1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Copyright (C) 2010, Lars-Peter Clausen <lars@metafoo.de>
4 * JZ4740 platform PWM support
5 *
6 * Limitations:
7 * - The .apply callback doesn't complete the currently running period before
8 * reconfiguring the hardware.
9 */
10
11 #include <linux/clk.h>
12 #include <linux/err.h>
13 #include <linux/gpio.h>
14 #include <linux/kernel.h>
15 #include <linux/mfd/ingenic-tcu.h>
16 #include <linux/mfd/syscon.h>
17 #include <linux/module.h>
18 #include <linux/of.h>
19 #include <linux/platform_device.h>
20 #include <linux/pwm.h>
21 #include <linux/regmap.h>
22
23 struct soc_info {
24 unsigned int num_pwms;
25 };
26
27 struct jz4740_pwm_chip {
28 struct pwm_chip chip;
29 struct regmap *map;
30 };
31
to_jz4740(struct pwm_chip * chip)32 static inline struct jz4740_pwm_chip *to_jz4740(struct pwm_chip *chip)
33 {
34 return container_of(chip, struct jz4740_pwm_chip, chip);
35 }
36
jz4740_pwm_can_use_chn(struct jz4740_pwm_chip * jz,unsigned int channel)37 static bool jz4740_pwm_can_use_chn(struct jz4740_pwm_chip *jz,
38 unsigned int channel)
39 {
40 /* Enable all TCU channels for PWM use by default except channels 0/1 */
41 u32 pwm_channels_mask = GENMASK(jz->chip.npwm - 1, 2);
42
43 device_property_read_u32(jz->chip.dev->parent,
44 "ingenic,pwm-channels-mask",
45 &pwm_channels_mask);
46
47 return !!(pwm_channels_mask & BIT(channel));
48 }
49
jz4740_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)50 static int jz4740_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
51 {
52 struct jz4740_pwm_chip *jz = to_jz4740(chip);
53 struct clk *clk;
54 char name[16];
55 int err;
56
57 if (!jz4740_pwm_can_use_chn(jz, pwm->hwpwm))
58 return -EBUSY;
59
60 snprintf(name, sizeof(name), "timer%u", pwm->hwpwm);
61
62 clk = clk_get(chip->dev, name);
63 if (IS_ERR(clk))
64 return dev_err_probe(chip->dev, PTR_ERR(clk),
65 "Failed to get clock\n");
66
67 err = clk_prepare_enable(clk);
68 if (err < 0) {
69 clk_put(clk);
70 return err;
71 }
72
73 pwm_set_chip_data(pwm, clk);
74
75 return 0;
76 }
77
jz4740_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)78 static void jz4740_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
79 {
80 struct clk *clk = pwm_get_chip_data(pwm);
81
82 clk_disable_unprepare(clk);
83 clk_put(clk);
84 }
85
jz4740_pwm_enable(struct pwm_chip * chip,struct pwm_device * pwm)86 static int jz4740_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
87 {
88 struct jz4740_pwm_chip *jz = to_jz4740(chip);
89
90 /* Enable PWM output */
91 regmap_set_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN);
92
93 /* Start counter */
94 regmap_write(jz->map, TCU_REG_TESR, BIT(pwm->hwpwm));
95
96 return 0;
97 }
98
jz4740_pwm_disable(struct pwm_chip * chip,struct pwm_device * pwm)99 static void jz4740_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
100 {
101 struct jz4740_pwm_chip *jz = to_jz4740(chip);
102
103 /*
104 * Set duty > period. This trick allows the TCU channels in TCU2 mode to
105 * properly return to their init level.
106 */
107 regmap_write(jz->map, TCU_REG_TDHRc(pwm->hwpwm), 0xffff);
108 regmap_write(jz->map, TCU_REG_TDFRc(pwm->hwpwm), 0x0);
109
110 /*
111 * Disable PWM output.
112 * In TCU2 mode (channel 1/2 on JZ4750+), this must be done before the
113 * counter is stopped, while in TCU1 mode the order does not matter.
114 */
115 regmap_clear_bits(jz->map, TCU_REG_TCSRc(pwm->hwpwm), TCU_TCSR_PWM_EN);
116
117 /* Stop counter */
118 regmap_write(jz->map, TCU_REG_TECR, BIT(pwm->hwpwm));
119 }
120
jz4740_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)121 static int jz4740_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
122 const struct pwm_state *state)
123 {
124 struct jz4740_pwm_chip *jz4740 = to_jz4740(pwm->chip);
125 unsigned long long tmp = 0xffffull * NSEC_PER_SEC;
126 struct clk *clk = pwm_get_chip_data(pwm);
127 unsigned long period, duty;
128 long rate;
129 int err;
130
131 /*
132 * Limit the clock to a maximum rate that still gives us a period value
133 * which fits in 16 bits.
134 */
135 do_div(tmp, state->period);
136
137 /*
138 * /!\ IMPORTANT NOTE:
139 * -------------------
140 * This code relies on the fact that clk_round_rate() will always round
141 * down, which is not a valid assumption given by the clk API, but only
142 * happens to be true with the clk drivers used for Ingenic SoCs.
