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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Expose a PWM controlled by the ChromeOS EC to the host processor.
- *
- * Copyright (C) 2016 Google, Inc.
- */
- #include <linux/module.h>
- #include <linux/platform_data/cros_ec_commands.h>
- #include <linux/platform_data/cros_ec_proto.h>
- #include <linux/platform_device.h>
- #include <linux/pwm.h>
- #include <linux/slab.h>
- #include <dt-bindings/mfd/cros_ec.h>
- /**
- * struct cros_ec_pwm_device - Driver data for EC PWM
- *
- * @dev: Device node
- * @ec: Pointer to EC device
- * @chip: PWM controller chip
- * @use_pwm_type: Use PWM types instead of generic channels
- */
- struct cros_ec_pwm_device {
- struct device *dev;
- struct cros_ec_device *ec;
- struct pwm_chip chip;
- bool use_pwm_type;
- };
- /**
- * struct cros_ec_pwm - per-PWM driver data
- * @duty_cycle: cached duty cycle
- */
- struct cros_ec_pwm {
- u16 duty_cycle;
- };
- static inline struct cros_ec_pwm_device *pwm_to_cros_ec_pwm(struct pwm_chip *c)
- {
- return container_of(c, struct cros_ec_pwm_device, chip);
- }
- static int cros_ec_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
- {
- struct cros_ec_pwm *channel;
- channel = kzalloc(sizeof(*channel), GFP_KERNEL);
- if (!channel)
- return -ENOMEM;
- pwm_set_chip_data(pwm, channel);
- return 0;
- }
- static void cros_ec_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
- {
- struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
- kfree(channel);
- }
- static int cros_ec_dt_type_to_pwm_type(u8 dt_index, u8 *pwm_type)
- {
- switch (dt_index) {
- case CROS_EC_PWM_DT_KB_LIGHT:
- *pwm_type = EC_PWM_TYPE_KB_LIGHT;
- return 0;
- case CROS_EC_PWM_DT_DISPLAY_LIGHT:
- *pwm_type = EC_PWM_TYPE_DISPLAY_LIGHT;
- return 0;
- default:
- return -EINVAL;
- }
- }
- static int cros_ec_pwm_set_duty(struct cros_ec_pwm_device *ec_pwm, u8 index,
- u16 duty)
- {
- struct cros_ec_device *ec = ec_pwm->ec;
- struct {
- struct cros_ec_command msg;
- struct ec_params_pwm_set_duty params;
- } __packed buf;
- struct ec_params_pwm_set_duty *params = &buf.params;
- struct cros_ec_command *msg = &buf.msg;
- int ret;
- memset(&buf, 0, sizeof(buf));
- msg->version = 0;
- msg->command = EC_CMD_PWM_SET_DUTY;
- msg->insize = 0;
- msg->outsize = sizeof(*params);
- params->duty = duty;
- if (ec_pwm->use_pwm_type) {
- ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
- if (ret) {
- dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
- return ret;
- }
- params->index = 0;
- } else {
- params->pwm_type = EC_PWM_TYPE_GENERIC;
- params->index = index;
- }
- return cros_ec_cmd_xfer_status(ec, msg);
- }
- static int cros_ec_pwm_get_duty(struct cros_ec_pwm_device *ec_pwm, u8 index)
- {
- struct cros_ec_device *ec = ec_pwm->ec;
- struct {
- struct cros_ec_command msg;
- union {
- struct ec_params_pwm_get_duty params;
- struct ec_response_pwm_get_duty resp;
- };
- } __packed buf;
- struct ec_params_pwm_get_duty *params = &buf.params;
- struct ec_response_pwm_get_duty *resp = &buf.resp;
- struct cros_ec_command *msg = &buf.msg;
- int ret;
- memset(&buf, 0, sizeof(buf));
- msg->version = 0;
- msg->command = EC_CMD_PWM_GET_DUTY;
- msg->insize = sizeof(*resp);
- msg->outsize = sizeof(*params);
- if (ec_pwm->use_pwm_type) {
- ret = cros_ec_dt_type_to_pwm_type(index, ¶ms->pwm_type);
- if (ret) {
- dev_err(ec->dev, "Invalid PWM type index: %d\n", index);
- return ret;
- }
- params->index = 0;
- } else {
- params->pwm_type = EC_PWM_TYPE_GENERIC;
- params->index = index;
- }
- ret = cros_ec_cmd_xfer_status(ec, msg);
- if (ret < 0)
- return ret;
- return resp->duty;
- }
- static int cros_ec_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
- const struct pwm_state *state)
- {
- struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
- struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
- u16 duty_cycle;
- int ret;
- /* The EC won't let us change the period */
- if (state->period != EC_PWM_MAX_DUTY)
- return -EINVAL;
- if (state->polarity != PWM_POLARITY_NORMAL)
- return -EINVAL;
- /*
- * EC doesn't separate the concept of duty cycle and enabled, but
- * kernel does. Translate.
