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.

Signed-off-by: Alexey Brodkin <[email protected]>
Cc: Vineet Gupta <[email protected]>

diff --git a/arch/arc/lib/bootm.c b/arch/arc/lib/bootm.c
index d185a50bd318938a130cf5bd97721d4e80944f29..04d9d9cce574cf0c98306f959bf1fedfb730a699 100644 (file)
--- 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 8c16410944d4714f6ffdfb8dc5b1e2eca3c5c026..d4280f743ad0b46e4da1bf16e54930c4cceb9f89 100644 (file)
--- 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