Enabling support for more than one BMIPS CPU in the same build may
result in different L1_CACHE_SHIFT values, e.g.

    CPU_BMIPS5000 selects MIPS_L1_CACHE_SHIFT_7
    CPU_BMIPS4380 selects MIPS_L1_CACHE_SHIFT_6
    anything else defaults to MIPS_L1_CACHE_SHIFT_5

Ensure that if more than one MIPS_L1_CACHE_SHIFT_x option is selected,
Kconfig sets CONFIG_MIPS_L1_CACHE_SHIFT to the highest value.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8847/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Some machines only have one bus type to register (e.g. "simple-bus").
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8845/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is the main peripheral IRQ controller on the BCM7xxx MIPS chips;
it has the following characteristics:

 - 64 to 160+ level IRQs
 - Atomic set/clear registers
 - Reasonably predictable register layout (N status words, then N
   mask status words, then N mask set words, then N mask clear words)
 - SMP affinity supported on most systems
 - Typically connected to MIPS IRQ 2,3,2,3 on CPUs 0,1,2,3

This driver registers one IRQ domain and one IRQ chip to cover all
instances of the block.  Up to 4 instances of the block may appear, as
it supports 4-way IRQ affinity on BCM7435.

The same block exists on the ARM BCM7xxx chips, but typically the ARM GIC
is used instead.  So this driver is primarily intended for MIPS STB chips.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8844/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

These controllers support multiple enable/status pairs (64+ IRQs),
can put the enable/status words at different offsets, and do not
support multiple parent IRQs.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8843/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

The BCM7xxx instances of this block (listed in the register manual as
simply "IRQ0") all have the following items in common:

 - brcm,int-map-mask: for routing different bits in the L2 to different
   parent IRQs

 - brcm,int-fwd-mask: for hardwiring certain IRQs to bypass the L2 and
   use dedicated L1 lines

 - one enable/status pair (32 bits only)

Much of the driver code can be shared with BCM3380-style controllers, but
in order to do this cleanly, let's split out the BCM7xxx-specific logic
first.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8842/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Currently the driver assumes that REG_BASE+0x00 is the IRQ enable mask,
and REG_BASE+0x04 is the IRQ status mask.  This is true on BCM3384 and
BCM7xxx, but it is not true for some of the controllers found on BCM63xx
chips.  So we will change a couple of key assumptions:

 - Don't assume that both the IRQEN and IRQSTAT registers will be
   covered by a single ioremap() operation.

 - Don't assume any particular ordering (IRQSTAT might show up before
   IRQEN on some chips).

 - For an L2 controller with >=64 IRQs, don't assume that every
   IRQEN/IRQSTAT pair will use the same register spacing.

This patch changes the "plumbing" but doesn't yet provide a way for users
to instantiate a controller with arbitrary IRQEN/IRQSTAT offsets.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8841/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Wakeable interrupts might be pending at boot/init time, because wakeup
interrupts might have triggered a resume from S5. So don't clear such
wakeups.

This means that any driver which requests a wakeable interrupt bit
should be prepared to handle an interrupt as soon as they call
request_irq(). (This is technically already the correct development
practice, but some drivers probably expect not to receive interrupts
until they have performed some I/O.)
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8840/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Several drivers now use this API, including the ARM GIC driver, so remove
the outdated comment.
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8839/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This platform is configured primarily through device tree, and we can
reuse the same code to support a bunch of other chips.  Change the name
to reflect this.

