From: Martin Sperl <[email protected]> Allow the cs-gpios property in DT to be used instead of the fixed two chip-selects provided by the SPI-HW itself
Signed-off-by: Martin Sperl <[email protected]> --- There is the question if we still need to support the chip_selects provided by the hardware (plus the buggy CSPOL_HIGH support for those cases) or if we could just make the cs-gpios a required setting for this driver. Going with the GPIO only solution would clean up the code a bit. drivers/spi/spi-bcm2835.c | 53 +++++++++++++++++++++++++++++++++++++++------ 1 file changed, 46 insertions(+), 7 deletions(-) diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c index 419a782..128a152 100644 --- a/drivers/spi/spi-bcm2835.c +++ b/drivers/spi/spi-bcm2835.c @@ -3,6 +3,7 @@ * * Copyright (C) 2012 Chris Boot * Copyright (C) 2013 Stephen Warren + * Copyright (C) 2015 Martin Sperl * * This driver is inspired by: * spi-ath79.c, Copyright (C) 2009-2011 Gabor Juhos <[email protected]> @@ -30,6 +31,7 @@ #include <linux/of.h> #include <linux/of_irq.h> #include <linux/of_device.h> +#include <linux/of_gpio.h> #include <linux/spi/spi.h> /* SPI register offsets */ @@ -116,6 +118,18 @@ static inline void bcm2835_wr_fifo(struct bcm2835_spi *bs, int len) } } +/* ideally spi_set_cs would be exported by spi-core */ +static inline void bcm2835_set_cs(struct spi_device *spi, bool enable) +{ + + if (spi->mode & SPI_CS_HIGH) + enable = !enable; + + if (spi->cs_gpio >= 0) + gpio_set_value(spi->cs_gpio, !enable); + +} + static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) { struct spi_master *master = dev_id; @@ -205,12 +219,24 @@ static int bcm2835_spi_start_transfer(struct spi_device *spi, cs |= BCM2835_SPI_CS_CPHA; if (!(spi->mode & SPI_NO_CS)) { - if (spi->mode & SPI_CS_HIGH) { - cs |= BCM2835_SPI_CS_CSPOL; - cs |= BCM2835_SPI_CS_CSPOL0 << spi->chip_select; - } + if (spi->cs_gpio >= 0) + bcm2835_set_cs(spi, 1); + else { + /* do we need to support this ? + * note that there is a bug in this when there are + * multiple devices on the bus with at least one + * having SPI_CS_HIGH set (the other CS_CSPOLX get + * reset to 0 when any other device + * starts a transfer + */ + if (spi->mode & SPI_CS_HIGH) { + cs |= BCM2835_SPI_CS_CSPOL; + cs |= BCM2835_SPI_CS_CSPOL0 + << spi->chip_select; + } - cs |= spi->chip_select; + cs |= spi->chip_select; + } } reinit_completion(&bs->done); @@ -245,9 +271,12 @@ static int bcm2835_spi_finish_transfer(struct spi_device *spi, if (tfr->delay_usecs) udelay(tfr->delay_usecs); - if (cs_change) + if (cs_change) { + /* reset CS */ + bcm2835_set_cs(spi, 0); /* Clear TA flag */ bcm2835_wr(bs, BCM2835_SPI_CS, cs & ~BCM2835_SPI_CS_TA); + } return 0; } @@ -285,15 +314,24 @@ static int bcm2835_spi_transfer_one(struct spi_master *master, } out: - /* Clear FIFOs, and disable the HW block */ + /* Clear FIFOs, reset CS and disable the HW block */ bcm2835_wr(bs, BCM2835_SPI_CS, BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); + bcm2835_set_cs(spi, 0); mesg->status = err; spi_finalize_current_message(master); return 0; } +static int bcm2835_spi_setup(struct spi_device *spi) +{ + /* setting up CS right from the start */ + bcm2835_set_cs(spi, 0); + + return 0; +} + static int bcm2835_spi_probe(struct platform_device *pdev) { struct spi_master *master; @@ -313,6 +351,7 @@ static int bcm2835_spi_probe(struct platform_device *pdev) master->bits_per_word_mask = SPI_BPW_MASK(8); master->num_chipselect = 3; master->transfer_one_message = bcm2835_spi_transfer_one; + master->setup = bcm2835_spi_setup; master->dev.of_node = pdev->dev.of_node; bs = spi_master_get_devdata(master); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
