1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Expose a PWM controlled by the ChromeOS EC to the host processor.
4 *
5 * Copyright (C) 2016 Google, Inc.
6 */
7
8 #include <linux/module.h>
9 #include <linux/of.h>
10 #include <linux/platform_data/cros_ec_commands.h>
11 #include <linux/platform_data/cros_ec_proto.h>
12 #include <linux/platform_device.h>
13 #include <linux/pwm.h>
14 #include <linux/slab.h>
15
16 #include <dt-bindings/mfd/cros_ec.h>
17
18 /**
19 * struct cros_ec_pwm_device - Driver data for EC PWM
20 *
21 * @dev: Device node
22 * @ec: Pointer to EC device
23 * @chip: PWM controller chip
24 * @use_pwm_type: Use PWM types instead of generic channels
25 */
26 struct cros_ec_pwm_device {
27 struct device *dev;
28 struct cros_ec_device *ec;
29 struct pwm_chip chip;
30 bool use_pwm_type;
31 };
32
33 /**
34 * struct cros_ec_pwm - per-PWM driver data
35 * @duty_cycle: cached duty cycle
36 */
37 struct cros_ec_pwm {
38 u16 duty_cycle;
39 };
40
pwm_to_cros_ec_pwm(struct pwm_chip * chip)41 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chip)
42 {
43 return container_of(chip, struct cros_ec_pwm_device, chip);
44 }
45
cros_ec_pwm_request(struct pwm_chip * chip,struct pwm_device * pwm)46 static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
47 {
48 struct cros_ec_pwm *channel;
49
50 channel = kzalloc(sizeof(*channel), GFP_KERNEL);
51 if (!channel)
52 return -ENOMEM;
53
54 pwm_set_chip_data(pwm, channel);
55
56 return 0;
57 }
58
cros_ec_pwm_free(struct pwm_chip * chip,struct pwm_device * pwm)59 static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
60 {
61 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
62
63 kfree(channel);
64 }
65
cros_ec_dt_type_to_pwm_type(u8 dt_index,u8 * pwm_type)66 static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type)
67 {
68 switch (dt_index) {
69 case CROS_EC_PWM_DT_KB_LIGHT:
70 *pwm_type = EC_PWM_TYPE_KB_LIGHT;
71 return 0;
72 case CROS_EC_PWM_DT_DISPLAY_LIGHT:
73 *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT;
74 return 0;
75 default:
76 return -EINVAL;
77 }
78 }
79
cros_ec_pwm_set_duty(struct cros_ec_pwm_device * ec_pwm,u8 index,u16 duty)80 static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index,
81 u16 duty)
82 {
83 struct cros_ec_device *ec = ec_pwm->ec;
84 struct {
85 struct cros_ec_command msg;
86 struct ec_params_pwm_set_duty params;
87 } __packed buf;
88 struct ec_params_pwm_set_duty *params = &buf.params;
89 struct cros_ec_command *msg = &buf.msg;
90 int ret;
91
92 memset(&buf, 0, sizeof(buf));
93
94 msg->version = 0;
95 msg->command = EC_CMD_PWM_SET_DUTY;
96 msg->insize = 0;
97 msg->outsize = sizeof(*params);
98
99 params->duty = duty;
100
101 if (ec_pwm->use_pwm_type) {
102 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
103 if (ret) {
104 dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
105 return ret;
106 }
107 params->index = 0;
108 } else {
109 params->pwm_type = EC_PWM_TYPE_GENERIC;
110 params->index = index;
111 }
112
113 return cros_ec_cmd_xfer_status(ec, msg);
114 }
115
cros_ec_pwm_get_duty(struct cros_ec_pwm_device * ec_pwm,u8 index)116 static int cros_ec_pwm_get_duty(struct cros_ec_pwm_device *ec_pwm, u8 index)
117 {
118 struct cros_ec_device *ec = ec_pwm->ec;
119 struct {
120 struct cros_ec_command msg;
121 union {
122 struct ec_params_pwm_get_duty params;
123 struct ec_response_pwm_get_duty resp;
124 };
125 } __packed buf;
126 struct ec_params_pwm_get_duty *params = &buf.params;
127 struct ec_response_pwm_get_duty *resp = &buf.resp;
128 struct cros_ec_command *msg = &buf.msg;
129 int ret;
130
131 memset(&buf, 0, sizeof(buf));
