Dear All, this series has been around for some time as RFC, and it has collected useful comments from the community along the way. The solution proposed by this patch set works for most R-Car Gen2 and RZ/G1 devices, but not all of them. We now know that for some R-Car Gen2 early revisions there is no proper software fix. Anyway, no product has been built around early revisions, but development boards mounting early revisions (basically prototypes) are still out there. As a result, this series isn't enabling the internal watchdog on R-Car Gen2 boards, developers may enable it in board specific device trees if needed. This series has been tested by me on the iwg20d, iwg22d, Lager, Alt, and Koelsch boards. The problem =========== 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. The fix ======= 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. Thank you All for your help. Best regards, Fabrizio Castro (26): 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 ARM: shmobile: rcar-gen2: Add watchdog support dt-bindings: watchdog: renesas-wdt: Add R-Car Gen2 support watchdog: renesas_wdt: Add R-Car Gen2 support watchdog: renesas_wdt: Add restart handler 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 | 19 ++++++-- 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 | 15 ++++-- 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 | 39 +++++++++++++-- 22 files changed, 229 insertions(+), 26 deletions(-) -- 2.7.4
