4 files changed, 535 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index ebc269152faf..082df56d5b9a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -288,6 +288,14 @@ L:	linux-pci@vger.kernel.org
 S:      Supported
 F:      drivers/pci/hotplug/acpi*
 
+ACPI PROCESSOR AGGREGATOR DRIVER
+P:      Shaohua Li
+M:      shaohua.li@intel.com
+L:      linux-acpi@vger.kernel.org
+W:      http://www.lesswatts.org/projects/acpi/
+S:      Supported
+F:      drivers/acpi/acpi_pad.c
+
 ACPI THERMAL DRIVER
 P:      Zhang Rui
 M:      rui.zhang@intel.com
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index 7ec7d88c5999..13531ed3cbd3 100644
--- a/drivers/acpi/Kconfig
+++ b/drivers/acpi/Kconfig
@@ -196,6 +196,17 @@ config ACPI_HOTPLUG_CPU
         select ACPI_CONTAINER
         default y
 
+config ACPI_PROCESSOR_AGGREGATOR
+        tristate "Processor Aggregator"
+        depends on ACPI_PROCESSOR
+        depends on EXPERIMENTAL
+        help
+          ACPI 4.0 defines processor Aggregator, which enables OS to perform
+          specfic processor configuration and control that applies to all
+          processors in the platform. Currently only logical processor idling
+          is defined, which is to reduce power consumption. This driver
+          support the new device.
+
 config ACPI_THERMAL
         tristate "Thermal Zone"
         depends on ACPI_PROCESSOR
diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
index 03a985be3fe3..8dae61c8a176 100644
--- a/drivers/acpi/Makefile
+++ b/drivers/acpi/Makefile
@@ -61,3 +61,5 @@ obj-$(CONFIG_ACPI_SBS)		+= sbs.o
 processor-y                     := processor_core.o processor_throttling.o
 processor-y                     += processor_idle.o processor_thermal.o
 processor-$(CONFIG_CPU_FREQ)    += processor_perflib.o
+
+obj-$(CONFIG_ACPI_PROCESSOR_AGGREGATOR) += acpi_pad.o
diff --git a/drivers/acpi/acpi_pad.c b/drivers/acpi/acpi_pad.c
new file mode 100644
index 000000000000..0d2cdb86158b
--- /dev/null
+++ b/drivers/acpi/acpi_pad.c
@@ -0,0 +1,514 @@
+/*
+ * acpi_pad.c ACPI Processor Aggregator Driver
+ *
+ * Copyright (c) 2009, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ * more details.
+ *
+ * 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.,
+ * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/cpumask.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/kthread.h>
+#include <linux/freezer.h>
+#include <linux/cpu.h>
+#include <linux/clockchips.h>
+#include <acpi/acpi_bus.h>
+#include <acpi/acpi_drivers.h>
+
+#define ACPI_PROCESSOR_AGGREGATOR_CLASS "processor_aggregator"
+#define ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME "Processor Aggregator"
+#define ACPI_PROCESSOR_AGGREGATOR_NOTIFY 0x80
+static DEFINE_MUTEX(isolated_cpus_lock);
+
+#define MWAIT_SUBSTATE_MASK     (0xf)
+#define MWAIT_CSTATE_MASK       (0xf)
+#define MWAIT_SUBSTATE_SIZE     (4)
+#define CPUID_MWAIT_LEAF (5)
+#define CPUID5_ECX_EXTENSIONS_SUPPORTED (0x1)
+#define CPUID5_ECX_INTERRUPT_BREAK      (0x2)
+static unsigned long power_saving_mwait_eax;
+static void power_saving_mwait_init(void)
+{
+        unsigned int eax, ebx, ecx, edx;
+        unsigned int highest_cstate = 0;
+        unsigned int highest_subcstate = 0;
+        int i;
+
+        if (!boot_cpu_has(X86_FEATURE_MWAIT))
+                return;
+        if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
+                return;
+
+        cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, &edx);
+
+        if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
+            !(ecx & CPUID5_ECX_INTERRUPT_BREAK))
+                return;
+
+        edx >>= MWAIT_SUBSTATE_SIZE;
+        for (i = 0; i < 7 && edx; i++, edx >>= MWAIT_SUBSTATE_SIZE) {
+                if (edx & MWAIT_SUBSTATE_MASK) {
+                        highest_cstate = i;
+                        highest_subcstate = edx & MWAIT_SUBSTATE_MASK;
+                }
+        }
+        power_saving_mwait_eax = (highest_cstate << MWAIT_SUBSTATE_SIZE) |
+                (highest_subcstate - 1);
+
+        for_each_online_cpu(i)
+                clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ON, &i);
+
+#if defined(CONFIG_GENERIC_TIME) && defined(CONFIG_X86)
+        switch (boot_cpu_data.x86_vendor) {
+        case X86_VENDOR_AMD:
+        case X86_VENDOR_INTEL:
+                /*
+                 * AMD Fam10h TSC will tick in all
+                 * C/P/S0/S1 states when this bit is set.
