124 lines
3.2 KiB
C
124 lines
3.2 KiB
C
// SPDX-License-Identifier: GPL-2.0+
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/*
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* Software Node helpers for the GPIO API
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*
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* Copyright 2022 Google LLC
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*/
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/gpio/consumer.h>
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#include <linux/gpio/driver.h>
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#include <linux/kernel.h>
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#include <linux/printk.h>
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#include <linux/property.h>
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#include <linux/string.h>
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#include "gpiolib.h"
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#include "gpiolib-swnode.h"
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static void swnode_format_propname(const char *con_id, char *propname,
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size_t max_size)
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{
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/*
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* Note we do not need to try both -gpios and -gpio suffixes,
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* as, unlike OF and ACPI, we can fix software nodes to conform
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* to the proper binding.
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*/
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if (con_id)
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snprintf(propname, max_size, "%s-gpios", con_id);
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else
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strscpy(propname, "gpios", max_size);
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}
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static int swnode_gpiochip_match_name(struct gpio_chip *chip, void *data)
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{
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return !strcmp(chip->label, data);
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}
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static struct gpio_chip *swnode_get_chip(struct fwnode_handle *fwnode)
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{
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const struct software_node *chip_node;
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struct gpio_chip *chip;
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chip_node = to_software_node(fwnode);
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if (!chip_node || !chip_node->name)
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return ERR_PTR(-EINVAL);
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chip = gpiochip_find((void *)chip_node->name, swnode_gpiochip_match_name);
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return chip ?: ERR_PTR(-EPROBE_DEFER);
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}
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struct gpio_desc *swnode_find_gpio(struct fwnode_handle *fwnode,
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const char *con_id, unsigned int idx,
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unsigned long *flags)
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{
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const struct software_node *swnode;
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struct fwnode_reference_args args;
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struct gpio_chip *chip;
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struct gpio_desc *desc;
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char propname[32]; /* 32 is max size of property name */
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int error;
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swnode = to_software_node(fwnode);
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if (!swnode)
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return ERR_PTR(-EINVAL);
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swnode_format_propname(con_id, propname, sizeof(propname));
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/*
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* We expect all swnode-described GPIOs have GPIO number and
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* polarity arguments, hence nargs is set to 2.
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*/
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error = fwnode_property_get_reference_args(fwnode, propname, NULL, 2, idx, &args);
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if (error) {
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pr_debug("%s: can't parse '%s' property of node '%pfwP[%d]'\n",
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__func__, propname, fwnode, idx);
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return ERR_PTR(error);
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}
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chip = swnode_get_chip(args.fwnode);
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fwnode_handle_put(args.fwnode);
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if (IS_ERR(chip))
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return ERR_CAST(chip);
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desc = gpiochip_get_desc(chip, args.args[0]);
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*flags = args.args[1]; /* We expect native GPIO flags */
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pr_debug("%s: parsed '%s' property of node '%pfwP[%d]' - status (%d)\n",
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__func__, propname, fwnode, idx, PTR_ERR_OR_ZERO(desc));
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return desc;
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}
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/**
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* swnode_gpio_count - count the GPIOs associated with a device / function
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* @fwnode: firmware node of the GPIO consumer, can be %NULL for
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* system-global GPIOs
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* @con_id: function within the GPIO consumer
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*
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* Return:
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* The number of GPIOs associated with a device / function or %-ENOENT,
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* if no GPIO has been assigned to the requested function.
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*/
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int swnode_gpio_count(const struct fwnode_handle *fwnode, const char *con_id)
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{
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struct fwnode_reference_args args;
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char propname[32];
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int count;
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swnode_format_propname(con_id, propname, sizeof(propname));
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/*
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* This is not very efficient, but GPIO lists usually have only
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* 1 or 2 entries.
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*/
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count = 0;
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while (fwnode_property_get_reference_args(fwnode, propname, NULL, 0,
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count, &args) == 0) {
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fwnode_handle_put(args.fwnode);
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count++;
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}
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return count ?: -ENOENT;
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}
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