/*
* Bus Clear
*/
static int omap_i2c_bus_clear(struct omap_i2c_dev *dev)
{
u16 w;
/* Per the I2C specification, if we are stuck in a bus busy state
* we can attempt a bus clear to try and recover the bus by sending
* at least 9 clock pulses on SCL. Put the I2C in a test mode so it
* will output a continuous clock on SCL.
*/
disable_irq(dev->irq);
w = omap_i2c_read_reg(dev, OMAP_I2C_SYSTEST_REG);
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG,
(OMAP_I2C_SYSTEST_ST_EN | OMAP_I2C_SYSTEST_TMODE_TEST));
msleep(1);
omap_i2c_write_reg(dev, OMAP_I2C_SYSTEST_REG, w);
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
omap_i2c_reset(dev);
omap_i2c_init(dev);
enable_irq(dev->irq);
return omap_i2c_wait_for_bb(dev);
}
/*
* Low level master read/write transaction.
*/
static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
struct i2c_msg *msg, int stop)
{
struct omap_i2c_dev *dev = i2c_get_adapdata(adap);
unsigned long timeout;
u16 w;
dev_dbg(dev->dev, "addr: 0x%04x, len: %d, flags: 0x%x, stop: %d\n",
msg->addr, msg->len, msg->flags, stop);
if (msg->len == 0)
return -EINVAL;
dev->receiver = !!(msg->flags & I2C_M_RD);
omap_i2c_resize_fifo(dev, msg->len, dev->receiver);
omap_i2c_write_reg(dev, OMAP_I2C_SA_REG, msg->addr);
/* REVISIT: Could the STB bit of I2C_CON be used with probing? */
dev->buf = msg->buf;
dev->buf_len = msg->len;
/* make sure writes to dev->buf_len are ordered */
barrier();
omap_i2c_write_reg(dev, OMAP_I2C_CNT_REG, dev->buf_len);
/* Clear the FIFO Buffers */
w = omap_i2c_read_reg(dev, OMAP_I2C_BUF_REG);
w |= OMAP_I2C_BUF_RXFIF_CLR | OMAP_I2C_BUF_TXFIF_CLR;
omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, w);
INIT_COMPLETION(dev->cmd_complete);
dev->cmd_err = 0;
w = OMAP_I2C_CON_EN | OMAP_I2C_CON_MST | OMAP_I2C_CON_STT;
/* High speed configuration */
if (dev->speed > 400)
w |= OMAP_I2C_CON_OPMODE_HS;
if (msg->flags & I2C_M_STOP)
stop = 1;
if (msg->flags & I2C_M_TEN)
w |= OMAP_I2C_CON_XA;
if (!(msg->flags & I2C_M_RD))
w |= OMAP_I2C_CON_TRX;
if (!dev->b_hw && stop)
w |= OMAP_I2C_CON_STP;
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
/*
* Don't write stt and stp together on some hardware.
*/
if (dev->b_hw && stop) {
unsigned long delay = jiffies + OMAP_I2C_TIMEOUT;
u16 con = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
while (con & OMAP_I2C_CON_STT) {
con = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
/* Let the user know if i2c is in a bad state */
if (time_after(jiffies, delay)) {
dev_err(dev->dev, "controller timed out "
"waiting for start condition to finish\n");
return -ETIMEDOUT;
}
cpu_relax();
}
w |= OMAP_I2C_CON_STP;
w &= ~OMAP_I2C_CON_STT;
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
}
/*
* REVISIT: We should abort the transfer on signals, but the bus goes
* into arbitration and we're currently unable to recover from it.
*/
timeout = wait_for_completion_timeout(&dev->cmd_complete,
OMAP_I2C_TIMEOUT);
if (timeout == 0) {
dev_err(dev->dev, "controller timed out\n");
omap_i2c_reset(dev);
__omap_i2c_init(dev);
return -ETIMEDOUT;
}
if (likely(!dev->cmd_err))
return 0;
/* We have an error */
if (dev->cmd_err & (OMAP_I2C_STAT_AL | OMAP_I2C_STAT_ROVR |
OMAP_I2C_STAT_XUDF)) {
omap_i2c_reset(dev);
__omap_i2c_init(dev);
return -EIO;
}
if (dev->cmd_err & OMAP_I2C_STAT_NACK) {
if (msg->flags & I2C_M_IGNORE_NAK)
return 0;
if (stop) {
w = omap_i2c_read_reg(dev, OMAP_I2C_CON_REG);
w |= OMAP_I2C_CON_STP;
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, w);
}
return -EREMOTEIO;
}
return -EIO;
}
static int omap_i2c_init(struct omap_i2c_dev *dev)
{
u16 psc = 0, scll = 0, sclh = 0, buf = 0;
u16 fsscll = 0, fssclh = 0, hsscll = 0, hssclh = 0;
unsigned long fclk_rate = 12000000;
unsigned long internal_clk = 0;
struct clk *fclk;
int ret;
/* Soft reset the I2C module */
ret = omap_i2c_reset(dev);
if (ret) {
dev_err(dev->dev, "Unable to softreset I2C module\n");
return ret;
}
if (dev->rev >= OMAP_I2C_REV_ON_3430) {
/*
* Enabling all wakup sources to stop I2C freezing on
* WFI instruction.
