diff options
| author | David Brownell <david-b@pacbell.net> | 2006-04-03 15:46:22 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2006-05-16 14:33:57 -0700 |
| commit | ccf77cc4af5b048e20cfd9327fcc286cb69c34cc (patch) | |
| tree | 0a19a6948fe8bbf2128010a655e170ffebc9d8b8 /drivers/spi | |
| parent | ff9f4771b5f017ee0f57629488b6cd7a6ef3d19b (diff) | |
| download | lwn-ccf77cc4af5b048e20cfd9327fcc286cb69c34cc.tar.gz lwn-ccf77cc4af5b048e20cfd9327fcc286cb69c34cc.zip | |
[PATCH] SPI: devices can require LSB-first encodings
Add spi_device hook for LSB-first word encoding, and update all the
(in-tree) controller drivers to reject such devices. Eventually,
some controller drivers will be updated to support lsb-first encodings
on the wire; no current drivers need this.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'drivers/spi')
| -rw-r--r-- | drivers/spi/spi_bitbang.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/drivers/spi/spi_bitbang.c b/drivers/spi/spi_bitbang.c index 6c3da64d609a..0f7f5c64391c 100644 --- a/drivers/spi/spi_bitbang.c +++ b/drivers/spi/spi_bitbang.c @@ -187,13 +187,22 @@ int spi_bitbang_setup(struct spi_device *spi) if (!spi->max_speed_hz) return -EINVAL; + bitbang = spi_master_get_devdata(spi->master); + + /* REVISIT: some systems will want to support devices using lsb-first + * bit encodings on the wire. In pure software that would be trivial, + * just bitbang_txrx_le_cphaX() routines shifting the other way, and + * some hardware controllers also have this support. + */ + if ((spi->mode & SPI_LSB_FIRST) != 0) + return -EINVAL; + if (!cs) { cs = kzalloc(sizeof *cs, SLAB_KERNEL); if (!cs) return -ENOMEM; spi->controller_state = cs; } - bitbang = spi_master_get_devdata(spi->master); if (!spi->bits_per_word) spi->bits_per_word = 8; |