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
swnode_format_propname(const char * con_id,char * propname,size_t max_size)20 static 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
swnode_gpiochip_match_name(struct gpio_chip * chip,void * data)34 static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
35 {
36 return !strcmp(chip->label, data);
37 }
38
swnode_get_chip(struct fwnode_handle * fwnode)39 static 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
swnode_find_gpio(struct fwnode_handle * fwnode,const char * con_id,unsigned int idx,unsigned long * flags)52 struct 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 */
swnode_gpio_count(const struct fwnode_handle * fwnode,const char * con_id)104 int 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
