/* * 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 _COMPONENT ACPI_PROCESSOR_COMPONENT ACPI_MODULE_NAME("processor_throttling"); /* -------------------------------------------------------------------------- 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; if (!pr) return -EINVAL; if (!pr->flags.throttling) return -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 0; } int acpi_processor_set_throttling(struct acpi_processor *pr, int state) { u32 value = 0; u32 duty_mask = 0; u32 duty_value = 0; if (!pr) return -EINVAL; if ((state < 0) || (state > (pr->throttling.state_count - 1))) return -EINVAL; if (!pr->flags.throttling) return -ENODEV; if (state == pr->throttling.state) return 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_gbl_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 0; } int acpi_processor_get_throttling_info(struct acpi_processor *pr) { int result = 0; int step = 0; int i = 0; 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 -EINVAL; /* TBD: Support ACPI 2.0 objects */ if (!pr->throttling.address) { ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling register\n")); return 0; } else if (!pr->throttling.duty_width) { ACPI_DEBUG_PRINT((ACPI_DB_INFO, "No throttling states\n")); return 0; } /* TBD: Support duty_cycle values that span bit 4. */ else if ((pr->throttling.duty_offset + pr->throttling.duty_width) > 4) { printk(KERN_WARNING PREFIX "duty_cycle spans bit 4\n"); return 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 0; } pr->throttling.state_count = 1 << acpi_gbl_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 result; } /* proc interface */ static int acpi_processor_throttling_seq_show(struct seq_file *seq, void *offset) { struct acpi_processor *pr = seq->private; int i = 0; int result = 0; 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 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); } static 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 = file->private_data; struct acpi_processor *pr = m->private; char state_string[12] = { '\0' }; if (!pr || (count > sizeof(state_string) - 1)) return -EINVAL; if (copy_from_user(state_string, buffer, count)) return -EFAULT; state_string[count] = '\0'; result = acpi_processor_set_throttling(pr, simple_strtoul(state_string, NULL, 0)); if (result) return result; return count; } struct file_operations acpi_processor_throttling_fops = { .open = acpi_processor_throttling_open_fs, .read = seq_read, .write = acpi_processor_write_throttling, .llseek = seq_lseek, .release = single_release, };