[IA64] Add ACPI based P-state support

Patch to support P-state transitions on ia64. This driver is based on ACPI,
and uses the ACPI processor driver interface to find out the P-state support
information for the processor. This driver plugs into generic cpufreq
infrastructure.

Once this driver is loaded successfully, ondemand/userspace governor can be
used to change the CPU frequency dynamically based on load or on request from
userspace process.

Refer :
ACPI specification -
      http://www.acpi.info
P-state related PAL calls -
      http://developer.intel.com/design/itanium/downloads/24869909.pdf

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

7 files changed, 562 insertions, 0 deletions

diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
index 80988136f26..3deced637f0 100644
--- a/arch/ia64/Kconfig
+++ b/arch/ia64/Kconfig
@@ -383,6 +383,12 @@ source "drivers/acpi/Kconfig"
 
 endif
 
+if PM
+
+source "arch/ia64/kernel/cpufreq/Kconfig"
+
+endif
+
 endmenu
 
 if !IA64_HP_SIM
diff --git a/arch/ia64/kernel/Makefile b/arch/ia64/kernel/Makefile
index e1fb68ddec2..b242594be55 100644
--- a/arch/ia64/kernel/Makefile
+++ b/arch/ia64/kernel/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_SMP)		+= smp.o smpboot.o domain.o
 obj-$(CONFIG_NUMA)              += numa.o
 obj-$(CONFIG_PERFMON)           += perfmon_default_smpl.o
 obj-$(CONFIG_IA64_CYCLONE)      += cyclone.o
+obj-$(CONFIG_CPU_FREQ)          += cpufreq/
 obj-$(CONFIG_IA64_MCA_RECOVERY) += mca_recovery.o
 obj-$(CONFIG_KPROBES)           += kprobes.o jprobes.o
 obj-$(CONFIG_IA64_UNCACHED_ALLOCATOR)   += uncached.o
diff --git a/arch/ia64/kernel/cpufreq/Kconfig b/arch/ia64/kernel/cpufreq/Kconfig
new file mode 100644
index 00000000000..2d9d5279b98
--- /dev/null
+++ b/arch/ia64/kernel/cpufreq/Kconfig
@@ -0,0 +1,29 @@
+
+#
+# CPU Frequency scaling
+#
+
+menu "CPU Frequency scaling"
+
+source "drivers/cpufreq/Kconfig"
+
+if CPU_FREQ
+
+comment "CPUFreq processor drivers"
+
+config IA64_ACPI_CPUFREQ
+        tristate "ACPI Processor P-States driver"
+        select CPU_FREQ_TABLE
+        depends on ACPI_PROCESSOR
+        help
+        This driver adds a CPUFreq driver which utilizes the ACPI
+        Processor Performance States.
+
+        For details, take a look at <file:Documentation/cpu-freq/>.
+
+        If in doubt, say N.
+
+endif   # CPU_FREQ
+
+endmenu
+
diff --git a/arch/ia64/kernel/cpufreq/Makefile b/arch/ia64/kernel/cpufreq/Makefile
new file mode 100644
index 00000000000..f748d34c02f
--- /dev/null
+++ b/arch/ia64/kernel/cpufreq/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_IA64_ACPI_CPUFREQ)         += acpi-cpufreq.o
diff --git a/arch/ia64/kernel/cpufreq/acpi-cpufreq.c b/arch/ia64/kernel/cpufreq/acpi-cpufreq.c
new file mode 100644
index 00000000000..da4d5cf80a4
--- /dev/null
+++ b/arch/ia64/kernel/cpufreq/acpi-cpufreq.c
@@ -0,0 +1,499 @@
+/*
+ * arch/ia64/kernel/cpufreq/acpi-cpufreq.c
+ * This file provides the ACPI based P-state support. This
+ * module works with generic cpufreq infrastructure. Most of
+ * the code is based on i386 version
+ * (arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c)
+ *
+ * Copyright (C) 2005 Intel Corp
+ *      Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
+ */
+
+#include <linux/config.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <asm/io.h>
+#include <asm/uaccess.h>
+#include <asm/pal.h>
+
+#include <linux/acpi.h>
+#include <acpi/processor.h>
+
+#define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "acpi-cpufreq", msg)
+
+MODULE_AUTHOR("Venkatesh Pallipadi");
+MODULE_DESCRIPTION("ACPI Processor P-States Driver");
+MODULE_LICENSE("GPL");
+
+
+struct cpufreq_acpi_io {
+        struct acpi_processor_performance       acpi_data;
+        struct cpufreq_frequency_table          *freq_table;
+        unsigned int                            resume;
+};
+
+static struct cpufreq_acpi_io   *acpi_io_data[NR_CPUS];
+
+static struct cpufreq_driver acpi_cpufreq_driver;
+
+
+static int
+processor_set_pstate (
+        u32     value)
+{
+        s64 retval;
+
+        dprintk("processor_set_pstate\n");
+
+        retval = ia64_pal_set_pstate((u64)value);
+
+        if (retval) {
+                dprintk("Failed to set freq to 0x%x, with error 0x%x\n",
+                        value, retval);
+                return -ENODEV;
+        }
+        return (int)retval;
+}
+
+
+static int
+processor_get_pstate (
+        u32     *value)
+{
+        u64     pstate_index = 0;
+        s64     retval;
+
+        dprintk("processor_get_pstate\n");
+