+                 */
+                if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+                        return;
+
+                /*FALL THROUGH*/
+        default:
+                /* TSC could halt in idle, so notify users */
+                mark_tsc_unstable("TSC halts in idle");
+        }
+#endif
+}
+
+static unsigned long cpu_weight[NR_CPUS];
+static int tsk_in_cpu[NR_CPUS] = {[0 ... NR_CPUS-1] = -1};
+static DECLARE_BITMAP(pad_busy_cpus_bits, NR_CPUS);
+static void round_robin_cpu(unsigned int tsk_index)
+{
+        struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
+        cpumask_var_t tmp;
+        int cpu;
+        unsigned long min_weight = -1, preferred_cpu;
+
+        if (!alloc_cpumask_var(&tmp, GFP_KERNEL))
+                return;
+
+        mutex_lock(&isolated_cpus_lock);
+        cpumask_clear(tmp);
+        for_each_cpu(cpu, pad_busy_cpus)
+                cpumask_or(tmp, tmp, topology_thread_cpumask(cpu));
+        cpumask_andnot(tmp, cpu_online_mask, tmp);
+        /* avoid HT sibilings if possible */
+        if (cpumask_empty(tmp))
+                cpumask_andnot(tmp, cpu_online_mask, pad_busy_cpus);
+        if (cpumask_empty(tmp)) {
+                mutex_unlock(&isolated_cpus_lock);
+                return;
+        }
+        for_each_cpu(cpu, tmp) {
+                if (cpu_weight[cpu] < min_weight) {
+                        min_weight = cpu_weight[cpu];
+                        preferred_cpu = cpu;
+                }
+        }
+
+        if (tsk_in_cpu[tsk_index] != -1)
+                cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
+        tsk_in_cpu[tsk_index] = preferred_cpu;
+        cpumask_set_cpu(preferred_cpu, pad_busy_cpus);
+        cpu_weight[preferred_cpu]++;
+        mutex_unlock(&isolated_cpus_lock);
+
+        set_cpus_allowed_ptr(current, cpumask_of(preferred_cpu));
+}
+
+static void exit_round_robin(unsigned int tsk_index)
+{
+        struct cpumask *pad_busy_cpus = to_cpumask(pad_busy_cpus_bits);
+        cpumask_clear_cpu(tsk_in_cpu[tsk_index], pad_busy_cpus);
+        tsk_in_cpu[tsk_index] = -1;
+}
+
+static unsigned int idle_pct = 5; /* percentage */
+static unsigned int round_robin_time = 10; /* second */
+static int power_saving_thread(void *data)
+{
+        struct sched_param param = {.sched_priority = 1};
+        int do_sleep;
+        unsigned int tsk_index = (unsigned long)data;
+        u64 last_jiffies = 0;
+
+        sched_setscheduler(current, SCHED_RR, &param);
+
+        while (!kthread_should_stop()) {
+                int cpu;
+                u64 expire_time;
+
+                try_to_freeze();
+
+                /* round robin to cpus */
+                if (last_jiffies + round_robin_time * HZ < jiffies) {
+                        last_jiffies = jiffies;
+                        round_robin_cpu(tsk_index);
+                }
+
+                do_sleep = 0;
+
+                current_thread_info()->status &= ~TS_POLLING;
+                /*
+                 * TS_POLLING-cleared state must be visible before we test
+                 * NEED_RESCHED:
+                 */
+                smp_mb();
+
+                expire_time = jiffies + HZ * (100 - idle_pct) / 100;
+
+                while (!need_resched()) {
+                        local_irq_disable();
+                        cpu = smp_processor_id();
+                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_ENTER,
+                                &cpu);
+                        stop_critical_timings();
+
+                        __monitor((void *)&current_thread_info()->flags, 0, 0);
+                        smp_mb();
+                        if (!need_resched())
+                                __mwait(power_saving_mwait_eax, 1);
+
+                        start_critical_timings();
+                        clockevents_notify(CLOCK_EVT_NOTIFY_BROADCAST_EXIT,
+                                &cpu);
+                        local_irq_enable();
+
+                        if (jiffies > expire_time) {
+                                do_sleep = 1;
+                                break;
+                        }
+                }
+
+                current_thread_info()->status |= TS_POLLING;
+
+                /*
+                 * current sched_rt has threshold for rt task running time.
