linux/drivers/gpio/gpio-sch.c
Daniel Krueger 1e0d982317 gpio-sch: set output level after configuration of direction
According to the datasheet, writing to the level register has no effect
when GPIO is programmed as input. Actually the the level register is
read-only when configured as input. Thus presetting the output level
before switching to output is _NOT_ possible. Any writes are lost!
Hence we set the level after configuring the GPIO as output.
But we cannot prevent a short low pulse if direction is set to high and
an external  pull-up is connected.

Signed-off-by: Daniel Krueger <daniel.krueger@systec-electronic.com>
Signed-off-by: Alexander Stein <alexander.stein@systec-electronic.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2014-04-28 12:35:08 -07:00

344 lines
7.8 KiB
C

/*
* GPIO interface for Intel Poulsbo SCH
*
* Copyright (c) 2010 CompuLab Ltd
* Author: Denis Turischev <denis@compulab.co.il>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; see the file COPYING. If not, write to
* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/io.h>
#include <linux/errno.h>
#include <linux/acpi.h>
#include <linux/platform_device.h>
#include <linux/pci_ids.h>
#include <linux/gpio.h>
static DEFINE_SPINLOCK(gpio_lock);
#define CGEN (0x00)
#define CGIO (0x04)
#define CGLV (0x08)
#define RGEN (0x20)
#define RGIO (0x24)
#define RGLV (0x28)
static unsigned short gpio_ba;
static int sch_gpio_core_direction_in(struct gpio_chip *gc, unsigned gpio_num)
{
u8 curr_dirs;
unsigned short offset, bit;
spin_lock(&gpio_lock);
offset = CGIO + gpio_num / 8;
bit = gpio_num % 8;
curr_dirs = inb(gpio_ba + offset);
if (!(curr_dirs & (1 << bit)))
outb(curr_dirs | (1 << bit), gpio_ba + offset);
spin_unlock(&gpio_lock);
return 0;
}
static int sch_gpio_core_get(struct gpio_chip *gc, unsigned gpio_num)
{
int res;
unsigned short offset, bit;
offset = CGLV + gpio_num / 8;
bit = gpio_num % 8;
res = !!(inb(gpio_ba + offset) & (1 << bit));
return res;
}
static void sch_gpio_core_set(struct gpio_chip *gc, unsigned gpio_num, int val)
{
u8 curr_vals;
unsigned short offset, bit;
spin_lock(&gpio_lock);
offset = CGLV + gpio_num / 8;
bit = gpio_num % 8;
curr_vals = inb(gpio_ba + offset);
if (val)
outb(curr_vals | (1 << bit), gpio_ba + offset);
else
outb((curr_vals & ~(1 << bit)), gpio_ba + offset);
spin_unlock(&gpio_lock);
}
static int sch_gpio_core_direction_out(struct gpio_chip *gc,
unsigned gpio_num, int val)
{
u8 curr_dirs;
unsigned short offset, bit;
spin_lock(&gpio_lock);
offset = CGIO + gpio_num / 8;
bit = gpio_num % 8;
curr_dirs = inb(gpio_ba + offset);
if (curr_dirs & (1 << bit))
outb(curr_dirs & ~(1 << bit), gpio_ba + offset);
spin_unlock(&gpio_lock);
/*
* according to the datasheet, writing to the level register has no
* effect when GPIO is programmed as input.
* Actually the the level register is read-only when configured as input.
* Thus presetting the output level before switching to output is _NOT_ possible.
* Hence we set the level after configuring the GPIO as output.
* But we cannot prevent a short low pulse if direction is set to high
* and an external pull-up is connected.
*/
sch_gpio_core_set(gc, gpio_num, val);
return 0;
}
static struct gpio_chip sch_gpio_core = {
.label = "sch_gpio_core",
.owner = THIS_MODULE,
.direction_input = sch_gpio_core_direction_in,
.get = sch_gpio_core_get,
.direction_output = sch_gpio_core_direction_out,
.set = sch_gpio_core_set,
};
static int sch_gpio_resume_direction_in(struct gpio_chip *gc,
unsigned gpio_num)
{
u8 curr_dirs;
unsigned short offset, bit;
spin_lock(&gpio_lock);
offset = RGIO + gpio_num / 8;
bit = gpio_num % 8;
curr_dirs = inb(gpio_ba + offset);
if (!(curr_dirs & (1 << bit)))
outb(curr_dirs | (1 << bit), gpio_ba + offset);
spin_unlock(&gpio_lock);
return 0;
}
static int sch_gpio_resume_get(struct gpio_chip *gc, unsigned gpio_num)
{
unsigned short offset, bit;
offset = RGLV + gpio_num / 8;
bit = gpio_num % 8;
