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 d176b5d..35201c3 100644
--- a/drivers/i2c/omap24xx_i2c.c
+++ b/drivers/i2c/omap24xx_i2c.c
@@ -218,7 +218,7 @@
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 @@
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) {
+ 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 out 1 byte */
- writeb (regoffset, &i2c_base->data);
- writew (I2C_STAT_XRDY, &i2c_base->stat);
+ /* send register offset */
+ 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 {
- i2c_error = 1;
- }
+ 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);