On Thu, Jul 07, 2016 at 11:01:07PM +0800, Shawn Guo wrote:
> On Thu, Jul 07, 2016 at 05:54:53PM +0800, Shawn Guo wrote:
> > I think this version of the patch is trying to address the comment you
> > put on v1, i.e. instead of extending platform driver we should try to
> > probe ZTE UART from AMBA bus.
> >
> > The solution here is to fake a AMBA peripheral ID which does not exist
> > on hardware with a magic number. While it's working, it looks too
> > hackish, and doesn't really scale in the long run. I hope that's also
> > the reason you are unwilling to provide your ACK :)
> >
> > Unless you have a better solution to suggest, I would think that
> > platform driver is a sensible way to support the device, and will go
> > back to v1 approach.
>
> Just found that Russell's email address changed. Resend to the new
> address.
So, if I were to do this, there wouldn't be any objection?
An alternative would be to use the real hardware ID if it exists, add
a compatible to DT, and use of_device_is_compatible() in the driver
to discover if it's a zte device.
8<====
Subject: [PATCH] amba: make ZTE pseudo-ID more "official"
Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxx>
---
drivers/tty/serial/amba-pl011.c | 4 ++--
include/linux/amba/bus.h | 5 +++++
2 files changed, 7 insertions(+), 2 deletions(-)
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 77b05f5bf866..2dbe5776ac56 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2659,8 +2659,8 @@ static struct amba_id pl011_ids[] = {
.data = &vendor_st,
},
{
- .id = 0xfefefe,
- .mask = 0xffffff,
+ .id = AMBA_LINUX_ID(0x00, 0xf, 0xefe),
+ .mask = 0x00ffffff,
.data = &vendor_zte,
},
{ 0, 0 },
diff --git a/include/linux/amba/bus.h b/include/linux/amba/bus.h
index 3d8dcdd1aeae..dc29d504b4fc 100644
--- a/include/linux/amba/bus.h
+++ b/include/linux/amba/bus.h
@@ -53,8 +53,13 @@ enum amba_vendor {
AMBA_VENDOR_ST = 0x80,
AMBA_VENDOR_QCOM = 0x51,
AMBA_VENDOR_LSI = 0xb6,
+ AMBA_VENDOR_LINUX = 0xef, /* This value is not official */
};
+#define AMBA_LINUX_ID(conf, rev, part) \
+ (((conf) & 0xff) << 24 | ((rev) & 0xf) << 20 | \
+ AMBA_VENDOR_LINUX << 12 | ((part) & 0xfff))
+
extern struct bus_type amba_bustype;
#define to_amba_device(d) container_of(d, struct amba_device, dev)
--
2.1.0
--
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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