+        retval = ia64_pal_get_pstate(&pstate_index);
+        *value = (u32) pstate_index;
+
+        if (retval)
+                dprintk("Failed to get current freq with "
+                        "error 0x%x, idx 0x%x\n", retval, *value);
+
+        return (int)retval;
+}
+
+
+/* To be used only after data->acpi_data is initialized */
+static unsigned
+extract_clock (
+        struct cpufreq_acpi_io *data,
+        unsigned value,
+        unsigned int cpu)
+{
+        unsigned long i;
+
+        dprintk("extract_clock\n");
+
+        for (i = 0; i < data->acpi_data.state_count; i++) {
+                if (value >= data->acpi_data.states[i].control)
+                        return data->acpi_data.states[i].core_frequency;
+        }
+        return data->acpi_data.states[i-1].core_frequency;
+}
+
+
+static unsigned int
+processor_get_freq (
+        struct cpufreq_acpi_io  *data,
+        unsigned int            cpu)
+{
+        int                     ret = 0;
+        u32                     value = 0;
+        cpumask_t               saved_mask;
+        unsigned long           clock_freq;
+
+        dprintk("processor_get_freq\n");
+
+        saved_mask = current->cpus_allowed;
+        set_cpus_allowed(current, cpumask_of_cpu(cpu));
+        if (smp_processor_id() != cpu) {
+                ret = -EAGAIN;
+                goto migrate_end;
+        }
+
+        /*
+         * processor_get_pstate gets the average frequency since the
+         * last get. So, do two PAL_get_freq()...
+         */
+        ret = processor_get_pstate(&value);
+        ret = processor_get_pstate(&value);
+
+        if (ret) {
+                set_cpus_allowed(current, saved_mask);
+                printk(KERN_WARNING "get performance failed with error %d\n",
+                       ret);
+                ret = -EAGAIN;
+                goto migrate_end;
+        }
+        clock_freq = extract_clock(data, value, cpu);
+        ret = (clock_freq*1000);
+
+migrate_end:
+        set_cpus_allowed(current, saved_mask);
+        return ret;
+}
+
+
+static int
+processor_set_freq (
+        struct cpufreq_acpi_io  *data,
+        unsigned int            cpu,
+        int                     state)
+{
+        int                     ret = 0;
+        u32                     value = 0;
+        struct cpufreq_freqs    cpufreq_freqs;
+        cpumask_t               saved_mask;
+        int                     retval;
+
+        dprintk("processor_set_freq\n");
+
+        saved_mask = current->cpus_allowed;
+        set_cpus_allowed(current, cpumask_of_cpu(cpu));
+        if (smp_processor_id() != cpu) {
+                retval = -EAGAIN;
+                goto migrate_end;
+        }
+
+        if (state == data->acpi_data.state) {
+                if (unlikely(data->resume)) {
+                        dprintk("Called after resume, resetting to P%d\n", state);
+                        data->resume = 0;
+                } else {
+                        dprintk("Already at target state (P%d)\n", state);
+                        retval = 0;
+                        goto migrate_end;
+                }
+        }
+
+        dprintk("Transitioning from P%d to P%d\n",
+                data->acpi_data.state, state);
+
+        /* cpufreq frequency struct */
+        cpufreq_freqs.cpu = cpu;
+        cpufreq_freqs.old = data->freq_table[data->acpi_data.state].frequency;
+        cpufreq_freqs.new = data->freq_table[state].frequency;
+
+        /* notify cpufreq */
+        cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
+
+        /*
+         * First we write the target state's 'control' value to the
+         * control_register.
+         */
+
+        value = (u32) data->acpi_data.states[state].control;
+
+        dprintk("Transitioning to state: 0x%08x\n", value);
+
+        ret = processor_set_pstate(value);
+        if (ret) {
+                unsigned int tmp = cpufreq_freqs.new;
+                cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
+                cpufreq_freqs.new = cpufreq_freqs.old;
+                cpufreq_freqs.old = tmp;
+                cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_PRECHANGE);
+                cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
+                printk(KERN_WARNING "Transition failed with error %d\n", ret);
+                retval = -ENODEV;
+                goto migrate_end;
+        }
+
+        cpufreq_notify_transition(&cpufreq_freqs, CPUFREQ_POSTCHANGE);
+
+        data->acpi_data.state = state;
+
+        retval = 0;