143 *
144 * Right now, there is no alternative as the clk API does not have a
145 * round-down function (and won't have one for a while), but if it ever
146 * comes to light, a round-down function should be used instead.
147 */
148 rate = clk_round_rate(clk, tmp);
149 if (rate < 0) {
150 dev_err(chip->dev, "Unable to round rate: %ld", rate);
151 return rate;
152 }
153
154 /* Calculate period value */
155 tmp = (unsigned long long)rate * state->period;
156 do_div(tmp, NSEC_PER_SEC);
157 period = tmp;
158
159 /* Calculate duty value */
160 tmp = (unsigned long long)rate * state->duty_cycle;
161 do_div(tmp, NSEC_PER_SEC);
162 duty = tmp;
163
164 if (duty >= period)
165 duty = period - 1;
166
167 jz4740_pwm_disable(chip, pwm);
168
169 err = clk_set_rate(clk, rate);
170 if (err) {
171 dev_err(chip->dev, "Unable to set rate: %d", err);
172 return err;
173 }
174
175 /* Reset counter to 0 */
176 regmap_write(jz4740->map, TCU_REG_TCNTc(pwm->hwpwm), 0);
177
178 /* Set duty */
179 regmap_write(jz4740->map, TCU_REG_TDHRc(pwm->hwpwm), duty);
180
181 /* Set period */
182 regmap_write(jz4740->map, TCU_REG_TDFRc(pwm->hwpwm), period);
183
184 /* Set abrupt shutdown */
185 regmap_set_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
186 TCU_TCSR_PWM_SD);
187
188 /*
189 * Set polarity.
190 *
191 * The PWM starts in inactive state until the internal timer reaches the
192 * duty value, then becomes active until the timer reaches the period
193 * value. In theory, we should then use (period - duty) as the real duty
194 * value, as a high duty value would otherwise result in the PWM pin
195 * being inactive most of the time.
196 *
197 * Here, we don't do that, and instead invert the polarity of the PWM
198 * when it is active. This trick makes the PWM start with its active
199 * state instead of its inactive state.
200 */
201 if ((state->polarity == PWM_POLARITY_NORMAL) ^ state->enabled)
202 regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
203 TCU_TCSR_PWM_INITL_HIGH, 0);
204 else
205 regmap_update_bits(jz4740->map, TCU_REG_TCSRc(pwm->hwpwm),
206 TCU_TCSR_PWM_INITL_HIGH,
207 TCU_TCSR_PWM_INITL_HIGH);
208
209 if (state->enabled)
210 jz4740_pwm_enable(chip, pwm);
211
212 return 0;
213 }
214
215 static const struct pwm_ops jz4740_pwm_ops = {
216 .request = jz4740_pwm_request,
217 .free = jz4740_pwm_free,
218 .apply = jz4740_pwm_apply,
219 .owner = THIS_MODULE,
220 };
221
jz4740_pwm_probe(struct platform_device * pdev)222 static int jz4740_pwm_probe(struct platform_device *pdev)
223 {
224 struct device *dev = &pdev->dev;
225 struct jz4740_pwm_chip *jz4740;
226 const struct soc_info *info;
227
228 info = device_get_match_data(dev);
229 if (!info)
230 return -EINVAL;
231
232 jz4740 = devm_kzalloc(dev, sizeof(*jz4740), GFP_KERNEL);
233 if (!jz4740)
234 return -ENOMEM;
235
236 jz4740->map = device_node_to_regmap(dev->parent->of_node);
237 if (IS_ERR(jz4740->map)) {
238 dev_err(dev, "regmap not found: %ld\n", PTR_ERR(jz4740->map));
239 return PTR_ERR(jz4740->map);
240 }
241
242 jz4740->chip.dev = dev;
243 jz4740->chip.ops = &jz4740_pwm_ops;
244 jz4740->chip.npwm = info->num_pwms;
245
246 return devm_pwmchip_add(dev, &jz4740->chip);
247 }
248
249 static const struct soc_info jz4740_soc_info = {
250 .num_pwms = 8,
251 };
252
253 static const struct soc_info jz4725b_soc_info = {
254 .num_pwms = 6,
255 };
256
257 static const struct soc_info x1000_soc_info = {
258 .num_pwms = 5,
259 };
260
261 static const struct of_device_id jz4740_pwm_dt_ids[] = {
262 { .compatible = "ingenic,jz4740-pwm", .data = &jz4740_soc_info },
263 { .compatible = "ingenic,jz4725b-pwm", .data = &jz4725b_soc_info },
264 { .compatible = "ingenic,x1000-pwm", .data = &x1000_soc_info },
265 {},
266 };
267 MODULE_DEVICE_TABLE(of, jz4740_pwm_dt_ids);
268
269 static struct platform_driver jz4740_pwm_driver = {
270 .driver = {
271 .name = "jz4740-pwm",
272 .of_match_table = jz4740_pwm_dt_ids,
273 },
274 .probe = jz4740_pwm_probe,
275 };
276 module_platform_driver(jz4740_pwm_driver);
277
278 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
279 MODULE_DESCRIPTION("Ingenic JZ4740 PWM driver");
280 MODULE_ALIAS("platform:jz4740-pwm");
281 MODULE_LICENSE("GPL");
282
