mxc_i2c: don't disable controller after every transaction

This helps in a multiple bus master environment which
is why I also added a wait for bus idle.

Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>

diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
index 717bc7a..1a5e379 100644 (file)
--- a/drivers/i2c/mxc_i2c.c
+++ b/drivers/i2c/mxc_i2c.c
@@ -192,24 +192,19 @@ static int tx_byte(struct mxc_i2c_regs *i2c_regs, u8 byte)
 }
 
 /*
- * Stop the controller
+ * Stop I2C transaction
  */
 void i2c_imx_stop(void)
 {
        int ret;
        struct mxc_i2c_regs *i2c_regs = (struct mxc_i2c_regs *)I2C_BASE;
-       unsigned int temp = 0;
+       unsigned int temp = readb(&i2c_regs->i2cr);
 
-       /* Stop I2C transaction */
-       temp = readb(&i2c_regs->i2cr);
        temp &= ~(I2CR_MSTA | I2CR_MTX);
        writeb(temp, &i2c_regs->i2cr);
-
        ret = wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
        if (ret < 0)
                printf("%s:trigger stop failed\n", __func__);
-       /* Disable I2C controller */
-       writeb(0, &i2c_regs->i2cr);
 }
 
 /*
@@ -223,11 +218,15 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
        int ret;
 
        /* Enable I2C controller */
+       if (!(readb(&i2c_regs->i2cr) & I2CR_IEN)) {
+               writeb(I2CR_IEN, &i2c_regs->i2cr);
+               /* Wait for controller to be stable */
+               udelay(50);
+       }
        writeb(0, &i2c_regs->i2sr);
-       writeb(I2CR_IEN, &i2c_regs->i2cr);
-
-       /* Wait for controller to be stable */
-       udelay(50);
+       ret = wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
+       if (ret < 0)
+               goto exit;
 
        /* Start I2C transaction */
        temp = readb(&i2c_regs->i2cr);
@@ -254,6 +253,8 @@ static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
        return 0;
 exit:
        i2c_imx_stop();
+       /* Disable I2C controller */
+       writeb(0, &i2c_regs->i2cr);
        return ret;
 }
 
@@ -303,10 +304,7 @@ int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
                 * controller from generating another clock cycle
                 */
                if (i == (len - 1)) {
-                       temp = readb(&i2c_regs->i2cr);
-                       temp &= ~(I2CR_MSTA | I2CR_MTX);
-                       writeb(temp, &i2c_regs->i2cr);
-                       wait_for_sr_state(i2c_regs, ST_BUS_IDLE);
+                       i2c_imx_stop();
                } else if (i == (len - 2)) {
                        temp = readb(&i2c_regs->i2cr);
                        temp |= I2CR_TX_NO_AK;