iommu/riscv: Add shutdown function for iommu driver

This commit supplies shutdown callback for iommu driver. The shutdown
callback resets necessary registers so that newly booted kernel can pass
riscv_iommu_init_check() after kexec. Also, the shutdown callback resets
iommu mode to bare instead of off so that new kernel can still use PCIE
devices even when CONFIG_RISCV_IOMMU is not enabled.

Signed-off-by: Xu Lu <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Joerg Roedel <[email protected]>

Author: Xu Lu

drivers/iommu/riscv/iommu-pci.c

@@ -101,6 +101,13 @@ static void riscv_iommu_pci_remove(struct pci_dev *pdev)
 	riscv_iommu_remove(iommu);
 }
 
+static void riscv_iommu_pci_shutdown(struct pci_dev *pdev)
+{
+	struct riscv_iommu_device *iommu = dev_get_drvdata(&pdev->dev);
+
+	riscv_iommu_disable(iommu);
+}
+
 static const struct pci_device_id riscv_iommu_pci_tbl[] = {
 	{PCI_VDEVICE(REDHAT, PCI_DEVICE_ID_REDHAT_RISCV_IOMMU), 0},
 	{PCI_VDEVICE(RIVOS, PCI_DEVICE_ID_RIVOS_RISCV_IOMMU_GA), 0},
@@ -112,6 +119,7 @@ static struct pci_driver riscv_iommu_pci_driver = {
 	.id_table = riscv_iommu_pci_tbl,
 	.probe = riscv_iommu_pci_probe,
 	.remove = riscv_iommu_pci_remove,
+	.shutdown = riscv_iommu_pci_shutdown,
 	.driver = {
 		.suppress_bind_attrs = true,
 	},

drivers/iommu/riscv/iommu-platform.c

@@ -140,6 +140,11 @@ static void riscv_iommu_platform_remove(struct platform_device *pdev)
 		platform_device_msi_free_irqs_all(&pdev->dev);
 };
 
+static void riscv_iommu_platform_shutdown(struct platform_device *pdev)
+{
+	riscv_iommu_disable(dev_get_drvdata(&pdev->dev));
+};
+
 static const struct of_device_id riscv_iommu_of_match[] = {
 	{.compatible = "riscv,iommu",},
 	{},
@@ -148,6 +153,7 @@ static const struct of_device_id riscv_iommu_of_match[] = {
 static struct platform_driver riscv_iommu_platform_driver = {
 	.probe = riscv_iommu_platform_probe,
 	.remove = riscv_iommu_platform_remove,
+	.shutdown = riscv_iommu_platform_shutdown,
 	.driver = {
 		.name = "riscv,iommu",
 		.of_match_table = riscv_iommu_of_match,

drivers/iommu/riscv/iommu.c

@@ -651,9 +651,11 @@ static struct riscv_iommu_dc *riscv_iommu_get_dc(struct riscv_iommu_device *iomm
  * This is best effort IOMMU translation shutdown flow.
  * Disable IOMMU without waiting for hardware response.
  */
-static void riscv_iommu_disable(struct riscv_iommu_device *iommu)
+void riscv_iommu_disable(struct riscv_iommu_device *iommu)
 {
-	riscv_iommu_writeq(iommu, RISCV_IOMMU_REG_DDTP, 0);
+	riscv_iommu_writeq(iommu, RISCV_IOMMU_REG_DDTP,
+			   FIELD_PREP(RISCV_IOMMU_DDTP_IOMMU_MODE,
+				      RISCV_IOMMU_DDTP_IOMMU_MODE_BARE));
 	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_CQCSR, 0);
 	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_FQCSR, 0);
 	riscv_iommu_writel(iommu, RISCV_IOMMU_REG_PQCSR, 0);

drivers/iommu/riscv/iommu.h

@@ -64,6 +64,7 @@ struct riscv_iommu_device {
 
 int riscv_iommu_init(struct riscv_iommu_device *iommu);
 void riscv_iommu_remove(struct riscv_iommu_device *iommu);
+void riscv_iommu_disable(struct riscv_iommu_device *iommu);
 
 #define riscv_iommu_readl(iommu, addr) \
 	readl_relaxed((iommu)->reg + (addr))