path: root/drivers/pinctrl/pinmux.c

/*
 * Core driver for the pin muxing portions of the pin control subsystem
 *
 * Copyright (C) 2011 ST-Ericsson SA
 * Written on behalf of Linaro for ST-Ericsson
 * Based on bits of regulator core, gpio core and clk core
 *
 * Author: Linus Walleij <linus.walleij@linaro.org>
 *
 * License terms: GNU General Public License (GPL) version 2
 */
#define pr_fmt(fmt) "pinmux core: " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/radix-tree.h>
#include <linux/err.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/spinlock.h>
#include <linux/string.h>
#include <linux/sysfs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/pinctrl/machine.h>
#include <linux/pinctrl/pinmux.h>
#include "core.h"

/* List of pinmuxes */
static DEFINE_MUTEX(pinmux_list_mutex);
static LIST_HEAD(pinmux_list);

/* Global pinmux maps */
static struct pinmux_map *pinmux_maps;
static unsigned pinmux_maps_num;

/**
 * struct pinmux_group - group list item for pinmux groups
 * @node: pinmux group list node
 * @group_selector: the group selector for this group
 */
struct pinmux_group {
	struct list_head node;
	unsigned group_selector;
};

/**
 * struct pinmux - per-device pinmux state holder
 * @node: global list node
 * @dev: the device using this pinmux
 * @usecount: the number of active users of this mux setting, used to keep
 *	track of nested use cases
 * @pctldev: pin control device handling this pinmux
 * @func_selector: the function selector for the pinmux device handling
 *	this pinmux
 * @groups: the group selectors for the pinmux device and
 *	selector combination handling this pinmux, this is a list that
 *	will be traversed on all pinmux operations such as
 *	get/put/enable/disable
 * @mutex: a lock for the pinmux state holder
 */
struct pinmux {
	struct list_head node;
	struct device *dev;
	unsigned usecount;
	struct pinctrl_dev *pctldev;
	unsigned func_selector;
	struct list_head groups;
	struct mutex mutex;
};

/**
 * struct pinmux_hog - a list item to stash mux hogs
 * @node: pinmux hog list node
 * @map: map entry responsible for this hogging
 * @pmx: the pinmux hogged by this item
 */
struct pinmux_hog {
	struct list_head node;
	struct pinmux_map const *map;
	struct pinmux *pmx;
};

/**
 * pin_request() - request a single pin to be muxed in, typically for GPIO
 * @pin: the pin number in the global pin space
 * @function: a functional name to give to this pin, passed to the driver
 *	so it knows what function to mux in, e.g. the string "gpioNN"
 *	means that you want to mux in the pin for use as GPIO number NN
 * @gpio_range: the range matching the GPIO pin if this is a request for a
 *	single GPIO pin
 */
static int pin_request(struct pinctrl_dev *pctldev,
		       int pin, const char *function,
		       struct pinctrl_gpio_range *gpio_range)
{
	struct pin_desc *desc;
	const struct pinmux_ops *ops = pctldev->desc->pmxops;
	int status = -EINVAL;

	dev_dbg(pctldev->dev, "request pin %d for %s\n", pin, function);

	desc = pin_desc_get(pctldev, pin);
	if (desc == NULL) {
		dev_err(pctldev->dev,
			"pin is not registered so it cannot be requested\n");
		goto out;
	}

	if (!function) {
		dev_err(pctldev->dev, "no function name given\n");
		return -EINVAL;
	}

	spin_lock(&desc->lock);
	if (desc->mux_function) {
		spin_unlock(&desc->lock);
		dev_err(pctldev->dev,
			"pin already requested\n");
		goto out;
	}