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path: root/drivers/acpi/processor_throttling.c
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Diffstat (limited to 'drivers/acpi/processor_throttling.c')
-rw-r--r--drivers/acpi/processor_throttling.c351
1 files changed, 351 insertions, 0 deletions
diff --git a/drivers/acpi/processor_throttling.c b/drivers/acpi/processor_throttling.c
new file mode 100644
index 00000000000..be9f569d39d
--- /dev/null
+++ b/drivers/acpi/processor_throttling.c
@@ -0,0 +1,351 @@
+/*
+ * processor_throttling.c - Throttling submodule of the ACPI processor driver
+ *
+ * Copyright (C) 2001, 2002 Andy Grover <andrew.grover@intel.com>
+ * Copyright (C) 2001, 2002 Paul Diefenbaugh <paul.s.diefenbaugh@intel.com>
+ * Copyright (C) 2004 Dominik Brodowski <linux@brodo.de>
+ * Copyright (C) 2004 Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
+ * - Added processor hotplug support
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * 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.
+ *
+ * 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. 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.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ */
+
+#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 <acpi/acpi_bus.h>
+#include <acpi/processor.h>
+
+#define ACPI_PROCESSOR_COMPONENT 0x01000000
+#define ACPI_PROCESSOR_CLASS "processor"
+#define ACPI_PROCESSOR_DRIVER_NAME "ACPI Processor Driver"
+#define _COMPONENT ACPI_PROCESSOR_COMPONENT
+ACPI_MODULE_NAME ("acpi_processor")
+
+
+/* --------------------------------------------------------------------------
+ Throttling Control
+ -------------------------------------------------------------------------- */
+
+static int
+acpi_processor_get_throttling (
+ struct acpi_processor *pr)
+{
+ int state = 0;
+ u32 value = 0;
+ u32 duty_mask = 0;
+ u32 duty_value = 0;
+
+ ACPI_FUNCTION_TRACE("acpi_processor_get_throttling");
+
+ if (!pr)
+ return_VALUE(-EINVAL);
+
+ if (!pr->flags.throttling)
+ return_VALUE(-ENODEV);
+
+ pr->throttling.state = 0;
+
+ duty_mask = pr->throttling.state_count - 1;
+
+ duty_mask <<= pr->throttling.duty_offset;
+
+ local_irq_disable();
+
+ value = inl(pr->throttling.address);
+
+ /*
+ * Compute the current throttling state when throttling is enabled
+ * (bit 4 is on).
+ */
+ if (value & 0x10) {
+ duty_value = value & duty_mask;
+ duty_value >>= pr->throttling.duty_offset;
+
+ if (duty_value)
+ state = pr->throttling.state_count-duty_value;
+ }
+
+ pr->throttling.state = state;
+
+ local_irq_enable();
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Throttling state is T%d (%d%% throttling applied)\n",
+ state, pr->throttling.states[state].performance));
+
+ return_VALUE(0);
+}
+
+
+int acpi_processor_set_throttling (
+ struct acpi_processor *pr,
+ int state)
+{
+ u32 value = 0;
+ u32 duty_mask = 0;
+ u32 duty_value = 0;
+
+ ACPI_FUNCTION_TRACE("acpi_processor_set_throttling");
+
+ if (!pr)
+ return_VALUE(-EINVAL);
+
+ if ((state < 0) || (state > (pr->throttling.state_count - 1)))
+ return_VALUE(-EINVAL);
+
+ if (!pr->flags.throttling)
+ return_VALUE(-ENODEV);
+
+ if (state == pr->throttling.state)
+ return_VALUE(0);
+
+ /*
+ * Calculate the duty_value and duty_mask.
+ */
+ if (state) {
+ duty_value = pr->throttling.state_count - state;
+
+ duty_value <<= pr->throttling.duty_offset;
+
+ /* Used to clear all duty_value bits */
+ duty_mask = pr->throttling.state_count - 1;
+
+ duty_mask <<= acpi_fadt.duty_offset;
+ duty_mask = ~duty_mask;
+ }
+
+ local_irq_disable();
+
+ /*
+ * Disable throttling by writing a 0 to bit 4. Note that we must
+ * turn it off before you can change the duty_value.
+ */
+ value = inl(pr->throttling.address);
+ if (value & 0x10) {
+ value &= 0xFFFFFFEF;
+ outl(value, pr->throttling.address);
+ }
+
+ /*
+ * Write the new duty_value and then enable throttling. Note
+ * that a state value of 0 leaves throttling disabled.
