RFC MIPS: Lexra LX5280 CPU + Realtek RTL8186 SoC support

Hi,

Changelog:

v2:
- Patch 5 in v1 added irqchip, timer and arch code for the SoC all in one patch. Split this patch into 3 patches:
- Patch 3 for irqchip (depends on MACH_RTL8186 in Kconfig)
- Patch 5 for timer (depends on MACH_RTL8186 in Kconfig)
- Patch 7 for SoC code in arch/mips (adds MACH_RTL8186 in mips and selects irqchip+timer drivers)
Also, reorder the patches in a way that each DT binding patch comes before
the respective driver patch.

- No code changes from v1

------

This RFC patch series adds all the necessary code to successfully boot Linux on the Realtek RTL8186 SoC.

Boot log with the v1 series applied (+one DT patch that adds partitions) is available here:
https://gist.github.com/yashac3/483decfa8db014edfb055ba5a1f9996e

Network drivers and other misc drivers are not included in this patch set, but are being worked on.

This patch series includes:
- Patch 1: Lexra LX5280 CPU support (MIPS)

- Patch 2: Device tree bindings for the RTL8186 interrupt controller
- Patch 3: RTL8186 interrupt controller driver

- Patch 4: Device tree bindings for the RTL8186 timer
- Patch 5: RTL8186 timer driver

- Patch 6: Device tree bindings for Realtek MIPS SoCs
- Patch 7: RTL8186 SoC support (MIPS, device tree)

What's still missing:
1) Upstream toolchain support for the Lexra LX5280 CPU. (Still WIP) GCC and binutils patches are available at [1][2]. Buildroot with these patches applied is available at [3].

The toolchain work is still WIP and I'm planning to send it for review when it will be ready.

Still, feel free to comment on this work too.

2) Reading the TLB size from device tree:
(The reason there's no DT bindings for the LX5280 in this series)

As there's no way to get the TLB size from the hardware, is must be passed in the DT.

Currently in arch/mips, the FDT is not available in the cpu_probe() stage, where the 'tlbsize' field of the cpu data is set.

Any ideas/suggestions on how to solve that?

This patch series is on top of v4.18 + 5 prerequisite patches that are in mips-next for 4.20. [4][5].

This patch series is also available at:
https://github.com/yashac3/linux-rtl8186/commits/rtl8186-porting-for-upstream-4.18-v2

Please review.

Thanks,
Yasha

[1] https://github.com/yashac3/gcc/commits/lx5280-gcc-8_2_0
[2] https://github.com/yashac3/binutils-gdb/commits/lx5280-porting-master
[3] https://github.com/yashac3/buildroot/commits/lx5280_master
[4] https://www.linux-mips.org/archives/linux-mips/2018-09/msg00769.html
[5] https://www.linux-mips.org/archives/linux-mips/2018-09/msg00775.html

Yasha Cherikovsky (7):
MIPS: Add support for the Lexra LX5280 CPU
dt-binding: interrupt-controller: Document RTL8186 SoC DT bindings irqchip/rtl8186: Add RTL8186 interrupt controller driver
dt-binding: timer: Document RTL8186 SoC DT bindings clocksource/drivers/rtl8186: Add RTL8186 timer driver
dt-binding: mips: Document Realtek SoC DT bindings
MIPS: Add Realtek RTL8186 SoC support

