diff mbox series

[v2,03/13] spi: dw: Add support for Pensando Elba SoC SPI

Message ID 20210329015938.20316-4-brad@pensando.io
State New
Headers show
Series Support Pensando Elba SoC | expand

Commit Message

Brad Larson March 29, 2021, 1:59 a.m. UTC
The Pensando Elba SoC uses a GPIO based chip select
for two DW SPI busses with each bus having two
chip selects.

Signed-off-by: Brad Larson <brad@pensando.io>
---
 drivers/spi/spi-dw-mmio.c | 28 +++++++++++++++++++++++++++-
 1 file changed, 27 insertions(+), 1 deletion(-)

Comments

Andy Shevchenko March 29, 2021, 10:43 a.m. UTC | #1
On Mon, Mar 29, 2021 at 5:01 AM Brad Larson <brad@pensando.io> wrote:
>
> The Pensando Elba SoC uses a GPIO based chip select
> for two DW SPI busses with each bus having two
> chip selects.

...

> +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
> +{
> +       struct dw_spi *dws = spi_master_get_devdata(spi->master);
> +
> +       if (!enable) {

Can you use positive conditional?

> +               /*
> +                * Using a GPIO-based chip-select, the DW SPI
> +                * controller still needs its own CS bit selected
> +                * to start the serial engine.  On Elba the specific
> +                * CS doesn't matter to start the serial engine,
> +                * so using CS0.
> +                */
> +               dw_writel(dws, DW_SPI_SER, BIT(0));
> +       } else {
> +               dw_writel(dws, DW_SPI_SER, 0);
> +       }
> +}
Mark Brown March 29, 2021, 3:58 p.m. UTC | #2
On Sun, Mar 28, 2021 at 06:59:28PM -0700, Brad Larson wrote:

> @@ -56,7 +56,7 @@ struct dw_spi_mscc {
>  /*
>   * The Designware SPI controller (referred to as master in the documentation)
>   * automatically deasserts chip select when the tx fifo is empty. The chip
> - * selects then needs to be either driven as GPIOs or, for the first 4 using the
> + * selects then needs to be either driven as GPIOs or, for the first 4 using
>   * the SPI boot controller registers. the final chip select is an OR gate
>   * between the Designware SPI controller and the SPI boot controller.
>   */

This is an unrelated fix, please send as a separate patch as covered in
submitting-patches.rst.

> @@ -237,6 +237,31 @@ static int dw_spi_canaan_k210_init(struct platform_device *pdev,
>  	return 0;
>  }
>  
> +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
> +{
> +	struct dw_spi *dws = spi_master_get_devdata(spi->master);
> +
> +	if (!enable) {
> +		/*
> +		 * Using a GPIO-based chip-select, the DW SPI
> +		 * controller still needs its own CS bit selected
> +		 * to start the serial engine.  On Elba the specific
> +		 * CS doesn't matter to start the serial engine,
> +		 * so using CS0.
> +		 */

Why does this comment only apply to one branch of the conditional?
Brad Larson March 30, 2021, 2:28 a.m. UTC | #3
On Mon, Mar 29, 2021 at 8:58 AM Mark Brown <broonie@kernel.org> wrote:
>

> On Sun, Mar 28, 2021 at 06:59:28PM -0700, Brad Larson wrote:

>

> > @@ -56,7 +56,7 @@ struct dw_spi_mscc {

> >  /*

> >   * The Designware SPI controller (referred to as master in the documentation)

> >   * automatically deasserts chip select when the tx fifo is empty. The chip

> > - * selects then needs to be either driven as GPIOs or, for the first 4 using the

> > + * selects then needs to be either driven as GPIOs or, for the first 4 using

> >   * the SPI boot controller registers. the final chip select is an OR gate

> >   * between the Designware SPI controller and the SPI boot controller.

> >   */

>

> This is an unrelated fix, please send as a separate patch as covered in

> submitting-patches.rst.


I'll remove this.  Belongs in a trivial patch set.

