RGBKBD: Support backlight control via EC_CMD_PWM_SET_DUTY

In a regular design, a keyboard backlight is connected to a PWM pin of
an EC. With an RGB keyboard, the brightness control is part of the RGB
keyboard functionality. Thus, EC_CMD_PWM_SET_DUTY with
EC_PWM_TYPE_KB_LIGHT should be handled by an RGB keyboard API to control
the keyboard backlight brightness.

On host, run:
  localhost ~ # ectool pwmsetduty kb 0x8000

EC prints:
  RGBKBD: Set GCC to 128

BUG=b:228525798,b:226215987
BRANCH=None
TEST=Taniks. See above.

Signed-off-by: Daisuke Nojiri <dnojiri@chromium.org>
Change-Id: Id8f23ba67728f03664673834be0903e0f593e744
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/3576897
Reviewed-by: Parth Malkan <parthmalkan@google.com>
Reviewed-by: Zhuohao Lee <zhuohao@chromium.org>

3 files changed, 75 insertions, 23 deletions

diff --git a/common/pwm.c b/common/pwm.c
index 74c079bbfd..7699405f3d 100644
--- a/common/pwm.c
+++ b/common/pwm.c
@@ -9,6 +9,7 @@
 #include "hooks.h"
 #include "host_command.h"
 #include "pwm.h"
+#include "rgb_keyboard.h"
 #include "util.h"
 
 #ifdef CONFIG_PWM
@@ -64,11 +65,18 @@ host_command_pwm_set_duty(struct host_cmd_handler_args *args)
 	const struct ec_params_pwm_set_duty *p = args->params;
 	enum pwm_channel channel;
 
-	if (get_target_channel(&channel, p->pwm_type, p->index))
-		return EC_RES_INVALID_PARAM;
-
-	pwm_set_raw_duty(channel, p->duty);
-	pwm_enable(channel, p->duty > 0);
+	if (IS_ENABLED(CONFIG_RGB_KEYBOARD) &&
+			(p->pwm_type == EC_PWM_TYPE_KB_LIGHT)) {
+		uint8_t gcc = DIV_ROUND_NEAREST(p->duty * RGBKBD_MAX_GCC_LEVEL,
+						EC_PWM_MAX_DUTY);
+		if (rgbkbd_set_global_brightness(gcc))
+			return EC_RES_ERROR;
+	} else {
+		if (get_target_channel(&channel, p->pwm_type, p->index))
+			return EC_RES_INVALID_PARAM;
+		pwm_set_raw_duty(channel, p->duty);
+		pwm_enable(channel, p->duty > 0);
+	}
 
 	return EC_RES_SUCCESS;
 }
@@ -82,12 +90,23 @@ host_command_pwm_get_duty(struct host_cmd_handler_args *args)
 	const struct ec_params_pwm_get_duty *p = args->params;
 	struct ec_response_pwm_get_duty *r = args->response;
 
-	enum pwm_channel channel;
+	if (IS_ENABLED(CONFIG_RGB_KEYBOARD) &&
+			(p->pwm_type == EC_PWM_TYPE_KB_LIGHT)) {
+		uint8_t gcc;
 
-	if (get_target_channel(&channel, p->pwm_type, p->index))
-		return EC_RES_INVALID_PARAM;
+		if (rgbkbd_get_global_brightness(&gcc))
+			return EC_RES_ERROR;
+		r->duty = DIV_ROUND_NEAREST(gcc * EC_PWM_MAX_DUTY,
+					    RGBKBD_MAX_GCC_LEVEL);
+	} else {
+		enum pwm_channel channel;
+
+		if (get_target_channel(&channel, p->pwm_type, p->index))
+			return EC_RES_INVALID_PARAM;
+
+		r->duty = pwm_get_raw_duty(channel);
+	}
 
-	r->duty = pwm_get_raw_duty(channel);
 	args->response_size = sizeof(*r);
 
 	return EC_RES_SUCCESS;
diff --git a/common/rgb_keyboard.c b/common/rgb_keyboard.c
index f581d5ae1a..0f66e6c242 100644
--- a/common/rgb_keyboard.c
+++ b/common/rgb_keyboard.c
@@ -233,6 +233,38 @@ void rgbkbd_init_lookup_table(void)
 	 */
 }
 
