spi: microchip: pci1xxxx: Add suspend and resume support for PCI1XXXX SPI driver

Implement suspend, resume callbacks, store config at suspend and restore
config at time of resume

Signed-off-by: Tharun Kumar P <tharunkumar.pasumarthi@microchip.com>
Link: https://lore.kernel.org/r/20221006050514.115564-3-tharunkumar.pasumarthi@microchip.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Tharun Kumar P

drivers/spi/spi-pci1xxxx.c

@@ -57,6 +57,9 @@
 #define SPI_CHIP_SEL_COUNT 7
 #define VENDOR_ID_MCHP 0x1055
 
+#define SPI_SUSPEND_CONFIG 0x101
+#define SPI_RESUME_CONFIG 0x303
+
 struct pci1xxxx_spi_internal {
 	u8 hw_inst;
 	bool spi_xfer_in_progress;
@@ -383,10 +386,85 @@ static int pci1xxxx_spi_probe(struct pci_dev *pdev, const struct pci_device_id *
 	return ret;
 }
 
+static void store_restore_config(struct pci1xxxx_spi *spi_ptr,
+				 struct pci1xxxx_spi_internal *spi_sub_ptr,
+				 u8 inst, bool store)
+{
+	u32 regval;
+
+	if (store) {
+		regval = readl(spi_ptr->reg_base +
+			       SPI_MST_CTL_REG_OFFSET(spi_sub_ptr->hw_inst));
+		regval &= SPI_MST_CTL_DEVSEL_MASK;
+		spi_sub_ptr->prev_val.dev_sel = (regval >> 25) & 7;
+		regval = readl(spi_ptr->reg_base +
+			       SPI_PCI_CTRL_REG_OFFSET(spi_sub_ptr->hw_inst));
+		regval &= SPI_MSI_VECTOR_SEL_MASK;
+		spi_sub_ptr->prev_val.msi_vector_sel = (regval >> 4) & 1;
+	} else {
+		regval = readl(spi_ptr->reg_base + SPI_MST_CTL_REG_OFFSET(inst));
+		regval &= ~SPI_MST_CTL_DEVSEL_MASK;
+		regval |= (spi_sub_ptr->prev_val.dev_sel << 25);
+		writel(regval,
+		       spi_ptr->reg_base + SPI_MST_CTL_REG_OFFSET(inst));
+		writel((spi_sub_ptr->prev_val.msi_vector_sel << 4),
+			spi_ptr->reg_base + SPI_PCI_CTRL_REG_OFFSET(inst));
+	}
+}
+
+static int pci1xxxx_spi_resume(struct device *dev)
+{
+	struct pci1xxxx_spi *spi_ptr = dev_get_drvdata(dev);
+	struct pci1xxxx_spi_internal *spi_sub_ptr;
+	u32 regval = SPI_RESUME_CONFIG;
+	u8 iter;
+
+	for (iter = 0; iter < spi_ptr->total_hw_instances; iter++) {
+		spi_sub_ptr = spi_ptr->spi_int[iter];
+		spi_master_resume(spi_sub_ptr->spi_host);
+		writel(regval, spi_ptr->reg_base +
+		       SPI_MST_EVENT_MASK_REG_OFFSET(iter));
+
+		/* Restore config at resume */
+		store_restore_config(spi_ptr, spi_sub_ptr, iter, 0);
+	}
+
+	return 0;
+}
+
+static int pci1xxxx_spi_suspend(struct device *dev)
+{
+	struct pci1xxxx_spi *spi_ptr = dev_get_drvdata(dev);
+	struct pci1xxxx_spi_internal *spi_sub_ptr;
+	u32 reg1 = SPI_SUSPEND_CONFIG;
+	u8 iter;
+
+	for (iter = 0; iter < spi_ptr->total_hw_instances; iter++) {
+		spi_sub_ptr = spi_ptr->spi_int[iter];
+
+		while (spi_sub_ptr->spi_xfer_in_progress)
+			msleep(20);
+
+		/* Store existing config before suspend */
+		store_restore_config(spi_ptr, spi_sub_ptr, iter, 1);
+		spi_master_suspend(spi_sub_ptr->spi_host);
+		writel(reg1, spi_ptr->reg_base +
+		       SPI_MST_EVENT_MASK_REG_OFFSET(iter));
+	}
+
+	return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(spi_pm_ops, pci1xxxx_spi_suspend,
+				pci1xxxx_spi_resume);
+
 static struct pci_driver pci1xxxx_spi_driver = {
 	.name		= DRV_NAME,
 	.id_table	= pci1xxxx_spi_pci_id_table,
 	.probe		= pci1xxxx_spi_probe,
+	.driver		=	{
+		.pm = pm_sleep_ptr(&spi_pm_ops),
+	},
 };
 
 module_pci_driver(pci1xxxx_spi_driver);