[PATCH v9 03/12] PCI: Introduce helper functions to deal with PCI I/O ranges.

[Liviu Dudau <Liviu.Dudau@arm.com>]

Some architectures do not have a simple view of the PCI I/O space
and instead use a range of CPU addresses that map to bus addresses.
For some architectures these ranges will be expressed by OF bindings
in a device tree file.

This patch introduces a pci_register_io_range() helper function with
a generic implementation that can be used by such architectures to
keep track of the I/O ranges described by the PCI bindings. If the
PCI_IOBASE macro is not defined that signals lack of support for PCI
and we return an error.

In order to retrieve the CPU address associated with an I/O port, a
new helper function pci_pio_to_address() is introduced. This will
search in the list of ranges registered with pci_register_io_range()
and return the CPU address that corresponds to the given port.

Cc: Grant Likely <grant.likely@linaro.org>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
---
 drivers/of/address.c       | 95 ++++++++++++++++++++++++++++++++++++++++++++++
 include/linux/of_address.h |  2 +
 2 files changed, 97 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 5edfcb0..4dab700 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -5,6 +5,7 @@
 #include <linux/module.h>
 #include <linux/of_address.h>
 #include <linux/pci_regs.h>
+#include <linux/slab.h>
 #include <linux/string.h>
 
 /* Max address size we deal with */
@@ -601,12 +602,106 @@ const __be32 *of_get_address(struct device_node *dev, int index, u64 *size,
 }
 EXPORT_SYMBOL(of_get_address);
 
+#ifdef PCI_IOBASE
+struct io_range {
+	struct list_head list;
+	phys_addr_t start;
+	resource_size_t size;
+};
+
+static LIST_HEAD(io_range_list);
+static DEFINE_SPINLOCK(io_range_lock);
+#endif
+
+/*
+ * Record the PCI IO range (expressed as CPU physical address + size).
+ * Return a negative value if an error has occured, zero otherwise
+ */
+int __weak pci_register_io_range(phys_addr_t addr, resource_size_t size)
+{
+#ifdef PCI_IOBASE
+	struct io_range *range;
+	resource_size_t allocated_size = 0;
+
+	/* check if the range hasn't been previously recorded */
+	spin_lock(&io_range_lock);
+	list_for_each_entry(range, &io_range_list, list) {
+		if (addr >= range->start && addr + size <= range->start + size)
+			return 0;
+		allocated_size += range->size;
+	}
+	spin_unlock(&io_range_lock);
+
+	/* range not registed yet, check for available space */
+	if (allocated_size + size - 1 > IO_SPACE_LIMIT) {
+		/* if it's too big check if 64K space can be reserved */
+		if (allocated_size + SZ_64K - 1 > IO_SPACE_LIMIT)
+			return -E2BIG;
+
+		size = SZ_64K;
+		pr_warn("Requested IO range too big, new size set to 64K\n");
+	}
+
+	/* add the range to the list */
+	range = kzalloc(sizeof(*range), GFP_KERNEL);
+	if (!range)
+		return -ENOMEM;
+
+	range->start = addr;
+	range->size = size;
+
+	list_add_tail(&range->list, &io_range_list);
+#endif
+
+	return 0;
+}
+
+phys_addr_t pci_pio_to_address(unsigned long pio)
+{
+	phys_addr_t address = (phys_addr_t)OF_BAD_ADDR;
+
+#ifdef PCI_IOBASE
+	struct io_range *range;
+	resource_size_t allocated_size = 0;
+
+	if (pio > IO_SPACE_LIMIT)
+		return address;
+
+	spin_lock(&io_range_lock);
+	list_for_each_entry(range, &io_range_list, list) {
+		if (pio >= allocated_size && pio < allocated_size + range->size) {
+			address = range->start + pio - allocated_size;
+			break;
+		}
+		allocated_size += range->size;
+	}
+	spin_unlock(&io_range_lock);
+#endif
+
+	return address;
+}
+
 unsigned long __weak pci_address_to_pio(phys_addr_t address)
 {
+#ifdef PCI_IOBASE
+	struct io_range *res;
+	resource_size_t offset = 0;
+
+	list_for_each_entry(res, &io_range_list, list) {
+		if (address >= res->start &&
+			address < res->start + res->size) {
+			return res->start - address + offset;
+		}
+		offset += res->size;
+	}
+
+	return (unsigned long)-1;
+#else
 	if (address > IO_SPACE_LIMIT)
 		return (unsigned long)-1;
 
 	return (unsigned long) address;
+#endif
 }
 
 static int __of_address_to_resource(struct device_node *dev,
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index c13b878..28e6836 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -55,7 +55,9 @@ extern void __iomem *of_iomap(struct device_node *device, int index);
 extern const __be32 *of_get_address(struct device_node *dev, int index,
 			   u64 *size, unsigned int *flags);
 
+extern int pci_register_io_range(phys_addr_t addr, resource_size_t size);
 extern unsigned long pci_address_to_pio(phys_addr_t addr);
+extern phys_addr_t pci_pio_to_address(unsigned long pio);
 
 extern int of_pci_range_parser_init(struct of_pci_range_parser *parser,
 			struct device_node *node);
-- 
2.0.4