From: Steve Sakoman <steve@sakoman.com>
Date: Wed, 20 Oct 2010 13:07:47 +0000 (-0700)
Subject: ARMV7: OMAP: I2C driver: Restructure i2c_probe function
X-Git-Tag: v2010.12-rc1~47^2
X-Git-Url: https://git.sur5r.net/?a=commitdiff_plain;h=fbad3555624a738a632ddb1b968e98a20e743941;p=u-boot

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 35201c3812..a72d1a1257 100644
--- 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);