ARM: at91: PIT: Rework probe functions

The PIT timer driver until now had a single probe function, disregarding wether
it was probed through DT or in the old-style way. This code later on was
calling some DT function to retrieve the proper values for its base address,
interrupts and clocks.

While this was working, it was preventing the usage of CLOCKSOURCE_OF_DECLARE,
and the two different probe path were not as clearly separated as they could
be.

Rework the probe path to take this into account, and switch to
CLOCKSOURCE_OF_DECLARE.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: dt: Remove init_time definitions

The current AT91 DT boards have a completely generic init_time definition.
Remove them from the machine declaration.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

Conflicts:
	arch/arm/mach-at91/board-dt-sam9.c
	arch/arm/mach-at91/board-dt-sama5.c
ARM: at91: PIT: Use consistent exit path in probe

The current probe code is, whenever it fails to retrieve a resource, either
panicing, silently returning, or returning and displaying an error.

Make the code consistent by always panicing whenever it fails to grab any
resource.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: PIT: Use pr_fmt

All the panic messages hardcode the same prefix. Define the pr_fmt macro to
unify its definition.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: PIT: use request_irq instead of setup_irq

We can use the generic request_irq now to register a timer interrupt handler,
instead of the more complex setup_irq.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: PIT: (Almost) remove the global variables

The timer driver is using some global variables to define some variables it has
to use in most of its functions, like the base address.

Use some container_of calls to have a single dynamic (and local) variable to
hold this content.

The only exception is in the !DT case, where the call chain to
at91sam926x_ioremap_pit and then at91sam926x_pit_init as init_time makes it
hard for the moment to pass the physical address of the timer.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: soc: Add init_time callback

Introduce an init_time callback to the at91_init_soc structure to be able to
tweak the init_time machine callback on a per-soc basis, instead of having to
rely on a global one.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

Conflicts:
	arch/arm/mach-at91/setup.c
ARM: at91: Convert the boards to the init_time callback

Now that we have the init_time callback in the at91_init_soc structure, convert
all the boards and SoC to this.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: PIT: Convert to an early_platform_device

Convert the legacy probing mechanism to the early_platform_driver probe.

This will allow a clear separation between the driver and the machine setup
code, which will in turn ease the move out of mach-at91.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
ARM: at91: PIT: Move the driver to drivers/clocksource

Now that we don't depend on anyting in the mach-at91 directory, we can just
move the driver to where it belongs.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Acked-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

Conflicts:
	arch/arm/mach-at91/Kconfig
	arch/arm/mach-at91/Makefile