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    Subject[PATCH 6/6] of_spi: Initialize cs_gpios and cs_gpio with -EEXIST
    Date
    Holes in the cs-gpios DT phandle list is supposed to mark that native
    chipselects is to be used. The value returned from of_get_named_gpio_flags in
    this case is -EEXIST. By initializing cs_gpios and cs_gpio with -EEXIST, this
    and only this errno will indicate to a spi controller driver that a native
    chipselect is to be used.

    Signed-off-by: Andreas Larsson <andreas@gaisler.com>
    ---
    drivers/spi/spi.c | 4 ++--
    include/linux/spi/spi.h | 7 +++++--
    2 files changed, 7 insertions(+), 4 deletions(-)

    diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
    index 6f1b717..7494bad 100644
    --- a/drivers/spi/spi.c
    +++ b/drivers/spi/spi.c
    @@ -334,7 +334,7 @@ struct spi_device *spi_alloc_device(struct spi_master *master)
    spi->dev.parent = &master->dev;
    spi->dev.bus = &spi_bus_type;
    spi->dev.release = spidev_release;
    - spi->cs_gpio = -EINVAL;
    + spi->cs_gpio = -EEXIST;
    device_initialize(&spi->dev);
    return spi;
    }
    @@ -1097,7 +1097,7 @@ static int of_spi_register_master(struct spi_master *master)
    }

    for (i = 0; i < master->num_chipselect; i++)
    - cs[i] = -EINVAL;
    + cs[i] = -EEXIST;

    for (i = 0; i < nb; i++)
    cs[i] = of_get_named_gpio_flags(np, "cs-gpios", i, &flags[i]);
    diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
    index 96b1055..0701882 100644
    --- a/include/linux/spi/spi.h
    +++ b/include/linux/spi/spi.h
    @@ -58,7 +58,8 @@ extern struct bus_type spi_bus_type;
    * @modalias: Name of the driver to use with this device, or an alias
    * for that name. This appears in the sysfs "modalias" attribute
    * for driver coldplugging, and in uevents used for hotplugging
    - * @cs_gpio: Negative or gpio for chip select.
    + * @cs_gpio: Negative or gpio for chip select. Set to -EEXIST when chipselect
    + * should be handled natively by the controller driver
    * @cs_gpio_flags: of_gpio_flags corresponding to cs_gpio
    *
    * A @spi_device is used to interchange data between an SPI slave
    @@ -262,7 +263,9 @@ static inline void spi_unregister_driver(struct spi_driver *sdrv)
    * @unprepare_transfer_hardware: there are currently no more messages on the
    * queue so the subsystem notifies the driver that it may relax the
    * hardware by issuing this call
    - * @cs_gpios: possible array of negative values or gpios for chip selects
    + * @cs_gpios: possible array of negative values or gpios for chip selects. A
    + * chipselect that should be handled natively by the controller driver is
    + * set to -EEXIST.
    * @cs_gpio_flags: possible array of of_gpio_flags corresponding to cs_gpios
    *
    * Each SPI master controller can communicate with one or more @spi_device
    --
    1.7.0.4


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