diff mbox

Re: [PATCH 1/1] dt: Add general DMA window parser

Message ID 20120418.133629.1664781135413277375.hdoyu@nvidia.com
State New
Headers show

Commit Message

Hiroshi Doyu April 18, 2012, 10:36 a.m. UTC 
From: Thierry Reding <thierry.reding@avionic-design.de>
Subject: Re: [PATCH 1/1] dt: Add general DMA window parser
Date: Wed, 18 Apr 2012 12:26:29 +0200
Message-ID: <20120418102629.GA14533@avionic-0098.mockup.avionic-design.de>

> * PGP Signed by an unknown key
> 
> * Hiroshi Doyu wrote:
> > +	cells = prop ? *(__be32 *)prop : of_n_addr_cells(dn);
> 
> I think this needs to be:
> 
> 	cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
> 
> Only casting isn't enough, you need the bytes to be swapped.

Right. Try again. Sorry for spamming.

From 1ee8a9b3a839456b170af74b11a4304bfda965c4 Mon Sep 17 00:00:00 2001
From: Hiroshi DOYU <hdoyu@nvidia.com>
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@nvidia.com>
---
 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(-)

Comments

Thierry Reding April 18, 2012, 10:54 a.m. UTC | #1 
* Hiroshi Doyu wrote:
> diff --git a/drivers/of/of_dma.c b/drivers/of/of_dma.c
> new file mode 100644
> index 0000000..45c9e88
> --- /dev/null
> +++ b/drivers/of/of_dma.c
> @@ -0,0 +1,35 @@
> +/*
> + * Stolen 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 __be32 *dma_window;
> +	u32 cells;
> +	const unsigned char *prop;

There's no need for this to be const unsigned char *, const void * will do
just as well.

> +
> +	dma_window = dma_window_prop;
> +
> +	/* busno is always one cell */
> +	if (busno)
> +		*busno = be32_to_cpup(dma_window++);
> +
> +	prop = of_get_property(dn, "#dma-address-cells", NULL);
> +	if (!prop)
> +		prop = of_get_property(dn, "#address-cells", NULL);
> +
> +	cells = prop ? be32_to_cpup(prop) : of_n_addr_cells(dn);
> +	*phys = of_read_number(dma_window, cells);

This should probably fail gracefully if phys == NULL, similar to what you do
for busno.

> +
> +	dma_window += cells;
> +
> +	prop = of_get_property(dn, "#dma-size-cells", NULL);
> +	cells = prop ? be32_to_cpup(prop) : of_n_size_cells(dn);
> +	*size = of_read_number(dma_window, cells);

Same here.

> +}
> +

And you might want to add a EXPORT_SYMBOL(of_parse_dma_window) here so the
function can be used from modules.

Sorry for having you go through another round. I should have looked more
closely before.

Thierry
diff mbox

Patch

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..45c9e88
--- /dev/null
+++ b/drivers/of/of_dma.c
@@ -0,0 +1,35 @@ 
+/*
+ * Stolen 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 __be32 *dma_window;
+	u32 cells;
+	const unsigned char *prop;
+
+	dma_window = dma_window_prop;
+
+	/* busno is always one cell */
+	if (busno)
+		*busno = be32_to_cpup(dma_window++);
+
+	prop = of_get_property(dn, "#dma-address-cells", NULL);
+	if (!prop)
+		prop = of_get_property(dn, "#address-cells", NULL);
+
+	cells = prop ? be32_to_cpup(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 ? be32_to_cpup(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 */