spi: Add Flag to Enable Slave Select with GPIO Chip Select. (6b1576aa) · Commits · 戴 / test

Some SPI masters require slave selection before the transfer can begin [1]. The SPI framework currently selects the chip using either 1) the internal CS mechanism or 2) the GPIO CS, but not both. This patch adds a new master->flags define to indicate both the GPIO CS and the internal chip select mechanism should be used. Tested On: Altera CycloneV development kit Compile tested for build errors on x86_64 (allyesconfigs) [1] DesignWare dw_apb_ssi Databook, Version 3.20a (page 39) Signed-off-by:

Thor Thayer <tthayer@opensource.altera.com> Signed-off-by:

Mark Brown <broonie@kernel.org>

drivers/spi/spi.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -697,10 +697,15 @@ static void spi_set_cs(struct spi_device *spi, bool enable)
		if (spi->mode & SPI_CS_HIGH)
		enable = !enable;

		if (gpio_is_valid(spi->cs_gpio))
		if (gpio_is_valid(spi->cs_gpio)) {
		gpio_set_value(spi->cs_gpio, !enable);
		else if (spi->master->set_cs)
		/* Some SPI masters need both GPIO CS & slave_select */
		if ((spi->master->flags & SPI_MASTER_GPIO_SS) &&
		spi->master->set_cs)
		spi->master->set_cs(spi, !enable);
		} else if (spi->master->set_cs) {
		spi->master->set_cs(spi, !enable);
		}
		}

		#ifdef CONFIG_HAS_DMA

include/linux/spi/spi.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -442,6 +442,7 @@ 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 */
		#define SPI_MASTER_GPIO_SS BIT(5) /* GPIO CS must select slave */

		/*
		* on some hardware transfer / message size may be constrained

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