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[PATCH] SPI: devices can require LSB-first encodings

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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>
This commit is contained in:
David Brownell 2006-04-03 15:46:22 -07:00 • committed by Greg Kroah-Hartman
parent ff9f4771b5
commit ccf77cc4af
2 changed files with 15 additions and 3 deletions
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11
drivers/spi/spi_bitbang.c
View file

@ -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;