This implements the 'nonposted-mmio' boolean property. Placing this
property in a bus marks all direct child devices as requiring
non-posted MMIO mappings. If no such property is found, the default
is posted MMIO.
of_mmio_is_nonposted() performs this check to determine if a given
device has requested non-posted MMIO.
of_address_to_resource() uses this to set the IORESOURCE_MEM_NONPOSTED
flag on resources that require non-posted MMIO.
of_iomap() and of_io_request_and_map() then use this flag to pick the
correct ioremap() variant.
This mechanism is currently restricted to builds that support Apple ARM
platforms, as an optimization.
Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Hector Martin <marcan@xxxxxxxxx>
---
drivers/of/address.c | 43 ++++++++++++++++++++++++++++++++++++--
include/linux/of_address.h | 1 +
2 files changed, 42 insertions(+), 2 deletions(-)
diff --git a/drivers/of/address.c b/drivers/of/address.c
index 73ddf2540f3f..6485cc536e81 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -847,6 +847,9 @@ static int __of_address_to_resource(struct device_node *dev,
return -EINVAL;
memset(r, 0, sizeof(struct resource));
+ if (of_mmio_is_nonposted(dev))
+ flags |= IORESOURCE_MEM_NONPOSTED;
+
r->start = taddr;
r->end = taddr + size - 1;
r->flags = flags;
@@ -896,7 +899,10 @@ void __iomem *of_iomap(struct device_node *np, int index)
if (of_address_to_resource(np, index, &res))
return NULL;
- return ioremap(res.start, resource_size(&res));
+ if (res.flags & IORESOURCE_MEM_NONPOSTED)
+ return ioremap_np(res.start, resource_size(&res));
+ else
+ return ioremap(res.start, resource_size(&res));
}
EXPORT_SYMBOL(of_iomap);
@@ -928,7 +934,11 @@ void __iomem *of_io_request_and_map(struct device_node *np, int index,
if (!request_mem_region(res.start, resource_size(&res), name))
return IOMEM_ERR_PTR(-EBUSY);
- mem = ioremap(res.start, resource_size(&res));
+ if (res.flags & IORESOURCE_MEM_NONPOSTED)
+ mem = ioremap_np(res.start, resource_size(&res));
+ else
+ mem = ioremap(res.start, resource_size(&res));
+
if (!mem) {
release_mem_region(res.start, resource_size(&res));
return IOMEM_ERR_PTR(-ENOMEM);
@@ -1094,3 +1104,32 @@ bool of_dma_is_coherent(struct device_node *np)
return false;
}
EXPORT_SYMBOL_GPL(of_dma_is_coherent);
+
+/**
+ * of_mmio_is_nonposted - Check if device uses non-posted MMIO
+ * @np: device node
+ *
+ * Returns true if the "nonposted-mmio" property was found for
+ * the device's bus.
+ *
+ * This is currently only enabled on builds that support Apple ARM devices, as
+ * an optimization.
+ */
+bool of_mmio_is_nonposted(struct device_node *np)
+{
+ struct device_node *parent;
+ bool nonposted;
+
+ if (!IS_ENABLED(CONFIG_ARCH_APPLE))
+ return false;
+
+ parent = of_get_parent(np);
+ if (!parent)
+ return false;
+
+ nonposted = of_property_read_bool(parent, "nonposted-mmio");
+
+ of_node_put(parent);
+ return nonposted;
+}
+EXPORT_SYMBOL_GPL(of_mmio_is_nonposted);
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 88bc943405cd..88f6333fee6c 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -62,6 +62,7 @@ extern struct of_pci_range *of_pci_range_parser_one(
struct of_pci_range_parser *parser,
struct of_pci_range *range);
extern bool of_dma_is_coherent(struct device_node *np);
+extern bool of_mmio_is_nonposted(struct device_node *np);
#else /* CONFIG_OF_ADDRESS */
static inline void __iomem *of_io_request_and_map(struct device_node *device,
int index, const char *name)
--
2.30.0
