ACPI: Cache battery status instead of re-evaluating AML

/proc exports _BST in a single file, and _BST is re-evaulated
whenever that file is read.

Sometimes user-space reads this file frequently, and on some
systems _BST takes a long time to evaluate due to a slow EC.

Further, when we move to sysfs, the values returned from _BST
will be in multiple files, and evaluating _BST for each
file read would make matters worse.

Here code is added to support caching the results of _BST.
A new module parameter "update_time" tells how many seconds the
cached _BST should be used before it is re-evaluated.
Currently, update_time defaults to 0, and so the
existing behaviour of re-evaluating on each read retained.

Signed-off-by: Vladimir Lebedev <vladimir.p.lebedev@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

1 files changed, 441 insertions, 172 deletions

diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
index df04f87dd491..f3b0024e5760 100644
--- a/drivers/acpi/battery.c
+++ b/drivers/acpi/battery.c
@@ -52,12 +52,24 @@
 #define ACPI_BATTERY_UNITS_AMPS         "mA"
 
 #define _COMPONENT              ACPI_BATTERY_COMPONENT
+
+#define ACPI_BATTERY_UPDATE_TIME        0
+
+#define ACPI_BATTERY_NONE_UPDATE        0
+#define ACPI_BATTERY_EASY_UPDATE        1
+#define ACPI_BATTERY_INIT_UPDATE        2
+
 ACPI_MODULE_NAME("battery");
 
 MODULE_AUTHOR("Paul Diefenbaugh");
 MODULE_DESCRIPTION("ACPI Battery Driver");
 MODULE_LICENSE("GPL");
 
+static unsigned int update_time = ACPI_BATTERY_UPDATE_TIME;
+
+/* 0 - every time, > 0 - by update_time */
+module_param(update_time, uint, 0644);
+
 extern struct proc_dir_entry *acpi_lock_battery_dir(void);
 extern void *acpi_unlock_battery_dir(struct proc_dir_entry *acpi_battery_dir);
 
@@ -100,32 +112,117 @@ struct acpi_battery_info {
 };
 
 struct acpi_battery_flags {
-        u8 present:1;           /* Bay occupied? */
-        u8 power_unit:1;        /* 0=watts, 1=apms */
-        u8 alarm:1;             /* _BTP present? */
-        u8 reserved:5;
-};
-
-struct acpi_battery_trips {
-        unsigned long warning;
-        unsigned long low;
+        u8 battery_present_prev;
+        u8 alarm_present;
+        u8 init_update;
+        u8 info_update;
+        u8 state_update;
+        u8 alarm_update;
+        u8 power_unit;
 };
 
 struct acpi_battery {
+        struct mutex mutex;
         struct acpi_device * device;
         struct acpi_battery_flags flags;
-        struct acpi_battery_trips trips;
+        struct acpi_buffer bif_data;
+        struct acpi_buffer bst_data;
         unsigned long alarm;
-        struct acpi_battery_info *info;
+        unsigned long info_update_time;
+        unsigned long state_update_time;
+        unsigned long alarm_update_time;
 };
 
+#define acpi_battery_present(battery) battery->device->status.battery_present
+#define acpi_battery_present_prev(battery) battery->flags.battery_present_prev
+#define acpi_battery_alarm_present(battery) battery->flags.alarm_present
+#define acpi_battery_init_update_flag(battery) battery->flags.init_update
+#define acpi_battery_info_update_flag(battery) battery->flags.info_update
+#define acpi_battery_state_update_flag(battery) battery->flags.state_update
+#define acpi_battery_alarm_update_flag(battery) battery->flags.alarm_update
+#define acpi_battery_power_units(battery) battery->flags.power_unit ? \
+                ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS
+#define acpi_battery_handle(battery) battery->device->handle
+#define acpi_battery_inserted(battery) (!acpi_battery_present_prev(battery) & acpi_battery_present(battery))
+#define acpi_battery_removed(battery) (acpi_battery_present_prev(battery) & !acpi_battery_present(battery))
+#define acpi_battery_bid(battery) acpi_device_bid(battery->device)
+#define acpi_battery_status_str(battery) acpi_battery_present(battery) ? "present" : "absent"
+
 /* --------------------------------------------------------------------------
                                Battery Management
    -------------------------------------------------------------------------- */
 
