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>
9 #include <linux/platform_data/cros_ec_commands.h>
10 #include <linux/platform_data/cros_ec_proto.h>
11 #include <linux/platform_device.h>
12 #include <linux/pwm.h>
13 #include <linux/slab.h>
16 * struct cros_ec_pwm_device - Driver data for EC PWM
19 * @ec: Pointer to EC device
20 * @chip: PWM controller chip
22 struct cros_ec_pwm_device {
24 struct cros_ec_device *ec;
29 * struct cros_ec_pwm - per-PWM driver data
30 * @duty_cycle: cached duty cycle
36 static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
38 return container_of(c, struct cros_ec_pwm_device, chip);
41 static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
43 struct cros_ec_pwm *channel;
45 channel = kzalloc(sizeof(*channel), GFP_KERNEL);
49 pwm_set_chip_data(pwm, channel);
54 static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
56 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
61 static int cros_ec_pwm_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
64 struct cros_ec_command msg;
65 struct ec_params_pwm_set_duty params;
67 struct ec_params_pwm_set_duty *params = &buf.params;
68 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);
78 params->pwm_type = EC_PWM_TYPE_GENERIC;
79 params->index = index;
81 return cros_ec_cmd_xfer_status(ec, msg);
84 static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
87 struct cros_ec_command msg;
89 struct ec_params_pwm_get_duty params;
90 struct ec_response_pwm_get_duty resp;
93 struct ec_params_pwm_get_duty *params = &buf.params;
94 struct ec_response_pwm_get_duty *resp = &buf.resp;
95 struct cros_ec_command *msg = &buf.msg;
98 memset(&buf, 0, sizeof(buf));
101 msg->command = EC_CMD_PWM_GET_DUTY;
102 msg->insize = sizeof(*resp);
103 msg->outsize = sizeof(*params);
105 params->pwm_type = EC_PWM_TYPE_GENERIC;
106 params->index = index;
108 ret = cros_ec_cmd_xfer_status(ec, msg);
115 static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
116 const struct pwm_state *state)
118 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
119 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
123 /* The EC won't let us change the period */
124 if (state->period != EC_PWM_MAX_DUTY)
128 * EC doesn't separate the concept of duty cycle and enabled, but
129 * kernel does. Translate.
131 duty_cycle = state->enabled ? state->duty_cycle : 0;
133 ret = cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
137 channel->duty_cycle = state->duty_cycle;
142 static void cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
143 struct pwm_state *state)
145 struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
146 struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
149 ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
151 dev_err(chip->dev, "error getting initial duty: %d\n", ret);
155 state->enabled = (ret > 0);
156 state->period = EC_PWM_MAX_DUTY;
157 state->polarity = PWM_POLARITY_NORMAL;
160 * Note that "disabled" and "duty cycle == 0" are treated the same. If
161 * the cached duty cycle is not zero, used the cached duty cycle. This
162 * ensures that the configured duty cycle is kept across a disable and
163 * enable operation and avoids potentially confusing consumers.
165 * For the case of the initial hardware readout, channel->duty_cycle
166 * will be 0 and the actual duty cycle read from the EC is used.
168 if (ret == 0 && channel->duty_cycle > 0)
169 state->duty_cycle = channel->duty_cycle;
171 state->duty_cycle = ret;
174 static struct pwm_device *
175 cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
177 struct pwm_device *pwm;
179 if (args->args[0] >= pc->npwm)
180 return ERR_PTR(-EINVAL);
182 pwm = pwm_request_from_chip(pc, args->args[0], NULL);
186 /* The EC won't let us change the period */
187 pwm->args.period = EC_PWM_MAX_DUTY;
192 static const struct pwm_ops cros_ec_pwm_ops = {
193 .request = cros_ec_pwm_request,
194 .free = cros_ec_pwm_free,
195 .get_state = cros_ec_pwm_get_state,
196 .apply = cros_ec_pwm_apply,
197 .owner = THIS_MODULE,
201 * Determine the number of supported PWMs. The EC does not return the number
202 * of PWMs it supports directly, so we have to read the pwm duty cycle for
203 * subsequent channels until we get an error.
205 static int cros_ec_num_pwms(struct cros_ec_device *ec)
209 /* The index field is only 8 bits */
210 for (i = 0; i <= U8_MAX; i++) {
211 ret = cros_ec_pwm_get_duty(ec, i);
213 * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
214 * responses; everything else is treated as an error.
215 * The EC error codes map to -EOPNOTSUPP and -EINVAL,
216 * so check for those.
219 case -EOPNOTSUPP: /* invalid command */
221 case -EINVAL: /* invalid parameter */
233 static int cros_ec_pwm_probe(struct platform_device *pdev)
235 struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
236 struct device *dev = &pdev->dev;
237 struct cros_ec_pwm_device *ec_pwm;
238 struct pwm_chip *chip;
242 dev_err(dev, "no parent EC device\n");
246 ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
249 chip = &ec_pwm->chip;
254 chip->ops = &cros_ec_pwm_ops;
255 chip->of_xlate = cros_ec_pwm_xlate;
256 chip->of_pwm_n_cells = 1;
258 ret = cros_ec_num_pwms(ec);
260 dev_err(dev, "Couldn't find PWMs: %d\n", ret);
264 dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
266 ret = pwmchip_add(chip);
268 dev_err(dev, "cannot register PWM: %d\n", ret);
272 platform_set_drvdata(pdev, ec_pwm);
277 static int cros_ec_pwm_remove(struct platform_device *dev)
279 struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
280 struct pwm_chip *chip = &ec_pwm->chip;
282 return pwmchip_remove(chip);
286 static const struct of_device_id cros_ec_pwm_of_match[] = {
287 { .compatible = "google,cros-ec-pwm" },
290 MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
293 static struct platform_driver cros_ec_pwm_driver = {
294 .probe = cros_ec_pwm_probe,
295 .remove = cros_ec_pwm_remove,
297 .name = "cros-ec-pwm",
298 .of_match_table = of_match_ptr(cros_ec_pwm_of_match),
301 module_platform_driver(cros_ec_pwm_driver);
303 MODULE_ALIAS("platform:cros-ec-pwm");
304 MODULE_DESCRIPTION("ChromeOS EC PWM driver");
305 MODULE_LICENSE("GPL v2");