132
133 msg->version = 0;
134 msg->command = EC_CMD_PWM_GET_DUTY;
135 msg->insize = sizeof(*resp);
136 msg->outsize = sizeof(*params);
137
138 if (ec_pwm->use_pwm_type) {
139 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
140 if (ret) {
141 dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
142 return ret;
143 }
144 params->index = 0;
145 } else {
146 params->pwm_type = EC_PWM_TYPE_GENERIC;
147 params->index = index;
148 }
149
150 ret = cros_ec_cmd_xfer_status(ec, msg);
151 if (ret < 0)
152 return ret;
153
154 return resp->duty;
155 }
156
cros_ec_pwm_apply(struct pwm_chip * chip,struct pwm_device * pwm,const struct pwm_state * state)157 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
158 const struct pwm_state *state)
159 {
160 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
161 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
162 u16 duty_cycle;
163 int ret;
164
165 /* The EC won't let us change the period */
166 if (state->period != EC_PWM_MAX_DUTY)
167 return -EINVAL;
168
169 if (state->polarity != PWM_POLARITY_NORMAL)
170 return -EINVAL;
171
172 /*
173 * EC doesn't separate the concept of duty cycle and enabled, but
174 * kernel does. Translate.
175 */
176 duty_cycle = state->enabled ? state->duty_cycle : 0;
177
178 ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle);
179 if (ret < 0)
180 return ret;
181
182 channel->duty_cycle = state->duty_cycle;
183
184 return 0;
185 }
186
cros_ec_pwm_get_state(struct pwm_chip * chip,struct pwm_device * pwm,struct pwm_state * state)187 static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
188 struct pwm_state *state)
189 {
190 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
191 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
192 int ret;
193
194 ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm);
195 if (ret < 0) {
196 dev_err(chip->dev, "error getting initial duty: %d\n", ret);
197 return ret;
198 }
199
200 state->enabled = (ret > 0);
201 state->period = EC_PWM_MAX_DUTY;
202 state->polarity = PWM_POLARITY_NORMAL;
203
204 /*
205 * Note that "disabled" and "duty cycle == 0" are treated the same. If
206 * the cached duty cycle is not zero, used the cached duty cycle. This
207 * ensures that the configured duty cycle is kept across a disable and
208 * enable operation and avoids potentially confusing consumers.
209 *
210 * For the case of the initial hardware readout, channel->duty_cycle
211 * will be 0 and the actual duty cycle read from the EC is used.
212 */
213 if (ret == 0 && channel->duty_cycle > 0)
214 state->duty_cycle = channel->duty_cycle;
215 else
216 state->duty_cycle = ret;
217
218 return 0;
219 }
220
221 static struct pwm_device *
cros_ec_pwm_xlate(struct pwm_chip * chip,const struct of_phandle_args * args)222 cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
223 {
224 struct pwm_device *pwm;
225
226 if (args->args[0] >= chip->npwm)
227 return ERR_PTR(-EINVAL);
228
229 pwm = pwm_request_from_chip(chip, args->args[0], NULL);
230 if (IS_ERR(pwm))
231 return pwm;
232
233 /* The EC won't let us change the period */
234 pwm->args.period = EC_PWM_MAX_DUTY;
235
236 return pwm;
237 }
238
239 static const struct pwm_ops cros_ec_pwm_ops = {
240 .request = cros_ec_pwm_request,
241 .free = cros_ec_pwm_free,
242 .get_state = cros_ec_pwm_get_state,
243 .apply = cros_ec_pwm_apply,
244 .owner = THIS_MODULE,
245 };
246
247 /*
248 * Determine the number of supported PWMs. The EC does not return the number
249 * of PWMs it supports directly, so we have to read the pwm duty cycle for
250 * subsequent channels until we get an error.
