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arc: implement slave cores kick-start for Linux kernel

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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>
This commit is contained in:
Alexey Brodkin 2015-04-13 13:37:05 +03:00
parent 9c6b05cb72
commit 8b2eb776b1
2 changed files with 36 additions and 0 deletions
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6
arch/arc/lib/bootm.c
View File

@ -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);
}

30
board/synopsys/axs101/axs101.c
View File

@ -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