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![Benoit Parrot](/assets/img/avatar_default.png)
Based on Boris Brezillion's work this is a reworked patch of his initial GPIO hogging mechanism. This patch provides a way to initially configure specific GPIO when the GPIO controller is probed. The actual DT scanning to collect the GPIO specific data is performed as part of gpiochip_add(). The purpose of this is to allow specific GPIOs to be configured without any driver specific code. This is particularly useful because board design are getting increasingly complex and given SoC pins can now have more than 10 mux values, a lot of connections are now dependent on external IO muxes to switch various modes. Specific drivers should not necessarily need to be aware of what accounts to a specific board implementation. This board level "description" should be best kept as part of the dts file. Signed-off-by: Benoit Parrot <bparrot@ti.com> Reviewed-by: Alexandre Courbot <acourbot@nvidia.com> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
445 lines
11 KiB
C
445 lines
11 KiB
C
/*
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* OF helpers for the GPIO API
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*
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* Copyright (c) 2007-2008 MontaVista Software, Inc.
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*
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* Author: Anton Vorontsov <avorontsov@ru.mvista.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*/
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#include <linux/device.h>
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#include <linux/err.h>
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#include <linux/errno.h>
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#include <linux/module.h>
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#include <linux/io.h>
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#include <linux/gpio/consumer.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_gpio.h>
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#include <linux/pinctrl/pinctrl.h>
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#include <linux/slab.h>
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#include <linux/gpio/machine.h>
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#include "gpiolib.h"
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/* Private data structure for of_gpiochip_find_and_xlate */
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struct gg_data {
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enum of_gpio_flags *flags;
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struct of_phandle_args gpiospec;
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struct gpio_desc *out_gpio;
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};
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/* Private function for resolving node pointer to gpio_chip */
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static int of_gpiochip_find_and_xlate(struct gpio_chip *gc, void *data)
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{
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struct gg_data *gg_data = data;
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int ret;
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if ((gc->of_node != gg_data->gpiospec.np) ||
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(gc->of_gpio_n_cells != gg_data->gpiospec.args_count) ||
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(!gc->of_xlate))
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return false;
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ret = gc->of_xlate(gc, &gg_data->gpiospec, gg_data->flags);
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if (ret < 0) {
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/* We've found the gpio chip, but the translation failed.
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* Return true to stop looking and return the translation
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* error via out_gpio
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*/
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gg_data->out_gpio = ERR_PTR(ret);
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return true;
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}
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gg_data->out_gpio = gpiochip_get_desc(gc, ret);
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return true;
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}
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/**
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* of_get_named_gpiod_flags() - Get a GPIO descriptor and flags for GPIO API
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* @np: device node to get GPIO from
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* @propname: property name containing gpio specifier(s)
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* @index: index of the GPIO
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* @flags: a flags pointer to fill in
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*
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* Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
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* value on the error condition. If @flags is not NULL the function also fills
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* in flags for the GPIO.
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*/
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struct gpio_desc *of_get_named_gpiod_flags(struct device_node *np,
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const char *propname, int index, enum of_gpio_flags *flags)
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{
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/* Return -EPROBE_DEFER to support probe() functions to be called
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* later when the GPIO actually becomes available
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*/
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struct gg_data gg_data = {
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.flags = flags,
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.out_gpio = ERR_PTR(-EPROBE_DEFER)
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};
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int ret;
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/* .of_xlate might decide to not fill in the flags, so clear it. */
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if (flags)
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*flags = 0;
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ret = of_parse_phandle_with_args(np, propname, "#gpio-cells", index,
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&gg_data.gpiospec);
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if (ret) {
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pr_debug("%s: can't parse '%s' property of node '%s[%d]'\n",
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__func__, propname, np->full_name, index);
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return ERR_PTR(ret);
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}
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gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
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of_node_put(gg_data.gpiospec.np);
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pr_debug("%s: parsed '%s' property of node '%s[%d]' - status (%d)\n",
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__func__, propname, np->full_name, index,
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PTR_ERR_OR_ZERO(gg_data.out_gpio));
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return gg_data.out_gpio;
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}
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int of_get_named_gpio_flags(struct device_node *np, const char *list_name,
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int index, enum of_gpio_flags *flags)
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{
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struct gpio_desc *desc;
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desc = of_get_named_gpiod_flags(np, list_name, index, flags);
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if (IS_ERR(desc))
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return PTR_ERR(desc);
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else
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return desc_to_gpio(desc);
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}
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EXPORT_SYMBOL(of_get_named_gpio_flags);
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/**
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* of_get_gpio_hog() - Get a GPIO hog descriptor, names and flags for GPIO API
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* @np: device node to get GPIO from
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* @name: GPIO line name
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* @lflags: gpio_lookup_flags - returned from of_find_gpio() or
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* of_get_gpio_hog()
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* @dflags: gpiod_flags - optional GPIO initialization flags
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*
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* Returns GPIO descriptor to use with Linux GPIO API, or one of the errno
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* value on the error condition.