251 */
cros_ec_num_pwms(struct cros_ec_pwm_device * ec_pwm)252 static int cros_ec_num_pwms(struct cros_ec_pwm_device *ec_pwm)
253 {
254 int i, ret;
255
256 /* The index field is only 8 bits */
257 for (i = 0; i <= U8_MAX; i++) {
258 ret = cros_ec_pwm_get_duty(ec_pwm, i);
259 /*
260 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
261 * responses; everything else is treated as an error.
262 * The EC error codes map to -EOPNOTSUPP and -EINVAL,
263 * so check for those.
264 */
265 switch (ret) {
266 case -EOPNOTSUPP: /* invalid command */
267 return -ENODEV;
268 case -EINVAL: /* invalid parameter */
269 return i;
270 default:
271 if (ret < 0)
272 return ret;
273 break;
274 }
275 }
276
277 return U8_MAX;
278 }
279
cros_ec_pwm_probe(struct platform_device * pdev)280 static int cros_ec_pwm_probe(struct platform_device *pdev)
281 {
282 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
283 struct device *dev = &pdev->dev;
284 struct device_node *np = pdev->dev.of_node;
285 struct cros_ec_pwm_device *ec_pwm;
286 struct pwm_chip *chip;
287 int ret;
288
289 if (!ec) {
290 dev_err(dev, "no parent EC device\n");
291 return -EINVAL;
292 }
293
294 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
295 if (!ec_pwm)
296 return -ENOMEM;
297 chip = &ec_pwm->chip;
298 ec_pwm->ec = ec;
299
300 if (of_device_is_compatible(np, "google,cros-ec-pwm-type"))
301 ec_pwm->use_pwm_type = true;
302
303 /* PWM chip */
304 chip->dev = dev;
305 chip->ops = &cros_ec_pwm_ops;
306 chip->of_xlate = cros_ec_pwm_xlate;
307 chip->of_pwm_n_cells = 1;
308
309 if (ec_pwm->use_pwm_type) {
310 chip->npwm = CROS_EC_PWM_DT_COUNT;
311 } else {
312 ret = cros_ec_num_pwms(ec_pwm);
313 if (ret < 0) {
314 dev_err(dev, "Couldn't find PWMs: %d\n", ret);
315 return ret;
316 }
317 chip->npwm = ret;
318 }
319
320 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
321
322 ret = pwmchip_add(chip);
323 if (ret < 0) {
324 dev_err(dev, "cannot register PWM: %d\n", ret);
325 return ret;
326 }
327
328 platform_set_drvdata(pdev, ec_pwm);
329
330 return ret;
331 }
332
cros_ec_pwm_remove(struct platform_device * dev)333 static void cros_ec_pwm_remove(struct platform_device *dev)
334 {
335 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
336 struct pwm_chip *chip = &ec_pwm->chip;
337
338 pwmchip_remove(chip);
339 }
340
341 #ifdef CONFIG_OF
342 static const struct of_device_id cros_ec_pwm_of_match[] = {
343 { .compatible = "google,cros-ec-pwm" },
344 { .compatible = "google,cros-ec-pwm-type" },
345 {},
346 };
347 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
348 #endif
349
350 static struct platform_driver cros_ec_pwm_driver = {
351 .probe = cros_ec_pwm_probe,
352 .remove_new = cros_ec_pwm_remove,
353 .driver = {
354 .name = "cros-ec-pwm",
355 .of_match_table = of_match_ptr(cros_ec_pwm_of_match),
356 },
357 };
358 module_platform_driver(cros_ec_pwm_driver);
359
360 MODULE_ALIAS("platform:cros-ec-pwm");
361 MODULE_DESCRIPTION("ChromeOS EC PWM driver");
362 MODULE_LICENSE("GPL v2");
363