[PATCH 2/7] Input: cros_ec_keyb - add function key support
From: Dmitry Torokhov
Date: Sat Feb 21 2026 - 19:38:03 EST
From: Fabio Baltieri <fabiobaltieri@xxxxxxxxxxxx>
Add support for handling an Fn button and sending separate keycodes for
a subset of keys in the matrix defined in the upper half of the keymap.
Signed-off-by: Fabio Baltieri <fabiobaltieri@xxxxxxxxxxxx>
Reviewed-by: Simon Glass <sjg@xxxxxxxxxxxx>
Link: https://patch.msgid.link/20260211173421.1206478-3-fabiobaltieri@xxxxxxxxxxxx
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
---
drivers/input/keyboard/cros_ec_keyb.c | 182 +++++++++++++++++++++++---
1 file changed, 166 insertions(+), 16 deletions(-)
diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
index 066aaa87d93f..bdbfd219f2e8 100644
--- a/drivers/input/keyboard/cros_ec_keyb.c
+++ b/drivers/input/keyboard/cros_ec_keyb.c
@@ -29,6 +29,12 @@
#include <linux/unaligned.h>
+/*
+ * Maximum size of the normal key matrix, this is limited by the host command
+ * key_matrix field defined in ec_response_get_next_data_v3
+ */
+#define CROS_EC_KEYBOARD_COLS_MAX 18
+
/**
* struct cros_ec_keyb - Structure representing EC keyboard device
*
@@ -44,6 +50,9 @@
* @bs_idev: The input device for non-matrix buttons and switches (or NULL).
* @notifier: interrupt event notifier for transport devices
* @vdata: vivaldi function row data
+ * @has_fn_map: whether the driver uses an fn function-map layer
+ * @fn_active: tracks whether the function key is currently pressed
+ * @fn_combo_active: tracks whether another key was pressed while fn is active
*/
struct cros_ec_keyb {
unsigned int rows;
@@ -61,6 +70,10 @@ struct cros_ec_keyb {
struct notifier_block notifier;
struct vivaldi_data vdata;
+
+ bool has_fn_map;
+ bool fn_active;
+ bool fn_combo_active;
};
/**
@@ -166,16 +179,89 @@ static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf)
return false;
}
+static void cros_ec_emit_fn_key(struct input_dev *input, unsigned int pos)
+{
+ input_event(input, EV_MSC, MSC_SCAN, pos);
+ input_report_key(input, KEY_FN, true);
+ input_sync(input);
+
+ input_event(input, EV_MSC, MSC_SCAN, pos);
+ input_report_key(input, KEY_FN, false);
+}
+
+static void cros_ec_keyb_process_key_plain(struct cros_ec_keyb *ckdev,
+ int row, int col, bool state)
+{
+ struct input_dev *idev = ckdev->idev;
+ const unsigned short *keycodes = idev->keycode;
+ int pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
+
+ input_event(idev, EV_MSC, MSC_SCAN, pos);
+ input_report_key(idev, keycodes[pos], state);
+}
+
+static void cros_ec_keyb_process_key_fn_map(struct cros_ec_keyb *ckdev,
+ int row, int col, bool state)
+{
+ struct input_dev *idev = ckdev->idev;
+ const unsigned short *keycodes = idev->keycode;
+ unsigned int pos, fn_pos;
+ unsigned int code, fn_code;
+
+ pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
+ code = keycodes[pos];
+
+ if (code == KEY_FN) {
+ ckdev->fn_active = state;
+ if (state) {
+ ckdev->fn_combo_active = false;
+ } else if (!ckdev->fn_combo_active) {
+ /*
+ * Send both Fn press and release events if nothing
+ * else has been pressed together with Fn.
+ */
+ cros_ec_emit_fn_key(idev, pos);
+ }
+ return;
+ }
+
+ fn_pos = MATRIX_SCAN_CODE(row + ckdev->rows, col, ckdev->row_shift);
+ fn_code = keycodes[fn_pos];
+
+ if (state) {
+ if (ckdev->fn_active) {
+ ckdev->fn_combo_active = true;
+ if (!fn_code)
+ return; /* Discard if no Fn mapping exists */
+
+ code = fn_code;
+ pos = fn_pos;
+ }
+ } else {
+ /*
+ * If the Fn-remapped code is currently pressed, release it.
+ * Otherwise, release the standard code (if it was pressed).
+ */
+ if (fn_code && test_bit(fn_code, idev->key)) {
+ code = fn_code;
+ pos = fn_pos;
+ } else if (!test_bit(code, idev->key)) {
+ return; /* Discard, key press code was not sent */
+ }
+ }
+
+ input_event(idev, EV_MSC, MSC_SCAN, pos);
+ input_report_key(idev, code, state);
+}
/*
* Compares the new keyboard state to the old one and produces key
- * press/release events accordingly. The keyboard state is 13 bytes (one byte
- * per column)
+ * press/release events accordingly. The keyboard state is one byte
+ * per column.
