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![David Howells](/assets/img/avatar_default.png)
When the kernel is running in secure boot mode, we lock down the kernel to prevent userspace from modifying the running kernel image. Whilst this includes prohibiting access to things like /dev/mem, it must also prevent access by means of configuring driver modules in such a way as to cause a device to access or modify the kernel image. To this end, annotate module_param* statements that refer to hardware configuration and indicate for future reference what type of parameter they specify. The parameter parser in the core sees this information and can skip such parameters with an error message if the kernel is locked down. The module initialisation then runs as normal, but just sees whatever the default values for those parameters is. Note that we do still need to do the module initialisation because some drivers have viable defaults set in case parameters aren't specified and some drivers support automatic configuration (e.g. PNP or PCI) in addition to manually coded parameters. This patch annotates drivers in drivers/cpufreq/. Suggested-by: Alan Cox <gnomes@lxorguk.ukuu.org.uk> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: "Rafael J. Wysocki" <rjw@rjwysocki.net> Acked-by: Viresh Kumar <viresh.kumar@linaro.org> cc: linux-pm@vger.kernel.org
397 lines
9.6 KiB
C
397 lines
9.6 KiB
C
/*
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* Intel SpeedStep SMI driver.
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*
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* (C) 2003 Hiroshi Miura <miura@da-cha.org>
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*
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* Licensed under the terms of the GNU GPL License version 2.
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*
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*/
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/*********************************************************************
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* SPEEDSTEP - DEFINITIONS *
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*********************************************************************/
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#define pr_fmt(fmt) "cpufreq: " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/delay.h>
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#include <linux/io.h>
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#include <asm/ist.h>
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#include <asm/cpu_device_id.h>
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#include "speedstep-lib.h"
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/* speedstep system management interface port/command.
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*
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* These parameters are got from IST-SMI BIOS call.
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* If user gives it, these are used.
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*
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*/
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static int smi_port;
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static int smi_cmd;
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static unsigned int smi_sig;
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/* info about the processor */
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static enum speedstep_processor speedstep_processor;
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/*
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* There are only two frequency states for each processor. Values
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* are in kHz for the time being.
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*/
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static struct cpufreq_frequency_table speedstep_freqs[] = {
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{0, SPEEDSTEP_HIGH, 0},
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{0, SPEEDSTEP_LOW, 0},
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{0, 0, CPUFREQ_TABLE_END},
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};
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#define GET_SPEEDSTEP_OWNER 0
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#define GET_SPEEDSTEP_STATE 1
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#define SET_SPEEDSTEP_STATE 2
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#define GET_SPEEDSTEP_FREQS 4
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/* how often shall the SMI call be tried if it failed, e.g. because
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* of DMA activity going on? */
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#define SMI_TRIES 5
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/**
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* speedstep_smi_ownership
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*/
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static int speedstep_smi_ownership(void)
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{
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u32 command, result, magic, dummy;
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u32 function = GET_SPEEDSTEP_OWNER;
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unsigned char magic_data[] = "Copyright (c) 1999 Intel Corporation";
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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magic = virt_to_phys(magic_data);
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pr_debug("trying to obtain ownership with command %x at port %x\n",
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command, smi_port);
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__asm__ __volatile__(
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"push %%ebp\n"
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"out %%al, (%%dx)\n"
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"pop %%ebp\n"
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: "=D" (result),
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"=a" (dummy), "=b" (dummy), "=c" (dummy), "=d" (dummy),
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"=S" (dummy)
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: "a" (command), "b" (function), "c" (0), "d" (smi_port),
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"D" (0), "S" (magic)
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: "memory"
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);
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pr_debug("result is %x\n", result);
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return result;
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}
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/**
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* speedstep_smi_get_freqs - get SpeedStep preferred & current freq.
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* @low: the low frequency value is placed here
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* @high: the high frequency value is placed here
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*
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* Only available on later SpeedStep-enabled systems, returns false results or
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* even hangs [cf. bugme.osdl.org # 1422] on earlier systems. Empirical testing
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* shows that the latter occurs if !(ist_info.event & 0xFFFF).