+
+migrate_end:
+        set_cpus_allowed(current, saved_mask);
+        return (retval);
+}
+
+
+static unsigned int
+acpi_cpufreq_get (
+        unsigned int            cpu)
+{
+        struct cpufreq_acpi_io *data = acpi_io_data[cpu];
+
+        dprintk("acpi_cpufreq_get\n");
+
+        return processor_get_freq(data, cpu);
+}
+
+
+static int
+acpi_cpufreq_target (
+        struct cpufreq_policy   *policy,
+        unsigned int target_freq,
+        unsigned int relation)
+{
+        struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
+        unsigned int next_state = 0;
+        unsigned int result = 0;
+
+        dprintk("acpi_cpufreq_setpolicy\n");
+
+        result = cpufreq_frequency_table_target(policy,
+                        data->freq_table, target_freq, relation, &next_state);
+        if (result)
+                return (result);
+
+        result = processor_set_freq(data, policy->cpu, next_state);
+
+        return (result);
+}
+
+
+static int
+acpi_cpufreq_verify (
+        struct cpufreq_policy   *policy)
+{
+        unsigned int result = 0;
+        struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
+
+        dprintk("acpi_cpufreq_verify\n");
+
+        result = cpufreq_frequency_table_verify(policy,
+                        data->freq_table);
+
+        return (result);
+}
+
+
+/*
+ * processor_init_pdc - let BIOS know about the SMP capabilities
+ * of this driver
+ * @perf: processor-specific acpi_io_data struct
+ * @cpu: CPU being initialized
+ *
+ * To avoid issues with legacy OSes, some BIOSes require to be informed of
+ * the SMP capabilities of OS P-state driver. Here we set the bits in _PDC
+ * accordingly. Actual call to _PDC is done in driver/acpi/processor.c
+ */
+static void
+processor_init_pdc (
+                struct acpi_processor_performance *perf,
+                unsigned int cpu,
+                struct acpi_object_list *obj_list
+                )
+{
+        union acpi_object *obj;
+        u32 *buf;
+
+        dprintk("processor_init_pdc\n");
+
+        perf->pdc = NULL;
+        /* Initialize pdc. It will be used later. */
+        if (!obj_list)
+                return;
+
+        if (!(obj_list->count && obj_list->pointer))
+                return;
+
+        obj = obj_list->pointer;
+        if ((obj->buffer.length == 12) && obj->buffer.pointer) {
+                buf = (u32 *)obj->buffer.pointer;
+                buf[0] = ACPI_PDC_REVISION_ID;
+                buf[1] = 1;
+                buf[2] = ACPI_PDC_EST_CAPABILITY_SMP;
+                perf->pdc = obj_list;
+        }
+        return;
+}
+
+
+static int
+acpi_cpufreq_cpu_init (
+        struct cpufreq_policy   *policy)
+{
+        unsigned int            i;
+        unsigned int            cpu = policy->cpu;
+        struct cpufreq_acpi_io  *data;
+        unsigned int            result = 0;
+
+        union acpi_object               arg0 = {ACPI_TYPE_BUFFER};
+        u32                             arg0_buf[3];
+        struct acpi_object_list         arg_list = {1, &arg0};
+
+        dprintk("acpi_cpufreq_cpu_init\n");
+        /* setup arg_list for _PDC settings */
+        arg0.buffer.length = 12;
+        arg0.buffer.pointer = (u8 *) arg0_buf;
+
+        data = kmalloc(sizeof(struct cpufreq_acpi_io), GFP_KERNEL);
+        if (!data)
+                return (-ENOMEM);
+
+        memset(data, 0, sizeof(struct cpufreq_acpi_io));
+
+        acpi_io_data[cpu] = data;
+
+        processor_init_pdc(&data->acpi_data, cpu, &arg_list);
+        result = acpi_processor_register_performance(&data->acpi_data, cpu);
+        data->acpi_data.pdc = NULL;
+
+        if (result)
+                goto err_free;
+
+        /* capability check */
+        if (data->acpi_data.state_count <= 1) {
+                dprintk("No P-States\n");
+                result = -ENODEV;
+                goto err_unreg;
+        }
+
+        if ((data->acpi_data.control_register.space_id !=
+                                        ACPI_ADR_SPACE_FIXED_HARDWARE) ||
+            (data->acpi_data.status_register.space_id !=
+                                        ACPI_ADR_SPACE_FIXED_HARDWARE)) {
+                dprintk("Unsupported address space [%d, %d]\n",
+                        (u32) (data->acpi_data.control_register.space_id),
+                        (u32) (data->acpi_data.status_register.space_id));
+                result = -ENODEV;
+                goto err_unreg;
+        }
+
+        /* alloc freq_table */
+        data->freq_table = kmalloc(sizeof(struct cpufreq_frequency_table) *
