/*
* I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
* Begin write, send address byte(s), begin read, receive data bytes, end.
*
* NOTE: some EEPROMS want a stop right before the second start, while
* some will choke if it is there. Deciding which we should do is eeprom
* stuff, not i2c, but at the moment the APIs won't let us put it in
* cmd_eeprom, so we have to choose here, and for the moment that'll be
* a repeated start without a preceding stop.
*/
int i2c_read(u8 dev, uint addr, int alen, u8 *data, int length)
{
int status;
/* begin i2c write to send the address bytes */
status = i2c_begin(MVTWSI_STATUS_START, (dev << 1));
/* send addr bytes */
while ((status == 0) && alen--)
status = twsi_send(addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK);
/* begin i2c read to receive eeprom data bytes */
if (status == 0)
status = i2c_begin(
MVTWSI_STATUS_REPEATED_START, (dev << 1) | 1);
/* prepare ACK if at least one byte must be received */
if (length > 0)
twsi_control_flags |= MVTWSI_CONTROL_ACK;
/* now receive actual bytes */
while ((status == 0) && length--) {
/* reset NAK if we if no more to read now */
if (length == 0)
twsi_control_flags &= ~MVTWSI_CONTROL_ACK;
/* read current byte */
status = twsi_recv(data++);
}
/* Stop transaction */
status = twsi_stop(status);
/* return 0 or status of first failure */
return status;
}
/*
* I2C probe called by cmd_i2c when doing 'i2c probe'.
* Begin read, nak data byte, end.
*/
int i2c_probe(uchar chip)
{
u8 dummy_byte;
int status;
/* begin i2c read */
status = i2c_begin(MVTWSI_STATUS_START, (chip << 1) | 1);
/* dummy read was accepted: receive byte but NAK it. */
if (status == 0)
status = twsi_recv(&dummy_byte);
/* Stop transaction */
twsi_stop(0);
/* return 0 or status of first failure */
return status;
}
/*
* Reset controller.
* Called at end of i2c_init unsuccessful i2c transactions.
* Controller reset also resets the baud rate and slave address, so
* re-establish them.
*/
static void twsi_reset(void)
{
/* ensure controller will be enabled by any twsi*() function */
twsi_control_flags = MVTWSI_CONTROL_TWSIEN;
/* reset controller */
writel(0, &twsi->soft_reset);
/* wait 2 ms -- this is what the Marvell LSP does */
udelay(20000);
/* set baud rate */
writel(twsi_baud_rate, &twsi->baudrate);
/* set slave address even though we don't use it */
writel(twsi_slave_address, &twsi->slave_address);
writel(0, &twsi->xtnd_slave_addr);
/* assert STOP but don't care for the result */
(void) twsi_stop(0);
}
/*
* I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
* Begin write, send address byte(s), send data bytes, end.
*/
int i2c_write(u8 dev, uint addr, int alen, u8 *data, int length)
{
int status;
/* begin i2c write to send the eeprom adress bytes then data bytes */
status = i2c_begin(MVTWSI_STATUS_START, (dev << 1));
/* send addr bytes */
while ((status == 0) && alen--)
status = twsi_send(addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK);
/* send data bytes */
while ((status == 0) && (length-- > 0))
status = twsi_send(*(data++), MVTWSI_STATUS_DATA_W_ACK);
/* Stop transaction */
status = twsi_stop(status);
/* return 0 or status of first failure */
return status;
}
/*
* timeout is given in us
*/
static int
twsi_start(device_t dev, u_char slave, int timeout)
{
struct twsi_softc *sc;
int rv;
sc = device_get_softc(dev);
mtx_lock(&sc->mutex);
rv = twsi_locked_start(dev, sc, TWSI_STATUS_START, slave, timeout);
mtx_unlock(&sc->mutex);
if (rv) {
twsi_stop(dev);
return (rv);
} else
return (IIC_NOERR);
}