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/*
* arch/arm/mach-tegra/i2c_error_recovery.c
*
* Copyright (c) 2011, NVIDIA Corporation.
*
* 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.
*
* 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; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include <linux/gpio.h>
#include <linux/delay.h>
#include <linux/init.h>
#include "board.h"
#define RETRY_MAX_COUNT (9*8+1) /*I2C controller supports eight-byte burst transfer*/
int arb_lost_recovery(int scl_gpio, int sda_gpio)
{
int ret;
int retry = RETRY_MAX_COUNT;
int recovered_successfully = 0;
int val;
if ((!scl_gpio) || (!sda_gpio)) {
pr_err("not proper input:scl_gpio 0x%08x,"
"sda_gpio 0x%08x\n", scl_gpio, sda_gpio);
return -EINVAL;;
}
ret = gpio_request(scl_gpio, "scl_gpio");
if (ret < 0) {
pr_err("error in gpio 0x%08x request 0x%08x\n",
scl_gpio, ret);
return -EINVAL;;
}
ret = gpio_request(sda_gpio, "sda_gpio");
if (ret < 0) {
pr_err("error in gpio 0x%08x request 0x%08x\n",
sda_gpio, ret);
goto err;
}
gpio_direction_input(sda_gpio);
while (retry--) {
gpio_direction_output(scl_gpio,0);
udelay(5);
gpio_direction_output(scl_gpio,1);
udelay(5);
/* check whether sda struct low release */
val = gpio_get_value(sda_gpio);
if (val) {
/* send START */
gpio_direction_output(sda_gpio,0);
udelay(5);
/* send STOP in next clock cycle */
gpio_direction_output(scl_gpio,0);
udelay(5);
gpio_direction_output(scl_gpio,1);
udelay(5);
gpio_direction_output(sda_gpio,1);
udelay(5);
recovered_successfully = 1;
break;
}
}
gpio_free(scl_gpio);
gpio_free(sda_gpio);
if (likely(recovered_successfully)) {
pr_err("arbitration lost recovered by re-try-count 0x%08x\n",
RETRY_MAX_COUNT - retry);
return 0;
} else {
pr_err("Un-recovered arbitration lost.\n");
return -EINVAL;
}
err:
gpio_free(scl_gpio);
return ret;
}
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