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/* Copyright (c) 2012 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
/* Power LED control for Chrome EC */
#include "console.h"
#include "onewire.h"
#include "power_led.h"
#include "timer.h"
#include "util.h"
#define POWERLED_RETRIES 10
static const uint8_t led_masks[POWERLED_COLOR_COUNT] = {0xff, 0xfe, 0xfc, 0xfd};
static const char * const color_names[POWERLED_COLOR_COUNT] = {
"off", "red", "yellow", "green"};
/**
* Set the power LED GPIO controller outputs
*
* @param mask Mask of outputs to enable
*
* @return EC_SUCCESS, or non-zero if error.
*/
static int powerled_set_mask(int mask)
{
int rv;
/* Reset the 1-wire bus */
rv = onewire_reset();
if (rv)
return rv;
/* Skip ROM, since only one device */
onewire_write(0xcc);
/* Write and turn on the LEDs */
onewire_write(0x5a);
onewire_write(mask);
onewire_write(~mask); /* Repeat inverted */
rv = onewire_read(); /* Confirmation byte */
if (rv != 0xaa)
return EC_ERROR_UNKNOWN;
/* The next byte is a read-back of the chip status. Since we're only
* using lines as outputs, we can ignore it. */
return EC_SUCCESS;
}
int powerled_set(enum powerled_color color)
{
int rv = EC_SUCCESS;
int i;
/*
* 1-wire communication can fail for timing reasons in the current
* system. We have a limited timing window to send/receive bits, but
* we can't disable interrupts for the rest of the system to guarantee
* we hit that window. Instead, simply retry the low-level command a
* few times.
*/
for (i = 0; i < POWERLED_RETRIES; i++) {
rv = powerled_set_mask(led_masks[color]);
if (rv == EC_SUCCESS)
break;
/*
* Sleep for a bit between tries. This gives the 1-wire GPIO
* chip time to recover from the failed attempt, and allows
* lower-priority tasks a chance to run.
*/
usleep(100);
}
return rv;
}
/*****************************************************************************/
/* Console commands */
static int command_powerled(int argc, char **argv)
{
int i;
/* Pick a color, any color... */
for (i = 0; i < POWERLED_COLOR_COUNT; i++) {
if (!strcasecmp(argv[1], color_names[i]))
return powerled_set(i);
}
return EC_ERROR_PARAM1;
}
DECLARE_CONSOLE_COMMAND(powerled, command_powerled,
"<off | red | yellow | green>",
"Set power LED color",
NULL);
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