ACPI: thinkpad-acpi: add tablet-mode reporting

A quick study of the 0x5009/0x500A HKEY event on the X61t DSDT revealed the
existence of the EC HTAB register (EC 0x0f, bit 7), and a compare with the
X41t DSDT shows that HKEY.MHKG can be used to verify if the ThinkPad is
tablet-capable (MHKG present), and in tablet mode (bit 3 of MHKG return is
set).

Add an attribute to report this information, "hotkey_tablet_mode".  This
attribute has poll()/select() support, and can be used along with EV_SW
SW_TABLET_MODE to hook userspace to tablet events.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>

2 files changed, 75 insertions, 11 deletions

diff --git a/Documentation/laptops/thinkpad-acpi.txt b/Documentation/laptops/thinkpad-acpi.txt
index 606af1628382..76cb428435da 100644
--- a/Documentation/laptops/thinkpad-acpi.txt
+++ b/Documentation/laptops/thinkpad-acpi.txt
@@ -313,6 +313,13 @@ sysfs notes:
 
                 This attribute has poll()/select() support.
 
+        hotkey_tablet_mode:
+                If the ThinkPad has tablet capabilities, this attribute
+                will read 0 if the ThinkPad is in normal mode, and
+                1 if the ThinkPad is in tablet mode.
+
+                This attribute has poll()/select() support.
+
         hotkey_report_mode:
                 Returns the state of the procfs ACPI event report mode
                 filter for hot keys.  If it is set to 1 (the default),
diff --git a/drivers/misc/thinkpad_acpi.c b/drivers/misc/thinkpad_acpi.c
index c119cf23e1ff..bb269d0c677e 100644
--- a/drivers/misc/thinkpad_acpi.c
+++ b/drivers/misc/thinkpad_acpi.c
@@ -221,6 +221,7 @@ static struct {
         u32 hotkey:1;
         u32 hotkey_mask:1;
         u32 hotkey_wlsw:1;
+        u32 hotkey_tablet:1;
         u32 light:1;
         u32 light_status:1;
         u32 bright_16levels:1;
@@ -1060,6 +1061,9 @@ static struct attribute_set *hotkey_dev_attributes;
 #define HOTKEY_CONFIG_CRITICAL_END
 #endif /* CONFIG_THINKPAD_ACPI_HOTKEY_POLL */
 
+/* HKEY.MHKG() return bits */
+#define TP_HOTKEY_TABLET_MASK (1 << 3)
+
 static int hotkey_get_wlsw(int *status)
 {
         if (!acpi_evalf(hkey_handle, status, "WLSW", "d"))
@@ -1067,6 +1071,16 @@ static int hotkey_get_wlsw(int *status)
         return 0;
 }
 
+static int hotkey_get_tablet_mode(int *status)
+{
+        int s;
+
+        if (!acpi_evalf(hkey_handle, &s, "MHKG", "d"))
+                return -EIO;
+
+        return ((s & TP_HOTKEY_TABLET_MASK) != 0);
+}
+
 /*
  * Call with hotkey_mutex held
  */
@@ -1172,15 +1186,20 @@ static void tpacpi_input_send_radiosw(void)
         }
 }
 
-static void tpacpi_input_send_tabletsw(unsigned int state)
+static void tpacpi_input_send_tabletsw(void)
 {
-        mutex_lock(&tpacpi_inputdev_send_mutex);
+        int state;
 
-        input_report_switch(tpacpi_inputdev,
-                            SW_TABLET_MODE, !!state);
-        input_sync(tpacpi_inputdev);
+        if (tp_features.hotkey_tablet &&
+            !hotkey_get_tablet_mode(&state)) {
+                mutex_lock(&tpacpi_inputdev_send_mutex);
 
-        mutex_unlock(&tpacpi_inputdev_send_mutex);
+                input_report_switch(tpacpi_inputdev,
+                                    SW_TABLET_MODE, !!state);
+                input_sync(tpacpi_inputdev);
+
+                mutex_unlock(&tpacpi_inputdev_send_mutex);
+        }
 }
 
 static void tpacpi_input_send_key(unsigned int scancode)
@@ -1691,6 +1710,29 @@ static void hotkey_radio_sw_notify_change(void)
                              "hotkey_radio_sw");
 }
 
