1 // SPDX-License-Identifier: GPL-2.0
3 * Expose a PWM controlled by the ChromeOS EC to the host processor.
5 * Copyright (C) 2016 Google, Inc.
8 #include <linux/module.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>
16 #include <dt-bindings/mfd/cros_ec.h>
19 * struct cros_ec_pwm_device - Driver data for EC PWM
21 * @ec: Pointer to EC device
22 * @use_pwm_type: Use PWM types instead of generic channels
23 * @channel: array with per-channel data
25 struct cros_ec_pwm_device {
26 struct cros_ec_device *ec;
28 struct cros_ec_pwm *channel;
32 * struct cros_ec_pwm - per-PWM driver data
33 * @duty_cycle: cached duty cycle
39 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *chip)
41 return pwmchip_get_drvdata(chip);
44 static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type)
47 case CROS_EC_PWM_DT_KB_LIGHT:
48 *pwm_type = EC_PWM_TYPE_KB_LIGHT;
50 case CROS_EC_PWM_DT_DISPLAY_LIGHT:
51 *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT;
58 static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index,
61 struct cros_ec_device *ec = ec_pwm->ec;
63 struct cros_ec_command msg;
64 struct ec_params_pwm_set_duty params;
66 struct ec_params_pwm_set_duty *params = &buf.params;
67 struct cros_ec_command *msg = &buf.msg;
70 memset(&buf, 0, sizeof(buf));
73 msg->command = EC_CMD_PWM_SET_DUTY;
75 msg->outsize = sizeof(*params);
79 if (ec_pwm->use_pwm_type) {
80 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
82 dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
87 params->pwm_type = EC_PWM_TYPE_GENERIC;
88 params->index = index;
91 return cros_ec_cmd_xfer_status(ec, msg);
94 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, bool use_pwm_type, u8 index)
97 struct cros_ec_command msg;
99 struct ec_params_pwm_get_duty params;
100 struct ec_response_pwm_get_duty resp;
103 struct ec_params_pwm_get_duty *params = &buf.params;
104 struct ec_response_pwm_get_duty *resp = &buf.resp;
105 struct cros_ec_command *msg = &buf.msg;
108 memset(&buf, 0, sizeof(buf));
111 msg->command = EC_CMD_PWM_GET_DUTY;
112 msg->insize = sizeof(*resp);
113 msg->outsize = sizeof(*params);
116 ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
118 dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
123 params->pwm_type = EC_PWM_TYPE_GENERIC;
124 params->index = index;
127 ret = cros_ec_cmd_xfer_status(ec, msg);
134 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
135 const struct pwm_state *state)
137 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
138 struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm];
142 /* The EC won't let us change the period */
143 if (state->period != EC_PWM_MAX_DUTY)
146 if (state->polarity != PWM_POLARITY_NORMAL)
150 * EC doesn't separate the concept of duty cycle and enabled, but
151 * kernel does. Translate.
153 duty_cycle = state->enabled ? state->duty_cycle : 0;
155 ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle);
159 channel->duty_cycle = state->duty_cycle;
164 static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
165 struct pwm_state *state)
167 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
168 struct cros_ec_pwm *channel = &ec_pwm->channel[pwm->hwpwm];
171 ret = cros_ec_pwm_get_duty(ec_pwm->ec, ec_pwm->use_pwm_type, pwm->hwpwm);
173 dev_err(pwmchip_parent(chip), "error getting initial duty: %d\n", ret);
177 state->enabled = (ret > 0);
178 state->period = EC_PWM_MAX_DUTY;
179 state->polarity = PWM_POLARITY_NORMAL;
182 * Note that "disabled" and "duty cycle == 0" are treated the same. If
183 * the cached duty cycle is not zero, used the cached duty cycle. This
184 * ensures that the configured duty cycle is kept across a disable and
185 * enable operation and avoids potentially confusing consumers.
187 * For the case of the initial hardware readout, channel->duty_cycle
188 * will be 0 and the actual duty cycle read from the EC is used.
190 if (ret == 0 && channel->duty_cycle > 0)
191 state->duty_cycle = channel->duty_cycle;
193 state->duty_cycle = ret;
198 static struct pwm_device *
199 cros_ec_pwm_xlate(struct pwm_chip *chip, const struct of_phandle_args *args)
201 struct pwm_device *pwm;
203 if (args->args[0] >= chip->npwm)
204 return ERR_PTR(-EINVAL);
206 pwm = pwm_request_from_chip(chip, args->args[0], NULL);
210 /* The EC won't let us change the period */
211 pwm->args.period = EC_PWM_MAX_DUTY;
216 static const struct pwm_ops cros_ec_pwm_ops = {
217 .get_state = cros_ec_pwm_get_state,
218 .apply = cros_ec_pwm_apply,
222 * Determine the number of supported PWMs. The EC does not return the number
223 * of PWMs it supports directly, so we have to read the pwm duty cycle for
224 * subsequent channels until we get an error.
226 static int cros_ec_num_pwms(struct cros_ec_device *ec)
230 /* The index field is only 8 bits */
231 for (i = 0; i <= U8_MAX; i++) {
233 * Note that this function is only called when use_pwm_type is
234 * false. With use_pwm_type == true the number of PWMs is fixed.
236 ret = cros_ec_pwm_get_duty(ec, false, i);
238 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
239 * responses; everything else is treated as an error.
240 * The EC error codes map to -EOPNOTSUPP and -EINVAL,
241 * so check for those.
244 case -EOPNOTSUPP: /* invalid command */
246 case -EINVAL: /* invalid parameter */
258 static int cros_ec_pwm_probe(struct platform_device *pdev)
260 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
261 struct device *dev = &pdev->dev;
262 struct device_node *np = pdev->dev.of_node;
263 struct cros_ec_pwm_device *ec_pwm;
264 struct pwm_chip *chip;
265 bool use_pwm_type = false;
270 return dev_err_probe(dev, -EINVAL, "no parent EC device\n");
272 if (of_device_is_compatible(np, "google,cros-ec-pwm-type")) {
274 npwm = CROS_EC_PWM_DT_COUNT;
276 ret = cros_ec_num_pwms(ec);
278 return dev_err_probe(dev, ret, "Couldn't find PWMs\n");
282 chip = devm_pwmchip_alloc(dev, npwm, sizeof(*ec_pwm));
284 return PTR_ERR(chip);
286 ec_pwm = pwm_to_cros_ec_pwm(chip);
287 ec_pwm->use_pwm_type = use_pwm_type;
291 chip->ops = &cros_ec_pwm_ops;
292 chip->of_xlate = cros_ec_pwm_xlate;
294 ec_pwm->channel = devm_kcalloc(dev, chip->npwm, sizeof(*ec_pwm->channel),
296 if (!ec_pwm->channel)
299 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
301 ret = devm_pwmchip_add(dev, chip);
303 return dev_err_probe(dev, ret, "cannot register PWM\n");
309 static const struct of_device_id cros_ec_pwm_of_match[] = {
310 { .compatible = "google,cros-ec-pwm" },
311 { .compatible = "google,cros-ec-pwm-type" },
314 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
317 static struct platform_driver cros_ec_pwm_driver = {
318 .probe = cros_ec_pwm_probe,
320 .name = "cros-ec-pwm",
321 .of_match_table = of_match_ptr(cros_ec_pwm_of_match),
324 module_platform_driver(cros_ec_pwm_driver);
326 MODULE_ALIAS("platform:cros-ec-pwm");
327 MODULE_DESCRIPTION("ChromeOS EC PWM driver");
328 MODULE_LICENSE("GPL v2");