So that interface drivers could be built as modules
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
This allows the switching between transfer modes between 'transmit only',
'receive only' and 'transmit and receive' modes. Due to the design of the SPI
block, changing transfer modes requires that the block be disabled; in doing
so the chipselect line is inherently deasserted and (usually) the attached
device discards its state. Consequentially, switching modes requires that a
platform-specific chipselect function has been defined so that the chipselect
is not dropped during the change.
Signed-off-by: George Shore <george@georgeshore.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
The 'poll_transfer' function employs a conditional to test whether the
transmit buffer is valid; in doing so, on a receive operation no data is
clocked out, thus no data is clocked in and ultimately errors appear.
This removes the conditional as the transmit function will be set to a null
writer when the transmit buffer is invalid, allowing the driver to clock
0x00 out to the device to receive data from the device.
Signed-off-by: George Shore <george@georgeshore.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
FIFO depth is configurable for each implementation of DW core,
so add a depth detection for those interface drivers who don't set
the fifo_len explicitly
Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Now dw_spi core fully supports 3 transfer modes: pure polling,
DMA and IRQ mode. IRQ mode will use the FIFO half empty as
the IRQ trigger, so each interface driver need set the fifo_len,
so that core driver can handle it properly
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Make the driver wait at least for 1 jiffie before issuing the
warning, no matter what HZ is set to
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Driver for the Designware SPI core, it supports multipul interfaces like
PCI/APB etc. User can use "dw_apb_ssi_db.pdf" from Synopsys as HW
datasheet.
[randy.dunlap@oracle.com: fix build]
[akpm@linux-foundation.org: build fix]
Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
