298 lines
8.0 KiB
C
298 lines
8.0 KiB
C
/*
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* Driver for basic memory-mapped GPIO controllers.
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*
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* Copyright 2008 MontaVista Software, Inc.
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* Copyright 2008,2010 Anton Vorontsov <cbouatmailru@gmail.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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* ....``.```~~~~````.`.`.`.`.```````'',,,.........`````......`.......
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* ...`` ```````..
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* ..The simplest form of a GPIO controller that the driver supports is``
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* `.just a single "data" register, where GPIO state can be read and/or `
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* `,..written. ,,..``~~~~ .....``.`.`.~~.```.`.........``````.```````
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* `````````
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___
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_/~~|___/~| . ```~~~~~~ ___/___\___ ,~.`.`.`.`````.~~...,,,,...
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__________|~$@~~~ %~ /o*o*o*o*o*o\ .. Implementing such a GPIO .
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o ` ~~~~\___/~~~~ ` controller in FPGA is ,.`
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`....trivial..'~`.```.```
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* ```````
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* .```````~~~~`..`.``.``.
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* . The driver supports `... ,..```.`~~~```````````````....````.``,,
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* . big-endian notation, just`. .. A bit more sophisticated controllers ,
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* . register the device with -be`. .with a pair of set/clear-bit registers ,
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* `.. suffix. ```~~`````....`.` . affecting the data register and the .`
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* ``.`.``...``` ```.. output pins are also supported.`
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* ^^ `````.`````````.,``~``~``~~``````
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* . ^^
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* ,..`.`.`...````````````......`.`.`.`.`.`..`.`.`..
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* .. The expectation is that in at least some cases . ,-~~~-,
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* .this will be used with roll-your-own ASIC/FPGA .` \ /
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* .logic in Verilog or VHDL. ~~~`````````..`````~~` \ /
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* ..````````......``````````` \o_
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* |
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* ^^ / \
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*
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* ...`````~~`.....``.`..........``````.`.``.```........``.
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* ` 8, 16, 32 and 64 bits registers are supported, and``.
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* . the number of GPIOs is determined by the width of ~
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* .. the registers. ,............```.`.`..`.`.~~~.`.`.`~
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* `.......````.```
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*/
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#include <linux/init.h>
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#include <linux/bug.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/compiler.h>
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#include <linux/types.h>
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#include <linux/errno.h>
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#include <linux/log2.h>
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#include <linux/ioport.h>
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#include <linux/io.h>
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#include <linux/gpio.h>
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#include <linux/slab.h>
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#include <linux/platform_device.h>
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#include <linux/mod_devicetable.h>
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#include <linux/basic_mmio_gpio.h>
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struct bgpio_chip {
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struct gpio_chip gc;
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void __iomem *reg_dat;
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void __iomem *reg_set;
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void __iomem *reg_clr;
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/* Number of bits (GPIOs): <register width> * 8. */
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int bits;
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/*
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* Some GPIO controllers work with the big-endian bits notation,
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* e.g. in a 8-bits register, GPIO7 is the least significant bit.
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*/
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int big_endian_bits;
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/*
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* Used to lock bgpio_chip->data. Also, this is needed to keep
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* shadowed and real data registers writes together.
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*/
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spinlock_t lock;
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/* Shadowed data register to clear/set bits safely. */
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unsigned long data;
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};
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static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
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{
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return container_of(gc, struct bgpio_chip, gc);
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}
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static unsigned long bgpio_in(struct bgpio_chip *bgc)
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{
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switch (bgc->bits) {
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case 8:
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return __raw_readb(bgc->reg_dat);
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case 16:
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return __raw_readw(bgc->reg_dat);
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case 32:
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return __raw_readl(bgc->reg_dat);
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#if BITS_PER_LONG >= 64
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case 64:
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return __raw_readq(bgc->reg_dat);
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#endif
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}
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return -EINVAL;
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}
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static void bgpio_out(struct bgpio_chip *bgc, void __iomem *reg,
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unsigned long data)
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{
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switch (bgc->bits) {
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case 8:
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__raw_writeb(data, reg);
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return;
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case 16:
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__raw_writew(data, reg);
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return;
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case 32:
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__raw_writel(data, reg);
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return;
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#if BITS_PER_LONG >= 64
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case 64:
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__raw_writeq(data, reg);
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return;
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#endif
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}
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}
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static unsigned long bgpio_pin2mask(struct bgpio_chip *bgc, unsigned int pin)
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{
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if (bgc->big_endian_bits)
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return 1 << (bgc->bits - 1 - pin);
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else
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return 1 << pin;
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}
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static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
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{
