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/kernel.h>
10#include <linux/printk.h>
11#include <linux/property.h>
12#include <linux/string.h>
13
14#include <linux/gpio/consumer.h>
15#include <linux/gpio/driver.h>
16
17#include "gpiolib.h"
18#include "gpiolib-swnode.h"
19
20static void swnode_format_propname(const char *con_id, char *propname,
21				   size_t max_size)
22{
23	/*
24	 * Note we do not need to try both -gpios and -gpio suffixes,
25	 * as, unlike OF and ACPI, we can fix software nodes to conform
26	 * to the proper binding.
27	 */
28	if (con_id)
29		snprintf(propname, max_size, "%s-gpios", con_id);
30	else
31		strscpy(propname, "gpios", max_size);
32}
33
34static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
35{
36	return !strcmp(chip->label, data);
37}
38
39static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
40{
41	const struct software_node *chip_node;
42	struct gpio_chip *chip;
43
44	chip_node = to_software_node(fwnode);
45	if (!chip_node || !chip_node->name)
46		return ERR_PTR(-EINVAL);
47
48	chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
49	return chip ?: ERR_PTR(-EPROBE_DEFER);
50}
51
52struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
53				   const char *con_id, unsigned int idx,
54				   unsigned long *flags)
55{
56	const struct software_node *swnode;
57	struct fwnode_reference_args args;
58	struct gpio_chip *chip;
59	struct gpio_desc *desc;
60	char propname[32]; /* 32 is max size of property name */
61	int error;
62
63	swnode = to_software_node(fwnode);
64	if (!swnode)
65		return ERR_PTR(-EINVAL);
66
67	swnode_format_propname(con_id, propname, sizeof(propname));
68
69	/*
70	 * We expect all swnode-described GPIOs have GPIO number and
71	 * polarity arguments, hence nargs is set to 2.
72	 */
73	error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args);
74	if (error) {
75		pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
76			__func__, propname, fwnode, idx);
77		return ERR_PTR(error);
78	}
79
80	chip = swnode_get_chip(args.fwnode);
81	fwnode_handle_put(args.fwnode);
82	if (IS_ERR(chip))
83		return ERR_CAST(chip);
84
85	desc = gpiochip_get_desc(chip, args.args[0]);
86	*flags = args.args[1]; /* We expect native GPIO flags */
87
88	pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
89		 __func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
90
91	return desc;
92}
93
94/**
95 * swnode_gpio_count - count the GPIOs associated with a device / function
96 * @fwnode:	firmware node of the GPIO consumer, can be %NULL for
97 *		system-global GPIOs
98 * @con_id:	function within the GPIO consumer
99 *
100 * Return:
101 * The number of GPIOs associated with a device / function or %-ENOENT,
102 * if no GPIO has been assigned to the requested function.
103 */
104int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
105{
106	struct fwnode_reference_args args;
107	char propname[32];
108	int count;
109
110	swnode_format_propname(con_id, propname, sizeof(propname));
111
112	/*
113	 * This is not very efficient, but GPIO lists usually have only
114	 * 1 or 2 entries.
115	 */
116	count = 0;
117	while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0,
118						  count, &args) == 0) {
119		fwnode_handle_put(args.fwnode);
120		count++;
121	}
122
123	return count ?: -ENOENT;
124}
125