From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ranjit Waghmode Subject: [LINUX RFC v2 1/4] spi: add support of two chip selects & data stripe Date: Wed, 26 Aug 2015 11:56:04 +0530 Message-ID: <1440570367-22569-2-git-send-email-ranjit.waghmode@xilinx.com> References: <1440570367-22569-1-git-send-email-ranjit.waghmode@xilinx.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , , , , , , Ranjit Waghmode To: , , , , , , , , , , , Return-path: In-Reply-To: <1440570367-22569-1-git-send-email-ranjit.waghmode-gjFFaj9aHVfQT0dZR+AlfA@public.gmane.org> Sender: linux-spi-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: To support dual parallel mode operation of ZynqMP GQSPI controller following API's are added inside the core: - Added API to support two chip selects: Dual parallel mode supports two SPI flash memories operating in parallel i.e 8 I/O lines. Chip selects and clock are shared to both the flash devices. So newly added API will help in enabling both the chips. - Added API to support data stripe feature: with data stripe enabled, even bytes i.e. 0, 2, 4,... are transmitted on lower data bus odd bytes i.e. 1, 3, 5,.. are transmitted on upper data bus. Signed-off-by: Ranjit Waghmode --- V2 Changes: - Added error handling condition for newly added features --- drivers/spi/spi.c | 8 ++++++++ include/linux/spi/spi.h | 11 +++++++++++ 2 files changed, 19 insertions(+) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index cf8b91b..22e8e7f 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1828,6 +1828,14 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message) if (list_empty(&message->transfers)) return -EINVAL; + /* + * Data stripe option is selected if and only if when + * two chips are enabled + */ + if ((master->flags & SPI_MASTER_DATA_STRIPE) + && !(master->flags & SPI_MASTER_BOTH_CS)) + return -EINVAL; + /* Half-duplex links include original MicroWire, and ones with * only one data pin like SPI_3WIRE (switches direction) or where * either MOSI or MISO is missing. They can also be caused by diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index d673072..53d3bc6 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -355,6 +355,17 @@ struct spi_master { #define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */ #define SPI_MASTER_MUST_RX BIT(3) /* requires rx */ #define SPI_MASTER_MUST_TX BIT(4) /* requires tx */ + /* Controller may support data stripe feature when more than one + * chips are present. + * Setting data stripe will send data in following manner: + * -> even bytes i.e. 0, 2, 4,... are transmitted on lower data bus + * -> odd bytes i.e. 1, 3, 5,.. are transmitted on upper data bus + */ +#define SPI_MASTER_DATA_STRIPE BIT(7) /* support data stripe */ + /* Controller may support more than one chip. + * This flag will enable that feature. + */ +#define SPI_MASTER_BOTH_CS BIT(8) /* enable both chips */ /* lock and mutex for SPI bus locking */ spinlock_t bus_lock_spinlock; -- 2.1.2 -- To unsubscribe from this list: send the line "unsubscribe linux-spi" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html