-static int
-acpi_battery_get_info(struct acpi_battery *battery,
-                      struct acpi_battery_info **bif)
+static void acpi_battery_mutex_lock(struct acpi_battery *battery)
+{
+        mutex_lock(&battery->mutex);
+}
+
+static void acpi_battery_mutex_unlock(struct acpi_battery *battery)
+{
+        mutex_unlock(&battery->mutex);
+}
+
+static void acpi_battery_check_result(struct acpi_battery *battery, int result)
+{
+        if (!battery)
+                return;
+
+        if (result) {
+                acpi_battery_init_update_flag(battery) = 1;
+        }
+}
+
+static int acpi_battery_extract_package(struct acpi_battery *battery,
+                                        union acpi_object *package,
+                                        struct acpi_buffer *format,
+                                        struct acpi_buffer *data,
+                                        char *package_name)
+{
+        acpi_status status = AE_OK;
+        struct acpi_buffer data_null = { 0, NULL };
+
+        status = acpi_extract_package(package, format, &data_null);
+        if (status != AE_BUFFER_OVERFLOW) {
+                ACPI_EXCEPTION((AE_INFO, status, "Extracting size %s",
+                                package_name));
+                return -ENODEV;
+        }
+
+        if (data_null.length != data->length) {
+                if (data->pointer) {
+                        kfree(data->pointer);
+                }
+                data->pointer = kzalloc(data_null.length, GFP_KERNEL);
+                if (!data->pointer) {
+                        ACPI_EXCEPTION((AE_INFO, AE_NO_MEMORY, "kzalloc()"));
+                        return -ENOMEM;
+                }
+                data->length = data_null.length;
+        }
+
+        status = acpi_extract_package(package, format, data);
+        if (ACPI_FAILURE(status)) {
+                ACPI_EXCEPTION((AE_INFO, status, "Extracting %s",
+                                package_name));
+                return -ENODEV;
+        }
+
+        return 0;
+}
+
+static int acpi_battery_get_status(struct acpi_battery *battery)
+{
+        int result = 0;
+
+        result = acpi_bus_get_status(battery->device);
+        if (result) {
+                ACPI_EXCEPTION((AE_INFO, AE_ERROR, "Evaluating _STA"));
+                return -ENODEV;
+        }
+        return result;
+}
+
+static int acpi_battery_get_info(struct acpi_battery *battery)
 {
         int result = 0;
         acpi_status status = 0;
@@ -133,16 +230,18 @@ acpi_battery_get_info(struct acpi_battery *battery,
         struct acpi_buffer format = { sizeof(ACPI_BATTERY_FORMAT_BIF),
                 ACPI_BATTERY_FORMAT_BIF
         };
-        struct acpi_buffer data = { 0, NULL };
         union acpi_object *package = NULL;
+        struct acpi_buffer *data = NULL;
+        struct acpi_battery_info *bif = NULL;
 
+        battery->info_update_time = get_seconds();
 
-        if (!battery || !bif)
-                return -EINVAL;
+        if (!acpi_battery_present(battery))
+                return 0;
 
         /* Evalute _BIF */
 
-        status = acpi_evaluate_object(battery->device->handle, "_BIF", NULL, &buffer);
+        status = acpi_evaluate_object(acpi_battery_handle(battery), "_BIF", NULL, &buffer);
         if (ACPI_FAILURE(status)) {
                 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _BIF"));
                 return -ENODEV;
@@ -150,41 +249,29 @@ acpi_battery_get_info(struct acpi_battery *battery,
 
         package = buffer.pointer;
 
+        data = &battery->bif_data;
+
         /* Extract Package Data */
 
-        status = acpi_extract_package(package, &format, &data);
-        if (status != AE_BUFFER_OVERFLOW) {
-                ACPI_EXCEPTION((AE_INFO, status, "Extracting _BIF"));
-                result = -ENODEV;
+        result = acpi_battery_extract_package(battery, package, &format, data, "_BIF");
+        if (result)
                 goto end;
-        }
 