[ralf@linux-mips.org: Fix conflicts with other patches.]
Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8838/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Add the dtbs_install Makefile target to install the dtb files into
$INSTALL_DTBS_PATH.
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8836/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Move the MIPS device-trees into the appropriate vendor sub-directories.
Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
Tested-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8835/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

With sched_clock being ready, it makes sense to add the option of IRQ time
accounting -- When we have a fast enough sched_clock, IRQ time accounting
will be enabled (see sched_clock_register).
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9489/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use sb1250 hpt for sched_clock source. This implementation will give high
resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9488/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is to make checkpatch.pl happy for the next patch. It would otherwise
say --

ERROR: Do not include the paragraph about writing to the Free Software
Foundation's mailing address from the sample GPL notice. The FSF has
changed addresses in the past, and may do so again. Linux already includes
a copy of the GPL.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9487/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is to prepare for the upcoming read_sched_clock implementation, which
will also need to get cycles from the high precision timer.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9486/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use jz4740 timer counter for sched_clock source. This implementation will
give high resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9485/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use txx9 up-counter for sched_clock source. This implementation will give
high resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9484/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use ip27 hub real time counter for sched_clock source. This implementation
will give high resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9483/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use DEC I/O ASIC's free-running counter for sched_clock source. This
implementation will give high resolution cputime accounting.
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9482/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is to make checkpatch.pl happy for the next patch. It would otherwise
say --

ERROR: Do not include the paragraph about writing to the Free Software
Foundation's mailing address from the sample GPL notice. The FSF has
changed addresses in the past, and may do so again. Linux already includes
a copy of the GPL.
Acked-by: Maciej W. Rozycki <macro@linux-mips.org>
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9481/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use the ZBbus cycle counter for sched_clock source. This implementation
will give high resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9480/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is to make checkpatch.pl happy for the next patch. It would otherwise
say --

ERROR: Do not include the paragraph about writing to the Free Software
Foundation's mailing address from the sample GPL notice. The FSF has
changed addresses in the past, and may do so again. Linux already includes
a copy of the GPL.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9479/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Use c0 count register for sched_clock source. This implementation will give
high resolution cputime accounting.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9478/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This will provide sched_clock interface to implement individual
read_sched_clock(). Not for CAVIUM_OCTEON_SOC as it defines its own
sched_clock() directly (not using the sched_clock_register interface).
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9477/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

GENERIC_SCHED_CLOCK can be selected by architectures other than ARM. The
current dependencies of CLKSRC_VERSATILE make it possible that other
architectures will have CLKSRC_VERSATILE available in configuration once
they select GENERIC_SCHED_CLOCK, whereas this clock source should be solely
available to ARM in reality.

This patch adds one more dependency to CLKSRC_VERSATILE to fix the issue.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Reported-by: Maciej W. Rozycki <macro@linux-mips.org>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: LKML <linux-kernel@vger.kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9476/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

With the correct cmpxchg64 on 32-bit platforms, we can now add the config
HAVE_VIRT_CPU_ACCOUNTING_GEN into arch/mips/Kconfig.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9475/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

This is in preparation of adding HAVE_VIRT_CPU_ACCOUNTING_GEN support in
the next patch.

Without having cmpxchg64 to use the generic implementation, kernel linking
will complain:

kernel/built-in.o: In function `cputime_adjust':
cputime.c:(.text+0x33748): undefined reference to `__cmpxchg_called_with_bad_pointer'
cputime.c:(.text+0x33810): undefined reference to `__cmpxchg_called_with_bad_pointer'
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9474/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

We have HIGH_RES_TIMERS to support SCHED_HRTICK. But SCHED_HRTICK is in
kernel/Kconfig.hz where HZ values unsuitable for MIPS are defined. So we
simply add this config in arch/mips/Kconfig as opposed to including the
whole kernel/Kconfig.hz.
Signed-off-by: Deng-Cheng Zhu <dengcheng.zhu@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: macro@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9473/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Now it is supported, so let people select it.

