1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Software Node helpers for the GPIO API 4 * 5 * Copyright 2022 Google LLC 6 */ 7 8 #define pr_fmt(fmt) "gpiolib: swnode: " fmt 9 10 #include <linux/err.h> 11 #include <linux/errno.h> 12 #include <linux/export.h> 13 #include <linux/init.h> 14 #include <linux/kernel.h> 15 #include <linux/printk.h> 16 #include <linux/property.h> 17 #include <linux/string.h> 18 19 #include <linux/gpio/consumer.h> 20 #include <linux/gpio/driver.h> 21 22 #include "gpiolib.h" 23 #include "gpiolib-swnode.h" 24 25 #define GPIOLIB_SWNODE_UNDEFINED_NAME "swnode-gpio-undefined" 26 27 static void swnode_format_propname(const char *con_id, char *propname, 28 size_t max_size) 29 { 30 /* 31 * Note we do not need to try both -gpios and -gpio suffixes, 32 * as, unlike OF and ACPI, we can fix software nodes to conform 33 * to the proper binding. 34 */ 35 if (con_id) 36 snprintf(propname, max_size, "%s-gpios", con_id); 37 else 38 strscpy(propname, "gpios", max_size); 39 } 40 41 static struct gpio_device *swnode_get_gpio_device(struct fwnode_handle *fwnode) 42 { 43 const struct software_node *gdev_node; 44 struct gpio_device *gdev; 45 46 gdev_node = to_software_node(fwnode); 47 if (!gdev_node || !gdev_node->name) 48 return ERR_PTR(-EINVAL); 49 50 /* 51 * Check for a special node that identifies undefined GPIOs, this is 52 * primarily used as a key for internal chip selects in SPI bindings. 53 */ 54 if (IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED) && 55 !strcmp(gdev_node->name, GPIOLIB_SWNODE_UNDEFINED_NAME)) 56 return ERR_PTR(-ENOENT); 57 58 gdev = gpio_device_find_by_label(gdev_node->name); 59 return gdev ?: ERR_PTR(-EPROBE_DEFER); 60 } 61 62 struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode, 63 const char *con_id, unsigned int idx, 64 unsigned long *flags) 65 { 66 const struct software_node *swnode; 67 struct fwnode_reference_args args; 68 struct gpio_desc *desc; 69 char propname[32]; /* 32 is max size of property name */ 70 int error; 71 72 swnode = to_software_node(fwnode); 73 if (!swnode) 74 return ERR_PTR(-EINVAL); 75 76 swnode_format_propname(con_id, propname, sizeof(propname)); 77 78 /* 79 * We expect all swnode-described GPIOs have GPIO number and 80 * polarity arguments, hence nargs is set to 2. 81 */ 82 error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args); 83 if (error) { 84 pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n", 85 __func__, propname, fwnode, idx); 86 return ERR_PTR(error); 87 } 88 89 struct gpio_device *gdev __free(gpio_device_put) = 90 swnode_get_gpio_device(args.fwnode); 91 fwnode_handle_put(args.fwnode); 92 if (IS_ERR(gdev)) 93 return ERR_CAST(gdev); 94 95 /* 96 * FIXME: The GPIO device reference is put at return but the descriptor 97 * is passed on. Find a proper solution. 98 */ 99 desc = gpio_device_get_desc(gdev, args.args[0]); 100 *flags = args.args[1]; /* We expect native GPIO flags */ 101 102 pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n", 103 __func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc)); 104 105 return desc; 106 } 107 108 /** 109 * swnode_gpio_count - count the GPIOs associated with a device / function 110 * @fwnode: firmware node of the GPIO consumer, can be %NULL for 111 * system-global GPIOs 112 * @con_id: function within the GPIO consumer 113 * 114 * Return: 115 * The number of GPIOs associated with a device / function or %-ENOENT, 116 * if no GPIO has been assigned to the requested function. 117 */ 118 int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id) 119 { 120 struct fwnode_reference_args args; 121 char propname[32]; 122 int count; 123 124 swnode_format_propname(con_id, propname, sizeof(propname)); 125 126 /* 127 * This is not very efficient, but GPIO lists usually have only 128 * 1 or 2 entries. 129 */ 130 count = 0; 131 while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0, 132 count, &args) == 0) { 133 fwnode_handle_put(args.fwnode); 134 count++; 135 } 136 137 return count ?: -ENOENT; 138 } 139 140 #if IS_ENABLED(CONFIG_GPIO_SWNODE_UNDEFINED) 141 /* 142 * A special node that identifies undefined GPIOs, this is primarily used as 143 * a key for internal chip selects in SPI bindings. 144 */ 145 const struct software_node swnode_gpio_undefined = { 146 .name = GPIOLIB_SWNODE_UNDEFINED_NAME, 147 }; 148 EXPORT_SYMBOL_NS_GPL(swnode_gpio_undefined, GPIO_SWNODE); 149 150 static int __init swnode_gpio_init(void) 151 { 152 int ret; 153 154 ret = software_node_register(&swnode_gpio_undefined); 155 if (ret < 0) 156 pr_err("failed to register swnode: %d\n", ret); 157 158 return ret; 159 } 160 subsys_initcall(swnode_gpio_init); 161 162 static void __exit swnode_gpio_cleanup(void) 163 { 164 software_node_unregister(&swnode_gpio_undefined); 165 } 166 __exitcall(swnode_gpio_cleanup); 167 #endif 168