN_PWM_TCNT);
308 berlin_pwm_writel(bpc, i, channel->enable, BERLIN_PWM_ENABLE);
309 }
310
311 return 0;
312 }
313 #endif
314
315 static SIMPLE_DEV_PM_OPS(berlin_pwm_pm_ops, berlin_pwm_suspend,
316 berlin_pwm_resume);
317
318 static struct platform_driver berlin_pwm_driver = {
319 .probe = berlin_pwm_probe,
320 .remove = berlin_pwm_remove,
321 .driver = {
322 .name = "berlin-pwm",
323 .of_match_table = berlin_pwm_match,
324 .pm = &berlin_pwm_pm_ops,
325 },
326 };
327 module_platform_driver(berlin_pwm_driver);
328
329 MODULE_AUTHOR("Antoine Tenart <antoine.tenart@free-electrons.com>");
330 MODULE_DESCRIPTION("Marvell Berlin PWM driver");
331 MODULE_LICENSE("GPL v2");
332