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linux/drivers/gpio/basic_mmio_gpio.c

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/*
* Driver for basic memory-mapped GPIO controllers.
*
* Copyright 2008 MontaVista Software, Inc.
* Copyright 2008,2010 Anton Vorontsov <cbouatmailru@gmail.com>
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License as published by the
* Free Software Foundation; either version 2 of the License, or (at your
* option) any later version.
*
* ....``.```~~~~````.`.`.`.`.```````'',,,.........`````......`.......
* ...`` ```````..
* ..The simplest form of a GPIO controller that the driver supports is``
* `.just a single "data" register, where GPIO state can be read and/or `
* `,..written. ,,..``~~~~ .....``.`.`.~~.```.`.........``````.```````
* `````````
___
_/~~|___/~| . ```~~~~~~ ___/___\___ ,~.`.`.`.`````.~~...,,,,...
__________|~$@~~~ %~ /o*o*o*o*o*o\ .. Implementing such a GPIO .
o ` ~~~~\___/~~~~ ` controller in FPGA is ,.`
`....trivial..'~`.```.```
* ```````
* .```````~~~~`..`.``.``.
* . The driver supports `... ,..```.`~~~```````````````....````.``,,
* . big-endian notation, just`. .. A bit more sophisticated controllers ,
* . register the device with -be`. .with a pair of set/clear-bit registers ,
* `.. suffix. ```~~`````....`.` . affecting the data register and the .`
* ``.`.``...``` ```.. output pins are also supported.`
* ^^ `````.`````````.,``~``~``~~``````
* . ^^
* ,..`.`.`...````````````......`.`.`.`.`.`..`.`.`..
* .. The expectation is that in at least some cases . ,-~~~-,
* .this will be used with roll-your-own ASIC/FPGA .` \ /
* .logic in Verilog or VHDL. ~~~`````````..`````~~` \ /
* ..````````......``````````` \o_
* |
* ^^ / \
*
* ...`````~~`.....``.`..........``````.`.``.```........``.
* ` 8, 16, 32 and 64 bits registers are supported, and``.
* . the number of GPIOs is determined by the width of ~
* .. the registers. ,............```.`.`..`.`.~~~.`.`.`~
* `.......````.```
*/
#include <linux/init.h>
#include <linux/bug.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/spinlock.h>
#include <linux/compiler.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/log2.h>
#include <linux/ioport.h>
#include <linux/io.h>
#include <linux/gpio.h>
#include <linux/slab.h>
#include <linux/platform_device.h>
#include <linux/mod_devicetable.h>
#include <linux/basic_mmio_gpio.h>
struct bgpio_chip {
struct gpio_chip gc;
void __iomem *reg_dat;
void __iomem *reg_set;
void __iomem *reg_clr;
/* Number of bits (GPIOs): <register width> * 8. */
int bits;
/*
* Some GPIO controllers work with the big-endian bits notation,
* e.g. in a 8-bits register, GPIO7 is the least significant bit.
*/
int big_endian_bits;
/*
* Used to lock bgpio_chip->data. Also, this is needed to keep
* shadowed and real data registers writes together.
*/
spinlock_t lock;
/* Shadowed data register to clear/set bits safely. */
unsigned long data;
};
static struct bgpio_chip *to_bgpio_chip(struct gpio_chip *gc)
{
return container_of(gc, struct bgpio_chip, gc);
}
static unsigned long bgpio_in(struct bgpio_chip *bgc)
{
switch (bgc->bits) {
case 8:
return __raw_readb(bgc->reg_dat);
case 16:
return __raw_readw(bgc->reg_dat);
case 32:
return __raw_readl(bgc->reg_dat);
#if BITS_PER_LONG >= 64
case 64:
return __raw_readq(bgc->reg_dat);
#endif
}
return -EINVAL;
}
static void bgpio_out(struct bgpio_chip *bgc, void __iomem *reg,
unsigned long data)
{
switch (bgc->bits) {
case 8:
__raw_writeb(data, reg);
return;
case 16:
__raw_writew(data, reg);
return;
case 32:
__raw_writel(data, reg);
return;
#if BITS_PER_LONG >= 64
case 64:
__raw_writeq(data, reg);
return;
#endif
}
}
static unsigned long bgpio_pin2mask(struct bgpio_chip *bgc, unsigned int pin)