-        data.pointer = kzalloc(data.length, GFP_KERNEL);
-        if (!data.pointer) {
-                result = -ENOMEM;
-                goto end;
-        }
+      end:
 
-        status = acpi_extract_package(package, &format, &data);
-        if (ACPI_FAILURE(status)) {
-                ACPI_EXCEPTION((AE_INFO, status, "Extracting _BIF"));
-                kfree(data.pointer);
-                result = -ENODEV;
-                goto end;
+        if (buffer.pointer) {
+                kfree(buffer.pointer);
         }
 
-      end:
-        kfree(buffer.pointer);
-
-        if (!result)
-                (*bif) = data.pointer;
+        if (!result) {
+                bif = data->pointer;
+                battery->flags.power_unit = bif->power_unit;
+        }
 
         return result;
 }
 
-static int
-acpi_battery_get_state(struct acpi_battery *battery,
-                        struct acpi_battery_state **bst)
+static int acpi_battery_get_state(struct acpi_battery *battery)
 {
         int result = 0;
         acpi_status status = 0;
@@ -192,16 +279,17 @@ acpi_battery_get_state(struct acpi_battery *battery,
         struct acpi_buffer format = { sizeof(ACPI_BATTERY_FORMAT_BST),
                 ACPI_BATTERY_FORMAT_BST
         };
-        struct acpi_buffer data = { 0, NULL };
         union acpi_object *package = NULL;
+        struct acpi_buffer *data = NULL;
 
+        battery->state_update_time = get_seconds();
 
-        if (!battery || !bst)
-                return -EINVAL;
+        if (!acpi_battery_present(battery))
+                return 0;
 
         /* Evalute _BST */
 
-        status = acpi_evaluate_object(battery->device->handle, "_BST", NULL, &buffer);
+        status = acpi_evaluate_object(acpi_battery_handle(battery), "_BST", NULL, &buffer);
         if (ACPI_FAILURE(status)) {
                 ACPI_EXCEPTION((AE_INFO, status, "Evaluating _BST"));
                 return -ENODEV;
@@ -209,55 +297,46 @@ acpi_battery_get_state(struct acpi_battery *battery,
 
         package = buffer.pointer;
 
-        /* Extract Package Data */
+        data = &battery->bst_data;
 
-        status = acpi_extract_package(package, &format, &data);
-        if (status != AE_BUFFER_OVERFLOW) {
-                ACPI_EXCEPTION((AE_INFO, status, "Extracting _BST"));
-                result = -ENODEV;
-                goto end;
-        }
+        /* Extract Package Data */
 
-        data.pointer = kzalloc(data.length, GFP_KERNEL);
-        if (!data.pointer) {
-                result = -ENOMEM;
+        result = acpi_battery_extract_package(battery, package, &format, data, "_BST");
+        if (result)
                 goto end;
-        }
 
-        status = acpi_extract_package(package, &format, &data);
-        if (ACPI_FAILURE(status)) {
-                ACPI_EXCEPTION((AE_INFO, status, "Extracting _BST"));
-                kfree(data.pointer);
-                result = -ENODEV;
-                goto end;
+      end:
+        if (buffer.pointer) {
+                kfree(buffer.pointer);
         }
 
-      end:
-        kfree(buffer.pointer);
+        return result;
+}
 
-        if (!result)
-                (*bst) = data.pointer;
+static int acpi_battery_get_alarm(struct acpi_battery *battery)
+{
+        battery->alarm_update_time = get_seconds();
 
-        return result;
+        return 0;
 }
 
-static int
-acpi_battery_set_alarm(struct acpi_battery *battery, unsigned long alarm)
+static int acpi_battery_set_alarm(struct acpi_battery *battery, unsigned long alarm)
 {
         acpi_status status = 0;
         union acpi_object arg0 = { ACPI_TYPE_INTEGER };
         struct acpi_object_list arg_list = { 1, &arg0 };
 
+        battery->alarm_update_time = get_seconds();
 
