Input: atkbd - receive and use physcode->keycode mapping from FW

Allow the firmware to specify the mapping between the scan code and the
linux keycode. This takes the form of a "linux,keymap" property which is
an array of u32 values, each value specifying mapping for a key.

Signed-off-by: Rajat Jain <rajatja@google.com>
Link: https://lore.kernel.org/r/20200427210259.91330-3-rajatja@google.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/atkbd.c

@@ -66,6 +66,9 @@ MODULE_PARM_DESC(terminal, "Enable break codes on an IBM Terminal keyboard conne
 
 #define MAX_FUNCTION_ROW_KEYS	24
 
+#define SCANCODE(keymap)	((keymap >> 16) & 0xFFFF)
+#define KEYCODE(keymap)		(keymap & 0xFFFF)
+
 /*
  * Scancode to keycode tables. These are just the default setting, and
  * are loadable via a userland utility.
@@ -1032,6 +1035,39 @@ static unsigned int atkbd_oqo_01plus_scancode_fixup(struct atkbd *atkbd,
 	return code;
 }
 
+static int atkbd_get_keymap_from_fwnode(struct atkbd *atkbd)
+{
+	struct device *dev = &atkbd->ps2dev.serio->dev;
+	int i, n;
+	u32 *ptr;
+	u16 scancode, keycode;
+
+	/* Parse "linux,keymap" property */
+	n = device_property_count_u32(dev, "linux,keymap");
+	if (n <= 0 || n > ATKBD_KEYMAP_SIZE)
+		return -ENXIO;
+
+	ptr = kcalloc(n, sizeof(u32), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
+	if (device_property_read_u32_array(dev, "linux,keymap", ptr, n)) {
+		dev_err(dev, "problem parsing FW keymap property\n");
+		kfree(ptr);
+		return -EINVAL;
+	}
+
+	memset(atkbd->keycode, 0, sizeof(atkbd->keycode));
+	for (i = 0; i < n; i++) {
+		scancode = SCANCODE(ptr[i]);
+		keycode = KEYCODE(ptr[i]);
+		atkbd->keycode[scancode] = keycode;
+	}
+
+	kfree(ptr);
+	return 0;
+}
+
 /*
  * atkbd_set_keycode_table() initializes keyboard's keycode table
  * according to the selected scancode set
@@ -1039,13 +1075,16 @@ static unsigned int atkbd_oqo_01plus_scancode_fixup(struct atkbd *atkbd,
 
 static void atkbd_set_keycode_table(struct atkbd *atkbd)
 {
+	struct device *dev = &atkbd->ps2dev.serio->dev;
 	unsigned int scancode;
 	int i, j;
 
 	memset(atkbd->keycode, 0, sizeof(atkbd->keycode));
 	bitmap_zero(atkbd->force_release_mask, ATKBD_KEYMAP_SIZE);
 
-	if (atkbd->translated) {
+	if (!atkbd_get_keymap_from_fwnode(atkbd)) {
+		dev_dbg(dev, "Using FW keymap\n");
+	} else if (atkbd->translated) {
 		for (i = 0; i < 128; i++) {
 			scancode = atkbd_unxlate_table[i];
 			atkbd->keycode[i] = atkbd_set2_keycode[scancode];