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struct bgpio_chip *bgc = to_bgpio_chip(gc);
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return bgpio_in(bgc) & bgpio_pin2mask(bgc, gpio);
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}
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static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
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{
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struct bgpio_chip *bgc = to_bgpio_chip(gc);
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unsigned long mask = bgpio_pin2mask(bgc, gpio);
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unsigned long flags;
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if (bgc->reg_set) {
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if (val)
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bgpio_out(bgc, bgc->reg_set, mask);
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else
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bgpio_out(bgc, bgc->reg_clr, mask);
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return;
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}
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spin_lock_irqsave(&bgc->lock, flags);
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if (val)
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bgc->data |= mask;
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else
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bgc->data &= ~mask;
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bgpio_out(bgc, bgc->reg_dat, bgc->data);
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spin_unlock_irqrestore(&bgc->lock, flags);
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}
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static int bgpio_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 bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
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{
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bgpio_set(gc, gpio, val);
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return 0;
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}
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static int __devinit bgpio_probe(struct platform_device *pdev)
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{
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const struct platform_device_id *platid = platform_get_device_id(pdev);
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struct device *dev = &pdev->dev;
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struct bgpio_pdata *pdata = dev_get_platdata(dev);
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struct bgpio_chip *bgc;
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struct resource *res_dat;
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struct resource *res_set;
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struct resource *res_clr;
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resource_size_t dat_sz;
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int bits;
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int ret;
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res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
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if (!res_dat)
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return -EINVAL;
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dat_sz = resource_size(res_dat);
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if (!is_power_of_2(dat_sz))
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return -EINVAL;
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bits = dat_sz * 8;
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if (bits > BITS_PER_LONG)
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return -EINVAL;
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bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
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if (!bgc)
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return -ENOMEM;
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bgc->reg_dat = devm_ioremap(dev, res_dat->start, dat_sz);
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if (!bgc->reg_dat)
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return -ENOMEM;
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res_set = platform_get_resource_byname(pdev, IORESOURCE_MEM, "set");
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res_clr = platform_get_resource_byname(pdev, IORESOURCE_MEM, "clr");
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if (res_set && res_clr) {
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if (resource_size(res_set) != resource_size(res_clr) ||
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resource_size(res_set) != dat_sz)
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return -EINVAL;
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bgc->reg_set = devm_ioremap(dev, res_set->start, dat_sz);
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bgc->reg_clr = devm_ioremap(dev, res_clr->start, dat_sz);
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if (!bgc->reg_set || !bgc->reg_clr)
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return -ENOMEM;
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} else if (res_set || res_clr) {
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return -EINVAL;
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}
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spin_lock_init(&bgc->lock);
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bgc->bits = bits;
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bgc->big_endian_bits = !strcmp(platid->name, "basic-mmio-gpio-be");
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bgc->data = bgpio_in(bgc);
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bgc->gc.ngpio = bits;
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bgc->gc.direction_input = bgpio_dir_in;
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bgc->gc.direction_output = bgpio_dir_out;
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bgc->gc.get = bgpio_get;
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bgc->gc.set = bgpio_set;
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bgc->gc.dev = dev;
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bgc->gc.label = dev_name(dev);
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if (pdata)
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bgc->gc.base = pdata->base;
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else
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bgc->gc.base = -1;
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dev_set_drvdata(dev, bgc);
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ret = gpiochip_add(&bgc->gc);
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if (ret)
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dev_err(dev, "gpiochip_add() failed: %d\n", ret);
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return ret;
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}
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static int __devexit bgpio_remove(struct platform_device *pdev)
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{
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struct bgpio_chip *bgc = dev_get_drvdata(&pdev->dev);
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return gpiochip_remove(&bgc->gc);
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}
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static const struct platform_device_id bgpio_id_table[] = {
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{ "basic-mmio-gpio", },
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{ "basic-mmio-gpio-be", },
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{},
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};
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MODULE_DEVICE_TABLE(platform, bgpio_id_table);
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static struct platform_driver bgpio_driver = {
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.driver = {
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.name = "basic-mmio-gpio",
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},
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.id_table = bgpio_id_table,
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.probe = bgpio_probe,
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.remove = __devexit_p(bgpio_remove),
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};
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static int __init bgpio_init(void)
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{
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return platform_driver_register(&bgpio_driver);
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}
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module_init(bgpio_init);
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static void __exit bgpio_exit(void)
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{
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platform_driver_unregister(&bgpio_driver);
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}
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module_exit(bgpio_exit);
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MODULE_DESCRIPTION("Driver for basic memory-mapped GPIO controllers");
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MODULE_AUTHOR("Anton Vorontsov <cbouatmailru@gmail.com>");
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MODULE_LICENSE("GPL");
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