Dear All, while trying to add watchdog support to RZ/G1M and RZ/G1E I discovered that it couldn't work out of the box. R-Car Gen2 and RZ/G1 are very similar from a design perspective, and therefore the same problem is observable on R-Car Gen2 too. To deal with SMP on R-Car Gen2 and RZ/G1, we install a reset vector to ICRAM1 and we program the [S]BAR registers so that when we turn ON the non-boot CPUs they are redirected to the reset vector installed by Linux in ICRAM1, and eventually they continue the execution to RAM, where the SMP bring-up code will take care of the rest. The content of the [S]BAR registers survives a watchdog triggered reset, and as such after the watchdog fires the boot core will try and execute the SMP bring-up code instead of jumping to the bootrom code. This series is a proposal for a fix to the aforementioned problem. The main strategy for the solution is to let the reset vector decide if it needs to jump to shmobile_boot_fn or to the bootrom code. In a watchdog triggered reset scenario, since the [S]BAR registers keep their values, the boot CPU will jump into the newly designed reset vector, the assembly routine will eventually test WOVF (a bit in register RWTCSRA that indicates if the watchdog counter has overflown, the value of this bit gets retained in this scenario), and jump to the bootrom code which will in turn load up the bootloader, etc. When bringing up SMP or using CPU hotplug, the reset vector will jump to shmobile_boot_fn instead. v3 takes into account all the feedbacks recieved, and implements a different logic in the reset vector in order to get rid of shmobile_wdt_clock_status. This work was rebased on top of tag renesas-devel-20180122-v4.15-rc9 from the below repository: git://git.kernel.org/pub/scm/linux/kernel/git/horms/renesas.git What do you guys think about this? Any volunteer for testing this work? Comments welcome! Best Regards, Fabrizio Castro (25): ARM: shmobile: Add watchdog support ARM: dts: r8a7743: Adjust SMP routine size ARM: dts: r8a7745: Adjust SMP routine size ARM: dts: r8a7790: Adjust SMP routine size ARM: dts: r8a7791: Adjust SMP routine size ARM: dts: r8a7792: Adjust SMP routine size ARM: dts: r8a7793: Adjust SMP routine size ARM: dts: r8a7794: Adjust SMP routine size soc: renesas: rcar-rst: Enable watchdog as reset trigger for Gen2 dt-bindings: watchdog: renesas-wdt: Add R-Car Gen2 support watchdog: renesas_wdt: Add R-Car Gen2 support ARM: shmobile: rcar-gen2: Add watchdog support ARM: shmobile: defconfig: Enable RENESAS_WDT_GEN clk: renesas: r8a7743: Add rwdt clock clk: renesas: r8a7745: Add rwdt clock clk: renesas: r8a7790: Add rwdt clock clk: renesas: r8a7791/r8a7793: Add rwdt clock clk: renesas: r8a7794: Add rwdt clock ARM: dts: r8a7743: Add watchdog support to SoC dtsi ARM: dts: r8a7745: Add watchdog support to SoC dtsi ARM: dts: r8a7790: Add watchdog support to SoC dtsi ARM: dts: r8a7791: Add watchdog support to SoC dtsi ARM: dts: r8a7794: Add watchdog support to SoC dtsi ARM: dts: iwg20m: Add watchdog support to SoM dtsi ARM: dts: iwg22m: Add watchdog support to SoM dtsi .../devicetree/bindings/watchdog/renesas-wdt.txt | 18 +++++-- arch/arm/boot/dts/r8a7743-iwg20m.dtsi | 5 ++ arch/arm/boot/dts/r8a7743.dtsi | 12 ++++- arch/arm/boot/dts/r8a7745-iwg22m.dtsi | 5 ++ arch/arm/boot/dts/r8a7745.dtsi | 12 ++++- arch/arm/boot/dts/r8a7790.dtsi | 12 ++++- arch/arm/boot/dts/r8a7791.dtsi | 12 ++++- arch/arm/boot/dts/r8a7792.dtsi | 2 +- arch/arm/boot/dts/r8a7793.dtsi | 2 +- arch/arm/boot/dts/r8a7794.dtsi | 12 ++++- arch/arm/configs/shmobile_defconfig | 1 + arch/arm/mach-shmobile/common.h | 6 +++ arch/arm/mach-shmobile/headsmp.S | 55 +++++++++++++++++++ arch/arm/mach-shmobile/platsmp-apmu.c | 1 + arch/arm/mach-shmobile/pm-rcar-gen2.c | 13 +++-- drivers/clk/renesas/r8a7743-cpg-mssr.c | 2 + drivers/clk/renesas/r8a7745-cpg-mssr.c | 2 + drivers/clk/renesas/r8a7790-cpg-mssr.c | 2 + drivers/clk/renesas/r8a7791-cpg-mssr.c | 2 + drivers/clk/renesas/r8a7794-cpg-mssr.c | 2 + drivers/soc/renesas/rcar-rst.c | 35 ++++++++++--- drivers/watchdog/renesas_wdt.c | 61 ++++++++++++++++++++-- 22 files changed, 248 insertions(+), 26 deletions(-) -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
