1 files changed, 297 insertions, 242 deletions

diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index 5f67e390e45c..f213997adaec 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -32,6 +32,7 @@
 #include <linux/platform_device.h>
 #include <linux/input-polldev.h>
 #include <linux/kernel.h>
+#include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/timer.h>
 #include <linux/dmi.h>
@@ -51,6 +52,7 @@
 
 #define APPLESMC_MAX_DATA_LENGTH 32
 
+/* wait up to 32 ms for a status change. */
 #define APPLESMC_MIN_WAIT	0x0040
 #define APPLESMC_MAX_WAIT	0x8000
 
@@ -200,6 +202,25 @@ struct dmi_match_data {
 	int temperature_set;
 };
 
+/* AppleSMC entry - cached register information */
+struct applesmc_entry {
+	char key[5];		/* four-letter key code */
+	u8 valid;		/* set when entry is successfully read once */
+	u8 len;			/* bounded by APPLESMC_MAX_DATA_LENGTH */
+	char type[5];		/* four-letter type code */
+	u8 flags;		/* 0x10: func; 0x40: write; 0x80: read */
+};
+
+/* Register lookup and registers common to all SMCs */
+static struct applesmc_registers {
+	struct mutex mutex;		/* register read/write mutex */
+	unsigned int key_count;		/* number of SMC registers */
+	bool init_complete;		/* true when fully initialized */
+	struct applesmc_entry *cache;	/* cached key entries */
+} smcreg = {
+	.mutex = __MUTEX_INITIALIZER(smcreg.mutex),
+};
+
 static const int debug;
 static struct platform_device *pdev;
 static s16 rest_x;
@@ -221,8 +242,6 @@ static unsigned int fans_handled;
 /* Indicates which temperature sensors set to use. */
 static unsigned int applesmc_temperature_set;
 
-static DEFINE_MUTEX(applesmc_lock);
-
 /*
  * Last index written to key_at_index sysfs file, and value to use for all other
  * key_at_index_* sysfs files.
@@ -245,16 +264,10 @@ static int __wait_status(u8 val)
 	for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
 		udelay(us);
 		if ((inb(APPLESMC_CMD_PORT) & APPLESMC_STATUS_MASK) == val) {
-			if (debug)
-				printk(KERN_DEBUG
-					"Waited %d us for status %x\n",
-					2 * us - APPLESMC_MIN_WAIT, val);
 			return 0;
 		}
 	}
 
-	pr_warn("wait status failed: %x != %x\n", val, inb(APPLESMC_CMD_PORT));
-
 	return -EIO;
 }
 
@@ -272,156 +285,228 @@ static int send_command(u8 cmd)
 		if ((inb(APPLESMC_CMD_PORT) & APPLESMC_STATUS_MASK) == 0x0c)
 			return 0;
 	}
-	pr_warn("command failed: %x -> %x\n", cmd, inb(APPLESMC_CMD_PORT));
 	return -EIO;
 }
 
-/*
- * applesmc_read_key - reads len bytes from a given key, and put them in buffer.
- * Returns zero on success or a negative error on failure. Callers must
- * hold applesmc_lock.
- */
-static int applesmc_read_key(const char* key, u8* buffer, u8 len)
+static int send_argument(const char *key)
 {
 	int i;
 
-	if (len > APPLESMC_MAX_DATA_LENGTH) {
-		pr_err("%s(): cannot read more than %d bytes\n",
-		       __func__, APPLESMC_MAX_DATA_LENGTH);
-		return -EINVAL;
-	}
-
-	if (send_command(APPLESMC_READ_CMD))
-		return -EIO;
-
 	for (i = 0; i < 4; i++) {
 		outb(key[i], APPLESMC_DATA_PORT);
 		if (__wait_status(0x04))
 			return -EIO;
 	}
-	if (debug)
-		printk(KERN_DEBUG "<%s", key);
+	return 0;
+}
+
+static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
+{
+	int i;
+
+	if (send_command(cmd) || send_argument(key)) {
+		pr_warn("%s: read arg fail\n", key);
+		return -EIO;
+	}
 
