Support backlight control via lid only

The old backlight_x86 code did

  (backlight enable) = (lid is open) && (GPIO request from AP)

Newer systems will AND those signals in hardware.  Support those
systems by separating CONFIG_BACKLIGHT_LID and
CONFIG_BACKLIGHT_REQ_GPIO, and add tests for the case where the enable
signal is dependent only on the lid position.

BUG=chrome-os-partner:22960
BRANCH=none
TEST=pass unit tests

Change-Id: I1909426e49f00a8acd5047fd88c801cba1dacd76
Reviewed-on: https://chromium-review.googlesource.com/170925
Tested-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Bill Richardson <wfrichar@chromium.org>
Commit-Queue: Randall Spangler <rspangler@chromium.org>

1 files changed, 71 insertions, 0 deletions

diff --git a/common/backlight_lid.c b/common/backlight_lid.c
new file mode 100644
index 0000000000..30b8b75eb7
--- /dev/null
+++ b/common/backlight_lid.c
@@ -0,0 +1,71 @@
+/* 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.
+ */
+
+/* Backlight control based on lid and optional request signal from AP */
+
+#include "common.h"
+#include "gpio.h"
+#include "hooks.h"
+#include "host_command.h"
+#include "lid_switch.h"
+
+/**
+ * Update backlight state.
+ */
+static void update_backlight(void)
+{
+#ifdef CONFIG_BACKLIGHT_REQ_GPIO
+	/* Enable the backlight if lid is open AND requested by AP */
+	gpio_set_level(GPIO_ENABLE_BACKLIGHT, lid_is_open() &&
+		       gpio_get_level(CONFIG_BACKLIGHT_REQ_GPIO));
+#else
+	/*
+	 * Enable backlight if lid is open; this is AND'd with the request from
+	 * the AP in hardware.
+	 */
+	gpio_set_level(GPIO_ENABLE_BACKLIGHT, lid_is_open());
+#endif
+}
+DECLARE_HOOK(HOOK_LID_CHANGE, update_backlight, HOOK_PRIO_DEFAULT);
+
+/**
+ * Initialize backlight module.
+ */
+static void backlight_init(void)
+{
+	update_backlight();
+
+#ifdef CONFIG_BACKLIGHT_REQ_GPIO
+	gpio_enable_interrupt(CONFIG_BACKLIGHT_REQ_GPIO);
+#endif
+}
+DECLARE_HOOK(HOOK_INIT, backlight_init, HOOK_PRIO_DEFAULT);
+
+#ifdef CONFIG_BACKLIGHT_REQ_GPIO
+void backlight_interrupt(enum gpio_signal signal)
+{
+	update_backlight();
+}
+#endif
+
+/**
+ * Host command to toggle backlight.
+ *
+ * The requested state will persist until the next lid-switch or request-gpio
+ * transition.
+ */
+static int switch_command_enable_backlight(struct host_cmd_handler_args *args)
+{
+	const struct ec_params_switch_enable_backlight *p = args->params;
+
+	gpio_set_level(GPIO_ENABLE_BACKLIGHT, p->enabled);
+
+	return EC_RES_SUCCESS;
+}
+DECLARE_HOST_COMMAND(EC_CMD_SWITCH_ENABLE_BKLIGHT,
+		     switch_command_enable_backlight,
+		     EC_VER_MASK(0));
+
+