From: Yi Zhang <yizhang@xxxxxxxxxxx>
Enable i2c module/unit before transmission and disable when it finishes.
why?
It's because the i2c bus may be distrubed if the slave device,
typically a touch, powers on.
Signed-off-by: Yi Zhang <yizhang@xxxxxxxxxxx>
[vaibhav.hiremath@xxxxxxxxxx: ported to latest kernel & also improved changelog]
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
Signed-off-by: Vaibhav Hiremath <vaibhav.hiremath@xxxxxxxxxx>
---
drivers/i2c/busses/i2c-pxa.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 844e1fc..f51d512 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -368,6 +368,16 @@ static void i2c_pxa_scream_blue_murder(struct pxa_i2c *i2c, const char *why)
static void i2c_pxa_master_complete(struct pxa_i2c *i2c, int ret);
static irqreturn_t i2c_pxa_handler(int this_irq, void *dev_id);
+/* enable/disable i2c unit */
+static inline void i2c_pxa_enable(struct pxa_i2c *i2c, bool enable)
+{
+ if (enable)
+ writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
+ else
+ writel(readl(_ICR(i2c)) & ~ICR_IUE, _ICR(i2c));
+ udelay(100);
+}
+
static inline int i2c_pxa_is_slavemode(struct pxa_i2c *i2c)
{
return !(readl(_ICR(i2c)) & ICR_SCLE);
@@ -575,8 +585,7 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
i2c_pxa_set_slave(i2c, 0);
/* enable unit */
- writel(readl(_ICR(i2c)) | ICR_IUE, _ICR(i2c));
- udelay(100);
+ i2c_pxa_enable(i2c, true);
}
@@ -933,6 +942,9 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
struct pxa_i2c *i2c = adap->algo_data;
int ret, i;
+ /* Enable i2c unit */
+ i2c_pxa_enable(i2c, true);
+
/* If the I2C controller is disabled we need to reset it
(probably due to a suspend/resume destroying state). We do
this here as we can then avoid worrying about resuming the
@@ -953,6 +965,10 @@ static int i2c_pxa_pio_xfer(struct i2c_adapter *adap,
ret = -EREMOTEIO;
out:
i2c_pxa_set_slave(i2c, ret);
+
+ /* disable i2c unit */
+ i2c_pxa_enable(i2c, false);
+
return ret;
}
@@ -1168,6 +1184,9 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num
struct pxa_i2c *i2c = adap->algo_data;
int ret, i;
+ /* Enable i2c unit */
+ i2c_pxa_enable(i2c, true);
+
enable_irq(i2c->irq);
for (i = adap->retries; i >= 0; i--) {
ret = i2c_pxa_do_xfer(i2c, msgs, num);
@@ -1183,6 +1202,9 @@ static int i2c_pxa_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num
out:
i2c_pxa_set_slave(i2c, ret);
disable_irq(i2c->irq);
+ /* disable i2c unit */
+ i2c_pxa_enable(i2c, false);
+
return ret;
}
@@ -1407,6 +1429,9 @@ static int i2c_pxa_probe(struct platform_device *dev)
ret = 0;
}
}
+
+ i2c_pxa_enable(i2c, false);
+
#ifdef CONFIG_I2C_PXA_SLAVE
pr_info("I2C: %s: PXA I2C adapter, slave address %d\n",
dev_name(&i2c->adap.dev), i2c->slave_addr);
--
1.9.1
--
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