Commit graph

7 commits

Author SHA1 Message Date
Cliff Cai
581d92eefc Blackfin: bfin_spi: round up clock divider
If the requested clock cannot be exactly obtained, round it up so that we
err on the side of slightly slower rather than slightly faster.

Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2010-01-17 09:17:27 -05:00
Cliff Cai
17ebd5bf33 Blackfin: bfin_spi: let boards control idle value
Some SPI devices like to see high idle values rather than low.

Signed-off-by: Cliff Cai <cliff.cai@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2010-01-17 09:17:27 -05:00
Mike Frysinger
7d6900ebe1 Blackfin: spi: fix pin handling of SPI0 SSEL4
CS4 on SPI0 has a dedicated PH8 pin which needs to be enabled as a
peripheral in order to work.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-05-29 17:11:33 -04:00
Todor I Mollov
d04371a116 Blackfin: spi: make cs deassert function deterministic
Blackfin SPI driver was not driving the SPI chip-select high before
putting the chip-select signals into tri-state mode.  This is probably
something that slipped by unnoticed in most designs.  If the signals are
put directly into a tri-state mode, then the board is relying on the
pull-up resistors to pull up the chip-select before the next transaction.
Most of the time this is fine, except when you have two transactions that
follow each other very closely, such as the flash erase and read status
register commands.  In this case I was seeing a 500ns separation between
the transactions.  In my setup, with a 10kOhm pull-up, it would meet
timing spec about half the time and resulted in intermittent errors.  (A
stronger pull up would fix this, but our design is targeted for low power
consumption and a 3.3kOhm @ 3.3v is 3.3mW of needless power consumption.)
I modified the spi_cs_deactivate() function in bfin_spi.c to drive the
chip-selects high before putting them into tri-state.  For me, this
resulted in a rise time of 5ns instead of the previous rise time of about
1us, and fully satisfied the timing spec of the chip.

Signed-off-by: Todor I Mollov <tmollov@ucsd.edu>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-04-06 03:49:31 -04:00
Mike Frysinger
bc72f50a65 Blackfin: add BF538/BF539 SPI portmux handling
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-04-02 06:42:18 -04:00
Sonic Zhang
974473caa7 Blackfin: spi: there is no PORTJ_FER MMR on BF537
Since the PORTJ on the BF537 is peripheral-only (no GPIO functionality),
then there is no PORTJ_FER register for us to worry about.

Signed-off-by: Sonic Zhang <Sonic.Zhang@analog.com>
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-03-23 15:14:52 -04:00
Mike Frysinger
400f5778f3 Blackfin: add driver for on-chip SPI controller
This fills out the SPI backend for the Blackfin on-chip SPI peripheral.

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
2009-02-02 12:24:30 -05:00