diff options
Diffstat (limited to 'drivers/gpio/gpio-delay.c')
| -rw-r--r-- | drivers/gpio/gpio-delay.c | 164 |
1 files changed, 164 insertions, 0 deletions
diff --git a/drivers/gpio/gpio-delay.c b/drivers/gpio/gpio-delay.c new file mode 100644 index 000000000000..b489b561b225 --- /dev/null +++ b/drivers/gpio/gpio-delay.c @@ -0,0 +1,164 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright 2022 TQ-Systems GmbH + * Author: Alexander Stein <linux@ew.tq-group.com> + */ + +#include <linux/err.h> +#include <linux/gpio/consumer.h> +#include <linux/gpio/driver.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/platform_device.h> +#include <linux/delay.h> + +#include "gpiolib.h" + +struct gpio_delay_timing { + unsigned long ramp_up_delay_us; + unsigned long ramp_down_delay_us; +}; + +struct gpio_delay_priv { + struct gpio_chip gc; + struct gpio_descs *input_gpio; + struct gpio_delay_timing *delay_timings; +}; + +static int gpio_delay_get_direction(struct gpio_chip *gc, unsigned int offset) +{ + return GPIO_LINE_DIRECTION_OUT; +} + +static void gpio_delay_set(struct gpio_chip *gc, unsigned int offset, int val) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_desc *gpio_desc = priv->input_gpio->desc[offset]; + const struct gpio_delay_timing *delay_timings; + bool ramp_up; + + gpiod_set_value(gpio_desc, val); + + delay_timings = &priv->delay_timings[offset]; + ramp_up = (!gpiod_is_active_low(gpio_desc) && val) || + (gpiod_is_active_low(gpio_desc) && !val); + + if (ramp_up && delay_timings->ramp_up_delay_us) + udelay(delay_timings->ramp_up_delay_us); + if (!ramp_up && delay_timings->ramp_down_delay_us) + udelay(delay_timings->ramp_down_delay_us); +} + +static void gpio_delay_set_can_sleep(struct gpio_chip *gc, unsigned int offset, int val) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_desc *gpio_desc = priv->input_gpio->desc[offset]; + const struct gpio_delay_timing *delay_timings; + bool ramp_up; + + gpiod_set_value_cansleep(gpio_desc, val); + + delay_timings = &priv->delay_timings[offset]; + ramp_up = (!gpiod_is_active_low(gpio_desc) && val) || + (gpiod_is_active_low(gpio_desc) && !val); + + if (ramp_up && delay_timings->ramp_up_delay_us) + fsleep(delay_timings->ramp_up_delay_us); + if (!ramp_up && delay_timings->ramp_down_delay_us) + fsleep(delay_timings->ramp_down_delay_us); +} + +static int gpio_delay_of_xlate(struct gpio_chip *gc, + const struct of_phandle_args *gpiospec, + u32 *flags) +{ + struct gpio_delay_priv *priv = gpiochip_get_data(gc); + struct gpio_delay_timing *timings; + u32 line; + + if (gpiospec->args_count != gc->of_gpio_n_cells) + return -EINVAL; + + line = gpiospec->args[0]; + if (line >= gc->ngpio) + return -EINVAL; + + timings = &priv->delay_timings[line]; + timings->ramp_up_delay_us = gpiospec->args[1]; + timings->ramp_down_delay_us = gpiospec->args[2]; + + return line; +} + +static bool gpio_delay_can_sleep(const struct gpio_delay_priv *priv) +{ + int i; + + for (i = 0; i < priv->input_gpio->ndescs; i++) + if (gpiod_cansleep(priv->input_gpio->desc[i])) + return true; + + return false; +} + +static int gpio_delay_probe(struct platform_device *pdev) +{ + struct gpio_delay_priv *priv; + + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->input_gpio = devm_gpiod_get_array(&pdev->dev, NULL, GPIOD_OUT_LOW); + if (IS_ERR(priv->input_gpio)) + return dev_err_probe(&pdev->dev, PTR_ERR(priv->input_gpio), + "Failed to get input-gpios"); + + priv->delay_timings = devm_kcalloc(&pdev->dev, + priv->input_gpio->ndescs, + sizeof(*priv->delay_timings), + GFP_KERNEL); + if (!priv->delay_timings) + return -ENOMEM; + + if (gpio_delay_can_sleep(priv)) { + priv->gc.can_sleep = true; + priv->gc.set = gpio_delay_set_can_sleep; + } else { + priv->gc.can_sleep = false; + priv->gc.set = gpio_delay_set; + } + + priv->gc.get_direction = gpio_delay_get_direction; + priv->gc.of_xlate = gpio_delay_of_xlate; + priv->gc.of_gpio_n_cells = 3; + priv->gc.ngpio = priv->input_gpio->ndescs; + priv->gc.owner = THIS_MODULE; + priv->gc.base = -1; + priv->gc.parent = &pdev->dev; + + platform_set_drvdata(pdev, priv); + + return devm_gpiochip_add_data(&pdev->dev, &priv->gc, priv); +} + +static const struct of_device_id gpio_delay_ids[] = { + { + .compatible = "gpio-delay", + }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, gpio_delay_ids); + +static struct platform_driver gpio_delay_driver = { + .driver = { + .name = "gpio-delay", + .of_match_table = gpio_delay_ids, + }, + .probe = gpio_delay_probe, +}; +module_platform_driver(gpio_delay_driver); + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Alexander Stein <alexander.stein@ew.tq-group.com>"); +MODULE_DESCRIPTION("GPIO delay driver"); |