forked from Qortal/Brooklyn
You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
144 lines
3.3 KiB
144 lines
3.3 KiB
// SPDX-License-Identifier: GPL-2.0+ |
|
/* |
|
* GPIO driver wrapping PWM API |
|
* |
|
* PWM 0% and PWM 100% are equivalent to digital GPIO |
|
* outputs, and there are times where it is useful to use |
|
* PWM outputs as straight GPIOs (eg outputs of NXP PCA9685 |
|
* I2C PWM chip). This driver wraps the PWM API as a GPIO |
|
* controller. |
|
* |
|
* Copyright (C) 2021 Raspberry Pi (Trading) Ltd. |
|
*/ |
|
|
|
#include <linux/err.h> |
|
#include <linux/gpio/driver.h> |
|
#include <linux/module.h> |
|
#include <linux/platform_device.h> |
|
#include <linux/pwm.h> |
|
|
|
struct pwm_gpio { |
|
struct gpio_chip gc; |
|
struct pwm_device **pwm; |
|
}; |
|
|
|
static int pwm_gpio_get_direction(struct gpio_chip *gc, unsigned int off) |
|
{ |
|
return GPIO_LINE_DIRECTION_OUT; |
|
} |
|
|
|
static void pwm_gpio_set(struct gpio_chip *gc, unsigned int off, int val) |
|
{ |
|
struct pwm_gpio *pwm_gpio = gpiochip_get_data(gc); |
|
struct pwm_state state; |
|
|
|
pwm_get_state(pwm_gpio->pwm[off], &state); |
|
state.duty_cycle = val ? state.period : 0; |
|
pwm_apply_state(pwm_gpio->pwm[off], &state); |
|
} |
|
|
|
static int pwm_gpio_parse_dt(struct pwm_gpio *pwm_gpio, |
|
struct device *dev) |
|
{ |
|
struct device_node *node = dev->of_node; |
|
struct pwm_state state; |
|
int ret = 0, i, num_gpios; |
|
const char *pwm_name; |
|
|
|
if (!node) |
|
return -ENODEV; |
|
|
|
num_gpios = of_property_count_strings(node, "pwm-names"); |
|
if (num_gpios <= 0) |
|
return 0; |
|
|
|
pwm_gpio->pwm = devm_kzalloc(dev, |
|
sizeof(*pwm_gpio->pwm) * num_gpios, |
|
GFP_KERNEL); |
|
if (!pwm_gpio->pwm) |
|
return -ENOMEM; |
|
|
|
for (i = 0; i < num_gpios; i++) { |
|
ret = of_property_read_string_index(node, "pwm-names", i, |
|
&pwm_name); |
|
if (ret) { |
|
dev_err(dev, "unable to get pwm device index %d, name %s", |
|
i, pwm_name); |
|
goto error; |
|
} |
|
|
|
pwm_gpio->pwm[i] = devm_pwm_get(dev, pwm_name); |
|
if (IS_ERR(pwm_gpio->pwm[i])) { |
|
ret = PTR_ERR(pwm_gpio->pwm[i]); |
|
if (ret != -EPROBE_DEFER) |
|
dev_err(dev, "unable to request PWM\n"); |
|
goto error; |
|
} |
|
|
|
/* Sync up PWM state. */ |
|
pwm_init_state(pwm_gpio->pwm[i], &state); |
|
|
|
state.duty_cycle = 0; |
|
pwm_apply_state(pwm_gpio->pwm[i], &state); |
|
} |
|
|
|
pwm_gpio->gc.ngpio = num_gpios; |
|
|
|
error: |
|
return ret; |
|
} |
|
|
|
static int pwm_gpio_probe(struct platform_device *pdev) |
|
{ |
|
struct device *dev = &pdev->dev; |
|
struct pwm_gpio *pwm_gpio; |
|
int ret; |
|
|
|
pwm_gpio = devm_kzalloc(dev, sizeof(*pwm_gpio), GFP_KERNEL); |
|
if (!pwm_gpio) |
|
return -ENOMEM; |
|
|
|
pwm_gpio->gc.parent = dev; |
|
pwm_gpio->gc.label = "pwm-gpio"; |
|
pwm_gpio->gc.owner = THIS_MODULE; |
|
pwm_gpio->gc.of_node = dev->of_node; |
|
pwm_gpio->gc.base = -1; |
|
|
|
pwm_gpio->gc.get_direction = pwm_gpio_get_direction; |
|
pwm_gpio->gc.set = pwm_gpio_set; |
|
pwm_gpio->gc.can_sleep = true; |
|
|
|
ret = pwm_gpio_parse_dt(pwm_gpio, dev); |
|
if (ret) |
|
return ret; |
|
|
|
if (!pwm_gpio->gc.ngpio) |
|
return 0; |
|
|
|
return devm_gpiochip_add_data(dev, &pwm_gpio->gc, pwm_gpio); |
|
} |
|
|
|
static int pwm_gpio_remove(struct platform_device *pdev) |
|
{ |
|
return 0; |
|
} |
|
|
|
static const struct of_device_id pwm_gpio_of_match[] = { |
|
{ .compatible = "pwm-gpio" }, |
|
{ } |
|
}; |
|
MODULE_DEVICE_TABLE(of, pwm_gpio_of_match); |
|
|
|
static struct platform_driver pwm_gpio_driver = { |
|
.driver = { |
|
.name = "pwm-gpio", |
|
.of_match_table = of_match_ptr(pwm_gpio_of_match), |
|
}, |
|
.probe = pwm_gpio_probe, |
|
.remove = pwm_gpio_remove, |
|
}; |
|
module_platform_driver(pwm_gpio_driver); |
|
|
|
MODULE_LICENSE("GPL"); |
|
MODULE_AUTHOR("Dave Stevenson <[email protected]>"); |
|
MODULE_DESCRIPTION("PWM GPIO driver");
|
|
|