[PATCH v2 4/5] PCI: designware: Add disable IO support

[Gabriel FERNANDEZ <gabriel.fernandez@st.com>]

ST sti SoCs PCIe IPs are built around DesignWare IP Core.
But in these SoCs PCIe IP doesn't support IO.

This patch adds the possibility to disable it through
a DT property, by creating an empty IO window and by
removing PCI_COMMAND_IO from the setup register.

Signed-off-by: Fabrice Gasnier <fabrice.gasnier@st.com>
Signed-off-by: Gabriel Fernandez <gabriel.fernandez@linaro.org>
---
 .../devicetree/bindings/pci/designware-pcie.txt    |  2 ++
 drivers/pci/host/pcie-designware.c                 | 24 ++++++++++++++++++++--
 drivers/pci/host/pcie-designware.h                 |  1 +
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/pci/designware-pcie.txt b/Documentation/devicetree/bindings/pci/designware-pcie.txt
index 9f4faa8..40544d4 100644
--- a/Documentation/devicetree/bindings/pci/designware-pcie.txt
+++ b/Documentation/devicetree/bindings/pci/designware-pcie.txt
@@ -26,3 +26,5 @@ Optional properties:
 - bus-range: PCI bus numbers covered (it is recommended for new devicetrees to
   specify this property, to keep backwards compatibility a range of 0x00-0xff
   is assumed if not present)
+- disable_io_support: set this property for PCIe host controller without IO
+  port access
diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
index 1f4ea6f..f9d70f5 100644
--- a/drivers/pci/host/pcie-designware.c
+++ b/drivers/pci/host/pcie-designware.c
@@ -471,6 +471,9 @@ int __init dw_pcie_host_init(struct pcie_port *pp)
 		return -EINVAL;
 	}
 
+	pp->disable_io_support = of_property_read_bool(np,
+			"disable_io_support");
+
 	if (IS_ENABLED(CONFIG_PCI_MSI)) {
 		if (!pp->ops->msi_host_init) {
 			pp->irq_domain = irq_domain_add_linear(pp->dev->of_node,
@@ -704,6 +707,7 @@ static struct pci_ops dw_pcie_ops = {
 static int dw_pcie_setup(int nr, struct pci_sys_data *sys)
 {
 	struct pcie_port *pp;
+	struct resource *res;
 
 	pp = sys_to_pcie(sys);
 
@@ -719,6 +723,18 @@ static int dw_pcie_setup(int nr, struct pci_sys_data *sys)
 	pci_add_resource_offset(&sys->resources, &pp->mem, sys->mem_offset);
 	pci_add_resource(&sys->resources, &pp->busn);
 
+	if (pp->disable_io_support) {
+		/* This PCIe controller does not support IO, set an empty one */
+		res = devm_kzalloc(pp->dev, sizeof(*res), GFP_KERNEL);
+		if (res) {
+			res->start = 0;
+			res->end = 0;
+			res->name = "PCIe empty IO space";
+			res->flags = IORESOURCE_IO;
+			pci_add_resource(&sys->resources, res);
+		}
+	}
+
 	return 1;
 }
 
@@ -822,8 +838,12 @@ void dw_pcie_setup_rc(struct pcie_port *pp)
 	/* setup command register */
 	dw_pcie_readl_rc(pp, PCI_COMMAND, &val);
 	val &= 0xffff0000;
-	val |= PCI_COMMAND_IO | PCI_COMMAND_MEMORY |
-		PCI_COMMAND_MASTER | PCI_COMMAND_SERR;
+
+	if (!pp->disable_io_support)
+		val |= PCI_COMMAND_IO;
+
+	val |= PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER | PCI_COMMAND_SERR;
+
 	dw_pcie_writel_rc(pp, val, PCI_COMMAND);
 }
 
diff --git a/drivers/pci/host/pcie-designware.h b/drivers/pci/host/pcie-designware.h
index d0bbd27..027045d 100644
--- a/drivers/pci/host/pcie-designware.h
+++ b/drivers/pci/host/pcie-designware.h
@@ -52,6 +52,7 @@ struct pcie_port {
 	int			msi_irq;
 	struct irq_domain	*irq_domain;
 	unsigned long		msi_data;
+	bool			disable_io_support;
 	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
 };
 
-- 
1.9.1