Hi Michal, On Thu, Jan 22, 2026 at 01:50:33PM +0100, Michal Simek wrote: >Add a GPIO controller driver that provides configurable delays when >setting GPIO output values. This is useful for hardware that requires >specific timing delays during power sequencing or GPIO state changes. > >The driver wraps underlying GPIO controllers and adds programmable >ramp-up and ramp-down delays specified in microseconds through the >device tree. Each GPIO can have independent delay timings. > >Device tree binding matches Linux. > >Signed-off-by: Michal Simek <[email protected]> >--- > > drivers/gpio/Kconfig | 8 +++ > drivers/gpio/Makefile | 1 + > drivers/gpio/gpio-delay.c | 133 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 142 insertions(+) > create mode 100644 drivers/gpio/gpio-delay.c > >diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig >index 60c5c54688e6..f69919abc05b 100644 >--- a/drivers/gpio/Kconfig >+++ b/drivers/gpio/Kconfig >@@ -1,3 +1,11 @@ >+config GPIO_DELAY >+ bool "GPIO delay driver" >+ depends on DM_GPIO >+ help >+ Enable the GPIO delay driver. >+ This driver allows wrapping another GPIO controller and inserting >+ ramp-up/ramp-down delays on output changes, as described in the >+ Linux gpio-delay binding.
Add an entry for SPL? > # > # GPIO infrastructure and drivers > # >diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile >index 910478c0c7a9..fec258f59f52 100644 >--- a/drivers/gpio/Makefile >+++ b/drivers/gpio/Makefile >@@ -21,6 +21,7 @@ obj-$(CONFIG_ATMEL_PIO4) += atmel_pio4.o > obj-$(CONFIG_BCM6345_GPIO) += bcm6345_gpio.o > obj-$(CONFIG_CORTINA_GPIO) += cortina_gpio.o > obj-$(CONFIG_FXL6408_GPIO) += gpio-fxl6408.o >+obj-$(CONFIG_GPIO_DELAY) += gpio-delay.o > obj-$(CONFIG_INTEL_GPIO) += intel_gpio.o > obj-$(CONFIG_INTEL_ICH6_GPIO) += intel_ich6_gpio.o > obj-$(CONFIG_INTEL_BROADWELL_GPIO) += intel_broadwell_gpio.o >diff --git a/drivers/gpio/gpio-delay.c b/drivers/gpio/gpio-delay.c >new file mode 100644 >index 000000000000..0c0d05ccb493 >--- /dev/null >+++ b/drivers/gpio/gpio-delay.c >@@ -0,0 +1,133 @@ >+// SPDX-License-Identifier: GPL-2.0 >+/* >+ * Copyright (C) 2025 - 2026, Advanced Micro Devices, Inc. Drop 2025? >+ * >+ * Michal Simek <[email protected]> >+ */ >+ >+#include <dm.h> >+#include <dm/device_compat.h> >+#include <dm/devres.h> >+#include <asm/gpio.h> >+#include <linux/delay.h> >+ >+struct gpio_delay_desc { >+ struct gpio_desc real_gpio; >+ u32 ramp_up_us; >+ u32 ramp_down_us; >+}; >+ >+struct gpio_delay_priv { >+ struct gpio_delay_desc *descs; >+}; >+ >+static int gpio_delay_direction_input(struct udevice *dev, unsigned int >offset) >+{ >+ return -ENOSYS; >+} >+ >+static int gpio_delay_get_value(struct udevice *dev, unsigned int offset) >+{ >+ return -ENOSYS; >+} >+ >+static int gpio_delay_set_value(struct udevice *dev, unsigned int offset, >+ int value) >+{ >+ struct gpio_delay_priv *priv = dev_get_priv(dev); >+ struct gpio_delay_desc *desc = &priv->descs[offset]; >+ int ret = dm_gpio_set_value(&desc->real_gpio, value); >+ u32 wait; Check return value. if (ret) { dev_err(dev, "Failed to set gpio %d\n", offset); } >+ >+ dev_dbg(dev, "gpio %d set to %d\n", offset, value); >+ >+ if (value) >+ wait = desc->ramp_up_us; >+ else >+ wait = desc->ramp_down_us; >+ >+ udelay(wait); >+ >+ dev_dbg(dev, "waited for %d us\n", wait); >+ >+ return ret; >+} >+ >+static int gpio_delay_direction_output(struct udevice *dev, unsigned int >offset, >+ int value) >+{ >+ return gpio_delay_set_value(dev, offset, value); >+} >+ >+static int gpio_delay_xlate(struct udevice *dev, struct gpio_desc *desc, >+ struct ofnode_phandle_args *args) >+{ >+ struct gpio_delay_priv *priv = dev_get_priv(dev); >+ >+ if (args->args_count < 3) >+ return -EINVAL; >+ >+ if (args->args[0] >= 32) >+ return -EINVAL; >+ >+ struct gpio_delay_desc *d = &priv->descs[args->args[0]]; >+ >+ d->ramp_up_us = args->args[1]; >+ d->ramp_down_us = args->args[2]; >+ >+ dev_dbg(dev, "pin: %d, ramp_up_us: %d, ramp_down_us: %d\n", >+ args->args[0], d->ramp_up_us, d->ramp_down_us); >+ >+ return 0; >+} >+ >+static const struct dm_gpio_ops gpio_delay_ops = { >+ .direction_output = gpio_delay_direction_output, >+ .direction_input = gpio_delay_direction_input, >+ .get_value = gpio_delay_get_value, >+ .set_value = gpio_delay_set_value, >+ .xlate = gpio_delay_xlate, >+}; >+ >+static int gpio_delay_probe(struct udevice *dev) >+{ >+ struct gpio_delay_priv *priv = dev_get_priv(dev); >+ struct gpio_delay_desc *d; >+ ofnode node = dev_ofnode(dev); >+ int i = 0, ret, ngpio; >+ >+ ngpio = gpio_get_list_count(dev, "gpios"); >+ if (ngpio < 0) >+ return ngpio; >+ >+ dev_dbg(dev, "gpios: %d\n", ngpio); >+ >+ priv->descs = devm_kmalloc_array(dev, ngpio, sizeof(*d), GFP_KERNEL); >+ if (!priv->descs) >+ return -ENOMEM; >+ >+ /* Request all GPIOs described in the controller node */ >+ for (i = 0; i < ngpio; i++) { >+ d = &priv->descs[i]; >+ ret = gpio_request_by_name_nodev(node, "gpios", i, >+ &d->real_gpio, GPIOD_IS_OUT); This will configure the GPIO as output and ACTIVE high/low flag will also be used per my understanding. Should the dir and value be deferred until set_value is invoked? Regards, Peng >+ if (ret) >+ return ret; >+ } >+ >+ return 0; >+} >+ >+static const struct udevice_id gpio_delay_ids[] = { >+ { .compatible = "gpio-delay" }, >+ { } >+}; >+ >+U_BOOT_DRIVER(gpio_delay) = { >+ .name = "gpio-delay", >+ .id = UCLASS_GPIO, >+ .of_match = gpio_delay_ids, >+ .ops = &gpio_delay_ops, >+ .priv_auto = sizeof(struct gpio_delay_priv), >+ .probe = gpio_delay_probe, >+}; >-- >2.43.0 >
