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

Liviu Dudau
2014-08-12T16:30:22Z

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