 	outb(len, APPLESMC_DATA_PORT);
-	if (debug)
-		printk(KERN_DEBUG ">%x", len);
 
 	for (i = 0; i < len; i++) {
-		if (__wait_status(0x05))
+		if (__wait_status(0x05)) {
+			pr_warn("%s: read data fail\n", key);
 			return -EIO;
+		}
 		buffer[i] = inb(APPLESMC_DATA_PORT);
-		if (debug)
-			printk(KERN_DEBUG "<%x", buffer[i]);
 	}
-	if (debug)
-		printk(KERN_DEBUG "\n");
 
 	return 0;
 }
 
-/*
- * applesmc_write_key - writes len bytes from buffer to a given key.
- * Returns zero on success or a negative error on failure. Callers must
- * hold applesmc_lock.
- */
-static int applesmc_write_key(const char* key, u8* buffer, u8 len)
+static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len)
 {
 	int i;
 
-	if (len > APPLESMC_MAX_DATA_LENGTH) {
-		pr_err("%s(): cannot write more than %d bytes\n",
-		       __func__, APPLESMC_MAX_DATA_LENGTH);
-		return -EINVAL;
-	}
-
-	if (send_command(APPLESMC_WRITE_CMD))
+	if (send_command(cmd) || send_argument(key)) {
+		pr_warn("%s: write arg fail\n", key);
 		return -EIO;
-
-	for (i = 0; i < 4; i++) {
-		outb(key[i], APPLESMC_DATA_PORT);
-		if (__wait_status(0x04))
-			return -EIO;
 	}
 
 	outb(len, APPLESMC_DATA_PORT);
 
 	for (i = 0; i < len; i++) {
-		if (__wait_status(0x04))
+		if (__wait_status(0x04)) {
+			pr_warn("%s: write data fail\n", key);
 			return -EIO;
+		}
 		outb(buffer[i], APPLESMC_DATA_PORT);
 	}
 
 	return 0;
 }
 
+static int read_register_count(unsigned int *count)
+{
+	__be32 be;
+	int ret;
+
+	ret = read_smc(APPLESMC_READ_CMD, KEY_COUNT_KEY, (u8 *)&be, 4);
+	if (ret)
+		return ret;
+
+	*count = be32_to_cpu(be);
+	return 0;
+}
+
 /*
- * applesmc_get_key_at_index - get key at index, and put the result in key
- * (char[6]). Returns zero on success or a negative error on failure. Callers
- * must hold applesmc_lock.
+ * Serialized I/O
+ *
+ * Returns zero on success or a negative error on failure.
+ * All functions below are concurrency safe - callers should NOT hold lock.
  */
-static int applesmc_get_key_at_index(int index, char* key)
+
+static int applesmc_read_entry(const struct applesmc_entry *entry,
+			       u8 *buf, u8 len)
 {
-	int i;
-	u8 readkey[4];
-	readkey[0] = index >> 24;
-	readkey[1] = index >> 16;
-	readkey[2] = index >> 8;
-	readkey[3] = index;
+	int ret;
 
-	if (send_command(APPLESMC_GET_KEY_BY_INDEX_CMD))
-		return -EIO;
+	if (entry->len != len)
+		return -EINVAL;
+	mutex_lock(&smcreg.mutex);
+	ret = read_smc(APPLESMC_READ_CMD, entry->key, buf, len);
+	mutex_unlock(&smcreg.mutex);
 