* REVISIT: Some wkup sources might not be needed.
*/
dev->westate = OMAP_I2C_WE_ALL;
omap_i2c_write_reg(dev, OMAP_I2C_WE_REG, dev->westate);
}
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, 0);
if (cpu_class_is_omap1()) {
/*
* The I2C functional clock is the armxor_ck, so there's
* no need to get "armxor_ck" separately. Now, if OMAP2420
* always returns 12MHz for the functional clock, we can
* do this bit unconditionally.
*/
fclk = clk_get(dev->dev, "fck");
fclk_rate = clk_get_rate(fclk);
clk_put(fclk);
/* TRM for 5912 says the I2C clock must be prescaled to be
* between 7 - 12 MHz. The XOR input clock is typically
* 12, 13 or 19.2 MHz. So we should have code that produces:
*
* XOR MHz Divider Prescaler
* 12 1 0
* 13 2 1
* 19.2 2 1
*/
if (fclk_rate > 12000000)
psc = fclk_rate / 12000000;
}
if (!(cpu_class_is_omap1() || cpu_is_omap2420())) {
/*
* HSI2C controller internal clk rate should be 19.2 Mhz for
* HS and for all modes on 2430. On 34xx we can use lower rate
* to get longer filter period for better noise suppression.
* The filter is iclk (fclk for HS) period.
*/
if (dev->speed > 400 || cpu_is_omap2430())
internal_clk = 19200;
else if (dev->speed > 100)
internal_clk = 9600;
else
internal_clk = 4000;
fclk = clk_get(dev->dev, "fck");
fclk_rate = clk_get_rate(fclk) / 1000;
clk_put(fclk);
/* Compute prescaler divisor */
psc = fclk_rate / internal_clk;
psc = psc - 1;
/* If configured for High Speed */
if (dev->speed > 400) {
unsigned long scl;
/* For first phase of HS mode */
scl = internal_clk / 400;
fsscll = scl - (scl / 3) - 7;
fssclh = (scl / 3) - 5;
/* For second phase of HS mode */
scl = fclk_rate / dev->speed;
hsscll = scl - (scl / 3) - 7;
hssclh = (scl / 3) - 5;
} else if (dev->speed > 100) {
unsigned long scl;
/* Fast mode */
scl = internal_clk / dev->speed;
fsscll = scl - (scl / 3) - 7;
fssclh = (scl / 3) - 5;
} else {
/* Standard mode */
fsscll = internal_clk / (dev->speed * 2) - 7;
fssclh = internal_clk / (dev->speed * 2) - 5;
}
scll = (hsscll << OMAP_I2C_SCLL_HSSCLL) | fsscll;
sclh = (hssclh << OMAP_I2C_SCLH_HSSCLH) | fssclh;
} else {
/* Program desired operating rate */
fclk_rate /= (psc + 1) * 1000;
if (psc > 2)
psc = 2;
scll = fclk_rate / (dev->speed * 2) - 7 + psc;
sclh = fclk_rate / (dev->speed * 2) - 7 + psc;
}
/* Setup clock prescaler to obtain approx 12MHz I2C module clock: */
omap_i2c_write_reg(dev, OMAP_I2C_PSC_REG, psc);
/* SCL low and high time values */
omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, scll);
omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, sclh);
if (dev->fifo_size) {
/* Note: setup required fifo size - 1. RTRSH and XTRSH */
buf = (dev->fifo_size - 1) << 8 | OMAP_I2C_BUF_RXFIF_CLR |
(dev->fifo_size - 1) | OMAP_I2C_BUF_TXFIF_CLR;
omap_i2c_write_reg(dev, OMAP_I2C_BUF_REG, buf);
}
/* Take the I2C module out of reset: */
omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
dev->errata = 0;
if (cpu_is_omap2430() || cpu_is_omap34xx())
dev->errata |= I2C_OMAP_ERRATA_I207;
if (cpu_is_omap34xx() || cpu_is_omap44xx()) {
dev->pscstate = psc;
dev->scllstate = scll;
dev->sclhstate = sclh;
dev->bufstate = buf;
}
return 0;
}
