lkml.org 
[lkml]   [2022]   [Aug]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] MIPS: Expose prid and globalnumber to sysfs
Date
Some application would like to know precise model and rev of processor
to do errata workaround or optimization.

Expose them in sysfs as:
/sys/devices/system/cpu/cpuX/regs/identification/prid
/sys/devices/system/cpu/cpuX/regs/identification/globalnumber

Reusing AArch64 CPU registers directory.

Signed-off-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
---
.../ABI/testing/sysfs-devices-system-cpu | 11 +++
arch/mips/kernel/topology.c | 96 +++++++++++++++++++
2 files changed, 107 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-devices-system-cpu b/Documentation/ABI/testing/sysfs-devices-system-cpu
index 5bf61881f012..adf855e7bb9b 100644
--- a/Documentation/ABI/testing/sysfs-devices-system-cpu
+++ b/Documentation/ABI/testing/sysfs-devices-system-cpu
@@ -512,6 +512,17 @@ Description: information about CPUs heterogeneity.

cpu_capacity: capacity of cpuX.

+What: /sys/devices/system/cpu/cpuX/regs/
+ /sys/devices/system/cpu/cpuX/regs/identification/
+ /sys/devices/system/cpu/cpuX/regs/identification/prid
+ /sys/devices/system/cpu/cpuX/regs/identification/globalnumber
+Date: Augest 2022
+Contact: Linux MIPS Kernel Mailing list <linux-mips@vger.kernel.org>
+Description: MIPS CPU registers
+
+ 'identification' directory exposes the Processor ID and Global Number
+ registers for identifying model and revision of the CPU.
+
What: /sys/devices/system/cpu/vulnerabilities
/sys/devices/system/cpu/vulnerabilities/meltdown
/sys/devices/system/cpu/vulnerabilities/spectre_v1
diff --git a/arch/mips/kernel/topology.c b/arch/mips/kernel/topology.c
index 9429d85a4703..90b5136afb63 100644
--- a/arch/mips/kernel/topology.c
+++ b/arch/mips/kernel/topology.c
@@ -5,6 +5,8 @@
#include <linux/node.h>
#include <linux/nodemask.h>
#include <linux/percpu.h>
+#include <linux/seq_file.h>
+#include <linux/smp.h>

static DEFINE_PER_CPU(struct cpu, cpu_devices);

@@ -26,3 +28,97 @@ static int __init topology_init(void)
}

subsys_initcall(topology_init);
+
+static struct kobj_type cpuregs_kobj_type = {
+ .sysfs_ops = &kobj_sysfs_ops,
+};
+
+struct cpureg {
+ struct kobject kobj;
+ struct cpuinfo_mips *info;
+};
+static DEFINE_PER_CPU(struct cpureg, cpuregs);
+
+#define kobj_to_cpureg(kobj) container_of(kobj, struct cpureg, kobj)
+#define CPUREGS_ATTR_RO(_name, _field) \
+ static ssize_t _name##_show(struct kobject *kobj, \
+ struct kobj_attribute *attr, char *buf) \
+ { \
+ struct cpuinfo_mips *info = kobj_to_cpureg(kobj)->info; \
+ \
+ return sprintf(buf, "0x%08x\n", info->_field); \
+ } \
+ static struct kobj_attribute cpuregs_attr_##_name = __ATTR_RO(_name)
+
+CPUREGS_ATTR_RO(prid, processor_id);
+CPUREGS_ATTR_RO(globalnumber, globalnumber);
+
+static struct attribute *cpuregs_id_attrs[] = {
+ &cpuregs_attr_prid.attr,
+ &cpuregs_attr_globalnumber.attr,
+ NULL
+};
+
+static const struct attribute_group cpuregs_attr_group = {
+ .attrs = cpuregs_id_attrs,
+ .name = "identification"
+};
+
+static int cpuregs_cpu_online(unsigned int cpu)
+{
+ int rc;
+ struct device *dev;
+ struct cpureg *reg = &per_cpu(cpuregs, cpu);
+
+ dev = get_cpu_device(cpu);
+ if (!dev) {
+ rc = -ENODEV;
+ goto out;
+ }
+ rc = kobject_add(&reg->kobj, &dev->kobj, "regs");
+ if (rc)
+ goto out;
+ rc = sysfs_create_group(&reg->kobj, &cpuregs_attr_group);
+ if (rc)
+ kobject_del(&reg->kobj);
+out:
+ return rc;
+}
+
+static int cpuregs_cpu_offline(unsigned int cpu)
+{
+ struct device *dev;
+ struct cpureg *reg = &per_cpu(cpuregs, cpu);
+
+ dev = get_cpu_device(cpu);
+ if (!dev)
+ return -ENODEV;
+ if (reg->kobj.parent) {
+ sysfs_remove_group(&reg->kobj, &cpuregs_attr_group);
+ kobject_del(&reg->kobj);
+ }
+
+ return 0;
+}
+
+static int __init cpuinfo_regs_init(void)
+{
+ int cpu, ret;
+
+ for_each_possible_cpu(cpu) {
+ struct cpureg *reg = &per_cpu(cpuregs, cpu);
+
+ reg->info = &cpu_data[cpu];
+ kobject_init(&reg->kobj, &cpuregs_kobj_type);
+ }
+
+ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "mips/topology:online",
+ cpuregs_cpu_online, cpuregs_cpu_offline);
+ if (ret < 0) {
+ pr_err("cpuinfo: failed to register hotplug callbacks.\n");
+ return ret;
+ }
+ return 0;
+}
+
+device_initcall(cpuinfo_regs_init);
--
2.34.1
\
 
 \ /
  Last update: 2022-08-09 13:36    [W:0.102 / U:1.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site