| Message ID | 20210329015938.20316-4-brad@pensando.io |
|---|---|
| State | New |
| Headers | show |
| Series | Support Pensando Elba SoC | expand |
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); > + } > +}
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?
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
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 --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);
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(-)