ACPI / SBS: Don't assume the existence of an SBS charger
Apple hardware continues to expose an ACPI AC charger even when using
SBS to report battery state. The charger status byte returns all 0s in
this case. Since the spec requires that bit 4 be 1 at all times, assume
that there's not really a charger if it's set to zero.
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>
diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 366ca40..b1df4ee 100644
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -109,6 +109,7 @@
u8 batteries_supported:4;
u8 manager_present:1;
u8 charger_present:1;
+ u8 charger_exists:1;
};
#define to_acpi_sbs(x) container_of(x, struct acpi_sbs, charger)
@@ -429,9 +430,19 @@
result = acpi_smbus_read(sbs->hc, SMBUS_READ_WORD, ACPI_SBS_CHARGER,
0x13, (u8 *) & status);
- if (!result)
- sbs->charger_present = (status >> 15) & 0x1;
- return result;
+
+ if (result)
+ return result;
+
+ /*
+ * The spec requires that bit 4 always be 1. If it's not set, assume
+ * that the implementation doesn't support an SBS charger
+ */
+ if (!(status >> 4) & 0x1)
+ return -ENODEV;
+
+ sbs->charger_present = (status >> 15) & 0x1;
+ return 0;
}
static ssize_t acpi_battery_alarm_show(struct device *dev,
@@ -554,6 +565,7 @@
if (result)
goto end;
+ sbs->charger_exists = 1;
sbs->charger.name = "sbs-charger";
sbs->charger.type = POWER_SUPPLY_TYPE_MAINS;
sbs->charger.properties = sbs_ac_props;
@@ -580,9 +592,12 @@
struct acpi_battery *bat;
u8 saved_charger_state = sbs->charger_present;
u8 saved_battery_state;
- acpi_ac_get_present(sbs);
- if (sbs->charger_present != saved_charger_state)
- kobject_uevent(&sbs->charger.dev->kobj, KOBJ_CHANGE);
+
+ if (sbs->charger_exists) {
+ acpi_ac_get_present(sbs);
+ if (sbs->charger_present != saved_charger_state)
+ kobject_uevent(&sbs->charger.dev->kobj, KOBJ_CHANGE);
+ }
if (sbs->manager_present) {
for (id = 0; id < MAX_SBS_BAT; ++id) {
@@ -619,7 +634,7 @@
device->driver_data = sbs;
result = acpi_charger_add(sbs);
- if (result)
+ if (result && result != -ENODEV)
goto end;
result = acpi_manager_get_info(sbs);