Commit 1ec9dd80 authored by Paul Burton's avatar Paul Burton Committed by Ralf Baechle
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MIPS: CPS: Detect CPUs in secondary clusters 



As a first step towards supporting multi-cluster systems, detect cores &
VPs in secondary clusters & record their cluster information in the
cpu_data array. The "VP topology" line printed during boot is extended
to display multiple clusters. On a single cluster it shows output like
the following:

  VP topology: {4,4}

This would indicate a system with 2 cores which each contain 4 VPs. We
extend this to cover multiple clusters in a natural way:

  VP topology: {4,4},{2,2}

This would indicate a system with 2 clusters. The first cluster contains
2 cores which each contain 4 VPs. The second cluster contains 2 cores
which each contain 2 VPs.

Actually booting these cores & VPs is left to further patches once other
pieces are in place.

Signed-off-by: default avatarPaul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/17017/


Signed-off-by: default avatarRalf Baechle <ralf@linux-mips.org>
parent 3c9b4166

arch/mips/kernel/smp-cps.c

+51 −29
Original line number Diff line number Diff line
@@ -40,44 +40,58 @@ static int __init setup_nothreads(char *s) 
}

early_param("nothreads", setup_nothreads);



static unsigned core_vpe_count(unsigned core)

static unsigned core_vpe_count(unsigned int cluster, unsigned core)

{

	if (threads_disabled)

		return 1;



	return mips_cps_numvps(0, core);

	return mips_cps_numvps(cluster, core);

}



static void __init cps_smp_setup(void)

{

	unsigned int ncores, nvpes, core_vpes;

	unsigned int nclusters, ncores, nvpes, core_vpes;

	unsigned long core_entry;

	int c, v;

	int cl, c, v;



	/* Detect & record VPE topology */

	ncores = mips_cps_numcores(0);

	nvpes = 0;

	nclusters = mips_cps_numclusters();

	pr_info("%s topology ", cpu_has_mips_r6 ? "VP" : "VPE");

	for (c = nvpes = 0; c < ncores; c++) {

		core_vpes = core_vpe_count(c);

		pr_cont("%c%u", c ? ',' : '{', core_vpes);

	for (cl = 0; cl < nclusters; cl++) {

		if (cl > 0)

			pr_cont(",");

		pr_cont("{");



		ncores = mips_cps_numcores(cl);

		for (c = 0; c < ncores; c++) {

			core_vpes = core_vpe_count(cl, c);



		/* Use the number of VPEs in core 0 for smp_num_siblings */

		if (!c)

			if (c > 0)

				pr_cont(",");

			pr_cont("%u", core_vpes);



			/* Use the number of VPEs in cluster 0 core 0 for smp_num_siblings */

			if (!cl && !c)

				smp_num_siblings = core_vpes;



			for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {

				cpu_set_cluster(&cpu_data[nvpes + v], cl);

				cpu_set_core(&cpu_data[nvpes + v], c);

				cpu_set_vpe_id(&cpu_data[nvpes + v], v);

			}



			nvpes += core_vpes;

		}

	pr_cont("} total %u\n", nvpes);



		pr_cont("}");

	}

	pr_cont(" total %u\n", nvpes);



	/* Indicate present CPUs (CPU being synonymous with VPE) */

	for (v = 0; v < min_t(unsigned, nvpes, NR_CPUS); v++) {

		set_cpu_possible(v, true);

		set_cpu_present(v, true);

		set_cpu_possible(v, cpu_cluster(&cpu_data[v]) == 0);

		set_cpu_present(v, cpu_cluster(&cpu_data[v]) == 0);

		__cpu_number_map[v] = v;

		__cpu_logical_map[v] = v;

	}
@@ -109,7 +123,7 @@ static void __init cps_smp_setup(void) 
static void __init cps_prepare_cpus(unsigned int max_cpus)

{

	unsigned ncores, core_vpes, c, cca;

	bool cca_unsuitable;

	bool cca_unsuitable, cores_limited;

	u32 *entry_code;



	mips_mt_set_cpuoptions();
@@ -129,18 +143,21 @@ static void __init cps_prepare_cpus(unsigned int max_cpus) 
	}



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

	ncores = mips_cps_numcores(0);

	if ((cca_unsuitable || cpu_has_dc_aliases) && ncores > 1) {

		pr_warn("Using only one core due to %s%s%s\n",

			cca_unsuitable ? "unsuitable CCA" : "",

			(cca_unsuitable && cpu_has_dc_aliases) ? " & " : "",

			cpu_has_dc_aliases ? "dcache aliasing" : "");



	cores_limited = false;

	if (cca_unsuitable || cpu_has_dc_aliases) {

		for_each_present_cpu(c) {

			if (!cpus_are_siblings(smp_processor_id(), c))

			if (cpus_are_siblings(smp_processor_id(), c))

				continue;



			set_cpu_present(c, false);

			cores_limited = true;

		}

	}

	if (cores_limited)

		pr_warn("Using only one core due to %s%s%s\n",

			cca_unsuitable ? "unsuitable CCA" : "",

			(cca_unsuitable && cpu_has_dc_aliases) ? " & " : "",

			cpu_has_dc_aliases ? "dcache aliasing" : "");



	/*

	 * Patch the start of mips_cps_core_entry to provide:
@@ -156,6 +173,7 @@ static void __init cps_prepare_cpus(unsigned int max_cpus) 
	__sync();



	/* Allocate core boot configuration structs */

	ncores = mips_cps_numcores(0);

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

					GFP_KERNEL);

	if (!mips_cps_core_bootcfg) {
@@ -165,7 +183,7 @@ static void __init cps_prepare_cpus(unsigned int max_cpus) 


	/* Allocate VPE boot configuration structs */

	for (c = 0; c < ncores; c++) {

		core_vpes = core_vpe_count(c);

		core_vpes = core_vpe_count(0, c);

		mips_cps_core_bootcfg[c].vpe_config = kcalloc(core_vpes,

				sizeof(*mips_cps_core_bootcfg[c].vpe_config),

				GFP_KERNEL);
@@ -288,6 +306,10 @@ static int cps_boot_secondary(int cpu, struct task_struct *idle) 
	unsigned int remote;

	int err;



	/* We don't yet support booting CPUs in other clusters */

	if (cpu_cluster(&cpu_data[cpu]) != cpu_cluster(&current_cpu_data))

		return -ENOSYS;



	vpe_cfg->pc = (unsigned long)&smp_bootstrap;

	vpe_cfg->sp = __KSTK_TOS(idle);

	vpe_cfg->gp = (unsigned long)task_thread_info(idle);

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