-        if (!battery)
-                return -EINVAL;
+        if (!acpi_battery_present(battery))
+                return -ENODEV;
 
-        if (!battery->flags.alarm)
+        if (!acpi_battery_alarm_present(battery))
                 return -ENODEV;
 
         arg0.integer.value = alarm;
 
-        status = acpi_evaluate_object(battery->device->handle, "_BTP", &arg_list, NULL);
+        status = acpi_evaluate_object(acpi_battery_handle(battery), "_BTP", &arg_list, NULL);
         if (ACPI_FAILURE(status))
                 return -ENODEV;
 
@@ -268,65 +347,110 @@ acpi_battery_set_alarm(struct acpi_battery *battery, unsigned long alarm)
         return 0;
 }
 
-static int acpi_battery_check(struct acpi_battery *battery)
+static int acpi_battery_init_alarm(struct acpi_battery *battery)
 {
         int result = 0;
         acpi_status status = AE_OK;
         acpi_handle handle = NULL;
-        struct acpi_device *device = NULL;
-        struct acpi_battery_info *bif = NULL;
-
+        struct acpi_battery_info *bif = battery->bif_data.pointer;
+        unsigned long alarm = battery->alarm;
 
-        if (!battery)
-                return -EINVAL;
+        /* See if alarms are supported, and if so, set default */
 
-        device = battery->device;
+        status = acpi_get_handle(acpi_battery_handle(battery), "_BTP", &handle);
+        if (ACPI_SUCCESS(status)) {
+                acpi_battery_alarm_present(battery) = 1;
+                if (!alarm && bif) {
+                        alarm = bif->design_capacity_warning;
+                }
+                result = acpi_battery_set_alarm(battery, alarm);
+                if (result)
+                        goto end;
+        } else {
+                acpi_battery_alarm_present(battery) = 0;
+        }
 
-        result = acpi_bus_get_status(device);
-        if (result)
-                return result;
+      end:
 
-        /* Insertion? */
+        return result;
+}
 
-        if (!battery->flags.present && device->status.battery_present) {
+static int acpi_battery_init_update(struct acpi_battery *battery)
+{
+        int result = 0;
 
-                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Battery inserted\n"));
+        result = acpi_battery_get_status(battery);
+        if (result)
+                return result;
 
-                /* Evalute _BIF to get certain static information */
+        acpi_battery_present_prev(battery) = acpi_battery_present(battery);
 
-                result = acpi_battery_get_info(battery, &bif);
+        if (acpi_battery_present(battery)) {
+                result = acpi_battery_get_info(battery);
+                if (result)
+                        return result;
+                result = acpi_battery_get_state(battery);
                 if (result)
                         return result;
 
-                battery->flags.power_unit = bif->power_unit;
-                battery->trips.warning = bif->design_capacity_warning;
-                battery->trips.low = bif->design_capacity_low;
-                kfree(bif);
+                acpi_battery_init_alarm(battery);
+        }
+
+        return result;
+}
+
+static int acpi_battery_update(struct acpi_battery *battery,
+                           int update, int *update_result_ptr)
+{
+        int result = 0;
+        int update_result = ACPI_BATTERY_NONE_UPDATE;
 
-                /* See if alarms are supported, and if so, set default */
+        if (!acpi_battery_present(battery)) {
+                update = 1;
+        }
 
-                status = acpi_get_handle(battery->device->handle, "_BTP", &handle);
-                if (ACPI_SUCCESS(status)) {
-                        battery->flags.alarm = 1;
-                        acpi_battery_set_alarm(battery, battery->trips.warning);
+        if (acpi_battery_init_update_flag(battery)) {
+                result = acpi_battery_init_update(battery);
+                if (result)
+                        goto end;;
+                update_result = ACPI_BATTERY_INIT_UPDATE;
+        } else if (update) {
+                result = acpi_battery_get_status(battery);
+                if (result)
+                        goto end;;
+                if (acpi_battery_inserted(battery) || acpi_battery_removed(battery)) {
+                        result = acpi_battery_init_update(battery);
+                        if (result)
+                                goto end;;
+                        update_result = ACPI_BATTERY_INIT_UPDATE;
+                } else {
+                        update_result = ACPI_BATTERY_EASY_UPDATE;
                 }
         }
 
