Re: [PATCH 2/3] MIPS: OCTEON: support disabling HOTPLUG_CPU run-time

[David Daney <ddaney.cavm@gmail.com>]

On 06/16/2014 01:06 PM, Aaro Koskinen wrote:
> If nosmp kernel option given, we can assume HOTPLUG_CPU is disabled.
> This is needed in order to be able to run the same kernel binary on
> single core OCTEONs with older/incompatible bootloaders.
>
> Signed-off-by: Aaro Koskinen <aaro.koskinen@iki.fi>
> Cc: linux-watchdog@vger.kernel.org
> ---
>   arch/mips/cavium-octeon/smp.c      |  5 ++-
>   drivers/watchdog/octeon-wdt-main.c | 62 +++++++++++++++++++++-----------------
>   2 files changed, 38 insertions(+), 29 deletions(-)
>

The changes to these two files are almost unrelated, they really need to 
be in separate patches.



> diff --git a/arch/mips/cavium-octeon/smp.c b/arch/mips/cavium-octeon/smp.c
> index 2c8d156..ea96930 100644
> --- a/arch/mips/cavium-octeon/smp.c
> +++ b/arch/mips/cavium-octeon/smp.c
> @@ -84,6 +84,9 @@ static void octeon_smp_hotplug_setup(void)
>   #ifdef CONFIG_HOTPLUG_CPU
>   	struct linux_app_boot_info *labi;
>
> +	if (!setup_max_cpus)
> +		return;
> +
>   	labi = (struct linux_app_boot_info *)PHYS_TO_XKSEG_CACHED(LABI_ADDR_IN_BOOTLOADER);
>   	if (labi->labi_signature != LABI_SIGNATURE)
>   		panic("The bootloader version on this board is incorrect.");
> @@ -129,7 +132,7 @@ static void octeon_smp_setup(void)
>   	 * will assign CPU numbers for possible cores as well.	Cores
>   	 * are always consecutively numberd from 0.
>   	 */
> -	for (id = 0; id < num_cores && id < NR_CPUS; id++) {
> +	for (id = 0; setup_max_cpus && id < num_cores && id < NR_CPUS; id++) {
>   		if (!(core_mask & (1 << id))) {
>   			set_cpu_possible(cpus, true);
>   			__cpu_number_map[id] = cpus;


This arch/mips/cavium-octeon/smp.c part seems plausible, so for it only 
you can add ...

Acked-by: David Daney <david.daney@cavium.com>


> diff --git a/drivers/watchdog/octeon-wdt-main.c b/drivers/watchdog/octeon-wdt-main.c
> index 4baf2d7..c5aee12 100644
> --- a/drivers/watchdog/octeon-wdt-main.c
> +++ b/drivers/watchdog/octeon-wdt-main.c
> @@ -145,35 +145,39 @@ static void __init octeon_wdt_build_stage1(void)
>
>   	uasm_i_mfc0(&p, K0, C0_STATUS);
>   #ifdef CONFIG_HOTPLUG_CPU
> -	uasm_il_bbit0(&p, &r, K0, ilog2(ST0_NMI), label_enter_bootloader);
> +	if (setup_max_cpus)


This bit has nothing to do with setup_max_cpus, but rather if 
hot-plugging CPUs is possible.

There should be a separate variable to indicate if hot-plugging CPUs is 
possible which would be used here instead.

See my comments in patch 3/3 also.

> +		uasm_il_bbit0(&p, &r, K0, ilog2(ST0_NMI),
> +			      label_enter_bootloader);
>   #endif
>   	/* Force 64-bit addressing enabled */
>   	uasm_i_ori(&p, K0, K0, ST0_UX | ST0_SX | ST0_KX);
>   	uasm_i_mtc0(&p, K0, C0_STATUS);
>
>   #ifdef CONFIG_HOTPLUG_CPU
> -	uasm_i_mfc0(&p, K0, C0_EBASE);
> -	/* Coreid number in K0 */
> -	uasm_i_andi(&p, K0, K0, 0xf);
> -	/* 8 * coreid in bits 16-31 */
> -	uasm_i_dsll_safe(&p, K0, K0, 3 + 16);
> -	uasm_i_ori(&p, K0, K0, 0x8001);
> -	uasm_i_dsll_safe(&p, K0, K0, 16);
> -	uasm_i_ori(&p, K0, K0, 0x0700);
> -	uasm_i_drotr_safe(&p, K0, K0, 32);
> -	/*
> -	 * Should result in: 0x8001,0700,0000,8*coreid which is
> -	 * CVMX_CIU_WDOGX(coreid) - 0x0500
> -	 *
> -	 * Now ld K0, CVMX_CIU_WDOGX(coreid)
> -	 */
> -	uasm_i_ld(&p, K0, 0x500, K0);
> -	/*
> -	 * If bit one set handle the NMI as a watchdog event.
> -	 * otherwise transfer control to bootloader.
> -	 */
> -	uasm_il_bbit0(&p, &r, K0, 1, label_enter_bootloader);
> -	uasm_i_nop(&p);
> +	if (setup_max_cpus) {
> +		uasm_i_mfc0(&p, K0, C0_EBASE);
> +		/* Coreid number in K0 */
> +		uasm_i_andi(&p, K0, K0, 0xf);
> +		/* 8 * coreid in bits 16-31 */
> +		uasm_i_dsll_safe(&p, K0, K0, 3 + 16);
> +		uasm_i_ori(&p, K0, K0, 0x8001);
> +		uasm_i_dsll_safe(&p, K0, K0, 16);
> +		uasm_i_ori(&p, K0, K0, 0x0700);
> +		uasm_i_drotr_safe(&p, K0, K0, 32);
> +		/*
> +		 * Should result in: 0x8001,0700,0000,8*coreid which is
> +		 * CVMX_CIU_WDOGX(coreid) - 0x0500
> +		 *
> +		 * Now ld K0, CVMX_CIU_WDOGX(coreid)
> +		 */
> +		uasm_i_ld(&p, K0, 0x500, K0);
> +		/*
> +		 * If bit one set handle the NMI as a watchdog event.
> +		 * otherwise transfer control to bootloader.
> +		 */
> +		uasm_il_bbit0(&p, &r, K0, 1, label_enter_bootloader);
> +		uasm_i_nop(&p);
> +	}
>   #endif
>
>   	/* Clear Dcache so cvmseg works right. */
> @@ -194,11 +198,13 @@ static void __init octeon_wdt_build_stage1(void)
>   	uasm_i_dmfc0(&p, K0, C0_DESAVE);
>
>   #ifdef CONFIG_HOTPLUG_CPU
> -	uasm_build_label(&l, p, label_enter_bootloader);
> -	/* Jump to the bootloader and restore K0 */
> -	UASM_i_LA(&p, K0, (long)octeon_bootloader_entry_addr);
> -	uasm_i_jr(&p, K0);
> -	uasm_i_dmfc0(&p, K0, C0_DESAVE);
> +	if (setup_max_cpus) {
> +		uasm_build_label(&l, p, label_enter_bootloader);
> +		/* Jump to the bootloader and restore K0 */
> +		UASM_i_LA(&p, K0, (long)octeon_bootloader_entry_addr);
> +		uasm_i_jr(&p, K0);
> +		uasm_i_dmfc0(&p, K0, C0_DESAVE);
> +	}
>   #endif
>   	uasm_resolve_relocs(relocs, labels);
>
>