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MFp4: first cut at getting I2C transfers working (generically). I'm

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unsure if this driver correctly implements all the start/stop junk
right (but it did or didn't before I made this commit).
This commit is contained in:
Warner Losh 2006-09-07 21:53:28 +00:00
parent 5dced01e59
commit 656595aa63
1 changed files with 55 additions and 8 deletions
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63
sys/arm/at91/at91_twi.c
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@ -128,20 +128,16 @@ at91_twi_attach(device_t dev)
sc->cwgr = TWI_CWGR_CKDIV(8 * AT91C_MASTER_CLOCK / 90000) |
TWI_CWGR_CHDIV(TWI_CWGR_DIV(TWI_DEF_CLK)) |
TWI_CWGR_CLDIV(TWI_CWGR_DIV(TWI_DEF_CLK));
WR4(sc, TWI_CR, TWI_CR_SWRST);
WR4(sc, TWI_CR, TWI_CR_MSEN | TWI_CR_SVDIS);
WR4(sc, TWI_CWGR, sc->cwgr);
WR4(sc, TWI_IER, TWI_SR_RXRDY | TWI_SR_OVRE | TWI_SR_UNRE |
TWI_SR_NACK);
if ((sc->iicbus = device_add_child(dev, "iicbus", -1)) == NULL)
device_printf(dev, "could not allocate iicbus instance\n");
/* probe and attach the iicbus */
bus_generic_attach(dev);
out:;
if (err)
at91_twi_deactivate(dev);
@ -228,12 +224,15 @@ at91_twi_intr(void *xsc)
}
static int
at91_twi_wait_stop_done(struct at91_twi_softc *sc)
at91_twi_wait(struct at91_twi_softc *sc, uint32_t bit)
{
int err = 0;
int counter = 10000;
while (!(RD4(sc, TWI_SR) & TWI_SR_TXCOMP))
while (!(RD4(sc, TWI_SR) & bit) && counter-- != 0)
continue;
if (counter == 0)
err = EIO;
return (err);
}
@ -252,7 +251,7 @@ at91_twi_stop(device_t dev)
sc = device_get_softc(dev);
if (sc->sc_started) {
WR4(sc, TWI_CR, TWI_CR_STOP);
err = at91_twi_wait_stop_done(sc);
err = at91_twi_wait(sc, TWI_SR_TXCOMP);
}
return (err);
}
@ -345,7 +344,7 @@ at91_twi_read(device_t dev, char *buf, int len, int *read, int last,
if (!last)
goto errout;
WR4(sc, TWI_CR, TWI_CR_STOP);
err = at91_twi_wait_stop_done(sc);
err = at91_twi_wait(sc, TWI_SR_TXCOMP);
*walker = RD4(sc, TWI_RHR) & 0xff;
if (read)
*read = walker - buf;
@ -419,6 +418,53 @@ at91_twi_callback(device_t dev, int index, caddr_t *data)
return (error);
}
static int
at91_twi_transfer(device_t dev, struct iic_msg *msgs, uint32_t nmsgs)
{
struct at91_twi_softc *sc;
int i, len;
uint32_t rdwr;
uint8_t *buf;
sc = device_get_softc(dev);
for (i = 0; i < nmsgs; i++) {
/*
* The linux atmel driver doesn't use the internal device
* address feature of twi. A separate i2c message needs to
* be written to use this.
* See http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html
* for details.
*/
rdwr = (msgs[i].flags & IIC_M_RD) ? TWI_MMR_MREAD : 0;
WR4(sc, TWI_MMR, TWI_MMR_DADR(msgs[i].slave) | rdwr);
len = msgs[i].len;
buf = msgs[i].buf;
if (len != 0 || buf == NULL)
return EINVAL;
WR4(sc, TWI_CR, TWI_CR_START);
if (msgs[i].flags & IIC_M_RD) {
while (len--) {
if (len == 0)
WR4(sc, TWI_CR, TWI_CR_STOP);
if (!at91_twi_wait(sc, TWI_SR_RXRDY))
return EIO;
*buf++ = RD4(sc, TWI_RHR) & 0xff;
}
} else {
while (len--) {
WR4(sc, TWI_THR, *buf++);
if (len == 0)
WR4(sc, TWI_CR, TWI_CR_STOP);
if (!at91_twi_wait(sc, TWI_SR_TXRDY))
return EIO;
}
}
if (!at91_twi_wait(sc, TWI_SR_TXCOMP))
return EIO;
}
return 0;
}
static device_method_t at91_twi_methods[] = {
/* Device interface */
DEVMETHOD(device_probe, at91_twi_probe),
@ -433,6 +479,7 @@ static device_method_t at91_twi_methods[] = {
DEVMETHOD(iicbus_write, at91_twi_write),
DEVMETHOD(iicbus_read, at91_twi_read),
DEVMETHOD(iicbus_reset, at91_twi_rst_card),
DEVMETHOD(iicbus_transfer, at91_twi_transfer),
{ 0, 0 }
};