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-rw-r--r--drivers/i2c/busses/i2c-s3c2410.c37
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;
}