On R-Car Gen2 and RZ/G1 platforms, we use the SBAR registers to make non boot CPUs run a routine designed to bring up SMP and deal with hot plug. The value contained in the SBAR registers is not initialized by a WDT triggered reset, which means that after a WDT triggered reset we jump to the SMP bring up routine, preventing the system from executing the bootrom code.
The purpose of this patch is to jump to the bootrom code in case of a WDT triggered reset, and keep the SMP functionality untouched. In order to tell if the code had been called due to the WDT overflowing we need to inspect flag WOVF from register RWTCSRA, however for this to work smoothly we need to make sure that RWDT clock is ON. Since it's not wise to interfere with the clock configuration from within this routine, a flag has been put in place (shmobile_wdt_clock_status) so that the watchdog driver can tell shmobile_boot_vector_gen2 when the clock is ON, and therefore there is no need for shmobile_boot_vector to mess up with the clock registers. Bit WOVF survives a watchdog triggered reset, and it is usually cleared by the bootloader. Checking the MMU enable bit from register SCTLR allows us to make the code a little bit more robust (just in case the bit wasn't cleared up), as right after a reset the MMU is disabled, and when Linux is running the MMU is enabled. Also, accessing RWTCSRA physical address is safe when the MMU is down. New function shmobile_boot_vector_gen2 isn't replacing shmobile_boot_vector for backward compatibility reasons. The kernel will install the best option (either shmobile_boot_vector or shmobile_boot_vector_gen2) to ICRAM1 after parsing the device tree. SMP bringup, CPU hot plug, and suspend to RAM work as normal. Since shmobile_boot_vector has become bigger, "reg" property of nodes compatible with "renesas,smp-sram" now need to be set to "<0 0x64>". Signed-off-by: Fabrizio Castro <[email protected]> Signed-off-by: Ramesh Shanmugasundaram <[email protected]> --- arch/arm/mach-shmobile/headsmp.S | 74 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 74 insertions(+) diff --git a/arch/arm/mach-shmobile/headsmp.S b/arch/arm/mach-shmobile/headsmp.S index 32e0bf6..4b14d4c 100644 --- a/arch/arm/mach-shmobile/headsmp.S +++ b/arch/arm/mach-shmobile/headsmp.S @@ -16,6 +16,13 @@ #include <asm/assembler.h> #include <asm/memory.h> +#define RWDT_CLOCK_ON 0xdeadbeef +#define RWDT_CLOCK_OFF 0x00000000 +#define SCTLR_MMU 0x01 +#define BOOTROM_ADDRESS 0xE6340000 +#define RWTCSRA_ADDRESS 0xE6020004 +#define RWTCSRA_WOVF 0x10 + /* * Reset vector for secondary CPUs. * This will be mapped at address 0 by SBAR register. @@ -37,6 +44,73 @@ shmobile_boot_fn: shmobile_boot_size: .long . - shmobile_boot_vector +#ifdef CONFIG_ARCH_RCAR_GEN2 +/* + * Reset vector for R-Car Gen2 and RZ/G1 secondary CPUs. + * This will be mapped at address 0 by SBAR register. + */ +ENTRY(shmobile_boot_vector_gen2) +/* + if (SCTLR_MMU == 1) + goto shmobile_smp_continue_gen2; +*/ + mrc p15, 0, r1, c1, c0, 0 @ r1 = SCTLR + and r0, r1, #SCTLR_MMU + cmp r0, #SCTLR_MMU + beq shmobile_smp_continue_gen2 + +/* + if (shmobile_wdt_clock_status != RWDT_CLOCK_ON) + goto shmobile_smp_continue_gen2; +*/ + ldr r0, #shmobile_wdt_clock_status + ldr r1, #clock_on + cmp r0, r1 + bne shmobile_smp_continue_gen2 + +/* + if (RWTCSRA_WOVF == 0) + goto shmobile_smp_continue_gen2; +*/ + ldr r0, rwtcsra + mov r1, #0 + ldrb r1, [r0] + and r0, r1, #RWTCSRA_WOVF + cmp r0, #RWTCSRA_WOVF + bne shmobile_smp_continue_gen2 + +/* + goto bootrom; +*/ + ldr r0, bootrom + bx r0 + +shmobile_smp_continue_gen2: + ldr r1, shmobile_boot_fn_gen2 + bx r1 + +ENDPROC(shmobile_boot_vector_gen2) + + .align 4 +rwtcsra: + .word RWTCSRA_ADDRESS +bootrom: + .word BOOTROM_ADDRESS +clock_on: + .word RWDT_CLOCK_ON + .globl shmobile_wdt_clock_status +shmobile_wdt_clock_status: + .word RWDT_CLOCK_OFF + + .align 2 + .globl shmobile_boot_fn_gen2 +shmobile_boot_fn_gen2: + .space 4 + .globl shmobile_boot_size_gen2 +shmobile_boot_size_gen2: + .long . - shmobile_boot_vector_gen2 +#endif /* CONFIG_ARCH_RCAR_GEN2 */ + /* * Per-CPU SMP boot function/argument selection code based on MPIDR */ -- 2.7.4
