On 1/30/26 08:21, Peng Fan wrote:
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?
Why? I don't have a need for it and someone should test it if this should be
used in SPL. That can be done on the top of this when tested.
#
# 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?
Why? Driver was developed in 2025 but upstreaming happens in 2026.
+ *
+ * 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);
}
will add.
+
+ 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?
It is clear that it should be output because you just setting it up later.
But I don't have any issue not to pass any flag here.
Please let me know if you want me to change it to 0.
Thanks,
Michal
