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linux/drivers/gpio/gpio-gpio-mm.c
William Breathitt Gray 6ea5dcdf79 gpio: Add GPIO support for the Diamond Systems GPIO-MM 
The Diamond Systems GPIO-MM device features 48 lines of digital I/O via
the emulation of dual 82C55A PPI chips. This driver provides GPIO
support for these 48 channels of digital I/O. The base port addresses
for the devices may be configured via the base array module parameter.

Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2016-08-11 13:37:25 +02:00

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/*
* GPIO driver for the Diamond Systems GPIO-MM
* Copyright (C) 2016 William Breathitt Gray
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License, version 2, as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* This driver supports the following Diamond Systems devices: GPIO-MM and
* GPIO-MM-12.
*/
#include <linux/bitops.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/gpio/driver.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/isa.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/spinlock.h>
#define GPIOMM_EXTENT 8
#define MAX_NUM_GPIOMM max_num_isa_dev(GPIOMM_EXTENT)
static unsigned int base[MAX_NUM_GPIOMM];
static unsigned int num_gpiomm;
module_param_array(base, uint, &num_gpiomm, 0);
MODULE_PARM_DESC(base, "Diamond Systems GPIO-MM base addresses");
/**
* struct gpiomm_gpio - GPIO device private data structure
* @chip: instance of the gpio_chip
* @io_state: bit I/O state (whether bit is set to input or output)
* @out_state: output bits state
* @control: Control registers state
* @lock: synchronization lock to prevent I/O race conditions
* @base: base port address of the GPIO device
*/
struct gpiomm_gpio {
struct gpio_chip chip;
unsigned char io_state[6];
unsigned char out_state[6];
unsigned char control[2];
spinlock_t lock;
unsigned int base;
};
static int gpiomm_gpio_get_direction(struct gpio_chip *chip,
unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
const unsigned int port = offset / 8;
const unsigned int mask = BIT(offset % 8);
return !!(gpiommgpio->io_state[port] & mask);
}
static int gpiomm_gpio_direction_input(struct gpio_chip *chip,
unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
const unsigned int io_port = offset / 8;
const unsigned int control_port = io_port / 3;
const unsigned int control_addr = gpiommgpio->base + 3 + control_port*4;
unsigned long flags;
unsigned int control;
spin_lock_irqsave(&gpiommgpio->lock, flags);
/* Check if configuring Port C */
if (io_port == 2 || io_port == 5) {
/* Port C can be configured by nibble */
if (offset % 8 > 3) {
gpiommgpio->io_state[io_port] |= 0xF0;
gpiommgpio->control[control_port] |= BIT(3);
} else {
gpiommgpio->io_state[io_port] |= 0x0F;
gpiommgpio->control[control_port] |= BIT(0);
}
} else {
gpiommgpio->io_state[io_port] |= 0xFF;
if (io_port == 0 || io_port == 3)
gpiommgpio->control[control_port] |= BIT(4);
else
gpiommgpio->control[control_port] |= BIT(1);
}
control = BIT(7) | gpiommgpio->control[control_port];
outb(control, control_addr);
spin_unlock_irqrestore(&gpiommgpio->lock, flags);
return 0;
}
static int gpiomm_gpio_direction_output(struct gpio_chip *chip,
unsigned int offset, int value)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
const unsigned int io_port = offset / 8;
const unsigned int control_port = io_port / 3;
const unsigned int mask = BIT(offset % 8);
const unsigned int control_addr = gpiommgpio->base + 3 + control_port*4;
const unsigned int out_port = (io_port > 2) ? io_port + 1 : io_port;
unsigned long flags;
unsigned int control;
spin_lock_irqsave(&gpiommgpio->lock, flags);
/* Check if configuring Port C */
if (io_port == 2 || io_port == 5) {
/* Port C can be configured by nibble */