+                                   (data->acpi_data.state_count + 1),
+                                   GFP_KERNEL);
+        if (!data->freq_table) {
+                result = -ENOMEM;
+                goto err_unreg;
+        }
+
+        /* detect transition latency */
+        policy->cpuinfo.transition_latency = 0;
+        for (i=0; i<data->acpi_data.state_count; i++) {
+                if ((data->acpi_data.states[i].transition_latency * 1000) >
+                    policy->cpuinfo.transition_latency) {
+                        policy->cpuinfo.transition_latency =
+                            data->acpi_data.states[i].transition_latency * 1000;
+                }
+        }
+        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
+
+        policy->cur = processor_get_freq(data, policy->cpu);
+
+        /* table init */
+        for (i = 0; i <= data->acpi_data.state_count; i++)
+        {
+                data->freq_table[i].index = i;
+                if (i < data->acpi_data.state_count) {
+                        data->freq_table[i].frequency =
+                              data->acpi_data.states[i].core_frequency * 1000;
+                } else {
+                        data->freq_table[i].frequency = CPUFREQ_TABLE_END;
+                }
+        }
+
+        result = cpufreq_frequency_table_cpuinfo(policy, data->freq_table);
+        if (result) {
+                goto err_freqfree;
+        }
+
+        /* notify BIOS that we exist */
+        acpi_processor_notify_smm(THIS_MODULE);
+
+        printk(KERN_INFO "acpi-cpufreq: CPU%u - ACPI performance management "
+               "activated.\n", cpu);
+
+        for (i = 0; i < data->acpi_data.state_count; i++)
+                dprintk("     %cP%d: %d MHz, %d mW, %d uS, %d uS, 0x%x 0x%x\n",
+                        (i == data->acpi_data.state?'*':' '), i,
+                        (u32) data->acpi_data.states[i].core_frequency,
+                        (u32) data->acpi_data.states[i].power,
+                        (u32) data->acpi_data.states[i].transition_latency,
+                        (u32) data->acpi_data.states[i].bus_master_latency,
+                        (u32) data->acpi_data.states[i].status,
+                        (u32) data->acpi_data.states[i].control);
+
+        cpufreq_frequency_table_get_attr(data->freq_table, policy->cpu);
+
+        /* the first call to ->target() should result in us actually
+         * writing something to the appropriate registers. */
+        data->resume = 1;
+
+        return (result);
+
+ err_freqfree:
+        kfree(data->freq_table);
+ err_unreg:
+        acpi_processor_unregister_performance(&data->acpi_data, cpu);
+ err_free:
+        kfree(data);
+        acpi_io_data[cpu] = NULL;
+
+        return (result);
+}
+
+
+static int
+acpi_cpufreq_cpu_exit (
+        struct cpufreq_policy   *policy)
+{
+        struct cpufreq_acpi_io *data = acpi_io_data[policy->cpu];
+
+        dprintk("acpi_cpufreq_cpu_exit\n");
+
+        if (data) {
+                cpufreq_frequency_table_put_attr(policy->cpu);
+                acpi_io_data[policy->cpu] = NULL;
+                acpi_processor_unregister_performance(&data->acpi_data,
+                                                      policy->cpu);
+                kfree(data);
+        }
+
+        return (0);
+}
+
+
+static struct freq_attr* acpi_cpufreq_attr[] = {
+        &cpufreq_freq_attr_scaling_available_freqs,
+        NULL,
+};
+
+
+static struct cpufreq_driver acpi_cpufreq_driver = {
+        .verify         = acpi_cpufreq_verify,
+        .target         = acpi_cpufreq_target,
+        .get            = acpi_cpufreq_get,
+        .init           = acpi_cpufreq_cpu_init,
+        .exit           = acpi_cpufreq_cpu_exit,
+        .name           = "acpi-cpufreq",
+        .owner          = THIS_MODULE,
+        .attr           = acpi_cpufreq_attr,
+};
+
+
+static int __init
+acpi_cpufreq_init (void)
+{
+        dprintk("acpi_cpufreq_init\n");
+
+        return cpufreq_register_driver(&acpi_cpufreq_driver);
+}
+
+
+static void __exit
+acpi_cpufreq_exit (void)
+{
+        dprintk("acpi_cpufreq_exit\n");
+
+        cpufreq_unregister_driver(&acpi_cpufreq_driver);
+        return;
+}
+
+
+late_initcall(acpi_cpufreq_init);
+module_exit(acpi_cpufreq_exit);
+
diff --git a/include/asm-ia64/acpi.h b/include/asm-ia64/acpi.h
index 4c06d455139..3a544ffc500 100644
--- a/include/asm-ia64/acpi.h
+++ b/include/asm-ia64/acpi.h
@@ -116,6 +116,11 @@ extern int __initdata nid_to_pxm_map[MAX_NUMNODES];
 