[ralf@linux-mips.org: Folded in fix for bogus CONFIG_ kconfig symbol
prefix.  Issue reported by Valentin Rothberg <valentinrothberg@gmail.com>.]
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Leonid Rosenboim <lrosenboim@caviumnetworks.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9592/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Needed for little-endian ioport access.
This fixes NOR flash in little-endian mode
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9591/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Compensate for the differences in the layout of in-memory bootloader
information as seen from little-endian mode.
Signed-off-by: David Daney <david.daney@cavium.com>
Signed-off-by: Aleksey Makarov <aleksey.makarov@auriga.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9590/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Start the GIC counter before we try to determine its frequency.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9596/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Start the GIC counter after configuring the clocksource since there
are no guarantees the counter will be running after a CPU reset.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9595/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

We add new functions to start and stop the GIC counter since there are no
guarantees the counter will be running after a CPU reset. The GIC counter
is stopped by setting the 29th bit on the GIC Config register and it is
started by clearing that bit.
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Qais Yousef <qais.yousef@imgtec.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/9594/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Implement KGDB IO operations for MIPS Fast Debug Channel (FDC). This can
be enabled via Kconfig, which also allows the channel number to be
chosen.

The magic sysrq hack is implemented in the TTY driver, detecting just ^C
for the KGDB channel, and ^O followed by a letter for the FDC console
channel.

The KGDB operations are reasonably efficient thanks to the flush
callback, with a 4 byte buffer being used in both directions to allow up
to 4 bytes to be encoded per FDC word. Reading of data for KGDB will
discard any data received on other channels, which clearly isn't ideal,
but given that there is a single FIFO shared between channels we can't
do much better.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: linux-mips@linux-mips.org
Cc: kgdb-bugreport@lists.sourceforge.net
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9147/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Add support for early console of MIPS Fast Debug Channel (FDC) on
channel 1 with a call very early from the MIPS setup_arch().
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9145/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Add TTY driver and consoles for the MIPS EJTAG Fast Debug Channel (FDC),
which is found on the per-CPU MIPS Common Device Mapped Memory (CDMM)
bus.

The FDC is a per-CPU device which is used to communicate with an EJTAG
probe. RX and TX FIFOs exist, containing 32-bits of data and 4-bit
channel numbers. 16 general data streams are implemented on this for TTY
and console use by encoding up to 4 bytes on each 32-bit FDC word.

The TTY devices are named e.g. /dev/ttyFDC3c2 for channel 2 of the FDC
attached to logical CPU 3.

These can be used for getting the kernel log, a login prompt, or as a
GDB remote transport, all over EJTAG and without needing a serial port.

It can have an interrupt to notify of when incoming data is available in
the RX FIFO or when the TX FIFO is no longer full. The detection of this
interrupt occurs in architecture / platform code, but it may be shared
with the timer and/or performance counter interrupt.

Due to the per-CPU nature of the hardware, all outgoing TTY data is
written out from a kthread which is pinned to the appropriate CPU.

The console is not bound to a specific CPU, so output will appear on the
chosen channel on whichever CPU the code is executing on. Enable with
e.g. console=fdc1 in kernel arguments. /dev/console is bound to the same
channel on the boot CPU's FDC if it exists.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9146/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

On certain cores (namely proAptiv and P5600) incoming data via a Fast
Debug Channel (FDC) while the core is blocked on a wait instruction will
cause the wait not to wake up even when another interrupt is received.
This makes an idle target stop as soon as you send FDC data to it, until
the debug probe interrupts it and restarts the wait instruction.

This is worked around by avoiding using r4k_wait on these cores if
CONFIG_MIPS_EJTAG_FDC_TTY is enabled (which would imply the user intends
to use the FDC).

[ralf@linux-mips.org: Fix conflict.]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9144/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Implement the weak get_c0_fdc_int() function for Malta. The Fast Debug
Channel (FDC) interrupt is obtained mainly depending on whether a GIC is
present. Vectored external interrupt mode isn't yet supported.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9143/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

Add a function to the MIPS GIC driver for retrieving the Fast Debug
Channel (FDC) interrupt number, similar to the existing ones for the
timer and perf counter interrupts. This will be used by platform
implementations of get_c0_fdc_int() if a GIC is present.

A workaround exists for interAptiv and proAptiv which claim to be able
to route the FDC interrupt but don't seem to be able to in practice (at
least on Malta).

[ralf@linux-mips.org: Fix conflict.]
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/9142/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>