From mboxrd@z Thu Jan 1 00:00:00 1970 From: kernel@martin.sperl.org Subject: [PATCH 3/5] spi: core: allow defining time that cs is deasserted as a multiple of SCK Date: Sat, 23 Feb 2019 08:49:50 +0000 Message-ID: <20190223084952.14758-4-kernel@martin.sperl.org> References: <20190223084952.14758-1-kernel@martin.sperl.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Martin Sperl To: Mark Brown , Eric Anholt , Stefan Wahren , linux-spi@vger.kernel.org, linux-rpi-kernel@lists.infradead.org, linux-arm-kernel@lists.infradead.org Return-path: In-Reply-To: <20190223084952.14758-1-kernel@martin.sperl.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=m.gmane.org@lists.infradead.org List-Id: linux-spi.vger.kernel.org From: Martin Sperl Support setting a delay between cs assert and deassert as a multiple of spi clock length. Signed-off-by: Martin Sperl --- drivers/spi/spi.c | 8 ++++++++ include/linux/spi/spi.h | 1 + 2 files changed, 9 insertions(+) diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c index 5a4616894d57..d5259bdd4b88 100644 --- a/drivers/spi/spi.c +++ b/drivers/spi/spi.c @@ -1092,6 +1092,7 @@ static void _spi_transfer_cs_change_delay(struct spi_message *msg, { u32 delay = xfer->cs_change_delay; u32 unit = xfer->cs_change_delay_unit; + u32 hz; /* return early on "fast" mode - for everything but USECS */ if (!delay && unit != SPI_DELAY_UNIT_USECS) @@ -1107,6 +1108,13 @@ static void _spi_transfer_cs_change_delay(struct spi_message *msg, break; case SPI_DELAY_UNIT_NSECS: /* nothing to do here */ break; + case SPI_DELAY_UNIT_SCK: + /* if there is no effective speed know, then approximate + * by underestimating with half the requested hz + */ + hz = xfer->effective_speed_hz ?: xfer->speed_hz / 2; + delay *= DIV_ROUND_UP(1000000000, hz); + break; default: dev_err_once(&msg->spi->dev, "Use of unsupported delay unit %i, using default of 10us\n", diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index f503a712423d..0b1d5e2b8b8b 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -799,6 +799,7 @@ struct spi_transfer { u8 cs_change_delay_unit; #define SPI_DELAY_UNIT_USECS 0 #define SPI_DELAY_UNIT_NSECS 1 +#define SPI_DELAY_UNIT_SCK 2 u32 speed_hz; u16 word_delay; -- 2.11.0