When CONFIG_I2C_DEBUG_BUS is enabled, it helps dump registers at operation
fail condition, and print i2c_msg to xfer.

Signed-off-by: Richard Zhao <linux...@gmail.com>

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index c1e541c..87faea4 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -125,6 +125,20 @@ struct imx_i2c_struct {
 /** Functions for IMX I2C adapter driver 
***************************************
 
*******************************************************************************/
 
+#ifdef CONFIG_I2C_DEBUG_BUS
+#define reg_dump(i2c_imx) \
+{ \
+       printk(KERN_DEBUG "fun %s:%d ", __func__, __LINE__); \
+       printk(KERN_DEBUG "IADR %02x IFDR %02x I2CR %02x I2SR %02x\n", \
+               readb(i2c_imx->base + IMX_I2C_IADR), \
+               readb(i2c_imx->base + IMX_I2C_IFDR), \
+               readb(i2c_imx->base + IMX_I2C_I2CR), \
+               readb(i2c_imx->base + IMX_I2C_I2SR)); \
+}
+#else
+#define reg_dump(i2c_imx)
+#endif
+
 static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
 {
        unsigned long orig_jiffies = jiffies;
@@ -146,6 +160,7 @@ static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, 
int for_busy)
                if (time_after(jiffies, orig_jiffies + HZ / 1000)) {
                        dev_dbg(&i2c_imx->adapter.dev,
                                "<%s> I2C bus is busy\n", __func__);
+                       reg_dump(i2c_imx);
                        return -EIO;
                }
                schedule();
@@ -164,9 +179,11 @@ static int i2c_imx_trx_complete(struct imx_i2c_struct 
*i2c_imx)
 
        if (unlikely(result < 0)) {
                dev_dbg(&i2c_imx->adapter.dev, "<%s> result < 0\n", __func__);
+               reg_dump(i2c_imx);
                return result;
        } else if (unlikely(!(i2c_imx->i2csr & I2SR_IIF))) {
                dev_dbg(&i2c_imx->adapter.dev, "<%s> Timeout\n", __func__);
+               reg_dump(i2c_imx);
                return -ETIMEDOUT;
        }
        dev_dbg(&i2c_imx->adapter.dev, "<%s> TRX complete\n", __func__);
@@ -178,6 +195,7 @@ static int i2c_imx_acked(struct imx_i2c_struct *i2c_imx)
 {
        if (readb(i2c_imx->base + IMX_I2C_I2SR) & I2SR_RXAK) {
                dev_dbg(&i2c_imx->adapter.dev, "<%s> No ACK\n", __func__);
+               reg_dump(i2c_imx);
                return -EIO;  /* No ACK */
        }
 
@@ -197,17 +215,20 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
        writeb(I2CR_IEN, i2c_imx->base + IMX_I2C_I2CR);
 
        result = i2c_imx_bus_busy(i2c_imx, 0);
-       if (result)
+       if (result) {
+               reg_dump(i2c_imx);
                return result;
+       }
 
        /* Start I2C transaction */
        temp = readb(i2c_imx->base + IMX_I2C_I2CR);
        temp |= I2CR_MSTA;
        writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
        result = i2c_imx_bus_busy(i2c_imx, 1);
-       if (result)
+       if (result) {
+               reg_dump(i2c_imx);
                return result;
-
+       }
        temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
        writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
        return result;
@@ -228,7 +249,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
         */
        udelay(i2c_imx->disable_delay);
 
-       i2c_imx_bus_busy(i2c_imx, 0);
+       if (i2c_imx_bus_busy(i2c_imx, 0))
+               reg_dump(i2c_imx);
 
        /* Disable I2C controller */
        writeb(0, i2c_imx->base + IMX_I2C_I2CR);
@@ -389,7 +411,18 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
        struct imx_i2c_struct *i2c_imx = i2c_get_adapdata(adapter);
 
        dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
-
+#ifdef CONFIG_I2C_DEBUG_BUS
+       for (i = 0; i < num; i++) {
+               printk(KERN_DEBUG "msg%d addr %02x RD %d cnt %d d:", i,
+                       msgs[i].addr, msgs[i].flags & I2C_M_RD, msgs[i].len);
+               if (!(msgs[i].flags & I2C_M_RD)) {
+                       int j;
+                       for (j = 0; j < msgs[i].len; j++)
+                               printk("%02x ", msgs[i].buf[j]);
+               }
+               printk("\n");
+       }
+#endif
        /* Start I2C transfer */
        result = i2c_imx_start(i2c_imx);
        if (result)
@@ -404,8 +437,10 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
                        temp |= I2CR_RSTA;
                        writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
                        result =  i2c_imx_bus_busy(i2c_imx, 1);
-                       if (result)
+                       if (result) {
+                               reg_dump(i2c_imx);
                                goto fail0;
+                       }
                }
                dev_dbg(&i2c_imx->adapter.dev,
                        "<%s> transfer message: %d\n", __func__, i);
@@ -562,7 +597,7 @@ static int __init i2c_imx_probe(struct platform_device 
*pdev)
                res_size, i2c_imx->res->start);
        dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
                i2c_imx->adapter.name);
-       dev_dbg(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
+       dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
 
        return 0;   /* Return OK */
 
-- 
1.6.0.4

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