support Thinkpad X1 Carbon 2nd generation's adaptive keyboard

Submit patch V4 to support Adaptive Keyboard on Thinkpad X1 Carbon 2nd
generation according to Tobias's comments.

Thanks,
Shuduo

>From b153a7b14791c6e01892c0e274e23eefd625fb8d Mon Sep 17 00:00:00 2001
From: Shuduo Sang <shuduo.sang@canonical.com>
Date: Mon, 3 Mar 2014 14:29:32 +0800
Subject: [PATCH] support thinkpad X1 Carbon's adaptive keyboard

Thinkpad X1 Carbon's adaptive keyboard has five modes including Home
mode, Web browser mode, Web conference mode, Function mode and Lay-flat
mode. We support Home mode and Function mode currently.
Signed-off-by: Bruce Ma <bruce.ma@canonical.com>
Signed-off-by: Shuduo Sang <shuduo.sang@canonical.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>

drivers/platform/x86/thinkpad_acpi.c

@@ -3437,6 +3437,106 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 	return (res < 0)? res : 1;
 }
 
+/* Thinkpad X1 Carbon support 5 modes including Home mode, Web browser
+ * mode, Web conference mode, Function mode and Lay-flat mode.
+ * We support Home mode and Function mode currently.
+ *
+ * Will consider support rest of modes in future.
+ *
+ */
+enum ADAPTIVE_KEY_MODE {
+	HOME_MODE,
+	WEB_BROWSER_MODE,
+	WEB_CONFERENCE_MODE,
+	FUNCTION_MODE,
+	LAYFLAT_MODE
+};
+
+const int adaptive_keyboard_modes[] = {
+	HOME_MODE,
+/*	WEB_BROWSER_MODE = 2,
+	WEB_CONFERENCE_MODE = 3, */
+	FUNCTION_MODE
+};
+
+#define DFR_CHANGE_ROW			0x101
+#define DFR_SHOW_QUICKVIEW_ROW		0x102
+
+/* press Fn key a while second, it will switch to Function Mode. Then
+ * release Fn key, previous mode be restored.
+ */
+static bool adaptive_keyboard_mode_is_saved;
+static int adaptive_keyboard_prev_mode;
+
+static int adaptive_keyboard_get_next_mode(int mode)
+{
+	size_t i;
+	size_t max_mode = ARRAY_SIZE(adaptive_keyboard_modes) - 1;
+
+	for (i = 0; i <= max_mode; i++) {
+		if (adaptive_keyboard_modes[i] == mode)
+			break;
+	}
+
+	if (i >= max_mode)
+		i = 0;
+	else
+		i++;
+
+	return adaptive_keyboard_modes[i];
+}
+
+static bool adaptive_keyboard_hotkey_notify_hotkey(unsigned int scancode)
+{
+	u32 current_mode = 0;
+	int new_mode = 0;
+
+	switch (scancode) {
+	case DFR_CHANGE_ROW:
+		if (adaptive_keyboard_mode_is_saved) {
+			new_mode = adaptive_keyboard_prev_mode;
+			adaptive_keyboard_mode_is_saved = false;
+		} else {
+			if (!acpi_evalf(
+					hkey_handle, &current_mode,
+					"GTRW", "dd", 0)) {
+				pr_err("Cannot read adaptive keyboard mode\n");
+				return false;
+			} else {
+				new_mode = adaptive_keyboard_get_next_mode(
+						current_mode);
+			}
+		}
+
+		if (!acpi_evalf(hkey_handle, NULL, "STRW", "vd", new_mode)) {
+			pr_err("Cannot set adaptive keyboard mode\n");
+			return false;
+		}
+
+		return true;
+
+	case DFR_SHOW_QUICKVIEW_ROW:
+		if (!acpi_evalf(hkey_handle,
+				&adaptive_keyboard_prev_mode,
+				"GTRW", "dd", 0)) {
+			pr_err("Cannot read adaptive keyboard mode\n");
+			return false;
+		} else {
+			adaptive_keyboard_mode_is_saved = true;
+
+			if (!acpi_evalf(hkey_handle,
+					NULL, "STRW", "vd", FUNCTION_MODE)) {
+				pr_err("Cannot set adaptive keyboard mode\n");
+				return false;
+			}
+		}
+		return true;
+
+	default:
+		return false;
+	}
+}
+
 static bool hotkey_notify_hotkey(const u32 hkey,
 				 bool *send_acpi_ev,
 				 bool *ignore_acpi_ev)
@@ -3456,6 +3556,8 @@ static bool hotkey_notify_hotkey(const u32 hkey,
 			*ignore_acpi_ev = true;
 		}
 		return true;
+	} else {
+		return adaptive_keyboard_hotkey_notify_hotkey(scancode);
 	}
 	return false;
 }