-	for (i = 0; i < 4; i++) {
-		outb(readkey[i], APPLESMC_DATA_PORT);
-		if (__wait_status(0x04))
-			return -EIO;
+	return ret;
+}
+
+static int applesmc_write_entry(const struct applesmc_entry *entry,
+				const u8 *buf, u8 len)
+{
+	int ret;
+
+	if (entry->len != len)
+		return -EINVAL;
+	mutex_lock(&smcreg.mutex);
+	ret = write_smc(APPLESMC_WRITE_CMD, entry->key, buf, len);
+	mutex_unlock(&smcreg.mutex);
+	return ret;
+}
+
+static const struct applesmc_entry *applesmc_get_entry_by_index(int index)
+{
+	struct applesmc_entry *cache = &smcreg.cache[index];
+	u8 key[4], info[6];
+	__be32 be;
+	int ret = 0;
+
+	if (cache->valid)
+		return cache;
+
+	mutex_lock(&smcreg.mutex);
+
+	if (cache->valid)
+		goto out;
+	be = cpu_to_be32(index);
+	ret = read_smc(APPLESMC_GET_KEY_BY_INDEX_CMD, (u8 *)&be, key, 4);
+	if (ret)
+		goto out;
+	ret = read_smc(APPLESMC_GET_KEY_TYPE_CMD, key, info, 6);
+	if (ret)
+		goto out;
+
+	memcpy(cache->key, key, 4);
+	cache->len = info[0];
+	memcpy(cache->type, &info[1], 4);
+	cache->flags = info[5];
+	cache->valid = 1;
+
+out:
+	mutex_unlock(&smcreg.mutex);
+	if (ret)
+		return ERR_PTR(ret);
+	return cache;
+}
+
+static int applesmc_get_lower_bound(unsigned int *lo, const char *key)
+{
+	int begin = 0, end = smcreg.key_count;
+	const struct applesmc_entry *entry;
+
+	while (begin != end) {
+		int middle = begin + (end - begin) / 2;
+		entry = applesmc_get_entry_by_index(middle);
+		if (IS_ERR(entry))
+			return PTR_ERR(entry);
+		if (strcmp(entry->key, key) < 0)
+			begin = middle + 1;
+		else
+			end = middle;
 	}
 
-	outb(4, APPLESMC_DATA_PORT);
+	*lo = begin;
+	return 0;
+}
 
-	for (i = 0; i < 4; i++) {
-		if (__wait_status(0x05))
-			return -EIO;
-		key[i] = inb(APPLESMC_DATA_PORT);
+static int applesmc_get_upper_bound(unsigned int *hi, const char *key)
+{
+	int begin = 0, end = smcreg.key_count;
+	const struct applesmc_entry *entry;
+
+	while (begin != end) {
+		int middle = begin + (end - begin) / 2;
+		entry = applesmc_get_entry_by_index(middle);
+		if (IS_ERR(entry))
+			return PTR_ERR(entry);
+		if (strcmp(key, entry->key) < 0)
+			end = middle;
+		else
+			begin = middle + 1;
 	}
-	key[4] = 0;
 
+	*hi = begin;
 	return 0;
 }
 
-/*
- * applesmc_get_key_type - get key type, and put the result in type (char[6]).
- * Returns zero on success or a negative error on failure. Callers must
- * hold applesmc_lock.
- */
-static int applesmc_get_key_type(char* key, char* type)
+static const struct applesmc_entry *applesmc_get_entry_by_key(const char *key)
 {
-	int i;
+	int begin, end;
+	int ret;
 
-	if (send_command(APPLESMC_GET_KEY_TYPE_CMD))
-		return -EIO;
+	ret = applesmc_get_lower_bound(&begin, key);
+	if (ret)
+		return ERR_PTR(ret);
+	ret = applesmc_get_upper_bound(&end, key);
+	if (ret)
+		return ERR_PTR(ret);
+	if (end - begin != 1)
+		return ERR_PTR(-EINVAL);
 
-	for (i = 0; i < 4; i++) {
-		outb(key[i], APPLESMC_DATA_PORT);
-		if (__wait_status(0x04))
-			return -EIO;
-	}
+	return applesmc_get_entry_by_index(begin);
+}
 
-	outb(6, APPLESMC_DATA_PORT);
+static int applesmc_read_key(const char *key, u8 *buffer, u8 len)
+{
+	const struct applesmc_entry *entry;
 
-	for (i = 0; i < 6; i++) {
-		if (__wait_status(0x05))
-			return -EIO;
-		type[i] = inb(APPLESMC_DATA_PORT);
-	}
-	type[5] = 0;
+	entry = applesmc_get_entry_by_key(key);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
 
