HDQ driver:protect the shared flag

This patch moves the shared variable into the local structure and
protects its updation.
Signed-off-by: Madhusudhan Chikkature <madhu.cr@ti.com>
Acked-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Acked-by: Felipe Balbi <felipe.balbi@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/w1/masters/omap_hdq.c

@@ -61,6 +61,12 @@ struct hdq_data {
 	struct	clk		*hdq_fck;
 	u8			hdq_irqstatus;
 	spinlock_t		hdq_spinlock;
+	/*
+	 * Used to control the call to omap_hdq_get and omap_hdq_put.
+	 * HDQ Protocol: Write the CMD|REG_address first, followed by
+	 * the data wrire or read.
+	 */
+	int			init_trans;
 };
 
 static int omap_hdq_get(struct hdq_data *hdq_data);
@@ -504,13 +510,6 @@ omap_hdq_put(struct hdq_data *hdq_data)
 	return ret;
 }
 
-/*
- * Used to control the call to omap_hdq_get and omap_hdq_put.
- * HDQ Protocol: Write the CMD|REG_address first, followed by
- * the data wrire or read.
- */
-static int init_trans;
-
 /*
  * Read a byte of data from the device.
  */
@@ -522,14 +521,26 @@ static u8 omap_w1_read_byte(void *_hdq)
 
 	ret = hdq_read_byte(hdq_data, &val);
 	if (ret) {
-		init_trans = 0;
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return -EINTR;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
 		omap_hdq_put(hdq_data);
 		return -1;
 	}
 
 	/* Write followed by a read, release the module */
-	if (init_trans) {
-		init_trans = 0;
+	if (hdq_data->init_trans) {
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return -EINTR;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
 		omap_hdq_put(hdq_data);
 	}
 
@@ -542,21 +553,34 @@ static u8 omap_w1_read_byte(void *_hdq)
 static void omap_w1_write_byte(void *_hdq, u8 byte)
 {
 	struct hdq_data *hdq_data = _hdq;
+	int ret;
 	u8 status;
 
 	/* First write to initialize the transfer */
-	if (init_trans == 0)
+	if (hdq_data->init_trans == 0)
 		omap_hdq_get(hdq_data);
 
-	init_trans++;
+	ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+	if (ret < 0) {
+		dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+		return;
+	}
+	hdq_data->init_trans++;
+	mutex_unlock(&hdq_data->hdq_mutex);
 
 	hdq_write_byte(hdq_data, byte, &status);
 	dev_dbg(hdq_data->dev, "Ctrl status %x\n", status);
 
 	/* Second write, data transfered. Release the module */
-	if (init_trans > 1) {
+	if (hdq_data->init_trans > 1) {
 		omap_hdq_put(hdq_data);
-		init_trans = 0;
+		ret = mutex_lock_interruptible(&hdq_data->hdq_mutex);
+		if (ret < 0) {
+			dev_dbg(hdq_data->dev, "Could not acquire mutex\n");
+			return;
+		}
+		hdq_data->init_trans = 0;
+		mutex_unlock(&hdq_data->hdq_mutex);
 	}
 
 	return;