1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * ECAP PWM driver
4 *
5 * Copyright (C) 2012 Texas Instruments, Inc. - https://www.ti.com/
6 */
7
8 #include <linux/module.h>
9 #include <linux/platform_device.h>
10 #include <linux/io.h>
11 #include <linux/err.h>
12 #include <linux/clk.h>
13 #include <linux/pm_runtime.h>
14 #include <linux/pwm.h>
15 #include <linux/of.h>
16
17 /* ECAP registers and bits definitions */
18 #define CAP1 0x08
19 #define CAP2 0x0C
20 #define CAP3 0x10
21 #define CAP4 0x14
22 #define ECCTL2 0x2A
23 #define ECCTL2_APWM_POL_LOW BIT(10)
24 #define ECCTL2_APWM_MODE BIT(9)
25 #define ECCTL2_SYNC_SEL_DISA (BIT(7) | BIT(6))
26 #define ECCTL2_TSCTR_FREERUN BIT(4)
27
28 struct ecap_context {
29 u32 cap3;
30 u32 cap4;
31 u16 ecctl2;
32 };
33
34 struct ecap_pwm_chip {
35 unsigned int clk_rate;
36 void __iomem *mmio_base;
37 struct ecap_context ctx;
38 };
39
to_ecap_pwm_chip(struct pwm_chip * chip)40 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
41 {
42 return pwmchip_get_drvdata(chip);
43 }
44
45 /*
46 * period_ns = 10^9 * period_cycles / PWM_CLK_RATE
47 * duty_ns = 10^9 * duty_cycles / PWM_CLK_RATE
48 */
ecap_pwm_config(struct pwm_chip * chip,struct pwm_device * pwm,int duty_ns,int period_ns,int enabled)49 static int ecap_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
50 int duty_ns, int period_ns, int enabled)
51 {
52 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
53 u32 period_cycles, duty_cycles;
54 unsigned long long c;
55 u16 value;
56
57 c = pc->clk_rate;
58 c = c * period_ns;
59 do_div(c, NSEC_PER_SEC);
60 period_cycles = (u32)c;
61
62 if (period_cycles < 1) {
63 period_cycles = 1;
64 duty_cycles = 1;
65 } else {
66 c = pc->clk_rate;
67 c = c * duty_ns;
68 do_div(c, NSEC_PER_SEC);
69 duty_cycles = (u32)c;
70 }
71
72 pm_runtime_get_sync(pwmchip_parent(chip));
73
74 value = readw(pc->mmio_base + ECCTL2);
75
76 /* Configure APWM mode & disable sync option */
77 value |= ECCTL2_APWM_MODE | ECCTL2_SYNC_SEL_DISA;
78
79 writew(value, pc->mmio_base + ECCTL2);
80
81 if (!enabled) {
82 /* Update active registers if not running */
83 writel(duty_cycles, pc->mmio_base + CAP2);
84 writel(period_cycles, pc->mmio_base + CAP1);
85 } else {
86 /*
87 * Update shadow registers to configure period and
88 * compare values. This helps current PWM period to
89 * complete on reconfiguring
90 */
91 writel(duty_cycles, pc->mmio_base + CAP4);
92 writel(period_cycles, pc->mmio_base + CAP3);
93 }
94
95 if (!enabled) {
96 value = readw(pc->mmio_base + ECCTL2);
97 /* Disable APWM mode to put APWM output Low */
98 value &= ~ECCTL2_APWM_MODE;
99 writew(value, pc->mmio_base + ECCTL2);
100 }
101
102 pm_runtime_put_sync(pwmchip_parent(chip));
103
104 return 0;
105 }
106
ecap_pwm_set_polarity(struct pwm_chip * chip,struct pwm_device * pwm,enum pwm_polarity polarity)107 static int ecap_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *pwm,
108 enum pwm_polarity polarity)
109 {
110 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
111 u16 value;
112
113 pm_runtime_get_sync(pwmchip_parent(chip));
114
115 value = readw(pc->mmio_base + ECCTL2);
116
117 if (polarity == PWM_POLARITY_INVERSED)
118 /* Duty cycle defines LOW period of PWM */
119 value |= ECCTL2_APWM_POL_LOW;
120 else
121 /* Duty cycle defines HIGH period of PWM */
122 value &= ~ECCTL2_APWM_POL_LOW;
123
124 writew(value, pc->mmio_base + ECCTL2);
125
126 pm_runtime_put_sync(pwmchip_parent(chip));
127
128 return 0;
129 }
130
ecap_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)131 static int ecap_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
132 {
133 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
134 u16 value;
135
136 /* Leave clock enabled on enabling PWM */
137 pm_runtime_get_sync(pwmchip_parent(chip));
138
139 /*
140 * Enable 'Free run Time stamp counter mode' to start counter
141 * and 'APWM mode' to enable APWM output
142 */
143 value = readw(pc->mmio_base + ECCTL2);
144 value |= ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE;
145 writew(value, pc->mmio_base + ECCTL2);
146
147 return 0;
148 }
149
ecap_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)150 static void ecap_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
151 {
152 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
153 u16 value;
154
155 /*
156 * Disable 'Free run Time stamp counter mode' to stop counter
157 * and 'APWM mode' to put APWM output to low
158 */
159 value = readw(pc->mmio_base + ECCTL2);
160 value &= ~(ECCTL2_TSCTR_FREERUN | ECCTL2_APWM_MODE);
161 writew(value, pc->mmio_base + ECCTL2);
162
163 /* Disable clock on PWM disable */
