Keyborg: implement fast scan mode

With fast scan mode, the scan rate can usually go up to 90-100 Hz. In
worst case, the rate still maintains at around 50 Hz.

BUG=None
TEST=Manual test. Check heat map.
BRANCH=None

Change-Id: I2dc25028ffa5b3175b856d3437004c21b84e7df7
Signed-off-by: Vic Yang <victoryang@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/200829
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

2 files changed, 97 insertions, 14 deletions

diff --git a/board/keyborg/touch_scan.c b/board/keyborg/touch_scan.c
index 6441899272..2a953258ae 100644
--- a/board/keyborg/touch_scan.c
+++ b/board/keyborg/touch_scan.c
@@ -24,6 +24,13 @@
 
 static uint8_t buf[2][ROW_COUNT * 2];
 
+#define SCAN_BUF_SIZE (DIV_ROUND_UP(COL_COUNT * 2, 32) + 2)
+#define GET_SCAN_NEEDED(x) (scan_needed[(x) / 32 + 1] & (1 << ((x) & 31)))
+static uint32_t scan_needed[SCAN_BUF_SIZE];
+
+#define SPAN_LENGTH (2 * COL_SPAN + 1)
+#define SPAN_MASK ((1 << SPAN_LENGTH) - 1)
+
 static uint32_t mccr_list[COL_COUNT];
 static uint32_t mrcr_list[ROW_COUNT];
 
@@ -115,6 +122,50 @@ static void enable_col(int idx, int enabled)
 	}
 }
 
+static inline void set_scan_needed(int col)
+{
+	uint8_t word = (col - COL_SPAN + 32) / 32;
+	uint8_t bit = (col - COL_SPAN + 32) & 31;
+
+	scan_needed[word] |= SPAN_MASK << bit;
+	if (bit + SPAN_LENGTH > 32)
+		scan_needed[word + 1] |= SPAN_MASK >> (32 - bit);
+}
+
+int fast_scan(uint32_t *data)
+{
+	int col;
+
+	memset(data, 0, SCAN_BUF_SIZE);
+
+	STM32_PMSE_MRCR = 1 << 31;
+	for (col = 0; col < COL_COUNT * 2; ++col) {
+		if (col < COL_COUNT) {
+			enable_col(col, 1);
+			STM32_PMSE_MCCR = mccr_list[col];
+		}
+
+		if (master_slave_sync(5) != EC_SUCCESS)
+			return EC_ERROR_UNKNOWN;
+
+		start_adc_sample(0, ADC_SMPL_CPU_CYCLE);
+		while (!(STM32_ADC_SR(0) & (1 << 1)))
+			;
+		if (ADC_DATA_WINDOW(flush_adc(0)) >= COL_THRESHOLD)
+			set_scan_needed(col);
+
+		if (master_slave_sync(5) != EC_SUCCESS)
+			return EC_ERROR_UNKNOWN;
+		if (col < COL_COUNT) {
+			enable_col(col, 0);
+			STM32_PMSE_MCCR = 0;
+		}
+	}
+	STM32_PMSE_MRCR = 0;
+
+	return EC_SUCCESS;
+}
+
 void scan_column(uint8_t *data)
 {
 	int i;
@@ -143,6 +194,12 @@ void touch_scan_slave_start(void)
 	int col, i, v;
 	struct spi_comm_packet *resp = (struct spi_comm_packet *)buf;
 
+	if (fast_scan(scan_needed) != EC_SUCCESS)
+		return;
+
+	/* Discharge the panel */
+	scan_column(buf[0]);
+
 	for (col = 0; col < COL_COUNT * 2; ++col) {
 		if (col < COL_COUNT) {
 			enable_col(col, 1);
@@ -152,23 +209,27 @@ void touch_scan_slave_start(void)
 		if (master_slave_sync(20) != EC_SUCCESS)
 			return;
 
