keyboard_scan: Add option to support keyboards with language ID

ID pins are considered additional KSOs while keycode scanning works
for the existing KSI0 ~ KSI7. While diriving ID pins, the state of
interconnection between ID pins and KSI pins could be used for
identifiers to tell keyboard itself. (e.g. US, Japan,and UK keyboard)

BRANCH=master
BUG=b:80168723
TEST="make -j buildall"
TEST=Verified 5 distinct keyboard samples w/ different Language ID values
     on the same reworked Coral, which VOL_UP and VOL_DOWN were reworked
     for ID pins. crrev.com/c/1053617 is my experimental patch on top of
     this for further verification

Change-Id: I1d6e647df74c50d60bc1264c045b2587d0bf23d8
Signed-off-by: paris_yeh <pyeh@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1068951
Commit-Ready: Paris Yeh <pyeh@chromium.org>
Tested-by: Paris Yeh <pyeh@chromium.org>
Reviewed-by: Paris Yeh <pyeh@chromium.org>
Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

1 files changed, 37 insertions, 0 deletions

diff --git a/common/keyboard_scan.c b/common/keyboard_scan.c
index fee48e6a26..96dececd78 100644
--- a/common/keyboard_scan.c
+++ b/common/keyboard_scan.c
@@ -89,6 +89,9 @@ static uint8_t __bss_slow prev_state[KEYBOARD_COLS];
 static uint8_t __bss_slow debouncing[KEYBOARD_COLS];
 /* Keys simulated-pressed */
 static uint8_t __bss_slow simulated_key[KEYBOARD_COLS];
+#ifdef CONFIG_KEYBOARD_LANGUAGE_ID
+static uint8_t __bss_slow keyboard_id[KEYBOARD_IDS];
+#endif
 
 /* Times of last scans */
 static uint32_t __bss_slow scan_time[SCAN_TIME_COUNT];
@@ -275,6 +278,35 @@ static int read_matrix(uint8_t *state)
 	return pressed ? 1 : 0;
 }
 
+#ifdef CONFIG_KEYBOARD_LANGUAGE_ID
+/**
+ * Read the raw keyboard IDs state.
+ *
+ * Used in pre-init, so must not make task-switching-dependent calls; udelay()
+ * is ok because it's a spin-loop.
+ *
+ * @param id		Destination for keyboard id (must be KEYBOARD_IDS long).
+ *
+ */
+static void read_matrix_id(uint8_t *id)
+{
+	int c;
+
+	for (c = 0; c < KEYBOARD_IDS; c++) {
+		/* Select the ID pin, then wait a bit for it to settle */
+		keyboard_raw_drive_column(KEYBOARD_COLS + c);
+		udelay(keyscan_config.output_settle_us);
+
+		/* Read the row state */
+		id[c] = keyboard_raw_read_rows();
+
+		CPRINTS("Keyboard ID%u: 0x%02x\n", c, id[c]);
+	}
+
+	keyboard_raw_drive_column(KEYBOARD_COLUMN_NONE);
+}
+#endif
+
 #ifdef CONFIG_KEYBOARD_RUNTIME_KEYS
 /**
  * Check special runtime key combinations.
@@ -647,6 +679,11 @@ void keyboard_scan_init(void)
 	read_matrix(debounced_state);
 	memcpy(prev_state, debounced_state, sizeof(prev_state));
 
+#ifdef CONFIG_KEYBOARD_LANGUAGE_ID
+	/* Check keyboard ID state */
+	read_matrix_id(keyboard_id);
+#endif
+
 #ifdef CONFIG_KEYBOARD_BOOT_KEYS
 	/* Check for keys held down at boot */
 	boot_key_value = check_boot_key(debounced_state);