-        /* Removal? */
+      end:
 
-        else if (battery->flags.present && !device->status.battery_present) {
-                ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Battery removed\n"));
-        }
+        acpi_battery_init_update_flag(battery) = (result != 0);
 
-        battery->flags.present = device->status.battery_present;
+        *update_result_ptr = update_result;
 
         return result;
 }
 
-static void acpi_battery_check_present(struct acpi_battery *battery)
+static void acpi_battery_notify_update(struct acpi_battery *battery)
 {
-        if (!battery->flags.present) {
-                acpi_battery_check(battery);
+        acpi_battery_get_status(battery);
+
+        if (acpi_battery_init_update_flag(battery)) {
+                return;
+        }
+
+        if (acpi_battery_inserted(battery) || acpi_battery_removed(battery)) {
+                acpi_battery_init_update_flag(battery) = 1;
+        } else {
+                acpi_battery_info_update_flag(battery) = 1;
+                acpi_battery_state_update_flag(battery) = 1;
+                acpi_battery_alarm_update_flag(battery) = 1;
         }
 }
 
@@ -335,37 +459,33 @@ static void acpi_battery_check_present(struct acpi_battery *battery)
    -------------------------------------------------------------------------- */
 
 static struct proc_dir_entry *acpi_battery_dir;
-static int acpi_battery_read_info(struct seq_file *seq, void *offset)
+
+static int acpi_battery_read_info_print(struct seq_file *seq, int result)
 {
-        int result = 0;
         struct acpi_battery *battery = seq->private;
         struct acpi_battery_info *bif = NULL;
         char *units = "?";
 
-
-        if (!battery)
+        if (result)
                 goto end;
 
-        acpi_battery_check_present(battery);
-
-        if (battery->flags.present)
+        if (acpi_battery_present(battery))
                 seq_printf(seq, "present:                 yes\n");
         else {
                 seq_printf(seq, "present:                 no\n");
                 goto end;
         }
 
-        /* Battery Info (_BIF) */
-
-        result = acpi_battery_get_info(battery, &bif);
-        if (result || !bif) {
-                seq_printf(seq, "ERROR: Unable to read battery information\n");
+        bif = battery->bif_data.pointer;
+        if (!bif) {
+                ACPI_EXCEPTION((AE_INFO, AE_ERROR, "BIF buffer is NULL"));
+                result = -ENODEV;
                 goto end;
         }
 
-        units =
-            bif->
-            power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
+        /* Battery Units */
+
+        units = acpi_battery_power_units(battery);
 
         if (bif->design_capacity == ACPI_BATTERY_VALUE_UNKNOWN)
                 seq_printf(seq, "design capacity:         unknown\n");
@@ -396,7 +516,6 @@ static int acpi_battery_read_info(struct seq_file *seq, void *offset)
         else
                 seq_printf(seq, "design voltage:          %d mV\n",
                            (u32) bif->design_voltage);
-
         seq_printf(seq, "design capacity warning: %d %sh\n",
                    (u32) bif->design_capacity_warning, units);
         seq_printf(seq, "design capacity low:     %d %sh\n",
@@ -411,9 +530,48 @@ static int acpi_battery_read_info(struct seq_file *seq, void *offset)
         seq_printf(seq, "OEM info:                %s\n", bif->oem_info);
 
       end:
-        kfree(bif);
 
-        return 0;
+        if (result)
+                seq_printf(seq, "ERROR: Unable to read battery info\n");
+
+        return result;
+}
+
+static int acpi_battery_read_info(struct seq_file *seq, void *offset)
+{
+        struct acpi_battery *battery = seq->private;
+        int result = 0;
+        int update_result = ACPI_BATTERY_NONE_UPDATE;
+        int update = 0;
+
+        acpi_battery_mutex_lock(battery);
+
+        update = (get_seconds() - battery->info_update_time >= update_time);
+        update = (update | acpi_battery_info_update_flag(battery));
+
+        result = acpi_battery_update(battery, update, &update_result);
+        if (result)
+                goto end;
+
+        /* Battery Info (_BIF) */
+
+        if (update_result == ACPI_BATTERY_EASY_UPDATE) {
+                result = acpi_battery_get_info(battery);
+                if (result)
+                        goto end;
+        }
+
+      end:
+
+        result = acpi_battery_read_info_print(seq, result);
+
+        acpi_battery_check_result(battery, result);
+
+        acpi_battery_info_update_flag(battery) = result;
+
+        acpi_battery_mutex_unlock(battery);
+
+        return result;
 }
 
