ACPI / SBS: Disable smart battery manager on Apple

Touching the smart battery manager at all on Apple hardware appears to
make it unhappy - unplugging the AC adapter triggers accesses that hang
the controller for several minutes. Quirk it out via DMI in order to
avoid this.  Compensate by changing battery presence if we fail to
communicate with the battery.
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>
Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/sbs.c

@@ -35,6 +35,7 @@
 #include <linux/jiffies.h>
 #include <linux/delay.h>
 #include <linux/power_supply.h>
+#include <linux/dmi.h>
 
 #include "sbshc.h"
 #include "battery.h"
@@ -61,6 +62,8 @@ static unsigned int cache_time = 1000;
 module_param(cache_time, uint, 0644);
 MODULE_PARM_DESC(cache_time, "cache time in milliseconds");
 
+static bool sbs_manager_broken;
+
 #define MAX_SBS_BAT			4
 #define ACPI_SBS_BLOCK_MAX		32
 
@@ -494,16 +497,21 @@ static int acpi_battery_read(struct acpi_battery *battery)
 				  ACPI_SBS_MANAGER, 0x01, (u8 *)&state, 2);
 	} else if (battery->id == 0)
 		battery->present = 1;
+
 	if (result || !battery->present)
 		return result;
 
 	if (saved_present != battery->present) {
 		battery->update_time = 0;
 		result = acpi_battery_get_info(battery);
-		if (result)
+		if (result) {
+			battery->present = 0;
 			return result;
+		}
 	}
 	result = acpi_battery_get_state(battery);
+	if (result)
+		battery->present = 0;
 	return result;
 }
 
@@ -535,6 +543,7 @@ static int acpi_battery_add(struct acpi_sbs *sbs, int id)
 	result = power_supply_register(&sbs->device->dev, &battery->bat);
 	if (result)
 		goto end;
+
 	result = device_create_file(battery->bat.dev, &alarm_attr);
 	if (result)
 		goto end;
@@ -613,12 +622,31 @@ static void acpi_sbs_callback(void *context)
 	}
 }
 
+static int disable_sbs_manager(const struct dmi_system_id *d)
+{
+	sbs_manager_broken = true;
+	return 0;
+}
+
+static struct dmi_system_id acpi_sbs_dmi_table[] = {
+	{
+		.callback = disable_sbs_manager,
+		.ident = "Apple",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "Apple Inc.")
+		},
+	},
+	{ },
+};
+
 static int acpi_sbs_add(struct acpi_device *device)
 {
 	struct acpi_sbs *sbs;
 	int result = 0;
 	int id;
 
+	dmi_check_system(acpi_sbs_dmi_table);
+
 	sbs = kzalloc(sizeof(struct acpi_sbs), GFP_KERNEL);
 	if (!sbs) {
 		result = -ENOMEM;
@@ -637,14 +665,21 @@ static int acpi_sbs_add(struct acpi_device *device)
 	if (result && result != -ENODEV)
 		goto end;
 
-	result = acpi_manager_get_info(sbs);
-	if (!result) {
-		sbs->manager_present = 1;
-		for (id = 0; id < MAX_SBS_BAT; ++id)
-			if ((sbs->batteries_supported & (1 << id)))
-				acpi_battery_add(sbs, id);
-	} else
+	result = 0;
+
+	if (!sbs_manager_broken) {
+		result = acpi_manager_get_info(sbs);
+		if (!result) {
+			sbs->manager_present = 0;
+			for (id = 0; id < MAX_SBS_BAT; ++id)
+				if ((sbs->batteries_supported & (1 << id)))
+					acpi_battery_add(sbs, id);
+		}
+	}
+
+	if (!sbs->manager_present)
 		acpi_battery_add(sbs, 0);
+
 	acpi_smbus_register_callback(sbs->hc, acpi_sbs_callback, sbs);
       end:
 	if (result)