{
if (bgc->big_endian_bits)
return 1 << (bgc->bits - 1 - pin);
else
return 1 << pin;
}
static int bgpio_get(struct gpio_chip *gc, unsigned int gpio)
{
struct bgpio_chip *bgc = to_bgpio_chip(gc);
return bgpio_in(bgc) & bgpio_pin2mask(bgc, gpio);
}
static void bgpio_set(struct gpio_chip *gc, unsigned int gpio, int val)
{
struct bgpio_chip *bgc = to_bgpio_chip(gc);
unsigned long mask = bgpio_pin2mask(bgc, gpio);
unsigned long flags;
if (bgc->reg_set) {
if (val)
bgpio_out(bgc, bgc->reg_set, mask);
else
bgpio_out(bgc, bgc->reg_clr, mask);
return;
}
spin_lock_irqsave(&bgc->lock, flags);
if (val)
bgc->data |= mask;
else
bgc->data &= ~mask;
bgpio_out(bgc, bgc->reg_dat, bgc->data);
spin_unlock_irqrestore(&bgc->lock, flags);
}
static int bgpio_dir_in(struct gpio_chip *gc, unsigned int gpio)
{
return 0;
}
static int bgpio_dir_out(struct gpio_chip *gc, unsigned int gpio, int val)
{
bgpio_set(gc, gpio, val);
return 0;
}
static int __devinit bgpio_probe(struct platform_device *pdev)
{
const struct platform_device_id *platid = platform_get_device_id(pdev);
struct device *dev = &pdev->dev;
struct bgpio_pdata *pdata = dev_get_platdata(dev);
struct bgpio_chip *bgc;
struct resource *res_dat;
struct resource *res_set;
struct resource *res_clr;
resource_size_t dat_sz;
int bits;
int ret;
res_dat = platform_get_resource_byname(pdev, IORESOURCE_MEM, "dat");
if (!res_dat)
return -EINVAL;
dat_sz = resource_size(res_dat);
if (!is_power_of_2(dat_sz))
return -EINVAL;
bits = dat_sz * 8;
if (bits > BITS_PER_LONG)
return -EINVAL;
bgc = devm_kzalloc(dev, sizeof(*bgc), GFP_KERNEL);
if (!bgc)
return -ENOMEM;
bgc->reg_dat = devm_ioremap(dev, res_dat->start, dat_sz);
if (!bgc->reg_dat)
return -ENOMEM;
res_set = platform_get_resource_byname(pdev, IORESOURCE_MEM, "set");
res_clr = platform_get_resource_byname(pdev, IORESOURCE_MEM, "clr");
if (res_set && res_clr) {
if (resource_size(res_set) != resource_size(res_clr) ||
resource_size(res_set) != dat_sz)
return -EINVAL;
bgc->reg_set = devm_ioremap(dev, res_set->start, dat_sz);
bgc->reg_clr = devm_ioremap(dev, res_clr->start, dat_sz);
if (!bgc->reg_set || !bgc->reg_clr)
return -ENOMEM;
} else if (res_set || res_clr) {
return -EINVAL;
}
spin_lock_init(&bgc->lock);
bgc->bits = bits;
bgc->big_endian_bits = !strcmp(platid->name, "basic-mmio-gpio-be");
bgc->data = bgpio_in(bgc);
bgc->gc.ngpio = bits;
bgc->gc.direction_input = bgpio_dir_in;
bgc->gc.direction_output = bgpio_dir_out;
bgc->gc.get = bgpio_get;
bgc->gc.set = bgpio_set;
bgc->gc.dev = dev;
bgc->gc.label = dev_name(dev);
if (pdata)
bgc->gc.base = pdata->base;
else
bgc->gc.base = -1;
dev_set_drvdata(dev, bgc);
ret = gpiochip_add(&bgc->gc);
if (ret)
dev_err(dev, "gpiochip_add() failed: %d\n", ret);
return ret;
}
static int __devexit bgpio_remove(struct platform_device *pdev)
{
struct bgpio_chip *bgc = dev_get_drvdata(&pdev->dev);
return gpiochip_remove(&bgc->gc);
}
static const struct platform_device_id bgpio_id_table[] = {
{ "basic-mmio-gpio", },
{ "basic-mmio-gpio-be", },
{},
};
MODULE_DEVICE_TABLE(platform, bgpio_id_table);
static struct platform_driver bgpio_driver = {
.driver = {
.name = "basic-mmio-gpio",
},
.id_table = bgpio_id_table,
.probe = bgpio_probe,
.remove = __devexit_p(bgpio_remove),
};
static int __init bgpio_init(void)
{
return platform_driver_register(&bgpio_driver);
}
module_init(bgpio_init);
static void __exit bgpio_exit(void)
{
platform_driver_unregister(&bgpio_driver);
}
module_exit(bgpio_exit);
MODULE_DESCRIPTION("Driver for basic memory-mapped GPIO controllers");
MODULE_AUTHOR("Anton Vorontsov <cbouatmailru@gmail.com>");
MODULE_LICENSE("GPL");
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