*/
static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev,
uint8_t *kb_state, int len)
{
- struct input_dev *idev = ckdev->idev;
int col, row;
int new_state;
int old_state;
@@ -192,20 +278,19 @@ static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev,
for (col = 0; col < ckdev->cols; col++) {
for (row = 0; row < ckdev->rows; row++) {
- int pos = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
- const unsigned short *keycodes = idev->keycode;
-
new_state = kb_state[col] & (1 << row);
old_state = ckdev->old_kb_state[col] & (1 << row);
- if (new_state != old_state) {
- dev_dbg(ckdev->dev,
- "changed: [r%d c%d]: byte %02x\n",
- row, col, new_state);
-
- input_event(idev, EV_MSC, MSC_SCAN, pos);
- input_report_key(idev, keycodes[pos],
- new_state);
- }
+
+ if (new_state == old_state)
+ continue;
+
+ dev_dbg(ckdev->dev, "changed: [r%d c%d]: byte %02x\n",
+ row, col, new_state);
+
+ if (ckdev->has_fn_map)
+ cros_ec_keyb_process_key_fn_map(ckdev, row, col, new_state);
+ else
+ cros_ec_keyb_process_key_plain(ckdev, row, col, new_state);
}
ckdev->old_kb_state[col] = kb_state[col];
}
@@ -583,6 +668,62 @@ static void cros_ec_keyb_parse_vivaldi_physmap(struct cros_ec_keyb *ckdev)
ckdev->vdata.num_function_row_keys = n_physmap;
}
+/* Returns true if there is a KEY_FN code defined in the normal keymap */
+static bool cros_ec_keyb_has_fn_key(struct cros_ec_keyb *ckdev)
+{
+ const unsigned short *keycodes = ckdev->idev->keycode;
+ int i;
+
+ for (i = 0; i < MATRIX_SCAN_CODE(ckdev->rows, 0, ckdev->row_shift); i++) {
+ if (keycodes[i] == KEY_FN)
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Returns true if there is a KEY_FN defined and at least one key in the fn
+ * layer keymap
+ */
+static bool cros_ec_keyb_has_fn_map(struct cros_ec_keyb *ckdev)
+{
+ struct input_dev *idev = ckdev->idev;
+ const unsigned short *keycodes = ckdev->idev->keycode;
+ int i;
+
+ if (!cros_ec_keyb_has_fn_key(ckdev))
+ return false;
+
+ for (i = MATRIX_SCAN_CODE(ckdev->rows, 0, ckdev->row_shift);
+ i < idev->keycodemax; i++) {
+ if (keycodes[i] != KEY_RESERVED)
+ return true;
+ }
+
+ return false;
+}
+
+/*
+ * Custom handler for the set keycode ioctl, calls the default handler and
+ * recomputes has_fn_map.
+ */
+static int cros_ec_keyb_setkeycode(struct input_dev *idev,
+ const struct input_keymap_entry *ke,
+ unsigned int *old_keycode)
+{
+ struct cros_ec_keyb *ckdev = input_get_drvdata(idev);
+ int ret;
+
+ ret = input_default_setkeycode(idev, ke, old_keycode);
+ if (ret)
+ return ret;
+
+ ckdev->has_fn_map = cros_ec_keyb_has_fn_map(ckdev);
+
+ return 0;
+}
+
/**
* cros_ec_keyb_register_matrix - Register matrix keys
*
@@ -604,6 +745,12 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
if (err)
return err;
+ if (ckdev->cols > CROS_EC_KEYBOARD_COLS_MAX) {
+ dev_err(dev, "keypad,num-columns too large: %d (max: %d)\n",
+ ckdev->cols, CROS_EC_KEYBOARD_COLS_MAX);
+ return -EINVAL;
+ }
+
ckdev->valid_keys = devm_kzalloc(dev, ckdev->cols, GFP_KERNEL);
if (!ckdev->valid_keys)
return -ENOMEM;
@@ -632,11 +779,12 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
idev->id.version = 1;
idev->id.product = 0;
idev->dev.parent = dev;
+ idev->setkeycode = cros_ec_keyb_setkeycode;
ckdev->ghost_filter = device_property_read_bool(dev,
"google,needs-ghost-filter");
- err = matrix_keypad_build_keymap(NULL, ckdev->rows, ckdev->cols,
+ err = matrix_keypad_build_keymap(NULL, ckdev->rows * 2, ckdev->cols,
NULL, idev);
if (err) {
dev_err(dev, "cannot build key matrix\n");
@@ -651,6 +799,8 @@ static int cros_ec_keyb_register_matrix(struct cros_ec_keyb *ckdev)
cros_ec_keyb_compute_valid_keys(ckdev);
cros_ec_keyb_parse_vivaldi_physmap(ckdev);
+ ckdev->has_fn_map = cros_ec_keyb_has_fn_map(ckdev);
+
err = input_register_device(ckdev->idev);
if (err) {
dev_err(dev, "cannot register input device\n");
--
2.53.0.345.g96ddfc5eaa-goog