+                 * When a rt task uses 95% CPU time, the rt thread will be
+                 * scheduled out for 5% CPU time to not starve other tasks. But
+                 * the mechanism only works when all CPUs have RT task running,
+                 * as if one CPU hasn't RT task, RT task from other CPUs will
+                 * borrow CPU time from this CPU and cause RT task use > 95%
+                 * CPU time. To make 'avoid staration' work, takes a nap here.
+                 */
+                if (do_sleep)
+                        schedule_timeout_killable(HZ * idle_pct / 100);
+        }
+
+        exit_round_robin(tsk_index);
+        return 0;
+}
+
+static struct task_struct *ps_tsks[NR_CPUS];
+static unsigned int ps_tsk_num;
+static int create_power_saving_task(void)
+{
+        ps_tsks[ps_tsk_num] = kthread_run(power_saving_thread,
+                (void *)(unsigned long)ps_tsk_num,
+                "power_saving/%d", ps_tsk_num);
+        if (ps_tsks[ps_tsk_num]) {
+                ps_tsk_num++;
+                return 0;
+        }
+        return -EINVAL;
+}
+
+static void destroy_power_saving_task(void)
+{
+        if (ps_tsk_num > 0) {
+                ps_tsk_num--;
+                kthread_stop(ps_tsks[ps_tsk_num]);
+        }
+}
+
+static void set_power_saving_task_num(unsigned int num)
+{
+        if (num > ps_tsk_num) {
+                while (ps_tsk_num < num) {
+                        if (create_power_saving_task())
+                                return;
+                }
+        } else if (num < ps_tsk_num) {
+                while (ps_tsk_num > num)
+                        destroy_power_saving_task();
+        }
+}
+
+static int acpi_pad_idle_cpus(unsigned int num_cpus)
+{
+        get_online_cpus();
+
+        num_cpus = min_t(unsigned int, num_cpus, num_online_cpus());
+        set_power_saving_task_num(num_cpus);
+
+        put_online_cpus();
+        return 0;
+}
+
+static uint32_t acpi_pad_idle_cpus_num(void)
+{
+        return ps_tsk_num;
+}
+
+static ssize_t acpi_pad_rrtime_store(struct device *dev,
+        struct device_attribute *attr, const char *buf, size_t count)
+{
+        unsigned long num;
+        if (strict_strtoul(buf, 0, &num))
+                return -EINVAL;
+        if (num < 1 || num >= 100)
+                return -EINVAL;
+        mutex_lock(&isolated_cpus_lock);
+        round_robin_time = num;
+        mutex_unlock(&isolated_cpus_lock);
+        return count;
+}
+
+static ssize_t acpi_pad_rrtime_show(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        return scnprintf(buf, PAGE_SIZE, "%d", round_robin_time);
+}
+static DEVICE_ATTR(rrtime, S_IRUGO|S_IWUSR,
+        acpi_pad_rrtime_show,
+        acpi_pad_rrtime_store);
+
+static ssize_t acpi_pad_idlepct_store(struct device *dev,
+        struct device_attribute *attr, const char *buf, size_t count)
+{
+        unsigned long num;
+        if (strict_strtoul(buf, 0, &num))
+                return -EINVAL;
+        if (num < 1 || num >= 100)
+                return -EINVAL;
+        mutex_lock(&isolated_cpus_lock);
+        idle_pct = num;
+        mutex_unlock(&isolated_cpus_lock);
+        return count;
+}
+
