ARMV7: OMAP: I2C driver: Restructure i2c_probe function

This patch removes the "magic number" delays and instead
monitors state changes in the status register bits.

Signed-off-by: Steve Sakoman <steve.sakoman@linaro.org>
Tested-by: Heiko Schocher <hs@denx.de>

diff --git a/drivers/i2c/omap24xx_i2c.c b/drivers/i2c/omap24xx_i2c.c
index 35201c38124ec19e7ef8cbae715123f9c9e2401f..a72d1a125702dd7f3f55ec2476a80b91ad6d7fea 100644 (file)
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -310,6 +310,7 @@ static void flush_fifo(void)
 
 int i2c_probe (uchar chip)
 {
+       u16 status;
        int res = 1; /* default = fail */
 
        if (chip == readw (&i2c_base->oa)) {
@@ -325,19 +326,37 @@ int i2c_probe (uchar chip)
        writew (chip, &i2c_base->sa);
        /* stop bit needed here */
        writew (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP, &i2c_base->con);
-       /* enough delay for the NACK bit set */
-       udelay (50000);
 
-       if (!(readw (&i2c_base->stat) & I2C_STAT_NACK)) {
-               res = 0;      /* success case */
-               flush_fifo();
-               writew(0xFFFF, &i2c_base->stat);
-       } else {
-               writew(0xFFFF, &i2c_base->stat);         /* failue, clear sources*/
-               writew (readw (&i2c_base->con) | I2C_CON_STP, &i2c_base->con); /* finish up xfer */
-               udelay(20000);
-               wait_for_bb ();
+       while (1) {
+               status = wait_for_pin();
+               if (status == 0) {
+                       res = 1;
+                       goto probe_exit;
+               }
+               if (status & I2C_STAT_NACK) {
+                       res = 1;
+                       writew(0xff, &i2c_base->stat);
+                       writew (readw (&i2c_base->con) | I2C_CON_STP, &i2c_base->con);
+                       wait_for_bb ();
+                       break;
+               }
+               if (status & I2C_STAT_ARDY) {
+                       writew(I2C_STAT_ARDY, &i2c_base->stat);
+                       break;
+               }
+               if (status & I2C_STAT_RRDY) {
+                       res = 0;
+#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
+    defined(CONFIG_OMAP44XX)
+                       readb(&i2c_base->data);
+#else
+                       readw(&i2c_base->data);
+#endif
+                       writew(I2C_STAT_RRDY, &i2c_base->stat);
+               }
        }
+
+probe_exit:
        flush_fifo();
        writew (0, &i2c_base->cnt); /* don't allow any more data in...we don't want it.*/
        writew(0xFFFF, &i2c_base->stat);