 static int acpi_battery_info_open_fs(struct inode *inode, struct file *file)
@@ -421,40 +579,33 @@ static int acpi_battery_info_open_fs(struct inode *inode, struct file *file)
         return single_open(file, acpi_battery_read_info, PDE(inode)->data);
 }
 
-static int acpi_battery_read_state(struct seq_file *seq, void *offset)
+static int acpi_battery_read_state_print(struct seq_file *seq, int result)
 {
-        int result = 0;
         struct acpi_battery *battery = seq->private;
         struct acpi_battery_state *bst = NULL;
         char *units = "?";
 
-
-        if (!battery)
+        if (result)
                 goto end;
 
-        acpi_battery_check_present(battery);
-
-        if (battery->flags.present)
+        if (acpi_battery_present(battery))
                 seq_printf(seq, "present:                 yes\n");
         else {
                 seq_printf(seq, "present:                 no\n");
                 goto end;
         }
 
-        /* Battery Units */
-
-        units =
-            battery->flags.
-            power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
-
-        /* Battery Status (_BST) */
-
-        result = acpi_battery_get_state(battery, &bst);
-        if (result || !bst) {
-                seq_printf(seq, "ERROR: Unable to read battery state\n");
+        bst = battery->bst_data.pointer;
+        if (!bst) {
+                ACPI_EXCEPTION((AE_INFO, AE_ERROR, "BST buffer is NULL"));
+                result = -ENODEV;
                 goto end;
         }
 
+        /* Battery Units */
+
+        units = acpi_battery_power_units(battery);
+
         if (!(bst->state & 0x04))
                 seq_printf(seq, "capacity state:          ok\n");
         else
@@ -490,9 +641,49 @@ static int acpi_battery_read_state(struct seq_file *seq, void *offset)
                            (u32) bst->present_voltage);
 
       end:
-        kfree(bst);
 
-        return 0;
+        if (result) {
+                seq_printf(seq, "ERROR: Unable to read battery state\n");
+        }
+
+        return result;
+}
+
+static int acpi_battery_read_state(struct seq_file *seq, void *offset)
+{
+        struct acpi_battery *battery = seq->private;
+        int result = 0;
+        int update_result = ACPI_BATTERY_NONE_UPDATE;
+        int update = 0;
+
+        acpi_battery_mutex_lock(battery);
+
+        update = (get_seconds() - battery->state_update_time >= update_time);
+        update = (update | acpi_battery_state_update_flag(battery));
+
+        result = acpi_battery_update(battery, update, &update_result);
+        if (result)
+                goto end;
+
+        /* Battery State (_BST) */
+
+        if (update_result == ACPI_BATTERY_EASY_UPDATE) {
+                result = acpi_battery_get_state(battery);
+                if (result)
+                        goto end;
+        }
+
+      end:
+
+        result = acpi_battery_read_state_print(seq, result);
+
+        acpi_battery_check_result(battery, result);
+
+        acpi_battery_state_update_flag(battery) = result;
+
+        acpi_battery_mutex_unlock(battery);
+
+        return result;
 }
 
 static int acpi_battery_state_open_fs(struct inode *inode, struct file *file)
@@ -500,38 +691,72 @@ static int acpi_battery_state_open_fs(struct inode *inode, struct file *file)
         return single_open(file, acpi_battery_read_state, PDE(inode)->data);
 }
 
-static int acpi_battery_read_alarm(struct seq_file *seq, void *offset)
+static int acpi_battery_read_alarm_print(struct seq_file *seq, int result)
 {
         struct acpi_battery *battery = seq->private;
         char *units = "?";
 