 .../interrupt-controller/realtek,rtl8186-intc |  18 ++
 .../devicetree/bindings/mips/realtek.txt      |   9 +
 .../bindings/timer/realtek,rtl8186-timer.txt  |  17 ++
 arch/mips/Kbuild.platforms                    |   1 +
 arch/mips/Kconfig                             |  47 +++-
 arch/mips/Makefile                            |   1 +
 arch/mips/boot/compressed/uart-16550.c        |   5 +
 arch/mips/boot/dts/Makefile                   |   1 +
 arch/mips/boot/dts/realtek/Makefile           |   4 +
 arch/mips/boot/dts/realtek/rtl8186.dtsi       |  86 ++++++
 .../dts/realtek/rtl8186_edimax_br_6204wg.dts  |  45 ++++
 arch/mips/configs/rtl8186_defconfig           | 112 ++++++++
 arch/mips/include/asm/cpu-features.h          |   3 +
 arch/mips/include/asm/cpu-type.h              |   4 +
 arch/mips/include/asm/cpu.h                   |   9 +
 arch/mips/include/asm/isadep.h                |   3 +-
 arch/mips/include/asm/mach-rtl8186/rtl8186.h  |  37 +++
 arch/mips/include/asm/mipsregs.h              |  10 +
 arch/mips/include/asm/module.h                |   2 +
 arch/mips/include/asm/pgtable-32.h            |   7 +-
 arch/mips/include/asm/pgtable-bits.h          |   9 +-
 arch/mips/include/asm/pgtable.h               |   6 +-
 arch/mips/include/asm/stackframe.h            |   9 +-
 arch/mips/include/asm/traps.h                 |   2 +
 arch/mips/kernel/Makefile                     |   2 +
 arch/mips/kernel/cpu-probe.c                  |   6 +
 arch/mips/kernel/entry.S                      |   3 +-
 arch/mips/kernel/genex.S                      |   6 +-
 arch/mips/kernel/idle.c                       |  10 +
 arch/mips/kernel/process.c                    |   3 +-
 arch/mips/kernel/traps.c                      |  42 +++
 arch/mips/lib/Makefile                        |   1 +
 arch/mips/mm/Makefile                         |   1 +
 arch/mips/mm/c-lx5280.c                       | 251 ++++++++++++++++++
 arch/mips/mm/cache.c                          |   6 +
 arch/mips/mm/fault.c                          |   4 +
 arch/mips/mm/tlbex.c                          |   1 +
 arch/mips/rtl8186/Makefile                    |   2 +
 arch/mips/rtl8186/Platform                    |   7 +
 arch/mips/rtl8186/irq.c                       |   8 +
 arch/mips/rtl8186/prom.c                      |  15 ++
 arch/mips/rtl8186/setup.c                     |  80 ++++++
 arch/mips/rtl8186/time.c                      |  10 +
 drivers/clocksource/Kconfig                   |   9 +
 drivers/clocksource/Makefile                  |   1 +
 drivers/clocksource/timer-rtl8186.c           | 220 +++++++++++++++
 drivers/irqchip/Kconfig                       |   5 +
 drivers/irqchip/Makefile                      |   1 +
 drivers/irqchip/irq-rtl8186.c                 | 107 ++++++++
 49 files changed, 1225 insertions(+), 23 deletions(-)
 create mode 100644 Documentation/devicetree/bindings/interrupt-controller/realtek,rtl8186-intc
 create mode 100644 Documentation/devicetree/bindings/mips/realtek.txt
 create mode 100644 Documentation/devicetree/bindings/timer/realtek,rtl8186-timer.txt
 create mode 100644 arch/mips/boot/dts/realtek/Makefile
 create mode 100644 arch/mips/boot/dts/realtek/rtl8186.dtsi
 create mode 100644 arch/mips/boot/dts/realtek/rtl8186_edimax_br_6204wg.dts
 create mode 100644 arch/mips/configs/rtl8186_defconfig
 create mode 100644 arch/mips/include/asm/mach-rtl8186/rtl8186.h
 create mode 100644 arch/mips/mm/c-lx5280.c
 create mode 100644 arch/mips/rtl8186/Makefile
 create mode 100644 arch/mips/rtl8186/Platform
 create mode 100644 arch/mips/rtl8186/irq.c
 create mode 100644 arch/mips/rtl8186/prom.c
 create mode 100644 arch/mips/rtl8186/setup.c
 create mode 100644 arch/mips/rtl8186/time.c
 create mode 100644 drivers/clocksource/timer-rtl8186.c
 create mode 100644 drivers/irqchip/irq-rtl8186.c

2.19.0