> > @@ -237,6 +237,31 @@ static int dw_spi_canaan_k210_init(struct platform_device *pdev,

> >       return 0;

> >  }

> >

> > +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)

> > +{

> > +     struct dw_spi *dws = spi_master_get_devdata(spi->master);

> > +

> > +     if (!enable) {

> > +             /*

> > +              * Using a GPIO-based chip-select, the DW SPI

> > +              * controller still needs its own CS bit selected

> > +              * to start the serial engine.  On Elba the specific

> > +              * CS doesn't matter to start the serial engine,

> > +              * so using CS0.

> > +              */

>

> Why does this comment only apply to one branch of the conditional?


It doesn't, I'll move it outside the conditional.
Serge Semin March 31, 2021, 6 p.m. UTC | #4
On Sun, Mar 28, 2021 at 06:59:28PM -0700, Brad Larson wrote:
> The Pensando Elba SoC uses a GPIO based chip select

> for two DW SPI busses with each bus having two

> chip selects.

> 

> Signed-off-by: Brad Larson <brad@pensando.io>

> ---

>  drivers/spi/spi-dw-mmio.c | 28 +++++++++++++++++++++++++++-

>  1 file changed, 27 insertions(+), 1 deletion(-)

> 

> diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c

> index 17c06039a74d..c323a5ceecb8 100644

> --- a/drivers/spi/spi-dw-mmio.c

> +++ b/drivers/spi/spi-dw-mmio.c

> @@ -56,7 +56,7 @@ struct dw_spi_mscc {

>  /*

>   * The Designware SPI controller (referred to as master in the documentation)

>   * automatically deasserts chip select when the tx fifo is empty. The chip

> - * selects then needs to be either driven as GPIOs or, for the first 4 using the

> + * selects then needs to be either driven as GPIOs or, for the first 4 using

>   * the SPI boot controller registers. the final chip select is an OR gate

>   * between the Designware SPI controller and the SPI boot controller.

>   */

> @@ -237,6 +237,31 @@ static int dw_spi_canaan_k210_init(struct platform_device *pdev,

>  	return 0;

>  }

>  

> +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)

> +{

> +	struct dw_spi *dws = spi_master_get_devdata(spi->master);

> +


> +	if (!enable) {


Please, be more attentive to the review-comments given to you before
resending a new patchset. One more time. This version of set_cs won't
work for Active-high CS. Each SPI controller working with GPIO-based
chip-select is marked as supporting that feature. So your DW
SPI controller won't be able to work correctly with SPI-devices
activated by active-high chip-select signal. Note default
dw_spi_set_cs() callback supports that.

-Sergey

> +		/*

> +		 * Using a GPIO-based chip-select, the DW SPI

> +		 * controller still needs its own CS bit selected

> +		 * to start the serial engine.  On Elba the specific

> +		 * CS doesn't matter to start the serial engine,

> +		 * so using CS0.

> +		 */

> +		dw_writel(dws, DW_SPI_SER, BIT(0));

> +	} else {

> +		dw_writel(dws, DW_SPI_SER, 0);

> +	}

> +}

> +

> +static int dw_spi_elba_init(struct platform_device *pdev,

> +			    struct dw_spi_mmio *dwsmmio)

> +{

> +	dwsmmio->dws.set_cs = dw_spi_elba_set_cs;

> +	return 0;

> +}

> +

>  static int dw_spi_mmio_probe(struct platform_device *pdev)

>  {

>  	int (*init_func)(struct platform_device *pdev,

> @@ -351,6 +376,7 @@ static const struct of_device_id dw_spi_mmio_of_match[] = {

>  	{ .compatible = "intel,keembay-ssi", .data = dw_spi_keembay_init},

>  	{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},

>  	{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},

> +	{ .compatible = "pensando,elba-spi", .data = dw_spi_elba_init},

>  	{ /* end of table */}

>  };

>  MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);

> -- 

> 2.17.1

>
Brad Larson Aug. 23, 2021, 1:25 a.m. UTC | #5
Hi Andy,

On Mon, Mar 29, 2021 at 3:43 AM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Mon, Mar 29, 2021 at 5:01 AM Brad Larson <brad@pensando.io> wrote:
> >
> > The Pensando Elba SoC uses a GPIO based chip select
> > for two DW SPI busses with each bus having two
> > chip selects.
...
> > +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
> > +{
> > +       struct dw_spi *dws = spi_master_get_devdata(spi->master);
> > +
> > +       if (!enable) {
>
> Can you use positive conditional?