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*/
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static struct gpio_desc *of_get_gpio_hog(struct device_node *np,
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const char **name,
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enum gpio_lookup_flags *lflags,
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enum gpiod_flags *dflags)
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{
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struct device_node *chip_np;
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enum of_gpio_flags xlate_flags;
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struct gpio_desc *desc;
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struct gg_data gg_data = {
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.flags = &xlate_flags,
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};
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u32 tmp;
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int i, ret;
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chip_np = np->parent;
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if (!chip_np)
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return ERR_PTR(-EINVAL);
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xlate_flags = 0;
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*lflags = 0;
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*dflags = 0;
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ret = of_property_read_u32(chip_np, "#gpio-cells", &tmp);
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if (ret)
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return ERR_PTR(ret);
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if (tmp > MAX_PHANDLE_ARGS)
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return ERR_PTR(-EINVAL);
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gg_data.gpiospec.args_count = tmp;
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gg_data.gpiospec.np = chip_np;
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for (i = 0; i < tmp; i++) {
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ret = of_property_read_u32_index(np, "gpios", i,
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&gg_data.gpiospec.args[i]);
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if (ret)
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return ERR_PTR(ret);
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}
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gpiochip_find(&gg_data, of_gpiochip_find_and_xlate);
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if (!gg_data.out_gpio) {
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if (np->parent == np)
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return ERR_PTR(-ENXIO);
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else
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return ERR_PTR(-EINVAL);
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}
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if (xlate_flags & OF_GPIO_ACTIVE_LOW)
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*lflags |= GPIO_ACTIVE_LOW;
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if (of_property_read_bool(np, "input"))
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*dflags |= GPIOD_IN;
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else if (of_property_read_bool(np, "output-low"))
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*dflags |= GPIOD_OUT_LOW;
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else if (of_property_read_bool(np, "output-high"))
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*dflags |= GPIOD_OUT_HIGH;
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else {
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pr_warn("GPIO line %d (%s): no hogging state specified, bailing out\n",
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desc_to_gpio(gg_data.out_gpio), np->name);
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return ERR_PTR(-EINVAL);
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}
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if (name && of_property_read_string(np, "line-name", name))
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*name = np->name;
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desc = gg_data.out_gpio;
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return desc;
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}
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/**
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* of_gpiochip_scan_hogs - Scan gpio-controller and apply GPIO hog as requested
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* @chip: gpio chip to act on
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*
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* This is only used by of_gpiochip_add to request/set GPIO initial
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* configuration.
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*/
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static void of_gpiochip_scan_hogs(struct gpio_chip *chip)
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{
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struct gpio_desc *desc = NULL;
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struct device_node *np;
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const char *name;
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enum gpio_lookup_flags lflags;
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enum gpiod_flags dflags;
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for_each_child_of_node(chip->of_node, np) {
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if (!of_property_read_bool(np, "gpio-hog"))
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continue;
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desc = of_get_gpio_hog(np, &name, &lflags, &dflags);
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if (IS_ERR(desc))
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continue;
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if (gpiod_hog(desc, name, lflags, dflags))
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continue;
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}
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}
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/**
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* of_gpio_simple_xlate - translate gpio_spec to the GPIO number and flags
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* @gc: pointer to the gpio_chip structure
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* @np: device node of the GPIO chip
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* @gpio_spec: gpio specifier as found in the device tree
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* @flags: a flags pointer to fill in
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*
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* This is simple translation function, suitable for the most 1:1 mapped
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* gpio chips. This function performs only one sanity check: whether gpio
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* is less than ngpios (that is specified in the gpio_chip).
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*/
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int of_gpio_simple_xlate(struct gpio_chip *gc,
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const struct of_phandle_args *gpiospec, u32 *flags)
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{
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/*
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* We're discouraging gpio_cells < 2, since that way you'll have to
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* write your own xlate function (that will have to retrive the GPIO
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* number and the flags from a single gpio cell -- this is possible,
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* but not recommended).
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*/
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if (gc->of_gpio_n_cells < 2) {
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WARN_ON(1);
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return -EINVAL;
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}
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if (WARN_ON(gpiospec->args_count < gc->of_gpio_n_cells))
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return -EINVAL;
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if (gpiospec->args[0] >= gc->ngpio)
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return -EINVAL;
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if (flags)
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*flags = gpiospec->args[1];
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return gpiospec->args[0];
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}
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EXPORT_SYMBOL(of_gpio_simple_xlate);
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/**
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* of_mm_gpiochip_add - Add memory mapped GPIO chip (bank)
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* @np: device node of the GPIO chip
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* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
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*
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* To use this function you should allocate and fill mm_gc with:
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*
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* 1) In the gpio_chip structure:
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* - all the callbacks
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* - of_gpio_n_cells
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* - of_xlate callback (optional)
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*
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* 3) In the of_mm_gpio_chip structure:
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* - save_regs callback (optional)
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*
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* If succeeded, this function will map bank's memory and will
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* do all necessary work for you. Then you'll able to use .regs
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* to manage GPIOs from the callbacks.