if (offset % 8 > 3) {
gpiommgpio->io_state[io_port] &= 0x0F;
gpiommgpio->control[control_port] &= ~BIT(3);
} else {
gpiommgpio->io_state[io_port] &= 0xF0;
gpiommgpio->control[control_port] &= ~BIT(0);
}
} else {
gpiommgpio->io_state[io_port] &= 0x00;
if (io_port == 0 || io_port == 3)
gpiommgpio->control[control_port] &= ~BIT(4);
else
gpiommgpio->control[control_port] &= ~BIT(1);
}
if (value)
gpiommgpio->out_state[io_port] |= mask;
else
gpiommgpio->out_state[io_port] &= ~mask;
control = BIT(7) | gpiommgpio->control[control_port];
outb(control, control_addr);
outb(gpiommgpio->out_state[io_port], gpiommgpio->base + out_port);
spin_unlock_irqrestore(&gpiommgpio->lock, flags);
return 0;
}
static int gpiomm_gpio_get(struct gpio_chip *chip, unsigned int offset)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
const unsigned int port = offset / 8;
const unsigned int mask = BIT(offset % 8);
const unsigned int in_port = (port > 2) ? port + 1 : port;
unsigned long flags;
unsigned int port_state;
spin_lock_irqsave(&gpiommgpio->lock, flags);
/* ensure that GPIO is set for input */
if (!(gpiommgpio->io_state[port] & mask)) {
spin_unlock_irqrestore(&gpiommgpio->lock, flags);
return -EINVAL;
}
port_state = inb(gpiommgpio->base + in_port);
spin_unlock_irqrestore(&gpiommgpio->lock, flags);
return !!(port_state & mask);
}
static void gpiomm_gpio_set(struct gpio_chip *chip, unsigned int offset,
int value)
{
struct gpiomm_gpio *const gpiommgpio = gpiochip_get_data(chip);
const unsigned int port = offset / 8;
const unsigned int mask = BIT(offset % 8);
const unsigned int out_port = (port > 2) ? port + 1 : port;
unsigned long flags;
spin_lock_irqsave(&gpiommgpio->lock, flags);
if (value)
gpiommgpio->out_state[port] |= mask;
else
gpiommgpio->out_state[port] &= ~mask;
outb(gpiommgpio->out_state[port], gpiommgpio->base + out_port);
spin_unlock_irqrestore(&gpiommgpio->lock, flags);
}
static int gpiomm_probe(struct device *dev, unsigned int id)
{
struct gpiomm_gpio *gpiommgpio;
const char *const name = dev_name(dev);
int err;
gpiommgpio = devm_kzalloc(dev, sizeof(*gpiommgpio), GFP_KERNEL);
if (!gpiommgpio)
return -ENOMEM;
if (!devm_request_region(dev, base[id], GPIOMM_EXTENT, name)) {
dev_err(dev, "Unable to lock port addresses (0x%X-0x%X)\n",
base[id], base[id] + GPIOMM_EXTENT);
return -EBUSY;
}
gpiommgpio->chip.label = name;
gpiommgpio->chip.parent = dev;
gpiommgpio->chip.owner = THIS_MODULE;
gpiommgpio->chip.base = -1;
gpiommgpio->chip.ngpio = 48;
gpiommgpio->chip.get_direction = gpiomm_gpio_get_direction;
gpiommgpio->chip.direction_input = gpiomm_gpio_direction_input;
gpiommgpio->chip.direction_output = gpiomm_gpio_direction_output;
gpiommgpio->chip.get = gpiomm_gpio_get;
gpiommgpio->chip.set = gpiomm_gpio_set;
gpiommgpio->base = base[id];
spin_lock_init(&gpiommgpio->lock);
dev_set_drvdata(dev, gpiommgpio);
err = gpiochip_add_data(&gpiommgpio->chip, gpiommgpio);
if (err) {
dev_err(dev, "GPIO registering failed (%d)\n", err);
return err;
}
/* initialize all GPIO as output */
outb(0x80, base[id] + 3);
outb(0x00, base[id]);
outb(0x00, base[id] + 1);
outb(0x00, base[id] + 2);
outb(0x80, base[id] + 7);
outb(0x00, base[id] + 4);
outb(0x00, base[id] + 5);
outb(0x00, base[id] + 6);
return 0;
}
static int gpiomm_remove(struct device *dev, unsigned int id)
{
struct gpiomm_gpio *const gpiommgpio = dev_get_drvdata(dev);
gpiochip_remove(&gpiommgpio->chip);
return 0;
}
static struct isa_driver gpiomm_driver = {
.probe = gpiomm_probe,
.driver = {
.name = "gpio-mm"
},
.remove = gpiomm_remove
};
module_isa_driver(gpiomm_driver, num_gpiomm);
MODULE_AUTHOR("William Breathitt Gray <vilhelm.gray@gmail.com>");
MODULE_DESCRIPTION("Diamond Systems GPIO-MM GPIO driver");
MODULE_LICENSE("GPL v2");
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