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

1 files changed, 130 insertions, 0 deletions

diff --git a/common/pwm_kblight.c b/common/pwm_kblight.c
new file mode 100644
index 0000000000..41448ce7e8
--- /dev/null
+++ b/common/pwm_kblight.c
@@ -0,0 +1,130 @@
+/* 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.
+ */
+
+/* PWM control module for Chromebook keyboard backlight. */
+
+#include "common.h"
+#include "console.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "host_command.h"
+#include "lid_switch.h"
+#include "pwm.h"
+#include "system.h"
+#include "util.h"
+
+#define PWMKBD_SYSJUMP_TAG 0x504b  /* "PK" */
+#define PWM_HOOK_VERSION 1
+/* Saved PWM state across sysjumps */
+struct pwm_kbd_state {
+	uint8_t kblight_en;
+	uint8_t kblight_percent;
+	uint8_t pad0, pad1; /* Pad to multiple of 4 bytes. */
+};
+
+/*****************************************************************************/
+/* Console commands */
+
+static int command_kblight(int argc, char **argv)
+{
+	if (argc >= 2) {
+		char *e;
+		int i = strtoi(argv[1], &e, 0);
+		if (*e)
+			return EC_ERROR_PARAM1;
+		pwm_set_duty(PWM_CH_KBLIGHT, i);
+	}
+
+	ccprintf("Keyboard backlight: %d%%\n", pwm_get_duty(PWM_CH_KBLIGHT));
+	return EC_SUCCESS;
+}
+DECLARE_CONSOLE_COMMAND(kblight, command_kblight,
+			"percent",
+			"Set keyboard backlight",
+			NULL);
+
+/*****************************************************************************/
+/* Host commands */
+
+int pwm_command_get_keyboard_backlight(struct host_cmd_handler_args *args)
+{
+	struct ec_response_pwm_get_keyboard_backlight *r = args->response;
+
+	r->percent = pwm_get_duty(PWM_CH_KBLIGHT);
+	r->enabled = pwm_get_enabled(PWM_CH_KBLIGHT);
+	args->response_size = sizeof(*r);
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_PWM_GET_KEYBOARD_BACKLIGHT,
+		     pwm_command_get_keyboard_backlight,
+		     EC_VER_MASK(0));
+
+int pwm_command_set_keyboard_backlight(struct host_cmd_handler_args *args)
+{
+	const struct ec_params_pwm_set_keyboard_backlight *p = args->params;
+
+	pwm_set_duty(PWM_CH_KBLIGHT, p->percent);
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_PWM_SET_KEYBOARD_BACKLIGHT,
+		     pwm_command_set_keyboard_backlight,
+		     EC_VER_MASK(0));
+
+/*****************************************************************************/
+/* Hooks */
+
+static void pwm_kblight_init(void)
+{
+	const struct pwm_kbd_state *prev;
+	int version, size;
+
+	/* Configure GPIO */
+	gpio_config_module(MODULE_PWM_KBLIGHT, 1);
+
+	prev = (const struct pwm_kbd_state *)
+		system_get_jump_tag(PWMKBD_SYSJUMP_TAG, &version, &size);
+	if (prev && version == PWM_HOOK_VERSION && size == sizeof(*prev)) {
+		/* Restore previous state. */
+		pwm_enable(PWM_CH_KBLIGHT, prev->kblight_en);
+		pwm_set_duty(PWM_CH_KBLIGHT, prev->kblight_percent);
+	} else {
+		/* Enable keyboard backlight control, turned down */
+		pwm_set_duty(PWM_CH_KBLIGHT, 0);
+		pwm_enable(PWM_CH_KBLIGHT, 1);
+	}
+}
+DECLARE_HOOK(HOOK_INIT, pwm_kblight_init, HOOK_PRIO_DEFAULT);
+
+static void pwm_kblight_preserve_state(void)
+{
+	struct pwm_kbd_state state;
+
+	state.kblight_en = pwm_get_enabled(PWM_CH_KBLIGHT);
+	state.kblight_percent = pwm_get_duty(PWM_CH_KBLIGHT);
+
+	system_add_jump_tag(PWMKBD_SYSJUMP_TAG, PWM_HOOK_VERSION,
+			    sizeof(state), &state);
+}
+DECLARE_HOOK(HOOK_SYSJUMP, pwm_kblight_preserve_state, HOOK_PRIO_DEFAULT);
+
+static void pwm_kblight_suspend(void)
+{
+	pwm_set_duty(PWM_CH_KBLIGHT, 0);
+}
+DECLARE_HOOK(HOOK_CHIPSET_SUSPEND, pwm_kblight_suspend, HOOK_PRIO_DEFAULT);
+
+static void pwm_kblight_shutdown(void)
+{
+	pwm_set_duty(PWM_CH_KBLIGHT, 0);
+}
+DECLARE_HOOK(HOOK_CHIPSET_SHUTDOWN, pwm_kblight_shutdown, HOOK_PRIO_DEFAULT);
+
+static void pwm_kblight_lid_change(void)
+{
+	pwm_enable(PWM_CH_KBLIGHT, lid_is_open());
+}
+DECLARE_HOOK(HOOK_LID_CHANGE, pwm_kblight_lid_change, HOOK_PRIO_DEFAULT);