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(buf: propname, size: max_size, fmt: "%s-gpios", con_id);
30 else
31 strscpy(propname, "gpios", max_size);
32}
33
34static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode)
35{
36 const struct software_node *gdev_node;
37 struct gpio_device *gdev;
38
39 gdev_node = to_software_node(fwnode);
40 if (!gdev_node || !gdev_node->name)
41 return ERR_PTR(error: -EINVAL);
42
43 gdev = gpio_device_find_by_label(label: gdev_node->name);
44 return gdev ?: ERR_PTR(error: -EPROBE_DEFER);
45}
46
47struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
48 const char *con_id, unsigned int idx,
49 unsigned long *flags)
50{
51 const struct software_node *swnode;
52 struct fwnode_reference_args args;
53 struct gpio_desc *desc;
54 char propname[32]; /* 32 is max size of property name */
55 int error;
56
57 swnode = to_software_node(fwnode);
58 if (!swnode)
59 return ERR_PTR(error: -EINVAL);
60
61 swnode_format_propname(con_id, propname, max_size: sizeof(propname));
62
63 /*
64 * We expect all swnode-described GPIOs have GPIO number and
65 * polarity arguments, hence nargs is set to 2.
66 */
67 error = fwnode_property_get_reference_args(fwnode, prop: propname, NULL, nargs: 2, index: idx, args: &args);
68 if (error) {
69 pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
70 __func__, propname, fwnode, idx);
71 return ERR_PTR(error);
72 }
73
74 struct gpio_device *gdev __free(gpio_device_put) =
75 swnode_get_gpio_device(fwnode: args.fwnode);
76 fwnode_handle_put(fwnode: args.fwnode);
77 if (IS_ERR(ptr: gdev))
78 return ERR_CAST(ptr: gdev);
79
80 /*
81 * FIXME: The GPIO device reference is put at return but the descriptor
82 * is passed on. Find a proper solution.
83 */
84 desc = gpio_device_get_desc(gdev, hwnum: 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, max_size: 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, prop: propname, NULL, nargs: 0,
117 index: count, args: &args) == 0) {
118 fwnode_handle_put(fwnode: args.fwnode);
119 count++;
120 }
121
122 return count ?: -ENOENT;
123}
124

source code of linux/drivers/gpio/gpiolib-swnode.c