Revert "i2c: rcar: remove spinlock"

This reverts commit 150b8be3cda54412ad7b54f5392b513b25c0aaa7.

The I2C core's per-adapter locks can't protect from IRQs, so the driver still
needs a spinlock to protect the register accesses.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: stable@vger.kernel.org # 3.16+
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 22 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index dc32f5fa75d0..1cc146cfc1f3 100644
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -34,6 +34,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
+#include <linux/spinlock.h>
 
 /* register offsets */
 #define ICSCR   0x00    /* slave ctrl */
@@ -95,6 +96,7 @@ struct rcar_i2c_priv {
         struct i2c_msg  *msg;
         struct clk *clk;
 
+        spinlock_t lock;
         wait_queue_head_t wait;
 
         int pos;
@@ -365,6 +367,9 @@ static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
         struct rcar_i2c_priv *priv = ptr;
         u32 msr;
 
+        /*-------------- spin lock -----------------*/
+        spin_lock(&priv->lock);
+
         msr = rcar_i2c_read(priv, ICMSR);
 
         /* Only handle interrupts that are currently enabled */
@@ -403,6 +408,9 @@ out:
                 wake_up(&priv->wait);
         }
 
+        spin_unlock(&priv->lock);
+        /*-------------- spin unlock -----------------*/
+
         return IRQ_HANDLED;
 }
 
@@ -412,14 +420,21 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
 {
         struct rcar_i2c_priv *priv = i2c_get_adapdata(adap);
         struct device *dev = rcar_i2c_priv_to_dev(priv);
+        unsigned long flags;
         int i, ret, timeout;
 
         pm_runtime_get_sync(dev);
 
+        /*-------------- spin lock -----------------*/
+        spin_lock_irqsave(&priv->lock, flags);
+
         rcar_i2c_init(priv);
         /* start clock */
         rcar_i2c_write(priv, ICCCR, priv->icccr);
 
+        spin_unlock_irqrestore(&priv->lock, flags);
+        /*-------------- spin unlock -----------------*/
+
         ret = rcar_i2c_bus_barrier(priv);
         if (ret < 0)
                 goto out;
@@ -431,6 +446,9 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
                         break;
                 }
 
+                /*-------------- spin lock -----------------*/
+                spin_lock_irqsave(&priv->lock, flags);
+
                 /* init each data */
                 priv->msg       = &msgs[i];
                 priv->pos       = 0;
@@ -440,6 +458,9 @@ static int rcar_i2c_master_xfer(struct i2c_adapter *adap,
 
                 ret = rcar_i2c_prepare_msg(priv);
 
+                spin_unlock_irqrestore(&priv->lock, flags);
+                /*-------------- spin unlock -----------------*/
+
                 if (ret < 0)
                         break;
 
@@ -543,6 +564,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 
         irq = platform_get_irq(pdev, 0);
         init_waitqueue_head(&priv->wait);
+        spin_lock_init(&priv->lock);
 
         adap = &priv->adap;
         adap->nr = pdev->id;