On Sun, 20 May 2012 15:46:19 +0200, John Crispin <blogic@xxxxxxxxxxx> wrote:
> From: Thomas Langer <thomas.langer@xxxxxxxxxx>
>
> The external bus unit (EBU) found on the FALCON SoC has spi emulation that is
> designed for serial flash access. This driver has only been tested with m25p80
> type chips. The hardware has no support for other types of spi peripherals.
>
> Signed-off-by: Thomas Langer <thomas.langer@xxxxxxxxxx>
> Signed-off-by: John Crispin <blogic@xxxxxxxxxxx>
> Cc: spi-devel-general@xxxxxxxxxxxxxxxxxxxxx
> ---
> This patch is part of a series moving the mips/lantiq target to OF and clkdev
> support. The patch, once Acked, should go upstream via Ralf's MIPS tree.
>
> Changes in V5
> * drop duplicate busnum assignment
>
> Changes in V4
> * drop busnum property
>
> Changes in V3
> * rephrase spi->SPI
> * fix rate detection
> * adds support for transfer_one & co
> * adds of support
>
> Changes in V2
> * remove several superflous calls to dev_dbg
> * make use of module_platform_driver
> * remove falcon_spi_cleanup as it was an empty function
> * return real error codes instead of -1
> * fixes operator spacing errors
> * split arch and driver specific patches
> * squash some lines to make use of the full 80 available chars
> * Kconfig is now alphabetic again
> * replace BUG() with WARN_ON()
> ---
> drivers/spi/Kconfig | 9 +
> drivers/spi/Makefile | 1 +
> drivers/spi/spi-falcon.c | 469 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 479 insertions(+), 0 deletions(-)
> create mode 100644 drivers/spi/spi-falcon.c
>
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 00c0240..62b2b5e 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -144,6 +144,15 @@ config SPI_EP93XX
> This enables using the Cirrus EP93xx SPI controller in master
> mode.
>
> +config SPI_FALCON
> + tristate "Falcon SPI controller support"
> + depends on SOC_FALCON
> + help
> + The external bus unit (EBU) found on the FALC-ON SoC has SPI
> + emulation that is designed for serial flash access. This driver
> + has only been tested with m25p80 type chips. The hardware has no
> + support for other types of SPI peripherals.
What exactly does this mean? How does it not support any other type
of SPI peripheral? SPI is a really simple protocol, so what is it
about this hardware that prevents it being used with other SPI
hardware?
I see a big state machine that appears to interpret the messages and
pretend to be an SPI slave instead of telling linux about the real
device. /me wonders if it should this instead be a block device
driver?
> +static int falcon_sflash_prepare_xfer(struct spi_master *master)
> +{
> + return 0;
> +}
> +
> +static int falcon_sflash_unprepare_xfer(struct spi_master *master)
> +{
> + return 0;
> +}
Don't use empty hooks. Just leave them uninitialized. The core will
do the right thing.
