]> err.no Git - linux-2.6/commitdiff
ACPI: Cache battery status instead of re-evaluating AML
authorVladimir Lebedev <vladimir.p.lebedev@intel.com>
Tue, 20 Feb 2007 12:48:06 +0000 (15:48 +0300)
committerLen Brown <len.brown@intel.com>
Wed, 7 Mar 2007 06:48:07 +0000 (01:48 -0500)
/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>
drivers/acpi/battery.c

index df04f87dd491949e3259f304cd0d734a7a54924e..f3b0024e57606b02ad35e41a7e69b6cef2b14edf 100644 (file)
 #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);