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 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(-EINVAL);
 42
 43	gdev = gpio_device_find_by_label(gdev_node->name);
 44	return gdev ?: ERR_PTR(-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(-EINVAL);
 60
 61	swnode_format_propname(con_id, propname, 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, propname, NULL, 2, idx, &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(args.fwnode);
 76	fwnode_handle_put(args.fwnode);
 77	if (IS_ERR(gdev))
 78		return ERR_CAST(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, 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}