Documentation: DT bindings: Tegra AHB: require the legacy base address for existing chips

Per Stephen Warren, note in the Tegra AHB DT binding documentation
that we specifically deprecate any attempt to use the IP block's
actual hardware base address, and advocate the use of the legacy
"off-by-four" address in the 'regs' property, for Tegra chips with
existing upstream Linux DT files that include a Tegra AHB node.  This
patch updates the documentation accordingly.

Changing the existing kernel DT data isn't under consideration because
Linux kernel DT data policy is to preserve compatibility between newer
DT data files and older kernels.  However, this additional step of
changing the documentation should discourage others from sending
kernel patches to try to change the legacy kernel DT data.
Furthermore, for out-of-tree software (such as bootloaders or other
operating systems) that may rely on Linux kernel DT binding
documentation as an ABI (but not the Linux kernel DT data itself),
such a change may allow future convergence with the Linux kernel DT
data without additional code changes.
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Acked-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NRussell King <rmk+kernel@arm.linux.org.uk>

Align compatible strings for several IP blocks present on Tegra chips
with the latest doctrine from the DT maintainers:

http://marc.info/?l=devicetree&m=142255654213019&w=2

The primary objective here is to avoid checkpatch warnings, per:

http://marc.info/?l=linux-tegra&m=142201349727836&w=2

DT binding text files have been updated for the following IP blocks:

- PCIe
- SOR
- SoC timers
- AHB "gizmo"
- APB_MISC
- pinmux control
- UART
- PWM
- I2C
- SPI
- RTC
- PMC
- eFuse
- AHCI
- HDA
- XUSB_PADCTRL
- SDHCI
- SOC_THERM
- AHUB
- I2S
- EHCI
- USB PHY

N.B. The nvidia,tegra20-timer compatible string is removed from the
nvidia,tegra30-timer.txt documentation file because it's already
mentioned in the nvidia,tegra20-timer.txt documentation file.

This second version takes into account the following requests from
Rob Herring <robherring2@gmail.com>:

- Per-IP block patches have been combined into a single patch

- Explicit documentation about which compatible strings are actually
  matched by the driver has been removed.  In its place is implicit
  documentation that loosely follows Rob's prescribed format:

  "Must contain '"nvidia,<chip>-pcie", "nvidia,tegra20-pcie"' where
   <chip> is tegra30, tegra132, ..." [...]  "You should attempt to
   document known values of <chip> if you use it"
Signed-off-by: NPaul Walmsley <paul@pwsan.com>
Cc: Alexandre Courbot <gnurou@gmail.com>
Cc: Dylan Reid <dgreid@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Hans de Goede <hdegoede@redhat.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Jingchang Lu <jingchang.lu@freescale.com>
Cc: John Crispin <blogic@openwrt.org>
Cc: Kumar Gala <galak@codeaurora.org>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mikko Perttunen <mperttunen@nvidia.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>
Cc: Paul Walmsley <pwalmsley@nvidia.com>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Peter De Schrijver <pdeschrijver@nvidia.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: Stephen Warren <swarren@wwwdotorg.org>
Cc: Takashi Iwai <tiwai@suse.de>
Cc: Tejun Heo <tj@kernel.org>
Cc: "Terje Bergström" <tbergstrom@nvidia.com>
Cc: Thierry Reding <thierry.reding@gmail.com>
Cc: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
Cc: Wolfram Sang <wsa@the-dreams.de>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-i2c@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-pci@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: linux-pwm@vger.kernel.org
Cc: linux-tegra@vger.kernel.org
Acked-by: NEduardo Valentin <edubezval@gmail.com>
Signed-off-by: NRob Herring <robh@kernel.org>

Tegra AHB Bus conforms to the AMBA Specification (Rev 2.0) Advanced
High-performance Bus (AHB) architecture.

The AHB Arbiter controls AHB bus master arbitration. This effectively
forms a second level of arbitration for access to the memory
controller through the AHB Slave Memory device. The AHB pre-fetch
logic can be configured to enhance performance for devices doing
sequential access. Each AHB master is assigned to either the high or
low priority bin. Both Tegra20/30 have this AHB bus.

Some of configuration params could be passed from DT too if needed.
Signed-off-by: NHiroshi DOYU <hdoyu@nvidia.com>
Acked-by: NArnd Bergmann <arnd@arndb.de>
Cc: Felipe Balbi <balbi@ti.com>
Signed-off-by: NStephen Warren <swarren@nvidia.com>