- */
- duty_cycle = state->enabled ? state->duty_cycle : 0;
- ret = cros_ec_pwm_set_duty(ec_pwm, pwm->hwpwm, duty_cycle);
- if (ret < 0)
- return ret;
- channel->duty_cycle = state->duty_cycle;
- return 0;
- }
- static int cros_ec_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
- struct pwm_state *state)
- {
- struct cros_ec_pwm_device *ec_pwm = pwm_to_cros_ec_pwm(chip);
- struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
- int ret;
- ret = cros_ec_pwm_get_duty(ec_pwm, pwm->hwpwm);
- if (ret < 0) {
- dev_err(chip->dev, "error getting initial duty: %d\n", ret);
- return 0;
- }
- state->enabled = (ret > 0);
- state->period = EC_PWM_MAX_DUTY;
- state->polarity = PWM_POLARITY_NORMAL;
- /*
- * Note that "disabled" and "duty cycle == 0" are treated the same. If
- * the cached duty cycle is not zero, used the cached duty cycle. This
- * ensures that the configured duty cycle is kept across a disable and
- * enable operation and avoids potentially confusing consumers.
- *
- * For the case of the initial hardware readout, channel->duty_cycle
- * will be 0 and the actual duty cycle read from the EC is used.
- */
- if (ret == 0 && channel->duty_cycle > 0)
- state->duty_cycle = channel->duty_cycle;
- else
- state->duty_cycle = ret;
- return 0;
- }
- static struct pwm_device *
- cros_ec_pwm_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
- {
- struct pwm_device *pwm;
- if (args->args[0] >= pc->npwm)
- return ERR_PTR(-EINVAL);
- pwm = pwm_request_from_chip(pc, args->args[0], NULL);
- if (IS_ERR(pwm))
- return pwm;
- /* The EC won't let us change the period */
- pwm->args.period = EC_PWM_MAX_DUTY;
- return pwm;
- }
- static const struct pwm_ops cros_ec_pwm_ops = {
- .request = cros_ec_pwm_request,
- .free = cros_ec_pwm_free,
- .get_state = cros_ec_pwm_get_state,
- .apply = cros_ec_pwm_apply,
- .owner = THIS_MODULE,
- };
- /*
- * Determine the number of supported PWMs. The EC does not return the number
- * of PWMs it supports directly, so we have to read the pwm duty cycle for
- * subsequent channels until we get an error.
- */
- static int cros_ec_num_pwms(struct cros_ec_pwm_device *ec_pwm)
- {
- int i, ret;
- /* The index field is only 8 bits */
- for (i = 0; i <= U8_MAX; i++) {
- ret = cros_ec_pwm_get_duty(ec_pwm, i);
- /*
- * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
- * responses; everything else is treated as an error.
- * The EC error codes map to -EOPNOTSUPP and -EINVAL,
- * so check for those.
- */
- switch (ret) {
- case -EOPNOTSUPP: /* invalid command */
- return -ENODEV;
- case -EINVAL: /* invalid parameter */
- return i;
- default:
- if (ret < 0)
- return ret;
- break;
- }
- }
- return U8_MAX;
- }
- static int cros_ec_pwm_probe(struct platform_device *pdev)
- {
- struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
- struct device *dev = &pdev->dev;
- struct device_node *np = pdev->dev.of_node;
- struct cros_ec_pwm_device *ec_pwm;
- struct pwm_chip *chip;
- int ret;
- if (!ec) {
- dev_err(dev, "no parent EC device\n");
- return -EINVAL;
- }
- ec_pwm = devm_kzalloc(dev, sizeof(*ec_pwm), GFP_KERNEL);
- if (!ec_pwm)
- return -ENOMEM;
- chip = &ec_pwm->chip;
- ec_pwm->ec = ec;
- if (of_device_is_compatible(np, "google,cros-ec-pwm-type"))
- ec_pwm->use_pwm_type = true;
- /* PWM chip */
- chip->dev = dev;
- chip->ops = &cros_ec_pwm_ops;
- chip->of_xlate = cros_ec_pwm_xlate;
- chip->of_pwm_n_cells = 1;
- if (ec_pwm->use_pwm_type) {
- chip->npwm = CROS_EC_PWM_DT_COUNT;
- } else {
- ret = cros_ec_num_pwms(ec_pwm);
- if (ret < 0) {
- dev_err(dev, "Couldn't find PWMs: %d\n", ret);
- return ret;
- }
- chip->npwm = ret;
- }
- dev_dbg(dev, "Probed %u PWMs\n", chip->npwm);
- ret = pwmchip_add(chip);
- if (ret < 0) {
- dev_err(dev, "cannot register PWM: %d\n", ret);
- return ret;
- }
- platform_set_drvdata(pdev, ec_pwm);
- return ret;
- }
- static int cros_ec_pwm_remove(struct platform_device *dev)
- {
- struct cros_ec_pwm_device *ec_pwm = platform_get_drvdata(dev);
- struct pwm_chip *chip = &ec_pwm->chip;
- pwmchip_remove(chip);
- return 0;
- }
- #ifdef CONFIG_OF
- static const struct of_device_id cros_ec_pwm_of_match[] = {
- { .compatible = "google,cros-ec-pwm" },
- { .compatible = "google,cros-ec-pwm-type" },
- {},
- };
- MODULE_DEVICE_TABLE(of, cros_ec_pwm_of_match);
- #endif
- static struct platform_driver cros_ec_pwm_driver = {
- .probe = cros_ec_pwm_probe,
- .remove = cros_ec_pwm_remove,
- .driver = {
- .name = "cros-ec-pwm",
- .of_match_table = of_match_ptr(cros_ec_pwm_of_match),
- },
- };
- module_platform_driver(cros_ec_pwm_driver);
- MODULE_ALIAS("platform:cros-ec-pwm");
- MODULE_DESCRIPTION("ChromeOS EC PWM driver");
- MODULE_LICENSE("GPL v2");
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