From: Arnd Bergmann <arnd@xxxxxxxx>
Subject: Re: [PATCH 1/1] arm/dts: Tegra30: Add device tree support for SMMU
Date: Wed, 18 Apr 2012 09:31:53 +0200
Message-ID: <201204180731.54064.arnd@xxxxxxxx>
> On Wednesday 18 April 2012, Hiroshi Doyu wrote:
> > If we can consider IOMMU as one of the implementation of DMA(Direct
> > Memory Access), the prefix "dma-(window)" may make sense here. Then,
> > we don't have to introduce a new concept "IO virtual address(iova)" in
> > addition to the existing "bus address"(?)
> >
> > Anyway, either name would be ok for me;)
>
> I would just use dma-window, without the "ibm," prefix but following the
> same conventions. Note that the of_parse_dma_window function is currently
> only defined in powerpc specific code, and should get moved to
> drivers/of from arch/powerpc/kernel/prom_parse.c.
Something like below?
At least, I verified that this works with "tegra-smmu".
>From 67c1dd493637c9e972d04e061a8e67049687021a Mon Sep 17 00:00:00 2001
From: Hiroshi DOYU <hdoyu@xxxxxxxxxx>
Date: Wed, 18 Apr 2012 12:09:03 +0300
Subject: [PATCH 1/1] dt: Add general DMA window parser
This code was stolen from:
"arch/microblaze/kernel/prom_parse.c"
"arch/powerpc/kernel/prom_parse.c"
Once "ibm," prefix is removed from dts file. This generic one could
replace the originals.
Signed-off-by: Hiroshi DOYU <hdoyu@xxxxxxxxxx>
---
drivers/of/Kconfig | 4 ++++
drivers/of/Makefile | 1 +
drivers/of/of_dma.c | 35 +++++++++++++++++++++++++++++++++++
include/linux/of_address.h | 10 ++++++++++
4 files changed, 50 insertions(+), 0 deletions(-)
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig
index dfba3e6..3b0298b 100644
--- a/drivers/of/Kconfig
+++ b/drivers/of/Kconfig
@@ -83,4 +83,8 @@ config OF_MTD
depends on MTD
def_bool y
+config OF_DMA
+ depends on HAS_DMA
+ def_bool y
+
endmenu # OF
diff --git a/drivers/of/Makefile b/drivers/of/Makefile
index e027f44..711ff5b 100644
--- a/drivers/of/Makefile
+++ b/drivers/of/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_OF_MDIO) += of_mdio.o
obj-$(CONFIG_OF_PCI) += of_pci.o
obj-$(CONFIG_OF_PCI_IRQ) += of_pci_irq.o
obj-$(CONFIG_OF_MTD) += of_mtd.o
+obj-$(CONFIG_OF_DMA) += of_dma.o
diff --git a/drivers/of/of_dma.c b/drivers/of/of_dma.c
new file mode 100644
index 0000000..1db1ccd
--- /dev/null
+++ b/drivers/of/of_dma.c
@@ -0,0 +1,35 @@
+/*
+ * Stealed from:
+ * "arch/microblaze/kernel/prom_parse.c"
+ * "arch/powerpc/kernel/prom_parse.c"
+ */
+
+#include <linux/of_address.h>
+
+void of_parse_dma_window(struct device_node *dn, const void *dma_window_prop,
+ unsigned long *busno, unsigned long *phys, unsigned long *size)
+{
+ const u32 *dma_window;
+ u32 cells;
+ const unsigned char *prop;
+
+ dma_window = dma_window_prop;
+
+ /* busno is always one cell */
+ if (busno)
+ *busno = *(dma_window++);
+
+ prop = of_get_property(dn, "#dma-address-cells", NULL);
+ if (!prop)
+ prop = of_get_property(dn, "#address-cells", NULL);
+
+ cells = prop ? *(u32 *)prop : of_n_addr_cells(dn);
+ *phys = of_read_number(dma_window, cells);
+
+ dma_window += cells;
+
+ prop = of_get_property(dn, "#dma-size-cells", NULL);
+ cells = prop ? *(u32 *)prop : of_n_size_cells(dn);
+ *size = of_read_number(dma_window, cells);
+}
+
diff --git a/include/linux/of_address.h b/include/linux/of_address.h
index 01b925a..2a0f7c6 100644
--- a/include/linux/of_address.h
+++ b/include/linux/of_address.h
@@ -21,6 +21,10 @@ extern void __iomem *of_iomap(struct device_node *device, int index);
extern const u32 *of_get_address(struct device_node *dev, int index,
u64 *size, unsigned int *flags);
+extern void of_parse_dma_window(struct device_node *dn,
+ const void *dma_window_prop, unsigned long *busno,
+ unsigned long *phys, unsigned long *size);
+
#ifndef pci_address_to_pio
static inline unsigned long pci_address_to_pio(phys_addr_t addr) { return -1; }
#define pci_address_to_pio pci_address_to_pio
@@ -48,6 +52,12 @@ static inline const u32 *of_get_address(struct device_node *dev, int index,
{
return NULL;
}
+
+static inline void of_parse_dma_window(struct device_node *dn,
+ const void *dma_window_prop, unsigned long *busno,
+ unsigned long *phys, unsigned long *size)
+{
+}
#endif /* CONFIG_OF_ADDRESS */
--
1.7.5.4
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