-	return 0;
+	return applesmc_read_entry(entry, buffer, len);
+}
+
+static int applesmc_write_key(const char *key, const u8 *buffer, u8 len)
+{
+	const struct applesmc_entry *entry;
+
+	entry = applesmc_get_entry_by_key(key);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
+
+	return applesmc_write_entry(entry, buffer, len);
 }
 
 /*
- * applesmc_read_motion_sensor - Read motion sensor (X, Y or Z). Callers must
- * hold applesmc_lock.
+ * applesmc_read_motion_sensor - Read motion sensor (X, Y or Z).
  */
 static int applesmc_read_motion_sensor(int index, s16* value)
 {
@@ -458,12 +543,10 @@ static void applesmc_device_init(void)
 	if (!applesmc_accelerometer)
 		return;
 
-	mutex_lock(&applesmc_lock);
-
 	for (total = INIT_TIMEOUT_MSECS; total > 0; total -= INIT_WAIT_MSECS) {
 		if (!applesmc_read_key(MOTION_SENSOR_KEY, buffer, 2) &&
 				(buffer[0] != 0x00 || buffer[1] != 0x00))
-			goto out;
+			return;
 		buffer[0] = 0xe0;
 		buffer[1] = 0x00;
 		applesmc_write_key(MOTION_SENSOR_KEY, buffer, 2);
@@ -471,34 +554,93 @@ static void applesmc_device_init(void)
 	}
 
 	pr_warn("failed to init the device\n");
-
-out:
-	mutex_unlock(&applesmc_lock);
 }
 
 /*
- * applesmc_get_fan_count - get the number of fans. Callers must NOT hold
- * applesmc_lock.
+ * applesmc_get_fan_count - get the number of fans.
  */
 static int applesmc_get_fan_count(void)
 {
 	int ret;
 	u8 buffer[1];
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(FANS_COUNT, buffer, 1);
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
 		return buffer[0];
 }
 
+/*
+ * applesmc_init_smcreg_try - Try to initialize register cache. Idempotent.
+ */
+static int applesmc_init_smcreg_try(void)
+{
+	struct applesmc_registers *s = &smcreg;
+	int ret;
+
+	if (s->init_complete)
+		return 0;
+
+	ret = read_register_count(&s->key_count);
+	if (ret)
+		return ret;
+
+	if (!s->cache)
+		s->cache = kcalloc(s->key_count, sizeof(*s->cache), GFP_KERNEL);
+	if (!s->cache)
+		return -ENOMEM;
+
+	s->init_complete = true;
+
+	pr_info("key=%d\n", s->key_count);
+
+	return 0;
+}
+
+/*
+ * applesmc_init_smcreg - Initialize register cache.
+ *
+ * Retries until initialization is successful, or the operation times out.
+ *
+ */
+static int applesmc_init_smcreg(void)
+{
+	int ms, ret;
+
+	for (ms = 0; ms < INIT_TIMEOUT_MSECS; ms += INIT_WAIT_MSECS) {
+		ret = applesmc_init_smcreg_try();
+		if (!ret) {
+			if (ms)
+				pr_info("init_smcreg() took %d ms\n", ms);
+			return 0;
+		}
+		msleep(INIT_WAIT_MSECS);
+	}
+
+	kfree(smcreg.cache);
+	smcreg.cache = NULL;
+
+	return ret;
+}
+
+static void applesmc_destroy_smcreg(void)
+{
+	kfree(smcreg.cache);
+	smcreg.cache = NULL;
+	smcreg.init_complete = false;
+}
+
 /* Device model stuff */
 static int applesmc_probe(struct platform_device *dev)
 {
+	int ret;
+
+	ret = applesmc_init_smcreg();
+	if (ret)
+		return ret;
+
 	applesmc_device_init();
 
 	return 0;
@@ -507,10 +649,8 @@ static int applesmc_probe(struct platform_device *dev)
 /* Synchronize device with memorized backlight state */
 static int applesmc_pm_resume(struct device *dev)
 {
-	mutex_lock(&applesmc_lock);
 	if (applesmc_light)
 		applesmc_write_key(BACKLIGHT_KEY, backlight_state, 2);
-	mutex_unlock(&applesmc_lock);
 	return 0;
 }
 
