parisc: Add CPU topology support

Add topology support, including multi-core scheduler support on
PA8800/PA8900 CPUs and enhanced output in /proc/cpuinfo, e.g.
lscpu now reports on a single-socket, dual-core machine:

Architecture:          parisc64
CPU(s):                2
On-line CPU(s) list:   0,1
Thread(s) per core:    1
Core(s) per socket:    2
Socket(s):             1
CPU family:            PA-RISC 2.0
Model name:            PA8800 (Mako)

Signed-off-by: Helge Deller <deller@gmx.de>

6 files changed, 198 insertions, 26 deletions

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 1fd3eb5b66c6..7171c21bb0af 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -32,6 +32,7 @@ config PARISC
         select GENERIC_PCI_IOMAP
         select ARCH_HAVE_NMI_SAFE_CMPXCHG
         select GENERIC_SMP_IDLE_THREAD
+        select GENERIC_CPU_DEVICES
         select GENERIC_STRNCPY_FROM_USER
         select SYSCTL_ARCH_UNALIGN_ALLOW
         select SYSCTL_EXCEPTION_TRACE
@@ -288,6 +289,21 @@ config SMP
 
           If you don't know what to do here, say N.
 
+config PARISC_CPU_TOPOLOGY
+        bool "Support cpu topology definition"
+        depends on SMP
+        default y
+        help
+          Support PARISC cpu topology definition.
+
+config SCHED_MC
+        bool "Multi-core scheduler support"
+        depends on PARISC_CPU_TOPOLOGY && PA8X00
+        help
+          Multi-core scheduler support improves the CPU scheduler's decision
+          making when dealing with multi-core CPU chips at a cost of slightly
+          increased overhead in some places. If unsure say N here.
+
 config IRQSTACKS
         bool "Use separate kernel stacks when processing interrupts"
         default y
diff --git a/arch/parisc/include/asm/topology.h b/arch/parisc/include/asm/topology.h
new file mode 100644
index 000000000000..6f0750c74e47
--- /dev/null
+++ b/arch/parisc/include/asm/topology.h
@@ -0,0 +1,36 @@
+#ifndef _ASM_PARISC_TOPOLOGY_H
+#define _ASM_PARISC_TOPOLOGY_H
+
+#ifdef CONFIG_PARISC_CPU_TOPOLOGY
+
+#include <linux/cpumask.h>
+
+struct cputopo_parisc {
+        int thread_id;
+        int core_id;
+        int socket_id;
+        cpumask_t thread_sibling;
+        cpumask_t core_sibling;
+};
+
+extern struct cputopo_parisc cpu_topology[NR_CPUS];
+
+#define topology_physical_package_id(cpu)       (cpu_topology[cpu].socket_id)
+#define topology_core_id(cpu)           (cpu_topology[cpu].core_id)
+#define topology_core_cpumask(cpu)      (&cpu_topology[cpu].core_sibling)
+#define topology_sibling_cpumask(cpu)   (&cpu_topology[cpu].thread_sibling)
+
+void init_cpu_topology(void);
+void store_cpu_topology(unsigned int cpuid);
+const struct cpumask *cpu_coregroup_mask(int cpu);
+
+#else
+
+static inline void init_cpu_topology(void) { }
+static inline void store_cpu_topology(unsigned int cpuid) { }
+
+#endif
+
+#include <asm-generic/topology.h>
+
+#endif /* _ASM_ARM_TOPOLOGY_H */
diff --git a/arch/parisc/kernel/Makefile b/arch/parisc/kernel/Makefile
index 649dc3eda448..eafd06ab59ef 100644
--- a/arch/parisc/kernel/Makefile
+++ b/arch/parisc/kernel/Makefile
@@ -9,8 +9,7 @@ obj-y	     	:= cache.o pacache.o setup.o pdt.o traps.o time.o irq.o \
                    pa7300lc.o syscall.o entry.o sys_parisc.o firmware.o \
                    ptrace.o hardware.o inventory.o drivers.o \
                    signal.o hpmc.o real2.o parisc_ksyms.o unaligned.o \
-                   process.o processor.o pdc_cons.o pdc_chassis.o unwind.o \
-                   topology.o
+                   process.o processor.o pdc_cons.o pdc_chassis.o unwind.o
 
