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a19e3da5bc
The OF gpio infrastructure is great for describing GPIO connections within the device tree. However, using a GPIO binding still requires changes to the gpio controller just to add an of_gpio structure. In most cases, the gpio controller doesn't actually need any special support and the simple OF gpio mapping function is more than sufficient. Additional, the current scheme of using of_gpio_chip requires a convoluted scheme to maintain 1:1 mappings between of_gpio_chip and gpio_chip instances. If the struct of_gpio_chip data members were moved into struct gpio_chip, then it would simplify the processing of OF gpio bindings, and it would make it trivial to use device tree OF connections on existing gpiolib controller drivers. This patch eliminates the of_gpio_chip structure and moves the relevant fields into struct gpio_chip (conditional on CONFIG_OF_GPIO). This move simplifies the existing code and prepares for adding automatic device tree support to existing drivers. Signed-off-by: Grant Likely <grant.likely@secretlab.ca> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Anton Vorontsov <avorontsov@ru.mvista.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: David Brownell <dbrownell@users.sourceforge.net> Cc: Bill Gatliff <bgat@billgatliff.com> Cc: Dmitry Eremin-Solenikov <dbaryshkov@gmail.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Jean Delvare <khali@linux-fr.org>
155 lines
3.3 KiB
C
155 lines
3.3 KiB
C
/*
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* Simple Memory-Mapped GPIOs
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*
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* Copyright (c) MontaVista Software, Inc. 2008.
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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 it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation; either version 2 of the License, or (at your
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* option) any later version.
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*/
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/spinlock.h>
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#include <linux/types.h>
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#include <linux/ioport.h>
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#include <linux/io.h>
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#include <linux/of.h>
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#include <linux/of_gpio.h>
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#include <linux/gpio.h>
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#include <linux/slab.h>
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#include <asm/prom.h>
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#include "simple_gpio.h"
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struct u8_gpio_chip {
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struct of_mm_gpio_chip mm_gc;
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spinlock_t lock;
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/* shadowed data register to clear/set bits safely */
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u8 data;
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};
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static struct u8_gpio_chip *to_u8_gpio_chip(struct of_mm_gpio_chip *mm_gc)
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{
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return container_of(mm_gc, struct u8_gpio_chip, mm_gc);
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}
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static u8 u8_pin2mask(unsigned int pin)
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{
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return 1 << (8 - 1 - pin);
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}
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static int u8_gpio_get(struct gpio_chip *gc, unsigned int gpio)
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{
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struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
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return in_8(mm_gc->regs) & u8_pin2mask(gpio);
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}
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static void u8_gpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
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{
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struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
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struct u8_gpio_chip *u8_gc = to_u8_gpio_chip(mm_gc);
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unsigned long flags;
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spin_lock_irqsave(&u8_gc->lock, flags);
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if (val)
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u8_gc->data |= u8_pin2mask(gpio);
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else
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u8_gc->data &= ~u8_pin2mask(gpio);
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out_8(mm_gc->regs, u8_gc->data);
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spin_unlock_irqrestore(&u8_gc->lock, flags);
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}
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static int u8_gpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
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{
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return 0;
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}
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static int u8_gpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
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{
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u8_gpio_set(gc, gpio, val);
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return 0;
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}
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static void u8_gpio_save_regs(struct of_mm_gpio_chip *mm_gc)
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{
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struct u8_gpio_chip *u8_gc = to_u8_gpio_chip(mm_gc);
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u8_gc->data = in_8(mm_gc->regs);
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}
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static int __init u8_simple_gpiochip_add(struct device_node *np)
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{
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int ret;
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struct u8_gpio_chip *u8_gc;
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struct of_mm_gpio_chip *mm_gc;
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struct gpio_chip *gc;
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u8_gc = kzalloc(sizeof(*u8_gc), GFP_KERNEL);
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if (!u8_gc)
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return -ENOMEM;
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spin_lock_init(&u8_gc->lock);
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mm_gc = &u8_gc->mm_gc;
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gc = &mm_gc->gc;
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mm_gc->save_regs = u8_gpio_save_regs;
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gc->of_gpio_n_cells = 2;
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gc->ngpio = 8;
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gc->direction_input = u8_gpio_dir_in;
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gc->direction_output = u8_gpio_dir_out;
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gc->get = u8_gpio_get;
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gc->set = u8_gpio_set;
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ret = of_mm_gpiochip_add(np, mm_gc);
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if (ret)
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goto err;
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return 0;
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err:
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kfree(u8_gc);
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return ret;
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}
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void __init simple_gpiochip_init(const char *compatible)
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{
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struct device_node *np;
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for_each_compatible_node(np, NULL, compatible) {
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int ret;
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struct resource r;
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ret = of_address_to_resource(np, 0, &r);
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if (ret)
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goto err;
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switch (resource_size(&r)) {
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case 1:
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ret = u8_simple_gpiochip_add(np);
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if (ret)
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goto err;
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break;
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default:
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/*
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* Whenever you need support for GPIO bank width > 1,
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* please just turn u8_ code into huge macros, and
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* construct needed uX_ code with it.
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*/
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ret = -ENOSYS;
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goto err;
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}
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continue;
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err:
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pr_err("%s: registration failed, status %d\n",
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np->full_name, ret);
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}
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}
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