@@ -551,20 +691,15 @@ static void applesmc_idev_poll(struct input_polled_dev *dev)
 	struct input_dev *idev = dev->input;
 	s16 x, y;
 
-	mutex_lock(&applesmc_lock);
-
 	if (applesmc_read_motion_sensor(SENSOR_X, &x))
-		goto out;
+		return;
 	if (applesmc_read_motion_sensor(SENSOR_Y, &y))
-		goto out;
+		return;
 
 	x = -x;
 	input_report_abs(idev, ABS_X, x - rest_x);
 	input_report_abs(idev, ABS_Y, y - rest_y);
 	input_sync(idev);
-
-out:
-	mutex_unlock(&applesmc_lock);
 }
 
 /* Sysfs Files */
@@ -581,8 +716,6 @@ static ssize_t applesmc_position_show(struct device *dev,
 	int ret;
 	s16 x, y, z;
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_motion_sensor(SENSOR_X, &x);
 	if (ret)
 		goto out;
@@ -594,7 +727,6 @@ static ssize_t applesmc_position_show(struct device *dev,
 		goto out;
 
 out:
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -604,18 +736,19 @@ out:
 static ssize_t applesmc_light_show(struct device *dev,
 				struct device_attribute *attr, char *sysfsbuf)
 {
+	const struct applesmc_entry *entry;
 	static int data_length;
 	int ret;
 	u8 left = 0, right = 0;
-	u8 buffer[10], query[6];
-
-	mutex_lock(&applesmc_lock);
+	u8 buffer[10];
 
 	if (!data_length) {
-		ret = applesmc_get_key_type(LIGHT_SENSOR_LEFT_KEY, query);
-		if (ret)
-			goto out;
-		data_length = clamp_val(query[0], 0, 10);
+		entry = applesmc_get_entry_by_key(LIGHT_SENSOR_LEFT_KEY);
+		if (IS_ERR(entry))
+			return PTR_ERR(entry);
+		if (entry->len > 10)
+			return -ENXIO;
+		data_length = entry->len;
 		pr_info("light sensor data length set to %d\n", data_length);
 	}
 
@@ -632,7 +765,6 @@ static ssize_t applesmc_light_show(struct device *dev,
 	right = buffer[2];
 
 out:
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -661,14 +793,10 @@ static ssize_t applesmc_show_temperature(struct device *dev,
 	const char* key =
 		temperature_sensors_sets[applesmc_temperature_set][attr->index];
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(key, buffer, 2);
 	temp = buffer[0]*1000;
 	temp += (buffer[1] >> 6) * 250;
 
-	mutex_unlock(&applesmc_lock);
-
 	if (ret)
 		return ret;
 	else
@@ -691,12 +819,9 @@ static ssize_t applesmc_show_fan_speed(struct device *dev,
 	newkey[3] = fan_speed_keys[sensor_attr->nr][3];
 	newkey[4] = 0;
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(newkey, buffer, 2);
 	speed = ((buffer[0] << 8 | buffer[1]) >> 2);
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -725,13 +850,10 @@ static ssize_t applesmc_store_fan_speed(struct device *dev,
 	newkey[3] = fan_speed_keys[sensor_attr->nr][3];
 	newkey[4] = 0;
 
-	mutex_lock(&applesmc_lock);
-
 	buffer[0] = (speed >> 6) & 0xff;
 	buffer[1] = (speed << 2) & 0xff;
 	ret = applesmc_write_key(newkey, buffer, 2);
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -746,12 +868,9 @@ static ssize_t applesmc_show_fan_manual(struct device *dev,
 	u8 buffer[2];
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(devattr);
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(FANS_MANUAL, buffer, 2);
 	manual = ((buffer[0] << 8 | buffer[1]) >> attr->index) & 0x01;
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -770,8 +889,6 @@ static ssize_t applesmc_store_fan_manual(struct device *dev,
 
