Commit 5c399f6e authored by Paul Burton's avatar Paul Burton
Browse files

MIPS: smp-cps: prevent multi-core SMP with unsuitable CCA 



If the user or bootloader sets the CCA to a value which is not suited
for multi-core SMP (ie. anything non-coherent) then limit the system to
using only a single core and warn the user.

Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
parent 1d8f1f5a

arch/mips/kernel/smp-cps.c

+28 −2
Original line number Diff line number Diff line
@@ -88,11 +88,38 @@ static void __init cps_smp_setup(void) 


static void __init cps_prepare_cpus(unsigned int max_cpus)

{

	unsigned ncores, core_vpes, c;

	unsigned ncores, core_vpes, c, cca;

	bool cca_unsuitable;

	u32 *entry_code;



	mips_mt_set_cpuoptions();



	/* Detect whether the CCA is unsuited to multi-core SMP */

	cca = read_c0_config() & CONF_CM_CMASK;

	switch (cca) {

	case 0x4: /* CWBE */

	case 0x5: /* CWB */

		/* The CCA is coherent, multi-core is fine */

		cca_unsuitable = false;

		break;



	default:

		/* CCA is not coherent, multi-core is not usable */

		cca_unsuitable = true;

	}



	/* Warn the user if the CCA prevents multi-core */

	ncores = mips_cm_numcores();

	if (cca_unsuitable && ncores > 1) {

		pr_warn("Using only one core due to unsuitable CCA 0x%x\n",

			cca);



		for_each_present_cpu(c) {

			if (cpu_data[c].core)

				set_cpu_present(c, false);

		}

	}



	/* Patch the start of mips_cps_core_entry to provide the CM base */

	entry_code = (u32 *)&mips_cps_core_entry;

	UASM_i_LA(&entry_code, 3, (long)mips_cm_base);
@@ -100,7 +127,6 @@ static void __init cps_prepare_cpus(unsigned int max_cpus) 
			    (void *)entry_code - (void *)&mips_cps_core_entry);



	/* Allocate core boot configuration structs */

	ncores = mips_cm_numcores();

	mips_cps_core_bootcfg = kcalloc(ncores, sizeof(*mips_cps_core_bootcfg),

					GFP_KERNEL);

	if (!mips_cps_core_bootcfg) {