[PATCH v4 1/4] of/pci: Add of_pci_check_probe_only to parse "linux, pci-probe-only"

[Marc Zyngier <marc.zyngier@arm.com>]

Both pci-host-generic and Pseries parse the "linux,pci-probe-only"
property to engage the PCI_PROBE_ONLY mode, and both have a subtle
bug that can be triggered if the property has no parameter.

Provide a generic, safe implementation that can be used by both.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
---
 drivers/of/of_pci.c    | 28 ++++++++++++++++++++++++++++
 include/linux/of_pci.h |  3 +++
 2 files changed, 31 insertions(+)

diff --git a/drivers/of/of_pci.c b/drivers/of/of_pci.c
index 5751dc5..5dd4966 100644
--- a/drivers/of/of_pci.c
+++ b/drivers/of/of_pci.c
@@ -118,6 +118,34 @@ int of_get_pci_domain_nr(struct device_node *node)
 EXPORT_SYMBOL_GPL(of_get_pci_domain_nr);
 
 /**
+ * of_pci_check_probe_only - Setup probe only mode if linux,pci-probe-only
+ *                           is present and valid
+ *
+ * @node: device tree node that may contain the property (usually "chosen")
+ *
+ */
+void of_pci_check_probe_only(void)
+{
+	u32 val;
+	int ret;
+
+	ret = of_property_read_u32(of_chosen, "linux,pci-probe-only", &val);
+	if (ret) {
+		if (ret == -ENODATA || ret == -EOVERFLOW)
+			pr_warn("linux,pci-probe-only without valid value, ignoring\n");
+		return;
+	}
+
+	if (val)
+		pci_add_flags(PCI_PROBE_ONLY);
+	else
+		pci_clear_flags(PCI_PROBE_ONLY);
+
+	pr_info("PCI: PROBE_ONLY %sabled\n", val ? "en" : "dis");
+}
+EXPORT_SYMBOL_GPL(of_pci_check_probe_only);
+
+/**
  * of_pci_dma_configure - Setup DMA configuration
  * @dev: ptr to pci_dev struct of the PCI device
  *
diff --git a/include/linux/of_pci.h b/include/linux/of_pci.h
index 29fd3fe..38c0533 100644
--- a/include/linux/of_pci.h
+++ b/include/linux/of_pci.h
@@ -17,6 +17,7 @@ int of_irq_parse_and_map_pci(const struct pci_dev *dev, u8 slot, u8 pin);
 int of_pci_parse_bus_range(struct device_node *node, struct resource *res);
 int of_get_pci_domain_nr(struct device_node *node);
 void of_pci_dma_configure(struct pci_dev *pci_dev);
+void of_pci_check_probe_only(void);
 #else
 static inline int of_irq_parse_pci(const struct pci_dev *pdev, struct of_phandle_args *out_irq)
 {
@@ -53,6 +54,8 @@ of_get_pci_domain_nr(struct device_node *node)
 }
 
 static inline void of_pci_dma_configure(struct pci_dev *pci_dev) { }
+
+static inline void of_pci_check_probe_only(void) { }
 #endif
 
 #if defined(CONFIG_OF_ADDRESS)
-- 
2.1.4