diff --git a/drivers/hwmon/applesmc.c b/drivers/hwmon/applesmc.c
index a18887990f4a..2500cc7ebca5 100644
--- a/drivers/hwmon/applesmc.c
+++ b/drivers/hwmon/applesmc.c
@@ -151,65 +151,58 @@ static unsigned int key_at_index;
 static struct workqueue_struct *applesmc_led_wq;
 
 /*
- * wait_read - Wait for a byte to appear on SMC port. Callers must
- * hold applesmc_lock.
+ * Wait for specific status bits on the SMC
  */
-static int wait_read(void)
+
+static int wait_status(u8 val, u8 mask)
 {
-	unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC;
 	u8 status;
 	int us;
+	unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC;
 
 	for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
-		usleep_range(us, us * 16);
 		status = inb(APPLESMC_CMD_PORT);
-		/* read: wait for smc to settle */
-		if (status & 0x01)
+		if ((status & mask) == val)
 			return 0;
-		/* timeout: give up */
 		if (time_after(jiffies, end))
 			break;
-	}
-
-	pr_warn("wait_read() fail: 0x%02x\n", status);
+		usleep_range(us, us * 16);
+		}
+	pr_warn("wait_status timeout: 0x%02x\n", status);
 	return -EIO;
 }
-
+	
 /*
  * send_byte - Write to SMC port, retrying when necessary. Callers
  * must hold applesmc_lock.
  */
-static int send_byte(u8 cmd, u16 port)
-{
-	u8 status;
-	int us;
-	unsigned long end = jiffies + (APPLESMC_MAX_WAIT * HZ) / USEC_PER_SEC;
 
+static int send_byte_data(u8 cmd, u16 port, bool skip)
+{
+	u8 wstat=0x44;
+	if (skip)
+		wstat=0x40;
+	if (wait_status(0x44, 0xF6))
+		goto fail;
 	outb(cmd, port);
-	for (us = APPLESMC_MIN_WAIT; us < APPLESMC_MAX_WAIT; us <<= 1) {
-		usleep_range(us, us * 16);
-		status = inb(APPLESMC_CMD_PORT);
-		/* write: wait for smc to settle */
-		if (status & 0x02)
-			continue;
-		/* ready: cmd accepted, return */
-		if (status & 0x04)
-			return 0;
-		/* timeout: give up */
-		if (time_after(jiffies, end))
-			break;
-		/* busy: long wait and resend */
-		udelay(APPLESMC_RETRY_WAIT);
-		outb(cmd, port);
-	}
-
-	pr_warn("send_byte(0x%02x, 0x%04x) fail: 0x%02x\n", cmd, port, status);
+	if (! wait_status(wstat, 0xFE))
+		return 0;
+fail:
+	pr_warn("send_byte_data(0x%02x, 0x%04x) fail\n", cmd, APPLESMC_CMD_PORT);
 	return -EIO;
 }
 
 static int send_command(u8 cmd)
 {
-	return send_byte(cmd, APPLESMC_CMD_PORT);
+	if (wait_status(0x40, 0xF2)) { pr_warn("send_command fail 1\n");
+		goto fail;}
+	outb(cmd, APPLESMC_CMD_PORT);
+	if (wait_status(0x4C, 0xFF)) { pr_warn("send_command fail 2\n");
+		goto fail;}
+	return 0;
+fail:
+	pr_warn("send_cmd(0x%02x, 0x%04x) fail\n", cmd, APPLESMC_CMD_PORT);
+	return -EIO;
 }
 
 static int send_argument(const char *key)
@@ -217,7 +210,7 @@ static int send_argument(const char *key)
 	int i;
 
 	for (i = 0; i < 4; i++)
-		if (send_byte(key[i], APPLESMC_DATA_PORT))
+		if (send_byte_data(key[i], APPLESMC_DATA_PORT,false))
 			return -EIO;
 	return 0;
 }
@@ -233,13 +226,13 @@ static int read_smc(u8 cmd, const char *key, u8 *buffer, u8 len)
 	}
 
 	/* This has no effect on newer (2012) SMCs */
-	if (send_byte(len, APPLESMC_DATA_PORT)) {
+	if (send_byte_data(len, APPLESMC_DATA_PORT,false)) {
 		pr_warn("%.4s: read len fail\n", key);
 		return -EIO;
 	}
 
 	for (i = 0; i < len; i++) {
-		if (wait_read()) {
+		if (wait_status(0x45,0xFF)) {
 			pr_warn("%.4s: read data[%d] fail\n", key, i);
 			return -EIO;
 		}
@@ -269,14 +262,14 @@ static int write_smc(u8 cmd, const char *key, const u8 *buffer, u8 len)
 		return -EIO;
 	}
 
-	if (send_byte(len, APPLESMC_DATA_PORT)) {
+	if (send_byte_data(len, APPLESMC_DATA_PORT,false)) {
 		pr_warn("%.4s: write len fail\n", key);
 		return -EIO;
 	}
 
 	for (i = 0; i < len; i++) {
-		if (send_byte(buffer[i], APPLESMC_DATA_PORT)) {
-			pr_warn("%s: write data fail\n", key);
+		if (send_byte_data(buffer[i], APPLESMC_DATA_PORT,(i==(len-1)))) {
+			pr_warn("%s: write data fail at %i\n", key, i);
 			return -EIO;
 		}
 	}