+int rgbkbd_set_global_brightness(uint8_t gcc)
+{
+	int e, grid;
+	int rv = EC_SUCCESS;
+
+	for (grid = 0; grid < rgbkbd_count; grid++) {
+		struct rgbkbd *ctx = &rgbkbds[grid];
+
+		e = ctx->cfg->drv->set_gcc(ctx, gcc);
+		if (e) {
+			CPRINTS("Failed to set GCC to %u for grid=%d (%d)",
+				gcc, grid, e);
+			rv = e;
+			continue;
+		}
+
+		ctx->gcc = gcc;
+	}
+
+	CPRINTS("Set GCC to %u", gcc);
+
+	/* Return EC_SUCCESS or the last error. */
+	return rv;
+}
+
+int rgbkbd_get_global_brightness(uint8_t *gcc)
+{
+	*gcc = rgbkbds[0].gcc;
+
+	return EC_SUCCESS;
+}
+
 __overridable void board_enable_rgb_keyboard(bool enable) {}
 
 static int rgbkbd_init(void)
@@ -307,19 +339,13 @@ static int rgbkbd_enable(int enable)
 void rgbkbd_task(void *u)
 {
 	uint32_t event;
-	int i, rv;
 
 	board_enable_rgb_keyboard(true);
 
 	rgbkbd_init_lookup_table();
 	rgbkbd_init();
 	rgbkbd_enable(1);
-	for (i = 0; i < rgbkbd_count; i++) {
-		struct rgbkbd *ctx = &rgbkbds[i];
-		rv = ctx->cfg->drv->set_gcc(ctx, 0x80);
-		if (rv)
-			CPRINTS("Failed to set GCC (%d)", rv);
-	}
+	rgbkbd_set_global_brightness(0x80);
 
 	while (1) {
 		event = task_wait_event(100 * MSEC);
@@ -380,7 +406,6 @@ DECLARE_HOST_COMMAND(EC_CMD_RGBKBD, hc_rgbkbd, EC_VER_MASK(0));
 
 test_export_static int cc_rgbk(int argc, char **argv)
 {
-	struct rgbkbd *ctx;
 	char *end, *comma;
 	struct rgb_s color;
 	int gcc, x, y, val;
@@ -421,12 +446,7 @@ test_export_static int cc_rgbk(int argc, char **argv)
 		gcc = strtoi(argv[1], &end, 0);
 		if (*end || gcc < 0 || gcc > UINT8_MAX)
 			return EC_ERROR_PARAM1;
-		demo = RGBKBD_DEMO_OFF;
-		for (i = 0; i < rgbkbd_count; i++) {
-			ctx = &rgbkbds[i];
-			ctx->cfg->drv->set_gcc(ctx, gcc);
-		}
-		return EC_SUCCESS;
+		return rgbkbd_set_global_brightness(gcc);
 	}
 
 	if (argc != 5)
diff --git a/include/rgb_keyboard.h b/include/rgb_keyboard.h
index 0500ce859f..f4c9540c63 100644
--- a/include/rgb_keyboard.h
+++ b/include/rgb_keyboard.h
@@ -12,6 +12,8 @@
 /* Use this instead of '3' for readability where applicable. */
 #define SIZE_OF_RGB		sizeof(struct rgb_s)
 
+#define RGBKBD_MAX_GCC_LEVEL	0xff
+
 enum rgbkbd_demo {
 	RGBKBD_DEMO_OFF = 0,
 	RGBKBD_DEMO_FLOW = 1,
@@ -37,6 +39,8 @@ struct rgbkbd {
 	const struct rgbkbd_cfg * const cfg;
 	/* Current state of the port */
 	enum rgbkbd_state state;
+	/* Global current control (a.k.a. backlight brightness) */
+	uint8_t gcc;
 	/* Buffer containing color info for each dot. */
 	struct rgb_s *buf;
 };
@@ -173,3 +177,12 @@ __override_proto void board_enable_rgb_keyboard(bool enable);
  */
 extern const uint8_t rgbkbd_map[];
 extern const size_t rgbkbd_map_size;
+
+/**
+ * Set/get global brightness of the RGB keyboard.
+ *
+ * @param  gcc  Brightness level 0 ~ RGBKBD_MAX_GCC_LEVEL.
+ * @return enum ec_error_list;
+ */
+int rgbkbd_set_global_brightness(uint8_t gcc);
+int rgbkbd_get_global_brightness(uint8_t *gcc);