ARMV7: OMAP: I2C driver: Restructure i2c_write_byte 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 d176b5dd89ca0e2cbba0bee121a148685435b04f..35201c38124ec19e7ef8cbae715123f9c9e2401f 100644 (file)
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -218,7 +218,7 @@ read_exit:
 static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
 {
        int i2c_error = 0;
-       u16 status, stat;
+       u16 status;
 
        /* wait until bus not busy */
        wait_for_bb ();
@@ -231,49 +231,55 @@ static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
        writew (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
                I2C_CON_STP, &i2c_base->con);
 
-       /* wait until state change */
-       status = wait_for_pin ();
-
-       if (status & I2C_STAT_XRDY) {
-#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
-    defined(CONFIG_OMAP44XX)
-               /* send out 1 byte */
-               writeb (regoffset, &i2c_base->data);
-               writew (I2C_STAT_XRDY, &i2c_base->stat);
-
-               status = wait_for_pin ();
-               if ((status & I2C_STAT_XRDY)) {
-                       /* send out next 1 byte */
-                       writeb (value, &i2c_base->data);
-                       writew (I2C_STAT_XRDY, &i2c_base->stat);
-               } else {
+       while (1) {
+               status = wait_for_pin();
+               if (status == 0 || status & I2C_STAT_NACK) {
                        i2c_error = 1;
+                       goto write_exit;
                }
+               if (status & I2C_STAT_XRDY) {
+#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
+    defined(CONFIG_OMAP44XX)
+                       /* send register offset */
+                       writeb(regoffset, &i2c_base->data);
+                       writew(I2C_STAT_XRDY, &i2c_base->stat);
+
+                       while (1) {
+                               status = wait_for_pin();
+                               if (status == 0 || status & I2C_STAT_NACK) {
+                                       i2c_error = 1;
+                                       goto write_exit;
+                               }
+                               if (status & I2C_STAT_XRDY) {
+                                       /* send data */
+                                       writeb(value, &i2c_base->data);
+                                       writew(I2C_STAT_XRDY, &i2c_base->stat);
+                               }
+                               if (status & I2C_STAT_ARDY) {
+                                       writew(I2C_STAT_ARDY, &i2c_base->stat);
+                                       break;
+                               }
+                       }
+                       break;
 #else
-               /* send out two bytes */
-               writew ((value << 8) + regoffset, &i2c_base->data);
+                       /* send out two bytes */
+                       writew((value << 8) + regoffset, &i2c_base->data);
+                       writew(I2C_STAT_XRDY, &i2c_base->stat);
 #endif
-               /* must have enough delay to allow BB bit to go low */
-               udelay (50000);
-               if (readw (&i2c_base->stat) & I2C_STAT_NACK) {
-                       i2c_error = 1;
                }
-       } else {
-               i2c_error = 1;
+               if (status & I2C_STAT_ARDY) {
+                       writew(I2C_STAT_ARDY, &i2c_base->stat);
+                       break;
+               }
        }
 
-       if (!i2c_error) {
-               int eout = 200;
+       wait_for_bb();
 
-               writew (I2C_CON_EN, &i2c_base->con);
-               while ((stat = readw (&i2c_base->stat)) || (readw (&i2c_base->con) & I2C_CON_MST)) {
-                       udelay (1000);
-                       /* have to read to clear intrrupt */
-                       writew (0xFFFF, &i2c_base->stat);
-                       if(--eout == 0) /* better leave with error than hang */
-                               break;
-               }
-       }
+       status = readw(&i2c_base->stat);
+       if (status & I2C_STAT_NACK)
+               i2c_error = 1;
+
+write_exit:
        flush_fifo();
        writew (0xFFFF, &i2c_base->stat);
        writew (0, &i2c_base->cnt);