int
iicbus_transfer_excl(device_t dev, struct iic_msg *msgs, uint32_t nmsgs,
int how)
{
device_t bus;
int error;
bus = device_get_parent(dev);
error = iicbus_request_bus(bus, dev, how);
if (error == 0)
error = IICBUS_TRANSFER(bus, msgs, nmsgs);
iicbus_release_bus(bus, dev);
return (error);
}
static int
gmbus_xfer(device_t adapter,
struct iic_msg *msgs,
uint32_t num)
{
struct intel_iic_softc *sc = device_get_softc(adapter);
struct intel_gmbus *bus = sc->bus;
struct drm_i915_private *dev_priv = bus->dev_priv;
int i, reg_offset;
int ret = 0;
sx_xlock(&dev_priv->gmbus_mutex);
if (bus->force_bit) {
ret = -IICBUS_TRANSFER(bus->bbbus, msgs, num);
goto out;
}
reg_offset = dev_priv->gpio_mmio_base;
I915_WRITE(GMBUS0 + reg_offset, bus->reg0);
for (i = 0; i < num; i++) {
u32 gmbus2;
if (gmbus_is_index_read(msgs, i, num)) {
ret = gmbus_xfer_index_read(dev_priv, &msgs[i]);
i += 1; /* set i to the index of the read xfer */
} else if (msgs[i].flags & I2C_M_RD) {
ret = gmbus_xfer_read(dev_priv, &msgs[i], 0);
} else {
ret = gmbus_xfer_write(dev_priv, &msgs[i]);
}
if (ret == -ETIMEDOUT)
goto timeout;
if (ret == -ENXIO)
goto clear_err;
ret = wait_for((gmbus2 = I915_READ(GMBUS2 + reg_offset)) &
(GMBUS_SATOER | GMBUS_HW_WAIT_PHASE),
50);
if (ret)
goto timeout;
if (gmbus2 & GMBUS_SATOER)
goto clear_err;
}
/* Generate a STOP condition on the bus. Note that gmbus can't generata
* a STOP on the very first cycle. To simplify the code we
* unconditionally generate the STOP condition with an additional gmbus
* cycle. */
I915_WRITE(GMBUS1 + reg_offset, GMBUS_CYCLE_STOP | GMBUS_SW_RDY);
/* Mark the GMBUS interface as disabled after waiting for idle.
* We will re-enable it at the start of the next xfer,
* till then let it sleep.
*/
if (wait_for((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0,
10)) {
DRM_DEBUG_KMS("GMBUS [%s] timed out waiting for idle\n",
device_get_desc(adapter));
ret = -ETIMEDOUT;
}
I915_WRITE(GMBUS0 + reg_offset, 0);
goto out;
clear_err:
/*
* Wait for bus to IDLE before clearing NAK.
* If we clear the NAK while bus is still active, then it will stay
* active and the next transaction may fail.
*
* If no ACK is received during the address phase of a transaction, the
* adapter must report -ENXIO. It is not clear what to return if no ACK
* is received at other times. But we have to be careful to not return
* spurious -ENXIO because that will prevent i2c and drm edid functions
* from retrying. So return -ENXIO only when gmbus properly quiescents -
* timing out seems to happen when there _is_ a ddc chip present, but
* it's slow responding and only answers on the 2nd retry.
*/
ret = -ENXIO;
if (wait_for((I915_READ(GMBUS2 + reg_offset) & GMBUS_ACTIVE) == 0,
10)) {
DRM_DEBUG_KMS("GMBUS [%s] timed out after NAK\n",
device_get_desc(adapter));
ret = -ETIMEDOUT;
}
/* Toggle the Software Clear Interrupt bit. This has the effect
* of resetting the GMBUS controller and so clearing the
* BUS_ERROR raised by the slave's NAK.
*/
I915_WRITE(GMBUS1 + reg_offset, GMBUS_SW_CLR_INT);
I915_WRITE(GMBUS1 + reg_offset, 0);
I915_WRITE(GMBUS0 + reg_offset, 0);
DRM_DEBUG_KMS("GMBUS [%s] NAK for addr: %04x %c(%d)\n",
device_get_desc(adapter), msgs[i].slave >> 1,
(msgs[i].flags & I2C_M_RD) ? 'r' : 'w', msgs[i].len);
goto out;
timeout:
DRM_INFO("GMBUS [%s] timed out, falling back to bit banging on pin %d\n",
device_get_desc(adapter), bus->reg0 & 0xff);
I915_WRITE(GMBUS0 + reg_offset, 0);
/* Hardware may not support GMBUS over these pins? Try GPIO bitbanging instead. */
bus->force_bit = 1;
ret = -IICBUS_TRANSFER(bus->bbbus, msgs, num);
out:
sx_xunlock(&dev_priv->gmbus_mutex);
return -ret;
}
/*
* iicbus_transfer()
*
* Do an aribtrary number of transfers on the iicbus. We pass these
* raw requests to the bridge driver. If the bridge driver supports
* them directly, then it manages all the details. If not, it can use
* the helper function iicbus_transfer_gen() which will do the
* transfers at a low level.
*
* Pointers passed in as part of iic_msg must be kernel pointers.
* Callers that have user addresses to manage must do so on their own.
*/
int
iicbus_transfer(device_t bus, struct iic_msg *msgs, uint32_t nmsgs)
{
return (IICBUS_TRANSFER(device_get_parent(bus), msgs, nmsgs));
}
