[PATCH] spi: spi-zynqmp-gqspi: Add two chip select support

[PATCH] spi: spi-zynqmp-gqspi: Add two chip select support

[Amit Kumar Mahapatra]

ZynqMP GQSPI controller can support up to two chip selects but the current
GQSPI driver only support CS0. With this update and num-cs DT property set
to 2 GQSPI driver can now support two slave devices each connected to one
chip select.

GQSPI driver configures the Lower CS and Upper CS based on the reg DT
property.

Changes tested on ZynqMP board with two SPI-NOR flashes each connected
to a different CS.

Signed-off-by: Amit Kumar Mahapatra <amit.kumar-mahapatra@xilinx.com>
---
BRANCH: mtd/next
---
 drivers/spi/spi-zynqmp-gqspi.c | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-zynqmp-gqspi.c b/drivers/spi/spi-zynqmp-gqspi.c
index 2b5afae8ff7f..c760aac070e5 100644
--- a/drivers/spi/spi-zynqmp-gqspi.c
+++ b/drivers/spi/spi-zynqmp-gqspi.c
@@ -134,6 +134,8 @@
 #define GQSPI_DMA_UNALIGN		0x3
 #define GQSPI_DEFAULT_NUM_CS	1	/* Default number of chip selects */
 
+#define GQSPI_MAX_NUM_CS	2	/* Maximum number of chip selects */
+
 #define SPI_AUTOSUSPEND_TIMEOUT		3000
 enum mode_type {GQSPI_MODE_IO, GQSPI_MODE_DMA};
 
@@ -363,8 +365,13 @@ static void zynqmp_qspi_chipselect(struct spi_device *qspi, bool is_high)
 	genfifoentry |= GQSPI_GENFIFO_MODE_SPI;
 
 	if (!is_high) {
-		xqspi->genfifobus = GQSPI_GENFIFO_BUS_LOWER;
-		xqspi->genfifocs = GQSPI_GENFIFO_CS_LOWER;
+		if (!qspi->chip_select) {
+			xqspi->genfifobus = GQSPI_GENFIFO_BUS_LOWER;
+			xqspi->genfifocs = GQSPI_GENFIFO_CS_LOWER;
+		} else {
+			xqspi->genfifobus = GQSPI_GENFIFO_BUS_UPPER;
+			xqspi->genfifocs = GQSPI_GENFIFO_CS_UPPER;
+		}
 		genfifoentry |= xqspi->genfifobus;
 		genfifoentry |= xqspi->genfifocs;
 		genfifoentry |= GQSPI_GENFIFO_CS_SETUP;
@@ -1099,6 +1106,7 @@ static int zynqmp_qspi_probe(struct platform_device *pdev)
 	struct zynqmp_qspi *xqspi;
 	struct device *dev = &pdev->dev;
 	struct device_node *np = dev->of_node;
+	u32 num_cs;
 
 	ctlr = spi_alloc_master(&pdev->dev, sizeof(*xqspi));
 	if (!ctlr)
@@ -1176,8 +1184,19 @@ static int zynqmp_qspi_probe(struct platform_device *pdev)
 	if (ret)
 		goto clk_dis_all;
 
+	ret = of_property_read_u32(np, "num-cs", &num_cs);
+	if (ret < 0) {
+		ctlr->num_chipselect = GQSPI_DEFAULT_NUM_CS;
+	} else if (num_cs > GQSPI_MAX_NUM_CS) {
+		ret = -EINVAL;
+		dev_err(&pdev->dev, "only %d chip selects are available\n",
+			GQSPI_MAX_NUM_CS);
+		goto clk_dis_all;
+	} else {
+		ctlr->num_chipselect = num_cs;
+	}
+
 	ctlr->bits_per_word_mask = SPI_BPW_MASK(8);
-	ctlr->num_chipselect = GQSPI_DEFAULT_NUM_CS;
 	ctlr->mem_ops = &zynqmp_qspi_mem_ops;
 	ctlr->setup = zynqmp_qspi_setup_op;
 	ctlr->max_speed_hz = clk_get_rate(xqspi->refclk) / 2;
-- 
2.17.1

Re: [PATCH] spi: spi-zynqmp-gqspi: Add two chip select support

[Mark Brown]

On Thu, 12 May 2022 20:28:20 +0530, Amit Kumar Mahapatra wrote:
> ZynqMP GQSPI controller can support up to two chip selects but the current
> GQSPI driver only support CS0. With this update and num-cs DT property set
> to 2 GQSPI driver can now support two slave devices each connected to one
> chip select.
> 
> GQSPI driver configures the Lower CS and Upper CS based on the reg DT
> property.
> 
> [...]

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: spi-zynqmp-gqspi: Add two chip select support
      commit: dd9c232d47277960aba0c603c87a1cfd85d69438

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark