1// SPDX-License-Identifier: GPL-2.0+
  2/*
  3 * Software Node helpers for the GPIO API
  4 *
  5 * Copyright 2022 Google LLC
  6 */
  7#include <linux/err.h>
  8#include <linux/errno.h>
  9#include <linux/gpio/consumer.h>
 10#include <linux/gpio/driver.h>
 11#include <linux/kernel.h>
 12#include <linux/printk.h>
 13#include <linux/property.h>
 14#include <linux/string.h>
 15
 16#include "gpiolib.h"
 17#include "gpiolib-swnode.h"
 18
 19static void swnode_format_propname(const char *con_id, char *propname,
 20				   size_t max_size)
 21{
 22	/*
 23	 * Note we do not need to try both -gpios and -gpio suffixes,
 24	 * as, unlike OF and ACPI, we can fix software nodes to conform
 25	 * to the proper binding.
 26	 */
 27	if (con_id)
 28		snprintf(propname, max_size, "%s-gpios", con_id);
 29	else
 30		strscpy(propname, "gpios", max_size);
 31}
 32
 33static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
 34{
 35	return !strcmp(chip->label, data);
 36}
 37
 38static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
 39{
 40	const struct software_node *chip_node;
 41	struct gpio_chip *chip;
 42
 43	chip_node = to_software_node(fwnode);
 44	if (!chip_node || !chip_node->name)
 45		return ERR_PTR(-EINVAL);
 46
 47	chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
 48	return chip ?: ERR_PTR(-EPROBE_DEFER);
 49}
 50
 51struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
 52				   const char *con_id, unsigned int idx,
 53				   unsigned long *flags)
 54{
 55	const struct software_node *swnode;
 56	struct fwnode_reference_args args;
 57	struct gpio_chip *chip;
 58	struct gpio_desc *desc;
 59	char propname[32]; /* 32 is max size of property name */
 60	int error;
 61
 62	swnode = to_software_node(fwnode);
 63	if (!swnode)
 64		return ERR_PTR(-EINVAL);
 65
 66	swnode_format_propname(con_id, propname, sizeof(propname));
 67
 68	/*
 69	 * We expect all swnode-described GPIOs have GPIO number and
 70	 * polarity arguments, hence nargs is set to 2.
 71	 */
 72	error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args);
 73	if (error) {
 74		pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
 75			__func__, propname, fwnode, idx);
 76		return ERR_PTR(error);
 77	}
 78
 79	chip = swnode_get_chip(args.fwnode);
 80	fwnode_handle_put(args.fwnode);
 81	if (IS_ERR(chip))
 82		return ERR_CAST(chip);
 83
 84	desc = gpiochip_get_desc(chip, args.args[0]);
 85	*flags = args.args[1]; /* We expect native GPIO flags */
 86
 87	pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
 88		 __func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
 89
 90	return desc;
 91}
 92
 93/**
 94 * swnode_gpio_count - count the GPIOs associated with a device / function
 95 * @fwnode:	firmware node of the GPIO consumer, can be %NULL for
 96 *		system-global GPIOs
 97 * @con_id:	function within the GPIO consumer
 98 *
 99 * Return:
100 * The number of GPIOs associated with a device / function or %-ENOENT,
101 * if no GPIO has been assigned to the requested function.
102 */
103int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
104{
105	struct fwnode_reference_args args;
106	char propname[32];
107	int count;
108
109	swnode_format_propname(con_id, propname, sizeof(propname));
110
111	/*
112	 * This is not very efficient, but GPIO lists usually have only
113	 * 1 or 2 entries.
114	 */
115	count = 0;
116	while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0,
117						  count, &args) == 0) {
118		fwnode_handle_put(args.fwnode);
119		count++;
120	}
121
122	return count ?: -ENOENT;
123}