This function has been re-written to use the existing dw_spi_set_cs().
This is what I currently plan for the v3 patchset.

static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
{
        spi->chip_select = 0;
        dw_spi_set_cs(spi, enable);
}

Regards,
Brad
Brad Larson Aug. 23, 2021, 1:26 a.m. UTC | #6
Hi Sergey,

On Wed, Mar 31, 2021 at 11:00 AM Serge Semin <fancer.lancer@gmail.com> wrote:
>

> On Sun, Mar 28, 2021 at 06:59:28PM -0700, Brad Larson wrote:

> > The Pensando Elba SoC uses a GPIO based chip select

> > for two DW SPI busses with each bus having two

> > chip selects.

(...)
> > +static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)

> > +{

> > +     struct dw_spi *dws = spi_master_get_devdata(spi->master);

> > +

>

> > +     if (!enable) {

>

> Please, be more attentive to the review-comments given to you before

> resending a new patchset. One more time. This version of set_cs won't

> work for Active-high CS. Each SPI controller working with GPIO-based

> chip-select is marked as supporting that feature. So your DW

> SPI controller won't be able to work correctly with SPI-devices

> activated by active-high chip-select signal. Note default

> dw_spi_set_cs() callback supports that.


Thanks for your patience.  It took me a while to understand what you
were asking about regarding dw_spi_set_cs() due to the unnecessarily
complicated function that was being used.  The current implementation
I propose for v3 patchset is this which as you identified handles cs
active high/low properly.

static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
{
        spi->chip_select = 0;
        dw_spi_set_cs(spi, enable);
}

Regards,
Brad
diff mbox series

Patch

diff --git a/drivers/spi/spi-dw-mmio.c b/drivers/spi/spi-dw-mmio.c
index 17c06039a74d..c323a5ceecb8 100644
--- a/drivers/spi/spi-dw-mmio.c
+++ b/drivers/spi/spi-dw-mmio.c
@@ -56,7 +56,7 @@  struct dw_spi_mscc {
 /*
  * The Designware SPI controller (referred to as master in the documentation)
  * automatically deasserts chip select when the tx fifo is empty. The chip
- * selects then needs to be either driven as GPIOs or, for the first 4 using the
+ * selects then needs to be either driven as GPIOs or, for the first 4 using
  * the SPI boot controller registers. the final chip select is an OR gate
  * between the Designware SPI controller and the SPI boot controller.
  */
@@ -237,6 +237,31 @@  static int dw_spi_canaan_k210_init(struct platform_device *pdev,
 	return 0;
 }
 
+static void dw_spi_elba_set_cs(struct spi_device *spi, bool enable)
+{
+	struct dw_spi *dws = spi_master_get_devdata(spi->master);
+
+	if (!enable) {
+		/*
+		 * Using a GPIO-based chip-select, the DW SPI
+		 * controller still needs its own CS bit selected
+		 * to start the serial engine.  On Elba the specific
+		 * CS doesn't matter to start the serial engine,
+		 * so using CS0.
+		 */
+		dw_writel(dws, DW_SPI_SER, BIT(0));
+	} else {
+		dw_writel(dws, DW_SPI_SER, 0);
+	}
+}
+
+static int dw_spi_elba_init(struct platform_device *pdev,
+			    struct dw_spi_mmio *dwsmmio)
+{
+	dwsmmio->dws.set_cs = dw_spi_elba_set_cs;
+	return 0;
+}
+
 static int dw_spi_mmio_probe(struct platform_device *pdev)
 {
 	int (*init_func)(struct platform_device *pdev,
@@ -351,6 +376,7 @@  static const struct of_device_id dw_spi_mmio_of_match[] = {
 	{ .compatible = "intel,keembay-ssi", .data = dw_spi_keembay_init},
 	{ .compatible = "microchip,sparx5-spi", dw_spi_mscc_sparx5_init},
 	{ .compatible = "canaan,k210-spi", dw_spi_canaan_k210_init},
+	{ .compatible = "pensando,elba-spi", .data = dw_spi_elba_init},
 	{ /* end of table */}
 };
 MODULE_DEVICE_TABLE(of, dw_spi_mmio_of_match);