diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig index a470ec8d617b..d45b55bef2e3 100644 --- a/drivers/gpio/Kconfig +++ b/drivers/gpio/Kconfig @@ -1733,6 +1733,14 @@ config GPIO_AGGREGATOR industrial control context, to be operated from userspace using the GPIO chardev interface. +config GPIO_DELAY + tristate "GPIO delay" + help + Say yes here to enable the GPIO delay, which provides a way to + configure platform specific delays for GPIO ramp-up or ramp-down + delays. This can serve the following purposes: + - Open-drain output using an RC filter + config GPIO_LATCH tristate "GPIO latch driver" help diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile index 20036af3acb1..abb6ead17d83 100644 --- a/drivers/gpio/Makefile +++ b/drivers/gpio/Makefile @@ -52,6 +52,7 @@ obj-$(CONFIG_GPIO_DA9052) += gpio-da9052.o obj-$(CONFIG_GPIO_DA9055) += gpio-da9055.o obj-$(CONFIG_GPIO_DAVINCI) += gpio-davinci.o obj-$(CONFIG_GPIO_DLN2) += gpio-dln2.o +obj-$(CONFIG_GPIO_DELAY) += gpio-delay.o obj-$(CONFIG_GPIO_DWAPB) += gpio-dwapb.o obj-$(CONFIG_GPIO_EIC_SPRD) += gpio-eic-sprd.o obj-$(CONFIG_GPIO_ELKHARTLAKE) += gpio-elkhartlake.o 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 + */ + +#include +#include +#include +#include +#include +#include +#include + +#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 "); +MODULE_DESCRIPTION("GPIO delay driver");