2 files changed, 92 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-driver-samsung-laptop b/Documentation/ABI/testing/sysfs-driver-samsung-laptop
index 0a810231aad..a6a56e11eba 100644
--- a/Documentation/ABI/testing/sysfs-driver-samsung-laptop
+++ b/Documentation/ABI/testing/sysfs-driver-samsung-laptop
@@ -17,3 +17,13 @@ Description:	Some Samsung laptops have different "performance levels"
                 Specifically, not all support the "overclock" option,
                 and it's still unknown if this value even changes
                 anything, other than making the user feel a bit better.
+
+What:           /sys/devices/platform/samsung/battery_life_extender
+Date:           December 1, 2011
+KernelVersion:  3.3
+Contact:        Corentin Chary <corentin.chary@gmail.com>
+Description:    Max battery charge level can be modified, battery cycle
+                life can be extended by reducing the max battery charge
+                level.
+                0 means normal battery mode (100% charge)
+                1 means battery life extender mode (80% charge)
diff --git a/drivers/platform/x86/samsung-laptop.c b/drivers/platform/x86/samsung-laptop.c
index b39fa53baa2..918fa358c11 100644
--- a/drivers/platform/x86/samsung-laptop.c
+++ b/drivers/platform/x86/samsung-laptop.c
@@ -104,6 +104,10 @@ struct sabi_commands {
         u16 get_performance_level;
         u16 set_performance_level;
 
+        /* 0x80 is off, 0x81 is on */
+        u16 get_battery_life_extender;
+        u16 set_battery_life_extender;
+
         /*
          * Tell the BIOS that Linux is running on this machine.
          * 81 is on, 80 is off
@@ -157,6 +161,9 @@ static const struct sabi_config sabi_configs[] = {
                         .get_performance_level = 0x08,
                         .set_performance_level = 0x09,
 
+                        .get_battery_life_extender = 0xFFFF,
+                        .set_battery_life_extender = 0xFFFF,
+
                         .set_linux = 0x0a,
                 },
 
@@ -204,6 +211,9 @@ static const struct sabi_config sabi_configs[] = {
                         .get_performance_level = 0x31,
                         .set_performance_level = 0x32,
 
+                        .get_battery_life_extender = 0x65,
+                        .set_battery_life_extender = 0x66,
+
                         .set_linux = 0xff,
                 },
 
@@ -543,8 +553,78 @@ static ssize_t set_performance_level(struct device *dev,
 static DEVICE_ATTR(performance_level, S_IWUSR | S_IRUGO,
                    get_performance_level, set_performance_level);
 
+static int read_battery_life_extender(struct samsung_laptop *samsung)
+{
+        const struct sabi_commands *commands = &samsung->config->commands;
+        struct sabi_data data;
+        int retval;
+
+        if (commands->get_battery_life_extender == 0xFFFF)
+                return -ENODEV;
+
+        memset(&data, 0, sizeof(data));
+        data.data[0] = 0x80;
+        retval = sabi_command(samsung, commands->get_battery_life_extender,
+                              &data, &data);
+
+        if (retval)
+                return retval;
+
+        if (data.data[0] != 0 && data.data[0] != 1)
+                return -ENODEV;
+
+        return data.data[0];
+}
+
+static int write_battery_life_extender(struct samsung_laptop *samsung,
+                                       int enabled)
+{
+        const struct sabi_commands *commands = &samsung->config->commands;
+        struct sabi_data data;
+
+        memset(&data, 0, sizeof(data));
+        data.data[0] = 0x80 | enabled;
+        return sabi_command(samsung, commands->set_battery_life_extender,
+                            &data, NULL);
+}
+
+static ssize_t get_battery_life_extender(struct device *dev,
+                                         struct device_attribute *attr,
+                                         char *buf)
+{
+        struct samsung_laptop *samsung = dev_get_drvdata(dev);
+        int ret;
+
+        ret = read_battery_life_extender(samsung);
+        if (ret < 0)
+                return ret;
+
+        return sprintf(buf, "%d\n", ret);
+}
+
+static ssize_t set_battery_life_extender(struct device *dev,
+                                        struct device_attribute *attr,
+                                        const char *buf, size_t count)
+{
+        struct samsung_laptop *samsung = dev_get_drvdata(dev);
+        int ret, value;
+
+        if (!count || sscanf(buf, "%i", &value) != 1)
+                return -EINVAL;
+
+        ret = write_battery_life_extender(samsung, !!value);
+        if (ret < 0)
+                return ret;
+
+        return count;
+}
+
+static DEVICE_ATTR(battery_life_extender, S_IWUSR | S_IRUGO,
+                   get_battery_life_extender, set_battery_life_extender);
+
 static struct attribute *platform_attributes[] = {
         &dev_attr_performance_level.attr,
+        &dev_attr_battery_life_extender.attr,
         NULL
 };
 
@@ -643,6 +723,8 @@ static mode_t samsung_sysfs_is_visible(struct kobject *kobj,
 
         if (attr == &dev_attr_performance_level.attr)
                 ok = !!samsung->config->performance_levels[0].name;
+        if (attr == &dev_attr_battery_life_extender.attr)
+                ok = !!(read_battery_life_extender(samsung) >= 0);
 
         return ok ? attr->mode : 0;
 }