 	input = simple_strtoul(sysfsbuf, NULL, 10);
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(FANS_MANUAL, buffer, 2);
 	val = (buffer[0] << 8 | buffer[1]);
 	if (ret)
@@ -788,7 +905,6 @@ static ssize_t applesmc_store_fan_manual(struct device *dev,
 	ret = applesmc_write_key(FANS_MANUAL, buffer, 2);
 
 out:
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -810,12 +926,9 @@ static ssize_t applesmc_show_fan_position(struct device *dev,
 	newkey[3] = FAN_POSITION[3];
 	newkey[4] = 0;
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(newkey, buffer, 16);
 	buffer[16] = 0;
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -831,18 +944,14 @@ static ssize_t applesmc_calibrate_show(struct device *dev,
 static ssize_t applesmc_calibrate_store(struct device *dev,
 	struct device_attribute *attr, const char *sysfsbuf, size_t count)
 {
-	mutex_lock(&applesmc_lock);
 	applesmc_calibrate();
-	mutex_unlock(&applesmc_lock);
 
 	return count;
 }
 
 static void applesmc_backlight_set(struct work_struct *work)
 {
-	mutex_lock(&applesmc_lock);
 	applesmc_write_key(BACKLIGHT_KEY, backlight_state, 2);
-	mutex_unlock(&applesmc_lock);
 }
 static DECLARE_WORK(backlight_work, &applesmc_backlight_set);
 
@@ -865,13 +974,10 @@ static ssize_t applesmc_key_count_show(struct device *dev,
 	u8 buffer[4];
 	u32 count;
 
-	mutex_lock(&applesmc_lock);
-
 	ret = applesmc_read_key(KEY_COUNT_KEY, buffer, 4);
 	count = ((u32)buffer[0]<<24) + ((u32)buffer[1]<<16) +
 						((u32)buffer[2]<<8) + buffer[3];
 
-	mutex_unlock(&applesmc_lock);
 	if (ret)
 		return ret;
 	else
@@ -881,113 +987,53 @@ static ssize_t applesmc_key_count_show(struct device *dev,
 static ssize_t applesmc_key_at_index_read_show(struct device *dev,
 				struct device_attribute *attr, char *sysfsbuf)
 {
-	char key[5];
-	char info[6];
+	const struct applesmc_entry *entry;
 	int ret;
 
-	mutex_lock(&applesmc_lock);
-
-	ret = applesmc_get_key_at_index(key_at_index, key);
-
-	if (ret || !key[0]) {
-		mutex_unlock(&applesmc_lock);
-
-		return -EINVAL;
-	}
-
-	ret = applesmc_get_key_type(key, info);
-
-	if (ret) {
-		mutex_unlock(&applesmc_lock);
-
+	entry = applesmc_get_entry_by_index(key_at_index);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
+	ret = applesmc_read_entry(entry, sysfsbuf, entry->len);
+	if (ret)
 		return ret;
-	}
 
-	/*
-	 * info[0] maximum value (APPLESMC_MAX_DATA_LENGTH) is much lower than
-	 * PAGE_SIZE, so we don't need any checks before writing to sysfsbuf.
-	 */
-	ret = applesmc_read_key(key, sysfsbuf, info[0]);
-
-	mutex_unlock(&applesmc_lock);
-
-	if (!ret) {
-		return info[0];
-	} else {
-		return ret;
-	}
+	return entry->len;
 }
 
 static ssize_t applesmc_key_at_index_data_length_show(struct device *dev,
 				struct device_attribute *attr, char *sysfsbuf)
 {
-	char key[5];
-	char info[6];
-	int ret;
-
-	mutex_lock(&applesmc_lock);
+	const struct applesmc_entry *entry;
 
-	ret = applesmc_get_key_at_index(key_at_index, key);
+	entry = applesmc_get_entry_by_index(key_at_index);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
 
