On Sun, 16 Dec 2018 00:38:18 +0100
Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> This converts the ATH79 SPI master driver to use GPIO descriptors
> for chip select handling.
>
> The ATH79 driver was requesting the GPIO and driving it from the
> bitbang .chipselect callback. Do not request it anymore as the SPI
> core will request it, remove the line inversion semantics for the
> GPIO case (handled by gpiolib) and let the SPI core deal with
> requesting the GPIO line from the device tree node of the controller.
>
> This driver can be instantiated from a board file (no device tree)
> but the board files only use native CS (no GPIO lines) so we should
> be fine just letting the SPI core grab the GPIO from the device.
>
> The fact that the driver is actively driving the GPIO in the
> ath79_spi_chipselect() callback is confusing since the host does
> not set SPI_MASTER_GPIO_SS so this should not ever get called when
> using GPIO CS. I put in a comment about this.
The SPI_MASTER_GPIO_SS flag came after this driver has been written, so
I don't think we need to worry about this.
> Cc: Felix Fietkau <nbd@xxxxxxxx>
> Cc: Alban Bedel <albeu@xxxxxxx>
> Cc: Linuxarm <linuxarm@xxxxxxxxxx>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> ---
> drivers/spi/spi-ath79.c | 42
> ++++++++++++++--------------------------- 1 file changed, 14
> insertions(+), 28 deletions(-)
>
> diff --git a/drivers/spi/spi-ath79.c b/drivers/spi/spi-ath79.c
> index 3f6b657394de..ed1068ac055f 100644
> --- a/drivers/spi/spi-ath79.c
> +++ b/drivers/spi/spi-ath79.c
> @@ -21,7 +21,7 @@
> #include <linux/spi/spi.h>
> #include <linux/spi/spi_bitbang.h>
> #include <linux/bitops.h>
> -#include <linux/gpio.h>
> +#include <linux/gpio/consumer.h>
> #include <linux/clk.h>
> #include <linux/err.h>
>
> @@ -78,9 +78,16 @@ static void ath79_spi_chipselect(struct spi_device
> *spi, int is_active) ath79_spi_wr(sp, AR71XX_SPI_REG_IOC,
> sp->ioc_base); }
>
> - if (gpio_is_valid(spi->cs_gpio)) {
> - /* SPI is normally active-low */
> - gpio_set_value_cansleep(spi->cs_gpio, cs_high);
> + if (spi->cs_gpiod) {
> + /*
> + * SPI chipselect is normally active-low, but
> + * inversion semantics are handled by gpiolib.
> + *
> + * FIXME: is this ever used? The driver doesn't
> + * set SPI_MASTER_GPIO_SS so this callback should not
> + * get called if a CS GPIO is found by the SPI core.
> + */
> + gpiod_set_value_cansleep(spi->cs_gpiod, is_active);
AFAICT this whole block can be removed.
> } else {
> u32 cs_bit = AR71XX_SPI_IOC_CS(spi->chip_select);
>
> @@ -118,21 +125,8 @@ static void ath79_spi_disable(struct ath79_spi
> *sp) static int ath79_spi_setup_cs(struct spi_device *spi)
> {
> struct ath79_spi *sp = ath79_spidev_to_sp(spi);
> - int status;
>
> - status = 0;
> - if (gpio_is_valid(spi->cs_gpio)) {
> - unsigned long flags;
> -
> - flags = GPIOF_DIR_OUT;
> - if (spi->mode & SPI_CS_HIGH)
> - flags |= GPIOF_INIT_LOW;
> - else
> - flags |= GPIOF_INIT_HIGH;
> -
> - status = gpio_request_one(spi->cs_gpio, flags,
> - dev_name(&spi->dev));
> - } else {
> + if (!spi->cs_gpiod) {
> u32 cs_bit = AR71XX_SPI_IOC_CS(spi->chip_select);
>
> if (spi->mode & SPI_CS_HIGH)
The bitbang code already take care to properly configure CS in
spi_bitbang_setup(), if the core now take care of the GPIO setup we can
probably remove this whole function.
> @@ -143,13 +137,7 @@ static int ath79_spi_setup_cs(struct spi_device
> *spi) ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
> }
>
> - return status;
> -}
> -
> -static void ath79_spi_cleanup_cs(struct spi_device *spi)
> -{
> - if (gpio_is_valid(spi->cs_gpio))
> - gpio_free(spi->cs_gpio);
> + return 0;
> }
>
> static int ath79_spi_setup(struct spi_device *spi)
> @@ -163,15 +151,12 @@ static int ath79_spi_setup(struct spi_device
> *spi) }
>
> status = spi_bitbang_setup(spi);
> - if (status && !spi->controller_state)
> - ath79_spi_cleanup_cs(spi);
>
> return status;
> }
Now if we can remove ath79_spi_setup_cs() and ath79_spi_cleanup_cs() we
can also remove ath79_spi_setup() and directly use spi_bitbang_setup().
That would remove quiet a bit of code, very nice!
> static void ath79_spi_cleanup(struct spi_device *spi)
> {
> - ath79_spi_cleanup_cs(spi);
> spi_bitbang_cleanup(spi);
> }
Here we could also remove this function and directly use
spi_bitbang_cleanup().
> @@ -225,6 +210,7 @@ static int ath79_spi_probe(struct platform_device
> *pdev)
> pdata = dev_get_platdata(&pdev->dev);
>
> + master->use_gpio_descriptors = true;
> master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
> master->setup = ath79_spi_setup;
> master->cleanup = ath79_spi_cleanup;
I would really like to test this these changes, however I won't be able
to do that before next week. Could you please also add me to the CC
list in the first patch in the series for the next iteration? That
would make testing easier.
Alban
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