[PATCH v5 11/15] spi: cadence-quadspi: Add compatible for AMD Pensando Elba SoC

[Brad Larson <brad@pensando.io>]

From: Brad Larson <blarson@amd.com>

The AMD Pensando Elba SoC has the Cadence QSPI controller integrated.

The quirk CQSPI_NEEDS_APB_AHB_HAZARD_WAR is added and if enabled
a dummy readback from the controller is performed to ensure
synchronization.

Signed-off-by: Brad Larson <blarson@amd.com>
---
 drivers/spi/spi-cadence-quadspi.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/spi/spi-cadence-quadspi.c b/drivers/spi/spi-cadence-quadspi.c
index 72b1a5a2298c..ebb77ea8e6ba 100644
--- a/drivers/spi/spi-cadence-quadspi.c
+++ b/drivers/spi/spi-cadence-quadspi.c
@@ -39,6 +39,7 @@
 #define CQSPI_DISABLE_DAC_MODE		BIT(1)
 #define CQSPI_SUPPORT_EXTERNAL_DMA	BIT(2)
 #define CQSPI_NO_SUPPORT_WR_COMPLETION	BIT(3)
+#define CQSPI_NEEDS_APB_AHB_HAZARD_WAR	BIT(4)
 
 /* Capabilities */
 #define CQSPI_SUPPORTS_OCTAL		BIT(0)
@@ -87,6 +88,7 @@ struct cqspi_st {
 	bool			use_dma_read;
 	u32			pd_dev_id;
 	bool			wr_completion;
+	bool			apb_ahb_hazard;
 };
 
 struct cqspi_driver_platdata {
@@ -952,6 +954,13 @@ static int cqspi_indirect_write_execute(struct cqspi_flash_pdata *f_pdata,
 	if (cqspi->wr_delay)
 		ndelay(cqspi->wr_delay);
 
+	/*
+	 * If a hazard exists between the APB and AHB interfaces, perform a
+	 * dummy readback from the controller to ensure synchronization.
+	 */
+	if (cqspi->apb_ahb_hazard)
+		(void)readl(reg_base + CQSPI_REG_INDIRECTWR);
+
 	while (remaining > 0) {
 		size_t write_words, mod_bytes;
 
@@ -1667,6 +1676,8 @@ static int cqspi_probe(struct platform_device *pdev)
 			cqspi->use_dma_read = true;
 		if (ddata->quirks & CQSPI_NO_SUPPORT_WR_COMPLETION)
 			cqspi->wr_completion = false;
+		if (ddata->quirks & CQSPI_NEEDS_APB_AHB_HAZARD_WAR)
+			cqspi->apb_ahb_hazard = true;
 
 		if (of_device_is_compatible(pdev->dev.of_node,
 					    "xlnx,versal-ospi-1.0"))
@@ -1789,6 +1800,10 @@ static const struct cqspi_driver_platdata versal_ospi = {
 	.get_dma_status = cqspi_get_versal_dma_status,
 };
 
+static const struct cqspi_driver_platdata pen_cdns_qspi = {
+	.quirks = CQSPI_NEEDS_APB_AHB_HAZARD_WAR | CQSPI_DISABLE_DAC_MODE,
+};
+
 static const struct of_device_id cqspi_dt_ids[] = {
 	{
 		.compatible = "cdns,qspi-nor",
@@ -1814,6 +1829,10 @@ static const struct of_device_id cqspi_dt_ids[] = {
 		.compatible = "intel,socfpga-qspi",
 		.data = &socfpga_qspi,
 	},
+	{
+		.compatible = "amd,pensando-elba-qspi",
+		.data = &pen_cdns_qspi,
+	},
 	{ /* end of table */ }
 };
 
-- 
2.17.1