[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>

3 files changed, 529 insertions, 0 deletions

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);
+