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// SPDX-License-Identifier: GPL-2.0+
/*
* Software Node helpers for the GPIO API
*
* Copyright 2022 Google LLC
*/
#define pr_fmt(fmt) "gpiolib: swnode: " fmt
#include <linux/err.h>
#include <linux/errno.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/printk.h>
#include <linux/property.h>
#include <linux/string.h>
#include <linux/gpio/consumer.h>
#include <linux/gpio/driver.h>
#include <linux/gpio/property.h>
#include "gpiolib.h"
#include "gpiolib-swnode.h"
static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
{
const struct software_node *gdev_node;
struct gpio_device *gdev;
gdev_node = to_software_node(fwnode);
if (!gdev_node)
goto fwnode_lookup;
/*
* Check for a special node that identifies undefined GPIOs, this is
* primarily used as a key for internal chip selects in SPI bindings.
*/
if (IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED) &&
gdev_node == &swnode_gpio_undefined)
return ERR_PTR(-ENOENT);
fwnode_lookup:
gdev = gpio_device_find_by_fwnode(fwnode);
if (!gdev && gdev_node && gdev_node->name)
/*
* FIXME: We shouldn't need to compare the GPIO controller's
* label against the software node that is supposedly attached
* to it. However there are currently GPIO users that - knowing
* the expected label of the GPIO chip whose pins they want to
* control - set up dummy software nodes named after those GPIO
* controllers, which aren't actually attached to them. In this
* case gpio_device_find_by_fwnode() will fail as no device on
* the GPIO bus is actually associated with the fwnode we're
* looking for.
*
* As a fallback: continue checking the label if we have no
* match. However, the situation described above is an abuse
* of the software node API and should be phased out and the
* following line - eventually removed.
*/
gdev = gpio_device_find_by_label(gdev_node->name);
return gdev ?: ERR_PTR(-EPROBE_DEFER);
}
static int swnode_gpio_get_reference(const struct fwnode_handle *fwnode,
const char *propname, unsigned int idx,
struct fwnode_reference_args *args)
{
/*
* We expect all swnode-described GPIOs have GPIO number and
* polarity arguments, hence nargs is set to 2.
*/
return fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, args);
}
struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
const char *con_id, unsigned int idx,
unsigned long *flags)
{
const struct software_node *swnode;
struct fwnode_reference_args args;
struct gpio_desc *desc;
char propname[32]; /* 32 is max size of property name */
int ret = 0;
swnode = to_software_node(fwnode);
if (!swnode)
return ERR_PTR(-EINVAL);
for_each_gpio_property_name(propname, con_id) {
ret = swnode_gpio_get_reference(fwnode, propname, idx, &args);
if (ret == 0)
break;
}
if (ret) {
pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
__func__, propname, fwnode, idx);
return ERR_PTR(ret);
}
struct gpio_device *gdev __free(gpio_device_put) =
swnode_get_gpio_device(args.fwnode);
fwnode_handle_put(args.fwnode);
if (IS_ERR(gdev))
return ERR_CAST(gdev);
/*
* FIXME: The GPIO device reference is put at return but the descriptor
* is passed on. Find a proper solution.
*/
desc = gpio_device_get_desc(gdev, args.args[0]);
*flags = args.args[1]; /* We expect native GPIO flags */
pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
__func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
return desc;
}
/**
* swnode_gpio_count - count the GPIOs associated with a device / function
* @fwnode: firmware node of the GPIO consumer, can be %NULL for
* system-global GPIOs
* @con_id: function within the GPIO consumer
*
* Returns:
* The number of GPIOs associated with a device / function or %-ENOENT,
* if no GPIO has been assigned to the requested function.
*/
int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
{
struct fwnode_reference_args args;
char propname[32];
int count;
/*
* This is not very efficient, but GPIO lists usually have only
* 1 or 2 entries.
*/
for_each_gpio_property_name(propname, con_id) {
count = 0;
while (swnode_gpio_get_reference(fwnode, propname, count, &args) == 0) {
fwnode_handle_put(args.fwnode);
count++;
}
if (count)
return count;
}
return -ENOENT;
}
#if IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED)
/*
* A special node that identifies undefined GPIOs, this is primarily used as
* a key for internal chip selects in SPI bindings.
*/
const struct software_node swnode_gpio_undefined = {
.name = "swnode-gpio-undefined",
};
EXPORT_SYMBOL_NS_GPL(swnode_gpio_undefined, "GPIO_SWNODE");
static int __init swnode_gpio_init(void)
{
int ret;
ret = software_node_register(&swnode_gpio_undefined);
if (ret < 0)
pr_err("failed to register swnode: %d\n", ret);
return ret;
}
subsys_initcall(swnode_gpio_init);
static void __exit swnode_gpio_cleanup(void)
{
software_node_unregister(&swnode_gpio_undefined);
}
__exitcall(swnode_gpio_cleanup);
#endif
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