+static ssize_t acpi_pad_idlepct_show(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        return scnprintf(buf, PAGE_SIZE, "%d", idle_pct);
+}
+static DEVICE_ATTR(idlepct, S_IRUGO|S_IWUSR,
+        acpi_pad_idlepct_show,
+        acpi_pad_idlepct_store);
+
+static ssize_t acpi_pad_idlecpus_store(struct device *dev,
+        struct device_attribute *attr, const char *buf, size_t count)
+{
+        unsigned long num;
+        if (strict_strtoul(buf, 0, &num))
+                return -EINVAL;
+        mutex_lock(&isolated_cpus_lock);
+        acpi_pad_idle_cpus(num);
+        mutex_unlock(&isolated_cpus_lock);
+        return count;
+}
+
+static ssize_t acpi_pad_idlecpus_show(struct device *dev,
+        struct device_attribute *attr, char *buf)
+{
+        return cpumask_scnprintf(buf, PAGE_SIZE,
+                to_cpumask(pad_busy_cpus_bits));
+}
+static DEVICE_ATTR(idlecpus, S_IRUGO|S_IWUSR,
+        acpi_pad_idlecpus_show,
+        acpi_pad_idlecpus_store);
+
+static int acpi_pad_add_sysfs(struct acpi_device *device)
+{
+        int result;
+
+        result = device_create_file(&device->dev, &dev_attr_idlecpus);
+        if (result)
+                return -ENODEV;
+        result = device_create_file(&device->dev, &dev_attr_idlepct);
+        if (result) {
+                device_remove_file(&device->dev, &dev_attr_idlecpus);
+                return -ENODEV;
+        }
+        result = device_create_file(&device->dev, &dev_attr_rrtime);
+        if (result) {
+                device_remove_file(&device->dev, &dev_attr_idlecpus);
+                device_remove_file(&device->dev, &dev_attr_idlepct);
+                return -ENODEV;
+        }
+        return 0;
+}
+
+static void acpi_pad_remove_sysfs(struct acpi_device *device)
+{
+        device_remove_file(&device->dev, &dev_attr_idlecpus);
+        device_remove_file(&device->dev, &dev_attr_idlepct);
+        device_remove_file(&device->dev, &dev_attr_rrtime);
+}
+
+/* Query firmware how many CPUs should be idle */
+static int acpi_pad_pur(acpi_handle handle, int *num_cpus)
+{
+        struct acpi_buffer buffer = {ACPI_ALLOCATE_BUFFER, NULL};
+        acpi_status status;
+        union acpi_object *package;
+        int rev, num, ret = -EINVAL;
+
+        status = acpi_evaluate_object(handle, "_PUR", NULL, &buffer);
+        if (ACPI_FAILURE(status))
+                return -EINVAL;
+        package = buffer.pointer;
+        if (package->type != ACPI_TYPE_PACKAGE || package->package.count != 2)
+                goto out;
+        rev = package->package.elements[0].integer.value;
+        num = package->package.elements[1].integer.value;
+        if (rev != 1)
+                goto out;
+        *num_cpus = num;
+        ret = 0;
+out:
+        kfree(buffer.pointer);
+        return ret;
+}
+
+/* Notify firmware how many CPUs are idle */
+static void acpi_pad_ost(acpi_handle handle, int stat,
+        uint32_t idle_cpus)
+{
+        union acpi_object params[3] = {
+                {.type = ACPI_TYPE_INTEGER,},
+                {.type = ACPI_TYPE_INTEGER,},
+                {.type = ACPI_TYPE_BUFFER,},
+        };
+        struct acpi_object_list arg_list = {3, params};
+
+        params[0].integer.value = ACPI_PROCESSOR_AGGREGATOR_NOTIFY;
+        params[1].integer.value =  stat;
+        params[2].buffer.length = 4;