 ifdef CONFIG_FUNCTION_TRACER
 # Do not profile debug and lowlevel utilities
@@ -30,5 +29,6 @@ obj-$(CONFIG_AUDIT)	+= audit.o
 obj64-$(CONFIG_AUDIT)   += compat_audit.o
 # only supported for PCX-W/U in 64-bit mode at the moment
 obj-$(CONFIG_64BIT)     += perf.o perf_asm.o $(obj64-y)
+obj-$(CONFIG_PARISC_CPU_TOPOLOGY)       += topology.o
 obj-$(CONFIG_FUNCTION_TRACER)           += ftrace.o
 obj-$(CONFIG_FUNCTION_GRAPH_TRACER)     += ftrace.o
diff --git a/arch/parisc/kernel/processor.c b/arch/parisc/kernel/processor.c
index e120d63c1b28..45cc65902fce 100644
--- a/arch/parisc/kernel/processor.c
+++ b/arch/parisc/kernel/processor.c
@@ -184,6 +184,9 @@ static int __init processor_probe(struct parisc_device *dev)
         p->txn_addr = txn_addr; /* save CPU IRQ address */
         p->cpu_num = cpu_info.cpu_num;
         p->cpu_loc = cpu_info.cpu_loc;
+
+        store_cpu_topology(cpuid);
+
 #ifdef CONFIG_SMP
         /*
         ** FIXME: review if any other initialization is clobbered
@@ -325,6 +328,8 @@ int __init init_per_cpu(int cpunum)
         set_firmware_width();
         ret = pdc_coproc_cfg(&coproc_cfg);
 
+        store_cpu_topology(cpunum);
+
         if(ret >= 0 && coproc_cfg.ccr_functional) {
                 mtctl(coproc_cfg.ccr_functional, 10);  /* 10 == Coprocessor Control Reg */
 
@@ -388,6 +393,14 @@ show_cpuinfo (struct seq_file *m, void *v)
                                  boot_cpu_data.cpu_hz / 1000000,
                                  boot_cpu_data.cpu_hz % 1000000  );
 
+#ifdef CONFIG_PARISC_CPU_TOPOLOGY
+                seq_printf(m, "physical id\t: %d\n",
+                                topology_physical_package_id(cpu));
+                seq_printf(m, "siblings\t: %d\n",
+                                cpumask_weight(topology_core_cpumask(cpu)));
+                seq_printf(m, "core id\t\t: %d\n", topology_core_id(cpu));
+#endif
+
                 seq_printf(m, "capabilities\t:");
                 if (boot_cpu_data.pdc.capabilities & PDC_MODEL_OS32)
                         seq_puts(m, " os32");
diff --git a/arch/parisc/kernel/setup.c b/arch/parisc/kernel/setup.c
index f7d0c3b33d70..0e9675f857a5 100644
--- a/arch/parisc/kernel/setup.c
+++ b/arch/parisc/kernel/setup.c
@@ -408,6 +408,8 @@ void __init start_parisc(void)
 
         cpunum = smp_processor_id();
 
+        init_cpu_topology();
+
         set_firmware_width_unlocked();
 
         ret = pdc_coproc_cfg_unlocked(&coproc_cfg);
diff --git a/arch/parisc/kernel/topology.c b/arch/parisc/kernel/topology.c
index f5159381fdd6..0a10e4ddc528 100644
--- a/arch/parisc/kernel/topology.c
+++ b/arch/parisc/kernel/topology.c
@@ -1,37 +1,142 @@
 /*
- * arch/parisc/kernel/topology.c - Populate sysfs with topology information
+ * arch/parisc/kernel/topology.c
  *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2 of the License, or
- * (at your option) any later version.
+ * Copyright (C) 2017 Helge Deller <deller@gmx.de>
  *
- * This program is distributed in the hope that it will be useful, but
- * WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
- * NON INFRINGEMENT.  See the GNU General Public License for more
- * details.
+ * based on arch/arm/kernel/topology.c
  *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, write to the Free Software
- * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
  */
 
-#include <linux/init.h>
-#include <linux/smp.h>
-#include <linux/cpu.h>
-#include <linux/cache.h>
+#include <linux/percpu.h>
+#include <linux/sched.h>
+#include <linux/sched/topology.h>
 
