From 851dde8255efda7ecf9b37a3b7b22f4edab8881f Mon Sep 17 00:00:00 2001 From: Aaron Durbin Date: Thu, 19 Apr 2018 21:15:25 -0600 Subject: drivers/spi: reduce confusion in the API Julius brought up confusion about the current spi api in [1]. In order alleviate the confusion stemming from supporting x86 spi flash controllers: - Remove spi_xfer_two_vectors() which was fusing transactions to accomodate the limitations of the spi controllers themselves. - Add spi_flash_vector_helper() for the x86 spi flash controllers to utilize in validating driver/controller current assumptions. - Remove the xfer() callback in the x86 spi flash drivers which will trigger an error as these controllers can't support the api. [1] https://mail.coreboot.org/pipermail/coreboot/2018-April/086561.html Change-Id: Id88adc6ad5234c29a739d43521c5f344bb7d3217 Signed-off-by: Aaron Durbin Reviewed-on: https://review.coreboot.org/25745 Tested-by: build bot (Jenkins) Reviewed-by: Julius Werner --- src/include/spi-generic.h | 28 ++++++++-------------------- 1 file changed, 8 insertions(+), 20 deletions(-) (limited to 'src/include/spi-generic.h') diff --git a/src/include/spi-generic.h b/src/include/spi-generic.h index 20c7cc72c7..e3e7f829f7 100644 --- a/src/include/spi-generic.h +++ b/src/include/spi-generic.h @@ -109,7 +109,10 @@ enum { }; /*----------------------------------------------------------------------- - * Representation of a SPI controller. + * Representation of a SPI controller. Note the xfer() and xfer_vector() + * callbacks are meant to process full duplex transactions. If the + * controller cannot handle these transactions then return an error when + * din and dout are both set. See spi_xfer() below for more details. * * claim_bus: Claim SPI bus and prepare for communication. * release_bus: Release SPI bus. @@ -232,6 +235,10 @@ void spi_release_bus(const struct spi_slave *slave); * din: Pointer to a string of bytes that will be filled in. * bytesin: How many bytes to read. * + * Note that din and dout are transferred simulataneously in a full duplex + * transaction. The number of clocks within one transaction is calculated + * as: MAX(bytesout*8, bytesin*8). + * * Returns: 0 on success, not 0 on failure */ int spi_xfer(const struct spi_slave *slave, const void *dout, size_t bytesout, @@ -281,23 +288,4 @@ static inline int spi_w8r8(const struct spi_slave *slave, unsigned char byte) return ret < 0 ? ret : din[1]; } -/* - * Helper function to allow chipsets to combine two vectors if possible. It can - * only handle upto 2 vectors. - * - * This function is provided to support command-response kind of transactions - * expected by users like flash. Some special SPI flash controllers can handle - * such command-response operations in a single transaction. For these special - * controllers, separate command and response vectors can be combined into a - * single operation. - * - * Two vectors are combined if first vector has a non-NULL dout and NULL din and - * second vector has a non-NULL din and NULL dout. Otherwise, each vector is - * operated upon one at a time. - * - * Returns 0 on success and non-zero on failure. - */ -int spi_xfer_two_vectors(const struct spi_slave *slave, - struct spi_op vectors[], size_t count); - #endif /* _SPI_GENERIC_H_ */ -- cgit v1.2.3