 extern u16 ia64_acpiid_to_sapicid[];
 
+/*
+ * Refer Intel ACPI _PDC support document for bit definitions
+ */
+#define ACPI_PDC_EST_CAPABILITY_SMP     0x8
+
 #endif /*__KERNEL__*/
 
 #endif /*_ASM_ACPI_H*/
diff --git a/include/asm-ia64/pal.h b/include/asm-ia64/pal.h
index 2303a10ee59..e828377ad29 100644
--- a/include/asm-ia64/pal.h
+++ b/include/asm-ia64/pal.h
@@ -75,6 +75,8 @@
 #define PAL_CACHE_READ          259     /* read tag & data of cacheline for diagnostic testing */
 #define PAL_CACHE_WRITE         260     /* write tag & data of cacheline for diagnostic testing */
 #define PAL_VM_TR_READ          261     /* read contents of translation register */
+#define PAL_GET_PSTATE          262     /* get the current P-state */
+#define PAL_SET_PSTATE          263     /* set the P-state */
 
 #ifndef __ASSEMBLY__
 
@@ -1111,6 +1113,25 @@ ia64_pal_halt_info (pal_power_mgmt_info_u_t *power_buf)
         return iprv.status;
 }
 
+/* Get the current P-state information */
+static inline s64
+ia64_pal_get_pstate (u64 *pstate_index)
+{
+        struct ia64_pal_retval iprv;
+        PAL_CALL_STK(iprv, PAL_GET_PSTATE, 0, 0, 0);
+        *pstate_index = iprv.v0;
+        return iprv.status;
+}
+
+/* Set the P-state */
+static inline s64
+ia64_pal_set_pstate (u64 pstate_index)
+{
+        struct ia64_pal_retval iprv;
+        PAL_CALL_STK(iprv, PAL_SET_PSTATE, pstate_index, 0, 0);
+        return iprv.status;
+}
+
 /* Cause the processor to enter LIGHT HALT state, where prefetching and execution are
  * suspended, but cache and TLB coherency is maintained.
  */