-static DEFINE_PER_CPU(struct cpu, cpu_devices);
+#include <asm/topology.h>
 
-static int __init topology_init(void)
+ /*
+  * cpu topology table
+  */
+struct cputopo_parisc cpu_topology[NR_CPUS] __read_mostly;
+EXPORT_SYMBOL_GPL(cpu_topology);
+
+const struct cpumask *cpu_coregroup_mask(int cpu)
 {
-        int num;
+        return &cpu_topology[cpu].core_sibling;
+}
+
+static void update_siblings_masks(unsigned int cpuid)
+{
+        struct cputopo_parisc *cpu_topo, *cpuid_topo = &cpu_topology[cpuid];
+        int cpu;
+
+        /* update core and thread sibling masks */
+        for_each_possible_cpu(cpu) {
+                cpu_topo = &cpu_topology[cpu];
+
+                if (cpuid_topo->socket_id != cpu_topo->socket_id)
+                        continue;
+
+                cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
+                if (cpu != cpuid)
+                        cpumask_set_cpu(cpu, &cpuid_topo->core_sibling);
+
+                if (cpuid_topo->core_id != cpu_topo->core_id)
+                        continue;
+
+                cpumask_set_cpu(cpuid, &cpu_topo->thread_sibling);
+                if (cpu != cpuid)
+                        cpumask_set_cpu(cpu, &cpuid_topo->thread_sibling);
+        }
+        smp_wmb();
+}
+
+static int dualcores_found __initdata;
+
+/*
+ * store_cpu_topology is called at boot when only one cpu is running
+ * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
+ * which prevents simultaneous write access to cpu_topology array
+ */
+void __init store_cpu_topology(unsigned int cpuid)
+{
+        struct cputopo_parisc *cpuid_topo = &cpu_topology[cpuid];
+        struct cpuinfo_parisc *p;
+        int max_socket = -1;
+        unsigned long cpu;
+
+        /* If the cpu topology has been already set, just return */
+        if (cpuid_topo->core_id != -1)
+                return;
 
-        for_each_present_cpu(num) {
-                register_cpu(&per_cpu(cpu_devices, num), num);
+        /* create cpu topology mapping */
+        cpuid_topo->thread_id = -1;
+        cpuid_topo->core_id = 0;
+
+        p = &per_cpu(cpu_data, cpuid);
+        for_each_online_cpu(cpu) {
+                const struct cpuinfo_parisc *cpuinfo = &per_cpu(cpu_data, cpu);
+
+                if (cpu == cpuid) /* ignore current cpu */
+                        continue;
+
+                if (cpuinfo->cpu_loc == p->cpu_loc) {
+                        cpuid_topo->core_id = cpu_topology[cpu].core_id;
+                        if (p->cpu_loc) {
+                                cpuid_topo->core_id++;
+                                cpuid_topo->socket_id = cpu_topology[cpu].socket_id;
+                                dualcores_found = 1;
+                                continue;
+                        }
+                }
+
+                if (cpuid_topo->socket_id == -1)
+                        max_socket = max(max_socket, cpu_topology[cpu].socket_id);
         }
-        return 0;
+
+        if (cpuid_topo->socket_id == -1)
+                cpuid_topo->socket_id = max_socket + 1;
+
+        update_siblings_masks(cpuid);
+
+        pr_info("CPU%u: thread %d, cpu %d, socket %d\n",
+                cpuid, cpu_topology[cpuid].thread_id,
+                cpu_topology[cpuid].core_id,
+                cpu_topology[cpuid].socket_id);
 }
 
-subsys_initcall(topology_init);
+static struct sched_domain_topology_level parisc_mc_topology[] = {
+#ifdef CONFIG_SCHED_MC
+        { cpu_coregroup_mask, cpu_core_flags, SD_INIT_NAME(MC) },
+#endif
+
+        { cpu_cpu_mask, SD_INIT_NAME(DIE) },
+        { NULL, },
+};
+
+/*
+ * init_cpu_topology is called at boot when only one cpu is running
+ * which prevent simultaneous write access to cpu_topology array
+ */
+void __init init_cpu_topology(void)
+{
+        unsigned int cpu;
+
+        /* init core mask and capacity */
+        for_each_possible_cpu(cpu) {
+                struct cputopo_parisc *cpu_topo = &(cpu_topology[cpu]);
+
+                cpu_topo->thread_id = -1;
+                cpu_topo->core_id =  -1;
+                cpu_topo->socket_id = -1;
+                cpumask_clear(&cpu_topo->core_sibling);
+                cpumask_clear(&cpu_topo->thread_sibling);
+        }
+        smp_wmb();
+
+        /* Set scheduler topology descriptor */
+        if (dualcores_found)
+                set_sched_topology(parisc_mc_topology);
+}