-
-        if (!battery)
+        if (result)
                 goto end;
 
-        acpi_battery_check_present(battery);
-
-        if (!battery->flags.present) {
+        if (!acpi_battery_present(battery)) {
                 seq_printf(seq, "present:                 no\n");
                 goto end;
         }
 
         /* Battery Units */
 
-        units =
-            battery->flags.
-            power_unit ? ACPI_BATTERY_UNITS_AMPS : ACPI_BATTERY_UNITS_WATTS;
-
-        /* Battery Alarm */
+        units = acpi_battery_power_units(battery);
 
         seq_printf(seq, "alarm:                   ");
         if (!battery->alarm)
                 seq_printf(seq, "unsupported\n");
         else
-                seq_printf(seq, "%d %sh\n", (u32) battery->alarm, units);
+                seq_printf(seq, "%lu %sh\n", battery->alarm, units);
 
       end:
-        return 0;
+
+        if (result)
+                seq_printf(seq, "ERROR: Unable to read battery alarm\n");
+
+        return result;
+}
+
+static int acpi_battery_read_alarm(struct seq_file *seq, void *offset)
+{
+        struct acpi_battery *battery = seq->private;
+        int result = 0;
+        int update_result = ACPI_BATTERY_NONE_UPDATE;
+        int update = 0;
+
+        acpi_battery_mutex_lock(battery);
+
+        update = (get_seconds() - battery->alarm_update_time >= update_time);
+        update = (update | acpi_battery_alarm_update_flag(battery));
+
+        result = acpi_battery_update(battery, update, &update_result);
+        if (result)
+                goto end;
+
+        /* Battery Alarm */
+
+        if (update_result == ACPI_BATTERY_EASY_UPDATE) {
+                result = acpi_battery_get_alarm(battery);
+                if (result)
+                        goto end;
+        }
+
+      end:
+
+        result = acpi_battery_read_alarm_print(seq, result);
+
+        acpi_battery_check_result(battery, result);
+
+        acpi_battery_alarm_update_flag(battery) = result;
+
+        acpi_battery_mutex_unlock(battery);
+
+        return result;
 }
 
 static ssize_t
@@ -543,27 +768,47 @@ acpi_battery_write_alarm(struct file *file,
         char alarm_string[12] = { '\0' };
         struct seq_file *m = file->private_data;
         struct acpi_battery *battery = m->private;
+        int update_result = ACPI_BATTERY_NONE_UPDATE;
 
 
         if (!battery || (count > sizeof(alarm_string) - 1))
                 return -EINVAL;
 
-        acpi_battery_check_present(battery);
+        acpi_battery_mutex_lock(battery);
 
-        if (!battery->flags.present)
-                return -ENODEV;
+        result = acpi_battery_update(battery, 1, &update_result);
+        if (result) {
+                result = -ENODEV;
+                goto end;
+        }
 
-        if (copy_from_user(alarm_string, buffer, count))
-                return -EFAULT;
+        if (!acpi_battery_present(battery)) {
+                result = -ENODEV;
+                goto end;
+        }
+
+        if (copy_from_user(alarm_string, buffer, count)) {
+                result = -EFAULT;
+                goto end;
+        }
 
         alarm_string[count] = '\0';
 
         result = acpi_battery_set_alarm(battery,
                                         simple_strtoul(alarm_string, NULL, 0));
         if (result)
-                return result;
+                goto end;
+
+      end:
+
+        acpi_battery_check_result(battery, result);
 