-		scan_column(resp->data);
-		resp->cmd_sts = EC_SUCCESS;
-
-		/* Reverse the scanned data */
-		for (i = 0; ROW_COUNT - 1 - i > i; ++i) {
-			v = resp->data[i];
-			resp->data[i] = resp->data[ROW_COUNT - 1 - i];
-			resp->data[ROW_COUNT - 1 - i] = v;
+		if (GET_SCAN_NEEDED(col)) {
+			scan_column(resp->data);
+
+			/* Reverse the scanned data */
+			for (i = 0; ROW_COUNT - 1 - i > i; ++i) {
+				v = resp->data[i];
+				resp->data[i] = resp->data[ROW_COUNT - 1 - i];
+				resp->data[ROW_COUNT - 1 - i] = v;
+			}
+			resp->size = ROW_COUNT;
+		} else {
+			resp->size = 0;
 		}
 
-		resp->size = ROW_COUNT;
+		resp->cmd_sts = EC_SUCCESS;
 
 		/* Flush the last response */
 		if (col != 0)
 			spi_slave_send_response_flush();
 
-		if (master_slave_sync(20) != EC_SUCCESS)
+		if (master_slave_sync(40) != EC_SUCCESS)
 			return;
 
 		/* Start sending the response for the current column */
@@ -198,6 +259,13 @@ int touch_scan_full_matrix(void)
 		return EC_ERROR_UNKNOWN;
 
 	encode_reset();
+
+	if (fast_scan(scan_needed) != EC_SUCCESS)
+		return EC_ERROR_UNKNOWN;
+
+	/* Discharge the panel */
+	scan_column(buf[0]);
+
 	for (col = 0; col < COL_COUNT * 2; ++col) {
 		if (col >= COL_COUNT) {
 			enable_col(col - COL_COUNT, 1);
@@ -210,18 +278,24 @@ int touch_scan_full_matrix(void)
 		last_dptr = dptr;
 		dptr = buf[col & 1];
 
-		scan_column(dptr + ROW_COUNT);
+		if (GET_SCAN_NEEDED(col))
+			scan_column(dptr + ROW_COUNT);
+		else
+			memset(dptr + ROW_COUNT, 0, ROW_COUNT);
 
 		if (col > 0) {
 			/* Flush the data from the slave for the last column */
 			resp = spi_master_wait_response_done();
 			if (resp == NULL)
 				return EC_ERROR_UNKNOWN;
-			memcpy(last_dptr, resp->data, ROW_COUNT);
+			if (resp->size)
+				memcpy(last_dptr, resp->data, ROW_COUNT);
+			else
+				memset(last_dptr, 0, ROW_COUNT);
 			encode_add_column(last_dptr);
 		}
 
-		if (master_slave_sync(20) != EC_SUCCESS)
+		if (master_slave_sync(40) != EC_SUCCESS)
 			return EC_ERROR_UNKNOWN;
 
 		/* Start receiving data for the current column */
@@ -237,7 +311,10 @@ int touch_scan_full_matrix(void)
 	resp = spi_master_wait_response_done();
 	if (resp == NULL)
 		return EC_ERROR_UNKNOWN;
-	memcpy(last_dptr, resp->data, ROW_COUNT);
+	if (resp->size)
+		memcpy(last_dptr, resp->data, ROW_COUNT);
+	else
+		memset(last_dptr, 0, ROW_COUNT);
 	encode_add_column(last_dptr);
 
 	master_slave_sync(20);
diff --git a/board/keyborg/touch_scan.h b/board/keyborg/touch_scan.h
index e3f694a1da..2d05ce486b 100644
--- a/board/keyborg/touch_scan.h
+++ b/board/keyborg/touch_scan.h
@@ -21,6 +21,12 @@ enum pin_type {
 /* Threshold for each cell */
 #define THRESHOLD 35
 
+/* Threshold for entire column */
+#define COL_THRESHOLD 16
+
+/* The span width of active columns */
+#define COL_SPAN 5 /* Must not exceed 15 */
+
 /* ADC speed */
 #define ADC_SMPR_VAL 0x2 /* 13.5 cycles */
 #define ADC_SMPL_CYCLE_2 27