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*/
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int of_mm_gpiochip_add(struct device_node *np,
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struct of_mm_gpio_chip *mm_gc)
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{
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int ret = -ENOMEM;
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struct gpio_chip *gc = &mm_gc->gc;
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gc->label = kstrdup(np->full_name, GFP_KERNEL);
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if (!gc->label)
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goto err0;
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mm_gc->regs = of_iomap(np, 0);
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if (!mm_gc->regs)
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goto err1;
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gc->base = -1;
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if (mm_gc->save_regs)
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mm_gc->save_regs(mm_gc);
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mm_gc->gc.of_node = np;
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ret = gpiochip_add(gc);
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if (ret)
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goto err2;
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return 0;
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err2:
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iounmap(mm_gc->regs);
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err1:
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kfree(gc->label);
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err0:
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pr_err("%s: GPIO chip registration failed with status %d\n",
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np->full_name, ret);
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return ret;
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}
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EXPORT_SYMBOL(of_mm_gpiochip_add);
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/**
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* of_mm_gpiochip_remove - Remove memory mapped GPIO chip (bank)
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* @mm_gc: pointer to the of_mm_gpio_chip allocated structure
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*/
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void of_mm_gpiochip_remove(struct of_mm_gpio_chip *mm_gc)
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{
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struct gpio_chip *gc = &mm_gc->gc;
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if (!mm_gc)
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return;
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gpiochip_remove(gc);
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iounmap(mm_gc->regs);
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kfree(gc->label);
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}
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EXPORT_SYMBOL(of_mm_gpiochip_remove);
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#ifdef CONFIG_PINCTRL
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static void of_gpiochip_add_pin_range(struct gpio_chip *chip)
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{
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struct device_node *np = chip->of_node;
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struct of_phandle_args pinspec;
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struct pinctrl_dev *pctldev;
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int index = 0, ret;
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const char *name;
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static const char group_names_propname[] = "gpio-ranges-group-names";
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struct property *group_names;
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if (!np)
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return;
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group_names = of_find_property(np, group_names_propname, NULL);
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for (;; index++) {
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ret = of_parse_phandle_with_fixed_args(np, "gpio-ranges", 3,
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index, &pinspec);
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if (ret)
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break;
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pctldev = of_pinctrl_get(pinspec.np);
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if (!pctldev)
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break;
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if (pinspec.args[2]) {
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if (group_names) {
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ret = of_property_read_string_index(np,
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group_names_propname,
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index, &name);
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if (strlen(name)) {
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pr_err("%s: Group name of numeric GPIO ranges must be the empty string.\n",
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np->full_name);
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break;
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}
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}
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/* npins != 0: linear range */
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ret = gpiochip_add_pin_range(chip,
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pinctrl_dev_get_devname(pctldev),
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pinspec.args[0],
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pinspec.args[1],
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pinspec.args[2]);
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if (ret)
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break;
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} else {
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/* npins == 0: special range */
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if (pinspec.args[1]) {
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pr_err("%s: Illegal gpio-range format.\n",
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np->full_name);
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break;
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}
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if (!group_names) {
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pr_err("%s: GPIO group range requested but no %s property.\n",
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np->full_name, group_names_propname);
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break;
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}
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ret = of_property_read_string_index(np,
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group_names_propname,
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index, &name);
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if (ret)
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break;
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if (!strlen(name)) {
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pr_err("%s: Group name of GPIO group range cannot be the empty string.\n",
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np->full_name);
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break;
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}
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ret = gpiochip_add_pingroup_range(chip, pctldev,
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pinspec.args[0], name);
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if (ret)
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break;
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}
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}
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}
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#else
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static void of_gpiochip_add_pin_range(struct gpio_chip *chip) {}
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#endif
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void of_gpiochip_add(struct gpio_chip *chip)
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{
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if ((!chip->of_node) && (chip->dev))
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chip->of_node = chip->dev->of_node;
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if (!chip->of_node)
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return;
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if (!chip->of_xlate) {
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chip->of_gpio_n_cells = 2;
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chip->of_xlate = of_gpio_simple_xlate;
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}
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of_gpiochip_add_pin_range(chip);
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of_node_get(chip->of_node);
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of_gpiochip_scan_hogs(chip);
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}
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void of_gpiochip_remove(struct gpio_chip *chip)
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{
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gpiochip_remove_pin_ranges(chip);
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of_node_put(chip->of_node);
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}
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