-        return count;
+        if (!result)
+                result = count;
+
+        acpi_battery_mutex_unlock(battery);
+
+        return result;
 }
 
 static int acpi_battery_alarm_open_fs(struct inode *inode, struct file *file)
@@ -648,7 +893,6 @@ static int acpi_battery_add_fs(struct acpi_device *device)
 
 static int acpi_battery_remove_fs(struct acpi_device *device)
 {
-
         if (acpi_device_dir(device)) {
                 remove_proc_entry(ACPI_BATTERY_FILE_ALARM,
                                   acpi_device_dir(device));
@@ -684,8 +928,11 @@ static void acpi_battery_notify(acpi_handle handle, u32 event, void *data)
         case ACPI_BATTERY_NOTIFY_INFO:
         case ACPI_NOTIFY_BUS_CHECK:
         case ACPI_NOTIFY_DEVICE_CHECK:
-                acpi_battery_check(battery);
-                acpi_bus_generate_event(device, event, battery->flags.present);
+                acpi_battery_mutex_lock(battery);
+                device = battery->device;
+                acpi_battery_notify_update(battery);
+                acpi_battery_mutex_unlock(battery);
+                acpi_bus_generate_event(device, event, acpi_battery_present(battery));
                 break;
         default:
                 ACPI_DEBUG_PRINT((ACPI_DB_INFO,
@@ -702,7 +949,6 @@ static int acpi_battery_add(struct acpi_device *device)
         acpi_status status = 0;
         struct acpi_battery *battery = NULL;
 
-
         if (!device)
                 return -EINVAL;
 
@@ -710,15 +956,21 @@ static int acpi_battery_add(struct acpi_device *device)
         if (!battery)
                 return -ENOMEM;
 
+        mutex_init(&battery->mutex);
+
+        acpi_battery_mutex_lock(battery);
+
         battery->device = device;
         strcpy(acpi_device_name(device), ACPI_BATTERY_DEVICE_NAME);
         strcpy(acpi_device_class(device), ACPI_BATTERY_CLASS);
         acpi_driver_data(device) = battery;
 
-        result = acpi_battery_check(battery);
+        result = acpi_battery_get_status(battery);
         if (result)
                 goto end;
 
+        acpi_battery_init_update_flag(battery) = 1;
+
         result = acpi_battery_add_fs(device);
         if (result)
                 goto end;
@@ -727,6 +979,7 @@ static int acpi_battery_add(struct acpi_device *device)
                                              ACPI_ALL_NOTIFY,
                                              acpi_battery_notify, battery);
         if (ACPI_FAILURE(status)) {
+                ACPI_EXCEPTION((AE_INFO, status, "Installing notify handler"));
                 result = -ENODEV;
                 goto end;
         }
@@ -736,11 +989,14 @@ static int acpi_battery_add(struct acpi_device *device)
                device->status.battery_present ? "present" : "absent");
 
       end:
+
         if (result) {
                 acpi_battery_remove_fs(device);
                 kfree(battery);
         }
 
+        acpi_battery_mutex_unlock(battery);
+
         return result;
 }
 
@@ -749,18 +1005,29 @@ static int acpi_battery_remove(struct acpi_device *device, int type)
         acpi_status status = 0;
         struct acpi_battery *battery = NULL;
 
-
         if (!device || !acpi_driver_data(device))
                 return -EINVAL;
 
         battery = acpi_driver_data(device);
 
+        acpi_battery_mutex_lock(battery);
+
         status = acpi_remove_notify_handler(device->handle,
                                             ACPI_ALL_NOTIFY,
                                             acpi_battery_notify);
 
         acpi_battery_remove_fs(device);
 
+        if (battery->bif_data.pointer)
+                kfree(battery->bif_data.pointer);
+
+        if (battery->bst_data.pointer)
+                kfree(battery->bst_data.pointer);
+
+        acpi_battery_mutex_unlock(battery);
+
+        mutex_destroy(&battery->mutex);
+
         kfree(battery);
 
         return 0;
@@ -775,7 +1042,10 @@ static int acpi_battery_resume(struct acpi_device *device)
                 return -EINVAL;
 
         battery = device->driver_data;
-        return acpi_battery_check(battery);
+
+        acpi_battery_init_update_flag(battery) = 1;
+
+        return 0;
 }
 
 static int __init acpi_battery_init(void)
@@ -800,7 +1070,6 @@ static int __init acpi_battery_init(void)
 
 static void __exit acpi_battery_exit(void)
 {
-
         acpi_bus_unregister_driver(&acpi_battery_driver);
 
         acpi_unlock_battery_dir(acpi_battery_dir);