ACPI / SBS: Don't assume the existence of an SBS charger

[cascardo/linux.git] / drivers / acpi / sbs.c

diff --git a/drivers/acpi/sbs.c b/drivers/acpi/sbs.c
index 366ca40..b1df4ee 100644 (file)
--- a/drivers/acpi/sbs.c
+++ b/drivers/acpi/sbs.c
@@ -109,6 +109,7 @@ struct acpi_sbs {
        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 @@ static int acpi_ac_get_present(struct acpi_sbs *sbs)
 
        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 @@ static int acpi_charger_add(struct acpi_sbs *sbs)
        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 @@ static void acpi_sbs_callback(void *context)
        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 @@ static int acpi_sbs_add(struct acpi_device *device)
        device->driver_data = sbs;
 
        result = acpi_charger_add(sbs);
-       if (result)
+       if (result && result != -ENODEV)
                goto end;
 
        result = acpi_manager_get_info(sbs);