+/* sysfs hotkey tablet mode (pollable) --------------------------------- */
+static ssize_t hotkey_tablet_mode_show(struct device *dev,
+                           struct device_attribute *attr,
+                           char *buf)
+{
+        int res, s;
+        res = hotkey_get_tablet_mode(&s);
+        if (res < 0)
+                return res;
+
+        return snprintf(buf, PAGE_SIZE, "%d\n", !!s);
+}
+
+static struct device_attribute dev_attr_hotkey_tablet_mode =
+        __ATTR(hotkey_tablet_mode, S_IRUGO, hotkey_tablet_mode_show, NULL);
+
+static void hotkey_tablet_mode_notify_change(void)
+{
+        if (tp_features.hotkey_tablet)
+                sysfs_notify(&tpacpi_pdev->dev.kobj, NULL,
+                             "hotkey_tablet_mode");
+}
+
 /* sysfs hotkey report_mode -------------------------------------------- */
 static ssize_t hotkey_report_mode_show(struct device *dev,
                            struct device_attribute *attr,
@@ -1903,7 +1945,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
                 str_supported(tp_features.hotkey));
 
         if (tp_features.hotkey) {
-                hotkey_dev_attributes = create_attr_set(12, NULL);
+                hotkey_dev_attributes = create_attr_set(13, NULL);
                 if (!hotkey_dev_attributes)
                         return -ENOMEM;
                 res = add_many_to_attr_set(hotkey_dev_attributes,
@@ -1982,6 +2024,18 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
                                         &dev_attr_hotkey_radio_sw.attr);
                 }
 
+                /* For X41t, X60t, X61t Tablets... */
+                if (!res && acpi_evalf(hkey_handle, &status, "MHKG", "qd")) {
+                        tp_features.hotkey_tablet = 1;
+                        printk(TPACPI_INFO
+                                "possible tablet mode switch found; "
+                                "ThinkPad in %s mode\n",
+                                (status & TP_HOTKEY_TABLET_MASK)?
+                                        "tablet" : "laptop");
+                        res = add_to_attr_set(hotkey_dev_attributes,
+                                        &dev_attr_hotkey_tablet_mode.attr);
+                }
+
                 if (!res)
                         res = register_attr_set_with_sysfs(
                                         hotkey_dev_attributes,
@@ -2031,7 +2085,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
                         set_bit(EV_SW, tpacpi_inputdev->evbit);
                         set_bit(SW_RADIO, tpacpi_inputdev->swbit);
                 }
-                if (thinkpad_id.vendor == PCI_VENDOR_ID_LENOVO) {
+                if (tp_features.hotkey_tablet) {
                         set_bit(EV_SW, tpacpi_inputdev->evbit);
                         set_bit(SW_TABLET_MODE, tpacpi_inputdev->swbit);
                 }
@@ -2057,6 +2111,7 @@ static int __init hotkey_init(struct ibm_init_struct *iibm)
 
                 hotkey_poll_setup_safe(1);
                 tpacpi_input_send_radiosw();
+                tpacpi_input_send_tabletsw();
         }
 
         return (tp_features.hotkey)? 0 : 1;
@@ -2187,9 +2242,10 @@ static void hotkey_notify(struct ibm_struct *ibm, u32 event)
                         case 0x500b: /* X61t: tablet pen inserted into bay */
                         case 0x500c: /* X61t: tablet pen removed from bay */
                                 break;
-                        case 0x5009: /* X61t: swivel up (tablet mode) */
-                        case 0x500a: /* X61t: swivel down (normal mode) */
-                                tpacpi_input_send_tabletsw((hkey == 0x5009));
+                        case 0x5009: /* X41t-X61t: swivel up (tablet mode) */
+                        case 0x500a: /* X41t-X61t: swivel down (normal mode) */
+                                tpacpi_input_send_tabletsw();
+                                hotkey_tablet_mode_notify_change();
                                 send_acpi_ev = 0;
                                 break;
                         case 0x5001:
@@ -2250,6 +2306,7 @@ static void hotkey_resume(void)
                        "from firmware\n");
         tpacpi_input_send_radiosw();
         hotkey_radio_sw_notify_change();
+        hotkey_tablet_mode_notify_change();
         hotkey_wakeup_reason_notify_change();
         hotkey_wakeup_hotunplug_complete_notify_change();
         hotkey_poll_setup_safe(0);