[RFC PATCH v3 6/6] of: Add plumbing for restricted DMA pool

From: Claire Chang
Date: Tue Jan 05 2021 - 22:43:10 EST


If a device is not behind an IOMMU, we look up the device node and set
up the restricted DMA when the restricted-dma-pool is presented.

Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
drivers/of/address.c | 21 +++++++++++++++++++++
drivers/of/device.c | 4 ++++
drivers/of/of_private.h | 5 +++++
3 files changed, 30 insertions(+)

diff --git a/drivers/of/address.c b/drivers/of/address.c
index 73ddf2540f3f..94eca8249854 100644
--- a/drivers/of/address.c
+++ b/drivers/of/address.c
@@ -8,6 +8,7 @@
#include <linux/logic_pio.h>
#include <linux/module.h>
#include <linux/of_address.h>
+#include <linux/of_reserved_mem.h>
#include <linux/pci.h>
#include <linux/pci_regs.h>
#include <linux/sizes.h>
@@ -1094,3 +1095,23 @@ bool of_dma_is_coherent(struct device_node *np)
return false;
}
EXPORT_SYMBOL_GPL(of_dma_is_coherent);
+
+int of_dma_set_restricted_buffer(struct device *dev)
+{
+ struct device_node *node;
+ int count, i;
+
+ if (!dev->of_node)
+ return 0;
+
+ count = of_property_count_elems_of_size(dev->of_node, "memory-region",
+ sizeof(phandle));
+ for (i = 0; i < count; i++) {
+ node = of_parse_phandle(dev->of_node, "memory-region", i);
+ if (of_device_is_compatible(node, "restricted-dma-pool"))
+ return of_reserved_mem_device_init_by_idx(
+ dev, dev->of_node, i);
+ }
+
+ return 0;
+}
diff --git a/drivers/of/device.c b/drivers/of/device.c
index aedfaaafd3e7..e2c7409956ab 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -182,6 +182,10 @@ int of_dma_configure_id(struct device *dev, struct device_node *np,
arch_setup_dma_ops(dev, dma_start, size, iommu, coherent);

dev->dma_range_map = map;
+
+ if (!iommu)
+ return of_dma_set_restricted_buffer(dev);
+
return 0;
}
EXPORT_SYMBOL_GPL(of_dma_configure_id);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index d9e6a324de0a..28a2dfa197ba 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -161,12 +161,17 @@ struct bus_dma_region;
#if defined(CONFIG_OF_ADDRESS) && defined(CONFIG_HAS_DMA)
int of_dma_get_range(struct device_node *np,
const struct bus_dma_region **map);
+int of_dma_set_restricted_buffer(struct device *dev);
#else
static inline int of_dma_get_range(struct device_node *np,
const struct bus_dma_region **map)
{
return -ENODEV;
}
+static inline int of_dma_get_restricted_buffer(struct device *dev)
+{
+ return -ENODEV;
+}
#endif

#endif /* _LINUX_OF_PRIVATE_H */
--
2.29.2.729.g45daf8777d-goog