[flashrom] [PATCH] linux_spi.c: set SPI mode, word justification and bits per word on init.

[Carl-Daniel Hailfinger]

Am 02.03.2012 00:43 schrieb Stefan Tauner:
> Previously we relied on a correctly set up state.
>
> ---
> untested.
>
> Signed-off-by: Stefan Tauner <stefan.tauner at student.tuwien.ac.at>
> ---
>  linux_spi.c |   23 +++++++++++++++++++++++
>  1 files changed, 23 insertions(+), 0 deletions(-)
>
> diff --git a/linux_spi.c b/linux_spi.c
> index d994389..d29c59a 100644
> --- a/linux_spi.c
> +++ b/linux_spi.c
> @@ -57,6 +57,8 @@ int linux_spi_init(void)
>  {
>  	char *p, *endp, *dev;
>  	uint32_t speed = 0;
> +	/* FIXME: make the following configurable by CLI options. */
> +	uint8_t mode = SPI_MODE_0, lsb = 0, bits = 0; /* mode 0, msb first, 8 bits */

Can you move that comment above the variable definitions?
Where should we note that SPI_MODE_0 also implies CS# active low?


>  
>  	dev = extract_programmer_param("dev");
>  	if (!dev || !strlen(dev)) {
> @@ -92,6 +94,27 @@ int linux_spi_init(void)
>  		msg_pdbg("Using %d kHz clock\n", speed);
>  	}
>  
> +	if (ioctl(fd, SPI_IOC_WR_MODE, &mode) == -1) {
> +		msg_perr("%s: failed to set SPI mode to %u: %s\n",
> +			 __func__, mode, strerror(errno));
> +		close(fd);
> +		return 1;
> +	}
> +
> +	if (ioctl(fd, SPI_IOC_WR_LSB_FIRST, &lsb) == -1) {
> +		msg_perr("%s: failed to set SPI justification to %u: %s\n",
> +			 __func__, lsb, strerror(errno));

This message would benefit from an explanation what SPI justification
is. Suggestion:
msg_perr("%s: failed to set SPI bit order to %s first: %s\n", __func_,
lsb ? "LSB" : "MSB", strerror(errno));

> +		close(fd);
> +		return 1;
> +	}
> +
> +	if (ioctl(fd, SPI_IOC_WR_BITS_PER_WORD, &bits) == -1) {
> +		msg_perr("%s: failed to set the number of bits in an SPI word to %u: %s\n",
> +			 __func__, bits, strerror(errno));

bits is 0. The error message would suggest that we tried to set the
number of bits to 0. Does 0 also mean 8 bits, or would we have to set 8
bits with bits=8?

> +		close(fd);
> +		return 1;
> +	}
> +
>  	if (register_shutdown(linux_spi_shutdown, NULL))
>  		return 1;
>  

As an alternative, we could avoid the whole close(fd) dance by calling
register_shutdown() first, and then letting it do the work for us
automatically after we return 1.

Regards,
Carl-Daniel

-- 
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