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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (C) 2025 - 2026, Advanced Micro Devices, Inc.
*
* Michal Simek <michal.simek@amd.com>
*/
#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];
u32 wait;
int ret;
dev_dbg(dev, "gpio %d set to %d\n", offset, value);
ret = dm_gpio_set_value(&desc->real_gpio, value);
if (ret) {
dev_err(dev, "Failed to set gpio %d, value %d\n", offset, value);
return ret;
}
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 0;
}
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, 0);
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,
};
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