123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261 |
- /*
- * Copyright (C) 2016 Google, Inc
- *
- * This program is free software; you can redistribute it and/or modify it
- * under the terms of the GNU General Public License version 2, as published by
- * the Free Software Foundation.
- *
- * Expose a PWM controlled by the ChromeOS EC to the host processor.
- */
- #include <linux/module.h>
- #include <linux/mfd/cros_ec.h>
- #include <linux/mfd/cros_ec_commands.h>
- #include <linux/platform_device.h>
- #include <linux/pwm.h>
- #include <linux/slab.h>
- /**
- * struct cros_ec_pwm_device - Driver data for EC PWM
- *
- * @dev: Device node
- * @ec: Pointer to EC device
- * @chip: PWM controller chip
- */
- struct cros_ec_pwm_device {
- struct device *dev;
- struct cros_ec_device *ec;
- struct pwm_chip chip;
- };
- 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_set_duty(struct cros_ec_device *ec, u8 index, u16 duty)
- {
- 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;
- 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;
- 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_device *ec, u8 index,
- u32 *result)
- {
- 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(*params);
- msg->outsize = sizeof(*resp);
- params->pwm_type = EC_PWM_TYPE_GENERIC;
- params->index = index;
- ret = cros_ec_cmd_xfer_status(ec, msg);
- if (result)
- *result = msg->result;
- if (ret < 0)
- return ret;
- return resp->duty;
- }
- static int cros_ec_pwm_get_duty(struct cros_ec_device *ec, u8 index)
- {
- return __cros_ec_pwm_get_duty(ec, index, NULL);
- }
- static int cros_ec_pwm_apply(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);
- int duty_cycle;
- /* The EC won't let us change the period */
- if (state->period != EC_PWM_MAX_DUTY)
- 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;
- return cros_ec_pwm_set_duty(ec_pwm->ec, pwm->hwpwm, duty_cycle);
- }
- static void 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);
- int ret;
- ret = cros_ec_pwm_get_duty(ec_pwm->ec, pwm->hwpwm);
- if (ret < 0) {
- dev_err(chip->dev, "error getting initial duty: %d\n", ret);
- return;
- }
- state->enabled = (ret > 0);
- state->period = EC_PWM_MAX_DUTY;
- /* Note that "disabled" and "duty cycle == 0" are treated the same */
- state->duty_cycle = ret;
- }
- 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 = {
- .get_state = cros_ec_pwm_get_state,
- .apply = cros_ec_pwm_apply,
- .owner = THIS_MODULE,
- };
- static int cros_ec_num_pwms(struct cros_ec_device *ec)
- {
- int i, ret;
- /* The index field is only 8 bits */
- for (i = 0; i <= U8_MAX; i++) {
- u32 result = 0;
- ret = __cros_ec_pwm_get_duty(ec, i, &result);
- /* We want to parse EC protocol errors */
- if (ret < 0 && !(ret == -EPROTO && result))
- return ret;
- /*
- * We look for SUCCESS, INVALID_COMMAND, or INVALID_PARAM
- * responses; everything else is treated as an error.
- */
- if (result == EC_RES_INVALID_COMMAND)
- return -ENODEV;
- else if (result == EC_RES_INVALID_PARAM)
- return i;
- else if (result)
- return -EPROTO;
- }
- 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 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;
- /* PWM chip */
- chip->dev = dev;
- chip->ops = &cros_ec_pwm_ops;
- chip->of_xlate = cros_ec_pwm_xlate;
- chip->of_pwm_n_cells = 1;
- chip->base = -1;
- ret = cros_ec_num_pwms(ec);
- 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;
- return pwmchip_remove(chip);
- }
- #ifdef CONFIG_OF
- static const struct of_device_id cros_ec_pwm_of_match[] = {
- { .compatible = "google,cros-ec-pwm" },
- {},
- };
- 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");
|