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ARMV7: OMAP: I2C driver: Restructure i2c_probe function

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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>
This commit is contained in:
Steve Sakoman 2010-10-20 06:07:47 -07:00 • committed by Heiko Schocher
parent d480c46773
commit fbad355562
1 changed files with 30 additions and 11 deletions
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41
drivers/i2c/omap24xx_i2c.c
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@ -310,6 +310,7 @@ static void flush_fifo(void)
int i2c_probe (uchar chip) int i2c_probe (uchar chip)
{ {
u16 status;
int res = 1; /* default = fail */ int res = 1; /* default = fail */
if (chip == readw (&i2c_base->oa)) { if (chip == readw (&i2c_base->oa)) {
@ -325,19 +326,37 @@ int i2c_probe (uchar chip)
writew (chip, &i2c_base->sa); writew (chip, &i2c_base->sa);
/* stop bit needed here */ /* stop bit needed here */
writew (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_STP, &i2c_base->con); 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)) { while (1) {
res = 0; /* success case */ status = wait_for_pin();
flush_fifo(); if (status == 0) {
writew(0xFFFF, &i2c_base->stat); res = 1;
} else { goto probe_exit;
writew(0xFFFF, &i2c_base->stat); /* failue, clear sources*/ }
writew (readw (&i2c_base->con) | I2C_CON_STP, &i2c_base->con); /* finish up xfer */ if (status & I2C_STAT_NACK) {
udelay(20000); res = 1;
wait_for_bb (); 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(); flush_fifo();
writew (0, &i2c_base->cnt); /* don't allow any more data in...we don't want it.*/ writew (0, &i2c_base->cnt); /* don't allow any more data in...we don't want it.*/
writew(0xFFFF, &i2c_base->stat); writew(0xFFFF, &i2c_base->stat);