rambi: Control LEDs using PWM

Rambi has a pair of LEDs which are attached to the PWM fan controller.
Add support for them.  Also add a generic 'pwmduty' command which can
be used to get/set the duty cycle for any PWM channel.

Also fix rounding errors in pwm module, so that set/get duty doesn't
keep rounding down.

BUG=chrome-os-partner:22895
BRANCH=none
TEST=Boot rambi. LEDs are off.
     pwmduty -> both are 0%
     pwmduty 0 10 -> green LED on dimly
     pwmduty 1 10 -> red LED on dimly
     pwmduty 0 99 -> green LED on brightly
     pwmduty 1 100 -> red LED on brightly
     pwmduty 1 0 -> red LED off
     pwmduty 1 -1 -> red LED turns back on because fan controller is disabled
     pwmduty -> channel 0 at 99%, channel 1 disabled
     Build all platforms.  Pass all unit tests.

Change-Id: Ib0a6289a757554e696a9a0153a85bdc34e2ee2ae
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/172094

5 files changed, 50 insertions, 5 deletions

diff --git a/board/host/board.h b/board/host/board.h
index 6db70771ff..2529e15bc1 100644
--- a/board/host/board.h
+++ b/board/host/board.h
@@ -14,7 +14,6 @@
 #define CONFIG_KEYBOARD_PROTOCOL_MKBP
 #define CONFIG_POWER_BUTTON
 #undef CONFIG_WATCHDOG
-#define CONFIG_PWM
 #define CONFIG_SWITCH
 
 #undef CONFIG_CONSOLE_HISTORY
diff --git a/board/rambi/board.c b/board/rambi/board.c
index b864de5ef1..7a6f926763 100644
--- a/board/rambi/board.c
+++ b/board/rambi/board.c
@@ -110,7 +110,7 @@ const struct gpio_alt_func gpio_alt_funcs[] = {
 	{GPIO_D, 0x0f, 2, MODULE_SPI},			/* SPI1 */
 	{GPIO_L, 0x3f, 15, MODULE_LPC},			/* LPC */
 	{GPIO_M, 0x33, 15, MODULE_LPC},			/* LPC */
-	{GPIO_N, 0x50, 1, MODULE_PWM_LED},		/* Power LEDs */
+	{GPIO_N, 0x50, 1, MODULE_PWM_LED, GPIO_OPEN_DRAIN}, /* Power LEDs */
 };
 const int gpio_alt_funcs_count = ARRAY_SIZE(gpio_alt_funcs);
 
@@ -152,8 +152,8 @@ BUILD_ASSERT(ARRAY_SIZE(adc_channels) == ADC_CH_COUNT);
 
 /* PWM channels */
 const struct pwm_t pwm_channels[] = {
-	[PWM_CH_LED_GREEN] = {4, 0},
-	[PWM_CH_LED_RED] = {3, 0},
+	[PWM_CH_LED_GREEN] = {4, PWM_CONFIG_ACTIVE_LOW},
+	[PWM_CH_LED_RED] = {3, PWM_CONFIG_ACTIVE_LOW},
 };
 
 BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
diff --git a/board/rambi/board.h b/board/rambi/board.h
index d9f038e850..2fdb718013 100644
--- a/board/rambi/board.h
+++ b/board/rambi/board.h
@@ -14,6 +14,7 @@
 #define CONFIG_CMD_GSV
 #define CONFIG_EXTPOWER_GPIO
 #define CONFIG_KEYBOARD_PROTOCOL_8042
+#define CONFIG_LED_COMMON
 #undef  CONFIG_PECI
 #define CONFIG_POWER_BUTTON
 #define CONFIG_POWER_BUTTON_X86
diff --git a/board/rambi/build.mk b/board/rambi/build.mk
index 1843369ed4..ea89781339 100644
--- a/board/rambi/build.mk
+++ b/board/rambi/build.mk
@@ -9,4 +9,4 @@
 # the IC is TI Stellaris LM4
 CHIP:=lm4
 
-board-y=board.o
+board-y=board.o led.o
diff --git a/board/rambi/led.c b/board/rambi/led.c
new file mode 100644
index 0000000000..451aae2bc3
--- /dev/null
+++ b/board/rambi/led.c
@@ -0,0 +1,45 @@
+/* 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.
+ *
+ * Battery LED control for Rambi
+ */
+
+#include "gpio.h"
+#include "hooks.h"
+#include "led_common.h"
+#include "pwm.h"
+#include "util.h"
+
+const enum ec_led_id supported_led_ids[] = {EC_LED_ID_BATTERY_LED};
+const int supported_led_ids_count = ARRAY_SIZE(supported_led_ids);
+
+void led_get_brightness_range(enum ec_led_id led_id, uint8_t *brightness_range)
+{
+	brightness_range[EC_LED_COLOR_RED] = 100;
+	brightness_range[EC_LED_COLOR_GREEN] = 100;
+}
+
+int led_set_brightness(enum ec_led_id led_id, const uint8_t *brightness)
+{
+	pwm_set_duty(PWM_CH_LED_RED, brightness[EC_LED_COLOR_RED]);
+	pwm_set_duty(PWM_CH_LED_GREEN, brightness[EC_LED_COLOR_GREEN]);
+	return EC_SUCCESS;
+}
+
+static void led_init(void)
+{
+	/* Configure GPIOs */
+	gpio_config_module(MODULE_PWM_LED, 1);
+
+	/*
+	 * Enable PWMs and set to 0% duty cycle.  If they're disabled, the LM4
+	 * seems to ground the pins instead of letting them float.
+	 */
+	pwm_enable(PWM_CH_LED_RED, 1);
+	pwm_set_duty(PWM_CH_LED_RED, 0);
+
+	pwm_enable(PWM_CH_LED_GREEN, 1);
+	pwm_set_duty(PWM_CH_LED_GREEN, 0);
+}
+DECLARE_HOOK(HOOK_INIT, led_init, HOOK_PRIO_DEFAULT);