164 pm_runtime_put_sync(pwmchip_parent(chip));
165 }
166
ecap_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)167 static int ecap_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
168 const struct pwm_state *state)
169 {
170 int err;
171 int enabled = pwm->state.enabled;
172
173 if (state->polarity != pwm->state.polarity) {
174
175 if (enabled) {
176 ecap_pwm_disable(chip, pwm);
177 enabled = false;
178 }
179
180 err = ecap_pwm_set_polarity(chip, pwm, state->polarity);
181 if (err)
182 return err;
183 }
184
185 if (!state->enabled) {
186 if (enabled)
187 ecap_pwm_disable(chip, pwm);
188 return 0;
189 }
190
191 if (state->period > NSEC_PER_SEC)
192 return -ERANGE;
193
194 err = ecap_pwm_config(chip, pwm, state->duty_cycle,
195 state->period, enabled);
196 if (err)
197 return err;
198
199 if (!enabled)
200 return ecap_pwm_enable(chip, pwm);
201
202 return 0;
203 }
204
205 static const struct pwm_ops ecap_pwm_ops = {
206 .apply = ecap_pwm_apply,
207 };
208
209 static const struct of_device_id ecap_of_match[] = {
210 { .compatible = "ti,am3352-ecap" },
211 { .compatible = "ti,am33xx-ecap" },
212 {},
213 };
214 MODULE_DEVICE_TABLE(of, ecap_of_match);
215
ecap_pwm_probe(struct platform_device * pdev)216 static int ecap_pwm_probe(struct platform_device *pdev)
217 {
218 struct device_node *np = pdev->dev.of_node;
219 struct ecap_pwm_chip *pc;
220 struct pwm_chip *chip;
221 struct clk *clk;
222 int ret;
223
224 chip = devm_pwmchip_alloc(&pdev->dev, 1, sizeof(*pc));
225 if (IS_ERR(chip))
226 return PTR_ERR(chip);
227 pc = to_ecap_pwm_chip(chip);
228
229 clk = devm_clk_get(&pdev->dev, "fck");
230 if (IS_ERR(clk)) {
231 if (of_device_is_compatible(np, "ti,am33xx-ecap")) {
232 dev_warn(&pdev->dev, "Binding is obsolete.\n");
233 clk = devm_clk_get(pdev->dev.parent, "fck");
234 }
235 }
236
237 if (IS_ERR(clk)) {
238 dev_err(&pdev->dev, "failed to get clock\n");
239 return PTR_ERR(clk);
240 }
241
242 pc->clk_rate = clk_get_rate(clk);
243 if (!pc->clk_rate) {
244 dev_err(&pdev->dev, "failed to get clock rate\n");
245 return -EINVAL;
246 }
247
248 chip->ops = &ecap_pwm_ops;
249
250 pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
251 if (IS_ERR(pc->mmio_base))
252 return PTR_ERR(pc->mmio_base);
253
254 ret = devm_pwmchip_add(&pdev->dev, chip);
255 if (ret < 0) {
256 dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
257 return ret;
258 }
259
260 platform_set_drvdata(pdev, chip);
261 pm_runtime_enable(&pdev->dev);
262
263 return 0;
264 }
265
ecap_pwm_remove(struct platform_device * pdev)266 static void ecap_pwm_remove(struct platform_device *pdev)
267 {
268 pm_runtime_disable(&pdev->dev);
269 }
270
ecap_pwm_save_context(struct pwm_chip * chip)271 static void ecap_pwm_save_context(struct pwm_chip *chip)
272 {
273 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
274
275 pm_runtime_get_sync(pwmchip_parent(chip));
276 pc->ctx.ecctl2 = readw(pc->mmio_base + ECCTL2);
277 pc->ctx.cap4 = readl(pc->mmio_base + CAP4);
278 pc->ctx.cap3 = readl(pc->mmio_base + CAP3);
279 pm_runtime_put_sync(pwmchip_parent(chip));
280 }
281
ecap_pwm_restore_context(struct pwm_chip * chip)282 static void ecap_pwm_restore_context(struct pwm_chip *chip)
283 {
284 struct ecap_pwm_chip *pc = to_ecap_pwm_chip(chip);
285
286 writel(pc->ctx.cap3, pc->mmio_base + CAP3);
287 writel(pc->ctx.cap4, pc->mmio_base + CAP4);
288 writew(pc->ctx.ecctl2, pc->mmio_base + ECCTL2);
289 }
290
ecap_pwm_suspend(struct device * dev)291 static int ecap_pwm_suspend(struct device *dev)
292 {
293 struct pwm_chip *chip = dev_get_drvdata(dev);
294 struct pwm_device *pwm = chip->pwms;
295
296 ecap_pwm_save_context(chip);
297
298 /* Disable explicitly if PWM is running */
299 if (pwm_is_enabled(pwm))
300 pm_runtime_put_sync(dev);
301
302 return 0;
303 }
304
ecap_pwm_resume(struct device * dev)305 static int ecap_pwm_resume(struct device *dev)
306 {
307 struct pwm_chip *chip = dev_get_drvdata(dev);
308 struct pwm_device *pwm = chip->pwms;
309
310 /* Enable explicitly if PWM was running */
311 if (pwm_is_enabled(pwm))
312 pm_runtime_get_sync(dev);
313
314 ecap_pwm_restore_context(chip);
315 return 0;
316 }
317
318 static DEFINE_SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume);
319
320 static struct platform_driver ecap_pwm_driver = {
321 .driver = {
322 .name = "ecap",
323 .of_match_table = ecap_of_match,
324 .pm = pm_ptr(&ecap_pwm_pm_ops),
325 },
326 .probe = ecap_pwm_probe,
327 .remove = ecap_pwm_remove,
328 };
329 module_platform_driver(ecap_pwm_driver);
330
331 MODULE_DESCRIPTION("ECAP PWM driver");
332 MODULE_AUTHOR("Texas Instruments");
333 MODULE_LICENSE("GPL");
334