On Wed, Jan 22, 2014 at 08:26:50AM +0000, Linus Walleij wrote:

On Fri, Jan 17, 2014 at 1:25 PM, Hanjun Guo [off-list ref] wrote:

quoted

From: Amit Daniel Kachhap <redacted>

This macro does the same job as CLOCKSOURCE_OF_DECLARE. The device
name from the ACPI timer table is matched with all the registered
timer controllers and matching initialisation routine is invoked.

Signed-off-by: Amit Daniel Kachhap <redacted>
Signed-off-by: Hanjun Guo <redacted>

Actually I have a fat patch renaming CLOCKSOURCE_OF_DECLARE()
to TIMER_OF_DECLARE() and I think this macro, if needed, should
be named TIMER_ACPI_DECLARE().

The reason is that "clocksource" is a Linux-internal name and this
macro pertains to the hardware name in respective system
description type.

quoted

+#ifdef CONFIG_ACPI
+#define CLOCKSOURCE_ACPI_DECLARE(name, compat, fn)                     \
+       static const struct acpi_device_id __clksrc_acpi_table_##name   \
+               __used __section(__clksrc_acpi_table)                   \
+                = { .id = compat,                              \
+                    .driver_data = (kernel_ulong_t)fn }
+#else
+#define CLOCKSOURCE_ACPI_DECLARE(name, compat, fn)
+#endif

This hammers down the world to compile one binary for ACPI
and one binary for device tree. Maybe that's fine, I don't know.

How does it do that?

As far as I could tell CONFIG_ACPI and CONFIG_OF are not mutually
exclusive, and this just means that we only build the datastructures for
matching from ACPI when CONFIG_ACPI is enabled.

Have I missed something?

I definitely don't want to see mutually exclusive ACPI and DT support.

Cheers,
Mark.