-	if (ret || !key[0]) {
-		mutex_unlock(&applesmc_lock);
-
-		return -EINVAL;
-	}
-
-	ret = applesmc_get_key_type(key, info);
-
-	mutex_unlock(&applesmc_lock);
-
-	if (!ret)
-		return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", info[0]);
-	else
-		return ret;
+	return snprintf(sysfsbuf, PAGE_SIZE, "%d\n", entry->len);
 }
 
 static ssize_t applesmc_key_at_index_type_show(struct device *dev,
 				struct device_attribute *attr, char *sysfsbuf)
 {
-	char key[5];
-	char info[6];
-	int ret;
-
-	mutex_lock(&applesmc_lock);
-
-	ret = applesmc_get_key_at_index(key_at_index, key);
-
-	if (ret || !key[0]) {
-		mutex_unlock(&applesmc_lock);
-
-		return -EINVAL;
-	}
-
-	ret = applesmc_get_key_type(key, info);
+	const struct applesmc_entry *entry;
 
-	mutex_unlock(&applesmc_lock);
+	entry = applesmc_get_entry_by_index(key_at_index);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
 
-	if (!ret)
-		return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", info+1);
-	else
-		return ret;
+	return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", entry->type);
 }
 
 static ssize_t applesmc_key_at_index_name_show(struct device *dev,
 				struct device_attribute *attr, char *sysfsbuf)
 {
-	char key[5];
-	int ret;
-
-	mutex_lock(&applesmc_lock);
+	const struct applesmc_entry *entry;
 
-	ret = applesmc_get_key_at_index(key_at_index, key);
+	entry = applesmc_get_entry_by_index(key_at_index);
+	if (IS_ERR(entry))
+		return PTR_ERR(entry);
 
-	mutex_unlock(&applesmc_lock);
-
-	if (!ret && key[0])
-		return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", key);
-	else
-		return -EINVAL;
+	return snprintf(sysfsbuf, PAGE_SIZE, "%s\n", entry->key);
 }
 
 static ssize_t applesmc_key_at_index_show(struct device *dev,
@@ -999,12 +1045,13 @@ static ssize_t applesmc_key_at_index_show(struct device *dev,
 static ssize_t applesmc_key_at_index_store(struct device *dev,
 	struct device_attribute *attr, const char *sysfsbuf, size_t count)
 {
-	mutex_lock(&applesmc_lock);
+	unsigned long newkey;
 
-	key_at_index = simple_strtoul(sysfsbuf, NULL, 10);
-
-	mutex_unlock(&applesmc_lock);
+	if (strict_strtoul(sysfsbuf, 10, &newkey) < 0
+	    || newkey >= smcreg.key_count)
+		return -EINVAL;
 
+	key_at_index = newkey;
 	return count;
 }
 
@@ -1646,10 +1693,15 @@ static int __init applesmc_init(void)
 		goto out_driver;
 	}
 
-	ret = sysfs_create_file(&pdev->dev.kobj, &dev_attr_name.attr);
+	/* create register cache */
+	ret = applesmc_init_smcreg();
 	if (ret)
 		goto out_device;
 
+	ret = sysfs_create_file(&pdev->dev.kobj, &dev_attr_name.attr);
+	if (ret)
+		goto out_smcreg;
+
 	/* Create key enumeration sysfs files */
 	ret = sysfs_create_group(&pdev->dev.kobj, &key_enumeration_group);
 	if (ret)
@@ -1751,6 +1803,8 @@ out_fans:
 	sysfs_remove_group(&pdev->dev.kobj, &key_enumeration_group);
 out_name:
 	sysfs_remove_file(&pdev->dev.kobj, &dev_attr_name.attr);
+out_smcreg:
+	applesmc_destroy_smcreg();
 out_device:
 	platform_device_unregister(pdev);
 out_driver:
@@ -1779,6 +1833,7 @@ static void __exit applesmc_exit(void)
 				   &fan_attribute_groups[--fans_handled]);
 	sysfs_remove_group(&pdev->dev.kobj, &key_enumeration_group);
 	sysfs_remove_file(&pdev->dev.kobj, &dev_attr_name.attr);
+	applesmc_destroy_smcreg();
 	platform_device_unregister(pdev);
 	platform_driver_unregister(&applesmc_driver);
 	release_region(APPLESMC_DATA_PORT, APPLESMC_NR_PORTS);