With new SMP-enabled CPUs with ARC HS38 cores and corresponding support in Linux kernel it's required to add basic SMP support in U-Boot.
Currently we assume the one and only core starts execution after power-on. So most of things in U-Boot is handled in UP mode.
But when U-Boot is used for loading and starting Linux kernel right before jumping to kernel's entry point U-Boot: [1] Sets all slave cores to jump to the same address [kernel's entry point] [2] Really starts all slav cores
In ARC's implemetation of SMP in Linux kernel all cores are supposed to run the same start-up code. But only core with ID 0 (master core) processes further while others are looping waiting for master core to complete some initialization.
That means it's safe to un-pause slave cores and let them execute kernel - they will wait for master anyway.
Signed-off-by: Alexey Brodkin abrodkin@synopsys.com Cc: Vineet Gupta vgupta@synopsys.com --- arch/arc/lib/bootm.c | 6 ++++++ board/synopsys/axs101/axs101.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+)
diff --git a/arch/arc/lib/bootm.c b/arch/arc/lib/bootm.c index d185a50..04d9d9c 100644 --- a/arch/arc/lib/bootm.c +++ b/arch/arc/lib/bootm.c @@ -53,6 +53,9 @@ static void boot_prep_linux(bootm_headers_t *images) hang(); }
+__weak void smp_set_core_boot_addr(unsigned long addr, int corenr) {} +__weak void smp_kick_all_cpus(void) {} + /* Subcommand: GO */ static void boot_jump_linux(bootm_headers_t *images, int flag) { @@ -80,6 +83,9 @@ static void boot_jump_linux(bootm_headers_t *images, int flag) r2 = (unsigned int)getenv("bootargs"); }
+ smp_set_core_boot_addr((unsigned long)kernel_entry, -1); + smp_kick_all_cpus(); + if (!fake) kernel_entry(r0, 0, r2); } diff --git a/board/synopsys/axs101/axs101.c b/board/synopsys/axs101/axs101.c index 8c16410..d4280f7 100644 --- a/board/synopsys/axs101/axs101.c +++ b/board/synopsys/axs101/axs101.c @@ -56,3 +56,33 @@ int board_early_init_f(void)
return 0; } + +#ifdef CONFIG_ISA_ARCV2 +#define RESET_VECTOR_ADDR 0x0 + +void smp_set_core_boot_addr(unsigned long addr, int corenr) +{ + /* All cores have reset vector pointing to 0 */ + writel(addr, (void __iomem *)RESET_VECTOR_ADDR); + + /* Make sure other cores see written value in memory */ + flush_dcache_range(RESET_VECTOR_ADDR, RESET_VECTOR_ADDR + sizeof(int)); +} + +void smp_kick_all_cpus(void) +{ +/* CPU start CREG */ +#define AXC003_CREG_CPU_START 0xF0001400 + +/* Bits positions in CPU start CREG */ +#define BITS_START 0 +#define BITS_POLARITY 8 +#define BITS_CORE_SEL 9 +#define BITS_MULTICORE 12 + +#define CMD (1 << BITS_MULTICORE) | (1 << BITS_CORE_SEL) | \ + (1 << BITS_POLARITY) | (1 << BITS_START) + + writel(CMD, (void __iomem *)AXC003_CREG_CPU_START); +} +#endif