diff options
Diffstat (limited to 'common/led_driver_ds2413.c')
-rw-r--r-- | common/led_driver_ds2413.c | 166 |
1 files changed, 166 insertions, 0 deletions
diff --git a/common/led_driver_ds2413.c b/common/led_driver_ds2413.c new file mode 100644 index 0000000000..9babd75992 --- /dev/null +++ b/common/led_driver_ds2413.c @@ -0,0 +1,166 @@ +/* Copyright (c) 2013 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 "charge_state.h" +#include "console.h" +#include "hooks.h" +#include "onewire.h" +#include "timer.h" +#include "util.h" + +#define ONEWIRE_RETRIES 10 + +enum led_color { + LED_OFF = 0, + LED_RED, + LED_YELLOW, + LED_GREEN, + LED_COLOR_COUNT /* Number of colors, not a color itself */ +}; + +static const uint8_t led_masks[LED_COLOR_COUNT] = {0xff, 0xfe, 0xfc, 0xfd}; +static const char * const color_names[LED_COLOR_COUNT] = { + "off", "red", "yellow", "green"}; + +/** + * Set the onewire LED GPIO controller outputs + * + * @param mask Mask of outputs to enable + * + * @return EC_SUCCESS, or non-zero if error. + */ +static int led_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; +} + +static int led_set(enum led_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 < ONEWIRE_RETRIES; i++) { + rv = led_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; +} + +/*****************************************************************************/ +/* Hooks */ + +static void onewire_led_tick(void) +{ + static enum led_color current_color = LED_COLOR_COUNT; + static int tick_count; + + enum led_color new_color = LED_OFF; + uint32_t chflags = charge_get_flags(); + + tick_count++; + + if (!(chflags & CHARGE_FLAG_EXTERNAL_POWER)) { + /* AC isn't present, so the power LED on the AC plug is off */ + current_color = LED_OFF; + return; + } + + /* Translate charge state to LED color */ + switch (charge_get_state()) { + case PWR_STATE_IDLE: + if (chflags & CHARGE_FLAG_FORCE_IDLE) + new_color = (tick_count & 1) ? LED_GREEN : LED_OFF; + else + new_color = LED_GREEN; + break; + case PWR_STATE_CHARGE: + new_color = LED_YELLOW; + break; + case PWR_STATE_CHARGE_NEAR_FULL: + new_color = LED_GREEN; + break; + case PWR_STATE_ERROR: + new_color = LED_RED; + break; + default: + /* Other states don't change LED color */ + break; + } + + /* + * The power adapter on link can partially unplug and lose its LED + * state. There's no way to detect this, so just assume it forgets its + * state every 10 seconds. + */ + if (!(tick_count % 10)) + current_color = LED_COLOR_COUNT; + + /* If current color is still correct, leave now */ + if (new_color == current_color) + return; + + /* Update LED */ + if (!led_set(new_color)) + current_color = new_color; +} +DECLARE_HOOK(HOOK_SECOND, onewire_led_tick, HOOK_PRIO_DEFAULT); + +/*****************************************************************************/ +/* Console commands */ + +static int command_powerled(int argc, char **argv) +{ + int i; + + /* Pick a color, any color... */ + for (i = 0; i < LED_COLOR_COUNT; i++) { + if (!strcasecmp(argv[1], color_names[i])) + return led_set(i); + } + return EC_ERROR_PARAM1; +} +DECLARE_CONSOLE_COMMAND(powerled, command_powerled, + "<off | red | yellow | green>", + "Set power LED color", + NULL); |