+ */
+ if (state) {
+ value &= duty_mask;
+ value |= duty_value;
+ outl(value, pr->throttling.address);
+
+ value |= 0x00000010;
+ outl(value, pr->throttling.address);
+ }
+
+ pr->throttling.state = state;
+
+ local_irq_enable();
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Throttling state set to T%d (%d%%)\n", state,
+ (pr->throttling.states[state].performance?pr->throttling.states[state].performance/10:0)));
+
+ return_VALUE(0);
+}
+
+
+int
+acpi_processor_get_throttling_info (
+ struct acpi_processor *pr)
+{
+ int result = 0;
+ int step = 0;
+ int i = 0;
+
+ ACPI_FUNCTION_TRACE("acpi_processor_get_throttling_info");
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "pblk_address[0x%08x] duty_offset[%d] duty_width[%d]\n",
+ pr->throttling.address,
+ pr->throttling.duty_offset,
+ pr->throttling.duty_width));
+
+ if (!pr)
+ return_VALUE(-EINVAL);
+
+ /* TBD: Support ACPI 2.0 objects */
+
+ if (!pr->throttling.address) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n"));
+ return_VALUE(0);
+ }
+ else if (!pr->throttling.duty_width) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n"));
+ return_VALUE(0);
+ }
+ /* TBD: Support duty_cycle values that span bit 4. */
+ else if ((pr->throttling.duty_offset
+ + pr->throttling.duty_width) > 4) {
+ ACPI_DEBUG_PRINT((ACPI_DB_WARN, "duty_cycle spans bit 4\n"));
+ return_VALUE(0);
+ }
+
+ /*
+ * PIIX4 Errata: We don't support throttling on the original PIIX4.
+ * This shouldn't be an issue as few (if any) mobile systems ever
+ * used this part.
+ */
+ if (errata.piix4.throttle) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "Throttling not supported on PIIX4 A- or B-step\n"));
+ return_VALUE(0);
+ }
+
+ pr->throttling.state_count = 1 << acpi_fadt.duty_width;
+
+ /*
+ * Compute state values. Note that throttling displays a linear power/
+ * performance relationship (at 50% performance the CPU will consume
+ * 50% power). Values are in 1/10th of a percent to preserve accuracy.
+ */
+
+ step = (1000 / pr->throttling.state_count);
+
+ for (i=0; i<pr->throttling.state_count; i++) {
+ pr->throttling.states[i].performance = step * i;
+ pr->throttling.states[i].power = step * i;
+ }
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Found %d throttling states\n",
+ pr->throttling.state_count));
+
+ pr->flags.throttling = 1;
+
+ /*
+ * Disable throttling (if enabled). We'll let subsequent policy (e.g.
+ * thermal) decide to lower performance if it so chooses, but for now
+ * we'll crank up the speed.
+ */
+
+ result = acpi_processor_get_throttling(pr);
+ if (result)
+ goto end;
+
+ if (pr->throttling.state) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Disabling throttling (was T%d)\n",
+ pr->throttling.state));
+ result = acpi_processor_set_throttling(pr, 0);
+ if (result)
+ goto end;
+ }
+
+end:
+ if (result)
+ pr->flags.throttling = 0;
+
+ return_VALUE(result);
+}
+
+
+/* proc interface */
+
+static int acpi_processor_throttling_seq_show(struct seq_file *seq, void *offset)
+{
+ struct acpi_processor *pr = (struct acpi_processor *)seq->private;
+ int i = 0;
+ int result = 0;
+
+ ACPI_FUNCTION_TRACE("acpi_processor_throttling_seq_show");
+
+ if (!pr)
+ goto end;
+
+ if (!(pr->throttling.state_count > 0)) {
+ seq_puts(seq, "<not supported>\n");
+ goto end;
+ }
+
+ result = acpi_processor_get_throttling(pr);
+
+ if (result) {
+ seq_puts(seq, "Could not determine current throttling state.\n");
+ goto end;
+ }
+
+ seq_printf(seq, "state count: %d\n"
+ "active state: T%d\n",
+ pr->throttling.state_count,
+ pr->throttling.state);
+
+ seq_puts(seq, "states:\n");
+ for (i = 0; i < pr->throttling.state_count; i++)
+ seq_printf(seq, " %cT%d: %02d%%\n",
+ (i == pr->throttling.state?'*':' '), i,
+ (pr->throttling.states[i].performance?pr->throttling.states[i].performance/10:0));
+
+end:
+ return_VALUE(0);
+}
+
+static int acpi_processor_throttling_open_fs(struct inode *inode, struct file *file)
+{
+ return single_open(file, acpi_processor_throttling_seq_show,
+ PDE(inode)->data);
+}
+
+ssize_t acpi_processor_write_throttling (
+ struct file *file,
+ const char __user *buffer,
+ size_t count,
+ loff_t *data)
+{
+ int result = 0;
+ struct seq_file *m = (struct seq_file *)file->private_data;
+ struct acpi_processor *pr = (struct acpi_processor *)m->private;
+ char state_string[12] = {'\0'};
+
+ ACPI_FUNCTION_TRACE("acpi_processor_write_throttling");
+
+ if (!pr || (count > sizeof(state_string) - 1))
+ return_VALUE(-EINVAL);
+
+ if (copy_from_user(state_string, buffer, count))
+ return_VALUE(-EFAULT);
+
+ state_string[count] = '\0';
+
+ result = acpi_processor_set_throttling(pr,
+ simple_strtoul(state_string, NULL, 0));
+ if (result)
+ return_VALUE(result);
+
+ return_VALUE(count);
+}
+
+struct file_operations acpi_processor_throttling_fops = {
+ .open = acpi_processor_throttling_open_fs,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = single_release,
+};
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