APPLIED: ARM: add infra-structure for BCM2835 and Raspberry Pi

The BCM2835 is an ARM SoC from Broadcom. This patch adds very basic
support for this SoC.

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

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. This is accounted for by the ranges property in the /soc node
in the device tree.

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>
Acked-by: Arnd Bergmann <arnd@arndb.de>
APPLIED: ARM: bcm2835: add interrupt controller driver

The BCM2835 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:

* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.
* Moved implementation to drivers/irchip/.
* 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.
* Simplified armctrl_of_init() using of_iomap().
* 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>
Acked-by: Arnd Bergmann <arnd@arndb.de>
APPLIED: ARM: bcm2835: 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 BCM2835 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:

* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.
* Moved to drivers/clocksource/. This looks like the desired location for
  such code now.
* Added DT binding docs.
* Moved struct sys_timer bcm2835_timer into time.c to encapsulate it more.
* Simplified bcm2835_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.
* Simplified bcm2835_time_init() using of_iomap().
* Renamed struct bcm2835_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>
Acked-by: Arnd Bergmann <arnd@arndb.de>
APPLIED: ARM: bcm2835: add stub clock driver

This patch adds a minimal stub clock driver for the BCM2835. 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:

* Reworked to call clk_register_fixed_rate(), and clk_register_clkdev()
  rather than using static data to represent the clocks.
* Moved implementation to drivers/clk/.
* Modified .dev_id for UART clocks to match UART DT node names.
* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.

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>
Acked-by: Mike Turquette <mturquette@linaro.org>
APPLIED: ARM: bcm2835: 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:

* s/bcm2708/bcm2835/.
* Modified device tree vendor prefix.
* Modified UART DT node to use a unit-address to create unique UART node
  names, rather than using non-type 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>
Acked-by: Arnd Bergmann <arnd@arndb.de>
APPLIED: MAINTAINERS: add an entry for the BCM2835 ARM sub-architecture

Add myself as the maintainer for the BCM2835 ARM support, and related
drivers. This is mainly so that the MAINTAINERS file contains some
relevant entry, and the rpi/ARM mailing lists; I'd be quite happy if
anyone else came along and wanted to maintain/co-maintain this.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
ARM: bcm2835: implement machine restart hook

Implement the machine restart hook using the SoC's watchdog timer module.
To support this, define a DT binding for the watchdog module, and add it
to the device tree.

The downstream rpi-split branch contains a full watchdog timer driver
implementation, which also implements the restart hook. However, the
restart function is largely separate from the watchdog driver, so for
simplicity, the restart hook is implemented here directly in the main
machine source file.

Overall structure (separate setup/restart) functions derived from the
picoxcell ARM support.

Watchdog register IO sequence taken from code by Simon Arlott. Note that
the watchdog module is not documented in BCM2835-ARM-Peripherals.pdf.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>
LOCAL HACK: configure initramfs in defconfig

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>