linux/drivers/gpio/gpio-kempld.c
Michael Brunner f230e8ffc0 gpio: gpio-kempld: Fix get_direction return value
This patch fixes an inverted return value of the gpio get_direction
function.

The wrong value causes the direction sysfs entry and GPIO debugfs file
to indicate incorrect GPIO direction settings. In some cases it also
prevents setting GPIO output values.

The problem is also present in all other stable kernel versions since
linux-3.12.

Cc: Stable <stable@vger.kernel.org> # v3.12+
Reported-by: Jochen Henneberg <jh@henneberg-systemdesign.com>
Signed-off-by: Michael Brunner <michael.brunner@kontron.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
2015-05-12 13:49:13 +02:00

220 lines
5.7 KiB
C

/*
* Kontron PLD GPIO driver
*
* Copyright (c) 2010-2013 Kontron Europe GmbH
* Author: Michael Brunner <michael.brunner@kontron.com>
*
* 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.
*/
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/bitops.h>
#include <linux/errno.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/mfd/kempld.h>
#define KEMPLD_GPIO_MAX_NUM 16
#define KEMPLD_GPIO_MASK(x) (BIT((x) % 8))
#define KEMPLD_GPIO_DIR_NUM(x) (0x40 + (x) / 8)
#define KEMPLD_GPIO_LVL_NUM(x) (0x42 + (x) / 8)
#define KEMPLD_GPIO_EVT_LVL_EDGE 0x46
#define KEMPLD_GPIO_IEN 0x4A
struct kempld_gpio_data {
struct gpio_chip chip;
struct kempld_device_data *pld;
};
/*
* Set or clear GPIO bit
* kempld_get_mutex must be called prior to calling this function.
*/
static void kempld_gpio_bitop(struct kempld_device_data *pld,
u8 reg, u8 bit, u8 val)
{
u8 status;
status = kempld_read8(pld, reg);
if (val)
status |= KEMPLD_GPIO_MASK(bit);
else
status &= ~KEMPLD_GPIO_MASK(bit);
kempld_write8(pld, reg, status);
}
static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
{
u8 status;
kempld_get_mutex(pld);
status = kempld_read8(pld, reg);
kempld_release_mutex(pld);
return !!(status & KEMPLD_GPIO_MASK(bit));
}
static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
{
struct kempld_gpio_data *gpio
= container_of(chip, struct kempld_gpio_data, chip);
struct kempld_device_data *pld = gpio->pld;
return kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
}
static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
{
struct kempld_gpio_data *gpio
= container_of(chip, struct kempld_gpio_data, chip);
struct kempld_device_data *pld = gpio->pld;
kempld_get_mutex(pld);
kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
kempld_release_mutex(pld);
}
static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
{
struct kempld_gpio_data *gpio
= container_of(chip, struct kempld_gpio_data, chip);
struct kempld_device_data *pld = gpio->pld;
kempld_get_mutex(pld);
kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
kempld_release_mutex(pld);
return 0;
}
static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
int value)
{
struct kempld_gpio_data *gpio
= container_of(chip, struct kempld_gpio_data, chip);
struct kempld_device_data *pld = gpio->pld;
kempld_get_mutex(pld);
kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
kempld_release_mutex(pld);
return 0;
}
static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
{
struct kempld_gpio_data *gpio
= container_of(chip, struct kempld_gpio_data, chip);
struct kempld_device_data *pld = gpio->pld;
return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset);
}
static int kempld_gpio_pincount(struct kempld_device_data *pld)
{
u16 evt, evt_back;
kempld_get_mutex(pld);
/* Backup event register as it might be already initialized */
evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
/* Clear event register */
kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
/* Read back event register */
evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
/* Restore event register */
kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
kempld_release_mutex(pld);
return evt ? __ffs(evt) : 16;
}
static int kempld_gpio_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
struct kempld_gpio_data *gpio;
struct gpio_chip *chip;
int ret;
if (pld->info.spec_major < 2) {
dev_err(dev,
"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
return -ENODEV;
}
gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
if (!gpio)
return -ENOMEM;
gpio->pld = pld;
platform_set_drvdata(pdev, gpio);
chip = &gpio->chip;
chip->label = "gpio-kempld";
chip->owner = THIS_MODULE;
chip->dev = dev;
chip->can_sleep = true;
if (pdata && pdata->gpio_base)
chip->base = pdata->gpio_base;
else
chip->base = -1;
chip->direction_input = kempld_gpio_direction_input;
chip->direction_output = kempld_gpio_direction_output;
chip->get_direction = kempld_gpio_get_direction;
chip->get = kempld_gpio_get;
chip->set = kempld_gpio_set;
chip->ngpio = kempld_gpio_pincount(pld);
if (chip->ngpio == 0) {
dev_err(dev, "No GPIO pins detected\n");
return -ENODEV;
}
ret = gpiochip_add(chip);
if (ret) {
dev_err(dev, "Could not register GPIO chip\n");
return ret;
}
dev_info(dev, "GPIO functionality initialized with %d pins\n",
chip->ngpio);
return 0;
}
static int kempld_gpio_remove(struct platform_device *pdev)
{
struct kempld_gpio_data *gpio = platform_get_drvdata(pdev);
gpiochip_remove(&gpio->chip);
return 0;
}
static struct platform_driver kempld_gpio_driver = {
.driver = {
.name = "kempld-gpio",
},
.probe = kempld_gpio_probe,
.remove = kempld_gpio_remove,
};
module_platform_driver(kempld_gpio_driver);
MODULE_DESCRIPTION("KEM PLD GPIO Driver");
MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:kempld-gpio");