arc: implement slave cores kick-start for Linux kernel
PATCH 1/1 arc: implement slave cores kick-start for Linux kernel
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.
--- arch/arc/lib/bootm.c | 6 ++++++ board/synopsys/axs101/axs101.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+)
arch/arc/lib/bootm.c +6 -0
@@ -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); }
board/synopsys/axs101/axs101.c +30 -0
@@ -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
Signature · 1 line
2.4.3
Alexey Brodkin
AppliedPATCH 1/1 arc: implement slave cores kick-start for Linux kernel
Quoted 23 lines · Alexey Brodkin
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 coresIn 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.
Quoted 6 lines
Signed-off-by Alexey Brodkin <[email protected]>Cc Vineet Gupta <[email protected]>--- arch/arc/lib/bootm.c | 6 ++++++ board/synopsys/axs101/axs101.c | 30 ++++++++++++++++++++++++++++++ 2 files changed, 36 insertions(+)
Applied, thanks.
-Alexey