Hi Simon,
On Sat, Apr 25, 2015 at 11:04 PM, Simon Glass <s...@chromium.org> wrote:
> The existing code is pretty ancient and is unreliable on modern hardware.
> Generally it will hang.
>
> We can use port 0xcf9 to initiate reset on more modern hardware (say in the
> last 10 years). Update the reset_cpu() function to do this, and add a new
> 'full reset' function to perform a full power cycle.
>
> Signed-off-by: Simon Glass <s...@chromium.org>
> ---
>
> arch/x86/cpu/cpu.c | 22 +++++++++-------------
> arch/x86/include/asm/processor.h | 11 +++++++++++
> 2 files changed, 20 insertions(+), 13 deletions(-)
>
> diff --git a/arch/x86/cpu/cpu.c b/arch/x86/cpu/cpu.c
> index c9614f1..13b3baa 100644
> --- a/arch/x86/cpu/cpu.c
> +++ b/arch/x86/cpu/cpu.c
> @@ -380,21 +380,17 @@ void flush_cache(unsigned long dummy1, unsigned long
> dummy2)
> asm("wbinvd\n");
> }
>
> -void __attribute__ ((regparm(0))) generate_gpf(void);
> -
> -/* segment 0x70 is an arbitrary segment which does not exist */
> -asm(".globl generate_gpf\n"
> - ".hidden generate_gpf\n"
> - ".type generate_gpf, @function\n"
> - "generate_gpf:\n"
> - "ljmp $0x70, $0x47114711\n");
> -
> __weak void reset_cpu(ulong addr)
> {
> - printf("Resetting using x86 Triple Fault\n");
> - set_vector(13, generate_gpf); /* general protection fault handler */
> - set_vector(8, generate_gpf); /* double fault handler */
> - generate_gpf(); /* start the show */
> + /* Do a hard reset through the chipset's reset control register */
> + outb(SYS_RST | RST_CPU, PORT_RESET);
> + for (;;)
> + cpu_hlt();
> +}
> +
> +void x86_full_reset(void)
> +{
> + outb(FULL_RST, PORT_RESET);
> }
>
> int dcache_status(void)
> diff --git a/arch/x86/include/asm/processor.h
> b/arch/x86/include/asm/processor.h
> index 3e26202..a24028d 100644
> --- a/arch/x86/include/asm/processor.h
> +++ b/arch/x86/include/asm/processor.h
> @@ -27,6 +27,17 @@
>
> #define PORT_RESET 0xcf9
>
> +enum {
> + SYS_RST = 1 << 1, /* clear for soft reset, set for hard
> */
The comment looks confusing. What does 'clear for soft reset' mean?
> + RST_CPU = 1 << 2, /* initiate reset */
CPU_RST? to follow the same convention as SYS_RST and FULL_RST?
> + FULL_RST = 1 << 3, /* full power cycle */
> +};
> +
> +/**
> + * x86_full_reset() - reset everything: perform a full power cycle
> + */
> +void x86_full_reset(void);
> +
> static inline __attribute__((always_inline)) void cpu_hlt(void)
> {
> asm("hlt");
> --
Regards,
Bin
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