1 files changed, 33 insertions, 4 deletions

diff --git a/drivers/i2c/busses/i2c-s3c2410.c b/drivers/i2c/busses/i2c-s3c2410.c
index 8162901ff753..ae4491062e41 100644
--- a/drivers/i2c/busses/i2c-s3c2410.c
+++ b/drivers/i2c/busses/i2c-s3c2410.c
@@ -601,6 +601,31 @@ static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
         return IRQ_HANDLED;
 }
 
+/*
+ * Disable the bus so that we won't get any interrupts from now on, or try
+ * to drive any lines. This is the default state when we don't have
+ * anything to send/receive.
+ *
+ * If there is an event on the bus, or we have a pre-existing event at
+ * kernel boot time, we may not notice the event and the I2C controller
+ * will lock the bus with the I2C clock line low indefinitely.
+ */
+static inline void s3c24xx_i2c_disable_bus(struct s3c24xx_i2c *i2c)
+{
+        unsigned long tmp;
+
+        /* Stop driving the I2C pins */
+        tmp = readl(i2c->regs + S3C2410_IICSTAT);
+        tmp &= ~S3C2410_IICSTAT_TXRXEN;
+        writel(tmp, i2c->regs + S3C2410_IICSTAT);
+
+        /* We don't expect any interrupts now, and don't want send acks */
+        tmp = readl(i2c->regs + S3C2410_IICCON);
+        tmp &= ~(S3C2410_IICCON_IRQEN | S3C2410_IICCON_IRQPEND |
+                S3C2410_IICCON_ACKEN);
+        writel(tmp, i2c->regs + S3C2410_IICCON);
+}
+
 
 /* s3c24xx_i2c_set_master
  *
@@ -735,7 +760,11 @@ static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c,
 
         s3c24xx_i2c_wait_idle(i2c);
 
+        s3c24xx_i2c_disable_bus(i2c);
+
  out:
+        i2c->state = STATE_IDLE;
+
         return ret;
 }
 
@@ -1004,7 +1033,6 @@ static void s3c24xx_i2c_dt_gpio_free(struct s3c24xx_i2c *i2c)
 
 static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
 {
-        unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
         struct s3c2410_platform_i2c *pdata;
         unsigned int freq;
 
@@ -1018,12 +1046,12 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
 
         dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);
 
-        writel(iicon, i2c->regs + S3C2410_IICCON);
+        writel(0, i2c->regs + S3C2410_IICCON);
+        writel(0, i2c->regs + S3C2410_IICSTAT);
 
         /* we need to work out the divisors for the clock... */
 
         if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
-                writel(0, i2c->regs + S3C2410_IICCON);
                 dev_err(i2c->dev, "cannot meet bus frequency required\n");
                 return -EINVAL;
         }
@@ -1031,7 +1059,8 @@ static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
         /* todo - check that the i2c lines aren't being dragged anywhere */
 
         dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
-        dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);
+        dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02x\n",
+                readl(i2c->regs + S3C2410_IICCON));
 
         return 0;
 }