spi: cadence-quadspi: Add compatible for AMD Pensando Elba SoC

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
Link: https://lore.kernel.org/r/20230515181606.65953-8-blarson@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org

drivers/spi/spi-cadence-quadspi.c

@@ -40,6 +40,7 @@
 #define CQSPI_SUPPORT_EXTERNAL_DMA	BIT(2)
 #define CQSPI_NO_SUPPORT_WR_COMPLETION	BIT(3)
 #define CQSPI_SLOW_SRAM		BIT(4)
+#define CQSPI_NEEDS_APB_AHB_HAZARD_WAR	BIT(5)
 
 /* Capabilities */
 #define CQSPI_SUPPORTS_OCTAL		BIT(0)
@@ -90,6 +91,7 @@ struct cqspi_st {
 	u32			pd_dev_id;
 	bool			wr_completion;
 	bool			slow_sram;
+	bool			apb_ahb_hazard;
 };
 
 struct cqspi_driver_platdata {
@@ -1027,6 +1029,13 @@ 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)
+		readl(reg_base + CQSPI_REG_INDIRECTWR);
+
 	while (remaining > 0) {
 		size_t write_words, mod_bytes;
 
@@ -1754,6 +1763,8 @@ static int cqspi_probe(struct platform_device *pdev)
 			cqspi->wr_completion = false;
 		if (ddata->quirks & CQSPI_SLOW_SRAM)
 			cqspi->slow_sram = true;
+		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"))
@@ -1885,6 +1896,10 @@ static const struct cqspi_driver_platdata jh7110_qspi = {
 	.quirks = CQSPI_DISABLE_DAC_MODE,
 };
 
+static const struct cqspi_driver_platdata pensando_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",
@@ -1914,6 +1929,10 @@ static const struct of_device_id cqspi_dt_ids[] = {
 		.compatible = "starfive,jh7110-qspi",
 		.data = &jh7110_qspi,
 	},
+	{
+		.compatible = "amd,pensando-elba-qspi",
+		.data = &pensando_cdns_qspi,
+	},
 	{ /* end of table */ }
 };