+        params[2].buffer.pointer = (void *)&idle_cpus;
+        acpi_evaluate_object(handle, "_OST", &arg_list, NULL);
+}
+
+static void acpi_pad_handle_notify(acpi_handle handle)
+{
+        int num_cpus, ret;
+        uint32_t idle_cpus;
+
+        mutex_lock(&isolated_cpus_lock);
+        if (acpi_pad_pur(handle, &num_cpus)) {
+                mutex_unlock(&isolated_cpus_lock);
+                return;
+        }
+        ret = acpi_pad_idle_cpus(num_cpus);
+        idle_cpus = acpi_pad_idle_cpus_num();
+        if (!ret)
+                acpi_pad_ost(handle, 0, idle_cpus);
+        else
+                acpi_pad_ost(handle, 1, 0);
+        mutex_unlock(&isolated_cpus_lock);
+}
+
+static void acpi_pad_notify(acpi_handle handle, u32 event,
+        void *data)
+{
+        struct acpi_device *device = data;
+
+        switch (event) {
+        case ACPI_PROCESSOR_AGGREGATOR_NOTIFY:
+                acpi_pad_handle_notify(handle);
+                acpi_bus_generate_proc_event(device, event, 0);
+                acpi_bus_generate_netlink_event(device->pnp.device_class,
+                        dev_name(&device->dev), event, 0);
+                break;
+        default:
+                printk(KERN_WARNING"Unsupported event [0x%x]\n", event);
+                break;
+        }
+}
+
+static int acpi_pad_add(struct acpi_device *device)
+{
+        acpi_status status;
+
+        strcpy(acpi_device_name(device), ACPI_PROCESSOR_AGGREGATOR_DEVICE_NAME);
+        strcpy(acpi_device_class(device), ACPI_PROCESSOR_AGGREGATOR_CLASS);
+
+        if (acpi_pad_add_sysfs(device))
+                return -ENODEV;
+
+        status = acpi_install_notify_handler(device->handle,
+                ACPI_DEVICE_NOTIFY, acpi_pad_notify, device);
+        if (ACPI_FAILURE(status)) {
+                acpi_pad_remove_sysfs(device);
+                return -ENODEV;
+        }
+
+        return 0;
+}
+
+static int acpi_pad_remove(struct acpi_device *device,
+        int type)
+{
+        mutex_lock(&isolated_cpus_lock);
+        acpi_pad_idle_cpus(0);
+        mutex_unlock(&isolated_cpus_lock);
+
+        acpi_remove_notify_handler(device->handle,
+                ACPI_DEVICE_NOTIFY, acpi_pad_notify);
+        acpi_pad_remove_sysfs(device);
+        return 0;
+}
+
+static const struct acpi_device_id pad_device_ids[] = {
+        {"ACPI000C", 0},
+        {"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, pad_device_ids);
+
+static struct acpi_driver acpi_pad_driver = {
+        .name = "processor_aggregator",
+        .class = ACPI_PROCESSOR_AGGREGATOR_CLASS,
+        .ids = pad_device_ids,
+        .ops = {
+                .add = acpi_pad_add,
+                .remove = acpi_pad_remove,
+        },
+};
+
+static int __init acpi_pad_init(void)
+{
+        power_saving_mwait_init();
+        if (power_saving_mwait_eax == 0)
+                return -EINVAL;
+
+        return acpi_bus_register_driver(&acpi_pad_driver);
+}
+
+static void __exit acpi_pad_exit(void)
+{
+        acpi_bus_unregister_driver(&acpi_pad_driver);
+}
+
+module_init(acpi_pad_init);
+module_exit(acpi_pad_exit);
+MODULE_AUTHOR("Shaohua Li<shaohua.li@intel.com>");
+MODULE_DESCRIPTION("ACPI Processor Aggregator Driver");
+MODULE_LICENSE("GPL");