ARM: add infra-structure for BCM2708/BCM2835 and Raspberry Pi

The BCM2708 is an ARM SoC from Broadcom. It is the primary SoC in a
series which contains the BCM2835 amongst other variants. This patch
adds very basic support for this series of SoCs, under the BCM2708 name.

http://www.broadcom.com/products/BCM2835
http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pd

Note that the documentation in the latter .pdf assumes the MMU setup
that's used on the "VideoCore" companion processor, and does not document
physical peripheral addresses. Subtract 0x5e000000 to obtain the physical
addresses.

The BCM2835 SoC is used in the Raspberry Pi. This patch also adds a
minimal device tree for this board; enough to see some very early kernel
boot messages through earlyprintk. However, this patch does not yet
provide a useful booting system.

http://www.raspberrypi.org/.

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split from 3-4 months ago, and significantly stripped down and
modified since.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
---
v3:
* Added DT binding documentation for the SoC itself.
* Changed patch subject from "support" to "infra-structure", and added
  to the commit description, to indicate that the patch isn't adding
  complete support for the SoC/board.
* Added all S-o-b tags from downstream, now that I have permission to
  fix them up to be valid.
* Changed patch author to Simon Arlott, now I have permission to change
  his email address to something valid.
* Limited my (c) additions to files I created; the other changes turnd
  out to be trivial.
v2:
* Rename *_BASE to *_PHYS to match Simon's rpi-split branch.
* Remove #define UART_BAUD since it isn't used.
* Don't select WATCHDOG from ARCH_BCM2708
* Remove 8250 and PL010 serial ports from bcm2708_defconfig
* Remove <mach/hardware.h>
* Rename common.c back to bcm2708.c; matches downstream and is
  preferred naming style.
ARM: bcm2708: add interrupt controller driver

The BCM2708 contains a custom interrupt controller, which supports 72
interrupt sources using a 2-level register scheme. The interrupt
controller, or the HW block containing it, is referred to occasionally
as "armctrl" in the SoC documentation, hence the symbol naming in the
code.

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split as of 2012/09/08, and modified as follows:

* Added devicetree documentation, and hence removed list of IRQs from
  bcm2835.dtsi.
* Changed shift in MAKE_HWIRQ() and HWIRQ_BANK() from 8 to 5 to reduce
  the size of the hwirq space, and pass the total size of the hwirq space
  to irq_domain_add_linear(), rather than just the number of valid hwirqs;
  the two are different due to the hwirq space being sparse.
* Added the interrupt controller DT node to the top-level of the DT,
  rather than nesting it inside a /axi node. Hence, changed the reg value
  since /axi had a ranges property. This seems simpler to me, but I'm not
  sure if everyone will like this change or not.
* Don't set struct irq_domain_ops.map = irq_domain_simple_map, hence
  removing the need to patch include/linux/irqdomain.h or
  kernel/irq/irqdomain.c.
* Removed unused IS_VALID_BANK()/IS_VALID_IRQ() macros.
* Renamed armctrl_handle_irq() to prevent possible symbol clashes.
* Made armctrl_of_init() static.
* Removed comment "Each bank is registered as a separate interrupt
  controller" since this is no longer true.
* Removed FSF address from license header.
* Added my name to copyright header.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
--
v3: New patch.

TODO: Should of_address_to_resource(), ioremap(), request_mem_region()
in armctrl_of_init() be collapsed into of_iomap(). This wouldn't request
the region, but a quick grep implies that's quite common with DT.
ARM: bcm2708: add system timer

The System Timer peripheral provides four 32-bit timer channels and a
single 64-bit free running counter. Each channel has an output compare
register, which is compared against the 32 least significant bits of the
free running counter values, and generates an interrupt.

Timer 3 is used as the Linux timer.

The BCM2708 also contains an SP804-based timer module. However, it
apparently has significant differences from the standard SP804 IP block,
and Broadcom's documentation recommends using the system timer instead.

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split as of 2012/09/08, and modified as follows:

* Moved struct sys_timer bcm2708_timer into time.c to encapsulate it more.
* Added DT binding docs.
* Moved to drivers/clocksource/. This looks like the desired location for
  such code now.
* Simplified bcm2708_time_init() to find one matching node and operate on
  it, rather than looping over all matching nodes. This seems more
  consistent with other clocksource code.
* Renamed struct bcm2708_timer.index to match_mask to better represent its
  purpose.
* s/printk(PR_INFO/pr_info(/

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
---
v3: New patch.

TODO: Should of_address_to_resource(), ioremap(), request_mem_region()
in bcm2708_time_init() be collapsed into of_iomap(). This wouldn't request
the region, but a quick grep implies that's quite common with DT.
ARM: bcm2708: add stub clock driver

This patch adds a minimal stub clock driver for the BCM2708. Its sole
purpose is to allow the PL011 AMBA clk_get() API calls to provide
something that looks enough like a clock that the driver probes and
operates correctly.

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split as of 2012/09/08, and modified as follows:

* Modified .dev_id for UART clocks to match UART DT node names.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
--
v3: New patch.
ARM: bcm2708: instantiate console UART

This patch was extracted from git://github.com/lp0/linux.git branch
rpi-split as of 2012/09/08, and modified as follows:

* Modified UART DT node to use a unit-address to differentiate UART node
  names, rather than using different base names "uart0" and "uart1".
  Note that UART 1 (the Broadcom "mini UART") is not yet present, but
  I'm naming the DT node in anticipation that it will be added.

Signed-off-by: Chris Boot <bootc@bootc.net>
Signed-off-by: Simon Arlott <simon@fire.lp0.eu>
Signed-off-by: Dom Cobley <popcornmix@gmail.com>
Signed-off-by: Dom Cobley <dc4@broadcom.com>
Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
--
v3: New patch.