linux/drivers/pwm/pwm-cros-ec.c
Uwe Kleine-König 9f0f6107e0 pwm: cros-ec: Refuse requests with unsupported polarity
The driver only supports normal polarity and so should refuse requests
for inversed polarity.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2021-03-22 12:08:06 +01:00

307 lines
7.1 KiB
C

// 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>
/**
* 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;
};
/**
* 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_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)
{
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);
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->ec, pwm->hwpwm, duty_cycle);
if (ret < 0)
return ret;
channel->duty_cycle = state->duty_cycle;
return 0;
}
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);
struct cros_ec_pwm *channel = pwm_get_chip_data(pwm);
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. 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;
}
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_device *ec)
{
int i, ret;
/* The index field is only 8 bits */
for (i = 0; i <= U8_MAX; i++) {
ret = cros_ec_pwm_get_duty(ec, 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 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;
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");