[PATCH] amba: add name based matching

[PATCH] amba: add name based matching

[Rabin Vincent]

Some peripherals on the DBx500 family of SoCs have changes in their
functionality and registers between different variants in the family but
retain the same AMBA peripheral ID, making it impossible to distinguish
between them in AMBA drivers with the current AMBA id_table.

To support this, add a name parameter to the amba_device and the amba_id
and allow name based matching as a second level filter after the
periphid match.

Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
---
 drivers/amba/bus.c       |    6 ++++++
 include/linux/amba/bus.h |    2 ++
 2 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index d31590e..926121a 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -28,6 +28,12 @@ amba_lookup(struct amba_id *table, struct amba_device *dev)
 
 	while (table->mask) {
 		ret = (dev->periphid & table->mask) == table->id;
+		if (ret && (table->name || dev->name)) {
+			if (table->name && dev->name)
+				ret = strcmp(dev->name, table->name) == 0;
+			else
+				ret = 0;
+		}
 		if (ret)
 			break;
 		table++;
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index b0c1740..61ec94a 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -29,12 +29,14 @@ struct amba_device {
 	struct clk		*pclk;
 	u64			dma_mask;
 	unsigned int		periphid;
+	const char		*name;
 	unsigned int		irq[AMBA_NR_IRQS];
 };
 
 struct amba_id {
 	unsigned int		id;
 	unsigned int		mask;
+	const char		*name;
 	void			*data;
 };
 
-- 
1.7.1

[PATCH] amba: add name based matching

[Russell King - ARM Linux]

On Sat, Oct 09, 2010 at 08:31:20PM +0530, Rabin Vincent wrote:
> Some peripherals on the DBx500 family of SoCs have changes in their
> functionality and registers between different variants in the family but
> retain the same AMBA peripheral ID, making it impossible to distinguish
> between them in AMBA drivers with the current AMBA id_table.
> 
> To support this, add a name parameter to the amba_device and the amba_id
> and allow name based matching as a second level filter after the
> periphid match.

I am really not very happy with this without an explaination of the kinds
of differences there are.

We've been through these kinds of problems where hardware has claimed to
be implemented by 'ARM' (0x41 in the implementer byte) "for compatibility"
but are a different design with their own differences.  Eventually the
vendor was forced (as I understand by ARM Ltd) to change that.

This sounds like another one of these situations - it seems that the
lesson hasn't been learnt.

[PATCH] amba: add name based matching

[Rabin Vincent]

On Tue, Oct 12, 2010 at 10:24:49 +0200, Russell King - ARM Linux wrote:
> On Sat, Oct 09, 2010 at 08:31:20PM +0530, Rabin Vincent wrote:
> > Some peripherals on the DBx500 family of SoCs have changes in their
> > functionality and registers between different variants in the family but
> > retain the same AMBA peripheral ID, making it impossible to distinguish
> > between them in AMBA drivers with the current AMBA id_table.
> > 
> > To support this, add a name parameter to the amba_device and the amba_id
> > and allow name based matching as a second level filter after the
> > periphid match.
> 
> I am really not very happy with this without an explaination of the kinds
> of differences there are.

For example:

 - The PL180 derivate has the ID 0x00480180 on both DB8500v1 and
   DB8500v2, but the DB8500v2 version moves the BLOCKSIZE in the
   DATACTRL register from a power of two at bits 7:4 to a normal value
   at bits 30:16.  The bits 7:4 become reserved in DB8500v2.

 - The PL022 derivate has the ID 0x00080023 on DB8500 and DB5500, but
   the DB5500 version has the "Loopback enable" bit, while the DB8500
   version doesn't.

Rabin