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

diff --git a/arch/mips/kernel/smp-cps.c b/arch/mips/kernel/smp-cps.c
index 4b9dcca..0d9cda6 100644 (file)
--- a/arch/mips/kernel/smp-cps.c
+++ b/arch/mips/kernel/smp-cps.c
@@ -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);
-
-               /* Use the number of VPEs in core 0 for smp_num_siblings */
-               if (!c)
-                       smp_num_siblings = 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);
+
+                       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);
+                       }
 
-               for (v = 0; v < min_t(int, core_vpes, NR_CPUS - nvpes); v++) {
-                       cpu_set_core(&cpu_data[nvpes + v], c);
-                       cpu_set_vpe_id(&cpu_data[nvpes + v], v);
+                       nvpes += core_vpes;
                }
 
-               nvpes += core_vpes;
+               pr_cont("}");
        }
-       pr_cont("} total %u\n", nvpes);
+       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();
@@ -129,19 +143,22 @@ 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) {
+       cores_limited = false;
+       if (cca_unsuitable || cpu_has_dc_aliases) {
+               for_each_present_cpu(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" : "");
 
-               for_each_present_cpu(c) {
-                       if (!cpus_are_siblings(smp_processor_id(), c))
-                               set_cpu_present(c, false);
-               }
-       }
-
        /*
         * 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);