return !!(inb(gpio_ba + offset) & (1 << bit));
}
static void sch_gpio_resume_set(struct gpio_chip *gc,
unsigned gpio_num, int val)
{
u8 curr_vals;
unsigned short offset, bit;
spin_lock(&gpio_lock);
offset = RGLV + gpio_num / 8;
bit = gpio_num % 8;
curr_vals = inb(gpio_ba + offset);
if (val)
outb(curr_vals | (1 << bit), gpio_ba + offset);
else
outb((curr_vals & ~(1 << bit)), gpio_ba + offset);
spin_unlock(&gpio_lock);
}
static int sch_gpio_resume_direction_out(struct gpio_chip *gc,
unsigned gpio_num, int val)
{
u8 curr_dirs;
unsigned short offset, bit;
offset = RGIO + gpio_num / 8;
bit = gpio_num % 8;
spin_lock(&gpio_lock);
curr_dirs = inb(gpio_ba + offset);
if (curr_dirs & (1 << bit))
outb(curr_dirs & ~(1 << bit), gpio_ba + offset);
spin_unlock(&gpio_lock);
/*
* according to the datasheet, writing to the level register has no
* effect when GPIO is programmed as input.
* Actually the the level register is read-only when configured as input.
* Thus presetting the output level before switching to output is _NOT_ possible.
* Hence we set the level after configuring the GPIO as output.
* But we cannot prevent a short low pulse if direction is set to high
* and an external pull-up is connected.
*/
sch_gpio_resume_set(gc, gpio_num, val);
return 0;
}
static struct gpio_chip sch_gpio_resume = {
.label = "sch_gpio_resume",
.owner = THIS_MODULE,
.direction_input = sch_gpio_resume_direction_in,
.get = sch_gpio_resume_get,
.direction_output = sch_gpio_resume_direction_out,
.set = sch_gpio_resume_set,
};
static int sch_gpio_probe(struct platform_device *pdev)
{
struct resource *res;
int err, id;
id = pdev->id;
if (!id)
return -ENODEV;
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
if (!res)
return -EBUSY;
if (!request_region(res->start, resource_size(res), pdev->name))
return -EBUSY;
gpio_ba = res->start;
switch (id) {
case PCI_DEVICE_ID_INTEL_SCH_LPC:
sch_gpio_core.base = 0;
sch_gpio_core.ngpio = 10;
sch_gpio_resume.base = 10;
sch_gpio_resume.ngpio = 4;
/*
* GPIO[6:0] enabled by default
* GPIO7 is configured by the CMC as SLPIOVR
* Enable GPIO[9:8] core powered gpios explicitly
*/
outb(0x3, gpio_ba + CGEN + 1);
/*
* SUS_GPIO[2:0] enabled by default
* Enable SUS_GPIO3 resume powered gpio explicitly
*/
outb(0x8, gpio_ba + RGEN);
break;
case PCI_DEVICE_ID_INTEL_ITC_LPC:
sch_gpio_core.base = 0;
sch_gpio_core.ngpio = 5;
sch_gpio_resume.base = 5;
sch_gpio_resume.ngpio = 9;
break;
case PCI_DEVICE_ID_INTEL_CENTERTON_ILB:
sch_gpio_core.base = 0;
sch_gpio_core.ngpio = 21;
sch_gpio_resume.base = 21;
sch_gpio_resume.ngpio = 9;
break;
default:
err = -ENODEV;
goto err_sch_gpio_core;
}
sch_gpio_core.dev = &pdev->dev;
sch_gpio_resume.dev = &pdev->dev;
err = gpiochip_add(&sch_gpio_core);
if (err < 0)
goto err_sch_gpio_core;
err = gpiochip_add(&sch_gpio_resume);
if (err < 0)
goto err_sch_gpio_resume;
return 0;
err_sch_gpio_resume:
if (gpiochip_remove(&sch_gpio_core))
dev_err(&pdev->dev, "%s gpiochip_remove failed\n", __func__);
err_sch_gpio_core:
release_region(res->start, resource_size(res));
gpio_ba = 0;
return err;
}
static int sch_gpio_remove(struct platform_device *pdev)
{
struct resource *res;
if (gpio_ba) {
int err;
err = gpiochip_remove(&sch_gpio_core);
if (err)
dev_err(&pdev->dev, "%s failed, %d\n",
"gpiochip_remove()", err);
err = gpiochip_remove(&sch_gpio_resume);
if (err)
dev_err(&pdev->dev, "%s failed, %d\n",
"gpiochip_remove()", err);
res = platform_get_resource(pdev, IORESOURCE_IO, 0);
release_region(res->start, resource_size(res));
gpio_ba = 0;
return err;
}
return 0;
}
static struct platform_driver sch_gpio_driver = {
.driver = {
.name = "sch_gpio",
.owner = THIS_MODULE,
},
.probe = sch_gpio_probe,
.remove = sch_gpio_remove,
};
module_platform_driver(sch_gpio_driver);
MODULE_AUTHOR("Denis Turischev <denis@compulab.co.il>");
MODULE_DESCRIPTION("GPIO interface for Intel Poulsbo SCH");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:sch_gpio");