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ARMV7: OMAP: I2C driver: Restructure i2c_write_byte 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 06:07:46 -07:00 • committed by Heiko Schocher
parent da0cc665bc
commit d480c46773
1 changed files with 42 additions and 36 deletions
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74
drivers/i2c/omap24xx_i2c.c
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@ -218,7 +218,7 @@ read_exit:
static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value) static int i2c_write_byte (u8 devaddr, u8 regoffset, u8 value)
{ {
int i2c_error = 0; int i2c_error = 0;
u16 status, stat; u16 status;
/* wait until bus not busy */ /* wait until bus not busy */
wait_for_bb (); 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 | writew (I2C_CON_EN | I2C_CON_MST | I2C_CON_STT | I2C_CON_TRX |
I2C_CON_STP, &i2c_base->con); I2C_CON_STP, &i2c_base->con);
/* wait until state change */ while (1) {
status = wait_for_pin (); status = wait_for_pin();
if (status == 0 || status & I2C_STAT_NACK) {
i2c_error = 1;
goto write_exit;
}
if (status & I2C_STAT_XRDY) { if (status & I2C_STAT_XRDY) {
#if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \ #if defined(CONFIG_OMAP243X) || defined(CONFIG_OMAP34XX) || \
defined(CONFIG_OMAP44XX) defined(CONFIG_OMAP44XX)
/* send out 1 byte */ /* send register offset */
writeb (regoffset, &i2c_base->data); writeb(regoffset, &i2c_base->data);
writew (I2C_STAT_XRDY, &i2c_base->stat); writew(I2C_STAT_XRDY, &i2c_base->stat);
status = wait_for_pin (); while (1) {
if ((status & I2C_STAT_XRDY)) { status = wait_for_pin();
/* send out next 1 byte */ if (status == 0 || status & I2C_STAT_NACK) {
writeb (value, &i2c_base->data);
writew (I2C_STAT_XRDY, &i2c_base->stat);
} else {
i2c_error = 1; i2c_error = 1;
goto write_exit;
} }
#else if (status & I2C_STAT_XRDY) {
/* send out two bytes */ /* send data */
writew ((value << 8) + regoffset, &i2c_base->data); writeb(value, &i2c_base->data);
#endif writew(I2C_STAT_XRDY, &i2c_base->stat);
/* 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 { if (status & I2C_STAT_ARDY) {
i2c_error = 1; writew(I2C_STAT_ARDY, &i2c_base->stat);
}
if (!i2c_error) {
int eout = 200;
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; break;
} }
} }
break;
#else
/* send out two bytes */
writew((value << 8) + regoffset, &i2c_base->data);
writew(I2C_STAT_XRDY, &i2c_base->stat);
#endif
}
if (status & I2C_STAT_ARDY) {
writew(I2C_STAT_ARDY, &i2c_base->stat);
break;
}
}
wait_for_bb();
status = readw(&i2c_base->stat);
if (status & I2C_STAT_NACK)
i2c_error = 1;
write_exit:
flush_fifo(); flush_fifo();
writew (0xFFFF, &i2c_base->stat); writew (0xFFFF, &i2c_base->stat);
writew (0, &i2c_base->cnt); writew (0, &i2c_base->cnt);