If a device is not behind an IOMMU, we look up the device node and set
up the bounced DMA when the bounced-dma property is presented. One can
specify two reserved-memory nodes in the device tree. One with
shared-dma-pool to handle the coherent DMA buffer allocation, and
another one with bounced-dma-pool for regular DMA to/from system memory,
which would be subject to bouncing.
Signed-off-by: Claire Chang <tientzu@xxxxxxxxxxxx>
---
drivers/of/address.c | 37 +++++++++++++++++++++++++++++++++++++
drivers/of/device.c | 3 +++
drivers/of/of_private.h | 6 ++++++
3 files changed, 46 insertions(+)
diff --git a/drivers/of/address.c b/drivers/of/address.c
index 8eea3f6e29a4..a767b80f8862 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>
@@ -1009,6 +1010,42 @@ int of_dma_get_range(struct device_node *np, u64 *dma_addr, u64 *paddr, u64 *siz
return ret;
}
+int of_dma_set_bounce_buffer(struct device *dev)
+{
+ int length, size, ret, i;
+ u32 idx[2];
+
+ if (!dev || !dev->of_node)
+ return -EINVAL;
+
+ if (!of_get_property(dev->of_node, "bounced-dma", &length))
+ return 0;
+
+ size = length / sizeof(idx[0]);
+ if (size > ARRAY_SIZE(idx)) {
+ dev_err(dev,
+ "bounced-dma expected less than or equal to 2 indexs, but got %d\n",
+ size);
+ return -EINVAL;
+ }
+
+ ret = of_property_read_u32_array(dev->of_node, "bounced-dma", idx,
+ size);
+
+ for (i = 0; i < size; i++) {
+ ret = of_reserved_mem_device_init_by_idx(dev, dev->of_node,
+ idx[i]);
+ if (ret) {
+ dev_err(dev,
+ "of_reserved_mem_device_init_by_idx() failed with %d\n",
+ ret);
+ return ret;
+ }
+ }
+
+ return 0;
+}
+
/**
* of_dma_is_coherent - Check if device is coherent
* @np: device node
diff --git a/drivers/of/device.c b/drivers/of/device.c
index 27203bfd0b22..238beef48a50 100644
--- a/drivers/of/device.c
+++ b/drivers/of/device.c
@@ -169,6 +169,9 @@ int of_dma_configure(struct device *dev, struct device_node *np, bool force_dma)
arch_setup_dma_ops(dev, dma_addr, size, iommu, coherent);
+ if (!iommu)
+ return of_dma_set_bounce_buffer(dev);
+
return 0;
}
EXPORT_SYMBOL_GPL(of_dma_configure);
diff --git a/drivers/of/of_private.h b/drivers/of/of_private.h
index edc682249c00..3d1b8cca1519 100644
--- a/drivers/of/of_private.h
+++ b/drivers/of/of_private.h
@@ -160,12 +160,18 @@ extern int of_bus_n_size_cells(struct device_node *np);
#ifdef CONFIG_OF_ADDRESS
extern int of_dma_get_range(struct device_node *np, u64 *dma_addr,
u64 *paddr, u64 *size);
+extern int of_dma_set_bounce_buffer(struct device *dev);
#else
static inline int of_dma_get_range(struct device_node *np, u64 *dma_addr,
u64 *paddr, u64 *size)
{
return -ENODEV;
}
+
+static inline int of_dma_get_bounce_buffer(struct device *dev)
+{
+ return -ENODEV;
+}
#endif
#endif /* _LINUX_OF_PRIVATE_H */
--
2.27.0.383.g050319c2ae-goog
