i2c-designware: enable/disable the controller properly
The correct way to disable or enable the controller is to wait until the
DW_IC_ENABLE_STATUS register bit matches the bit we program into DW_IC_ENABLE
register. This procedure is described in the DesignWare I2C databook.
By doing this we can be sure that the controller is in correct state once
the function returns.
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index 94fd818..5cc4ebf 100644
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -68,6 +68,7 @@
#define DW_IC_TXFLR 0x74
#define DW_IC_RXFLR 0x78
#define DW_IC_TX_ABRT_SOURCE 0x80
+#define DW_IC_ENABLE_STATUS 0x9c
#define DW_IC_COMP_PARAM_1 0xf4
#define DW_IC_COMP_TYPE 0xfc
#define DW_IC_COMP_TYPE_VALUE 0x44570140
@@ -248,6 +249,27 @@
return ((ic_clk * (tLOW + tf) + 5000) / 10000) - 1 + offset;
}
+static void __i2c_dw_enable(struct dw_i2c_dev *dev, bool enable)
+{
+ int timeout = 100;
+
+ do {
+ dw_writel(dev, enable, DW_IC_ENABLE);
+ if ((dw_readl(dev, DW_IC_ENABLE_STATUS) & 1) == enable)
+ return;
+
+ /*
+ * Wait 10 times the signaling period of the highest I2C
+ * transfer supported by the driver (for 400KHz this is
+ * 25us) as described in the DesignWare I2C databook.
+ */
+ usleep_range(25, 250);
+ } while (timeout--);
+
+ dev_warn(dev->dev, "timeout in %sabling adapter\n",
+ enable ? "en" : "dis");
+}
+
/**
* i2c_dw_init() - initialize the designware i2c master hardware
* @dev: device private data
@@ -278,7 +300,7 @@
}
/* Disable the adapter */
- dw_writel(dev, 0, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, false);
/* set standard and fast speed deviders for high/low periods */
@@ -345,7 +367,7 @@
u32 ic_con;
/* Disable the adapter */
- dw_writel(dev, 0, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, false);
/* set the slave (target) address */
dw_writel(dev, msgs[dev->msg_write_idx].addr, DW_IC_TAR);
@@ -359,7 +381,7 @@
dw_writel(dev, ic_con, DW_IC_CON);
/* Enable the adapter */
- dw_writel(dev, 1, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, true);
/* Enable interrupts */
dw_writel(dev, DW_IC_INTR_DEFAULT_MASK, DW_IC_INTR_MASK);
@@ -565,7 +587,7 @@
/* no error */
if (likely(!dev->cmd_err)) {
/* Disable the adapter */
- dw_writel(dev, 0, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, false);
ret = num;
goto done;
}
@@ -700,7 +722,7 @@
void i2c_dw_enable(struct dw_i2c_dev *dev)
{
/* Enable the adapter */
- dw_writel(dev, 1, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, true);
}
EXPORT_SYMBOL_GPL(i2c_dw_enable);
@@ -713,7 +735,7 @@
void i2c_dw_disable(struct dw_i2c_dev *dev)
{
/* Disable controller */
- dw_writel(dev, 0, DW_IC_ENABLE);
+ __i2c_dw_enable(dev, false);
/* Disable all interupts */
dw_writel(dev, 0, DW_IC_INTR_MASK);