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*/
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static int speedstep_smi_get_freqs(unsigned int *low, unsigned int *high)
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{
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u32 command, result = 0, edi, high_mhz, low_mhz, dummy;
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u32 state = 0;
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u32 function = GET_SPEEDSTEP_FREQS;
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if (!(ist_info.event & 0xFFFF)) {
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pr_debug("bug #1422 -- can't read freqs from BIOS\n");
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return -ENODEV;
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}
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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pr_debug("trying to determine frequencies with command %x at port %x\n",
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command, smi_port);
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__asm__ __volatile__(
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"push %%ebp\n"
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"out %%al, (%%dx)\n"
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"pop %%ebp"
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: "=a" (result),
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"=b" (high_mhz),
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"=c" (low_mhz),
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"=d" (state), "=D" (edi), "=S" (dummy)
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: "a" (command),
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"b" (function),
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"c" (state),
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"d" (smi_port), "S" (0), "D" (0)
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);
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pr_debug("result %x, low_freq %u, high_freq %u\n",
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result, low_mhz, high_mhz);
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/* abort if results are obviously incorrect... */
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if ((high_mhz + low_mhz) < 600)
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return -EINVAL;
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*high = high_mhz * 1000;
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*low = low_mhz * 1000;
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return result;
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}
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/**
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* speedstep_set_state - set the SpeedStep state
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* @state: new processor frequency state (SPEEDSTEP_LOW or SPEEDSTEP_HIGH)
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*
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*/
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static void speedstep_set_state(unsigned int state)
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{
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unsigned int result = 0, command, new_state, dummy;
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unsigned long flags;
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unsigned int function = SET_SPEEDSTEP_STATE;
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unsigned int retry = 0;
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if (state > 0x1)
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return;
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/* Disable IRQs */
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preempt_disable();
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local_irq_save(flags);
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command = (smi_sig & 0xffffff00) | (smi_cmd & 0xff);
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pr_debug("trying to set frequency to state %u "
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"with command %x at port %x\n",
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state, command, smi_port);
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do {
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if (retry) {
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/*
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* We need to enable interrupts, otherwise the blockage
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* won't resolve.
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*
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* We disable preemption so that other processes don't
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* run. If other processes were running, they could
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* submit more DMA requests, making the blockage worse.
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*/
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pr_debug("retry %u, previous result %u, waiting...\n",
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retry, result);
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local_irq_enable();
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mdelay(retry * 50);
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local_irq_disable();
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}
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retry++;
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__asm__ __volatile__(
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"push %%ebp\n"
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"out %%al, (%%dx)\n"
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"pop %%ebp"
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: "=b" (new_state), "=D" (result),
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"=c" (dummy), "=a" (dummy),
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"=d" (dummy), "=S" (dummy)
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: "a" (command), "b" (function), "c" (state),
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"d" (smi_port), "S" (0), "D" (0)
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);
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} while ((new_state != state) && (retry <= SMI_TRIES));
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/* enable IRQs */
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local_irq_restore(flags);
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preempt_enable();
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if (new_state == state)
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pr_debug("change to %u MHz succeeded after %u tries "
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"with result %u\n",
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(speedstep_freqs[new_state].frequency / 1000),
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retry, result);
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else
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pr_err("change to state %u failed with new_state %u and result %u\n",
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state, new_state, result);
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return;
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}
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/**
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* speedstep_target - set a new CPUFreq policy
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* @policy: new policy
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* @index: index of new freq
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*
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* Sets a new CPUFreq policy/freq.
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*/
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static int speedstep_target(struct cpufreq_policy *policy, unsigned int index)
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{
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speedstep_set_state(index);
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return 0;
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}
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static int speedstep_cpu_init(struct cpufreq_policy *policy)
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{
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int result;
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unsigned int *low, *high;
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/* capability check */
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if (policy->cpu != 0)
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return -ENODEV;
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result = speedstep_smi_ownership();
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if (result) {
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pr_debug("fails in acquiring ownership of a SMI interface.\n");
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return -EINVAL;
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}
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/* detect low and high frequency */
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low = &speedstep_freqs[SPEEDSTEP_LOW].frequency;
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high = &speedstep_freqs[SPEEDSTEP_HIGH].frequency;
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result = speedstep_smi_get_freqs(low, high);
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if (result) {
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/* fall back to speedstep_lib.c dection mechanism:
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* try both states out */
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pr_debug("could not detect low and high frequencies "
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"by SMI call.\n");
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result = speedstep_get_freqs(speedstep_processor,
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low, high,
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NULL,
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&speedstep_set_state);
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if (result) {
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pr_debug("could not detect two different speeds"
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" -- aborting.\n");
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return result;
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} else
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pr_debug("workaround worked.\n");
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}
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policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
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return cpufreq_table_validate_and_show(policy, speedstep_freqs);
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}
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static unsigned int speedstep_get(unsigned int cpu)
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{
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if (cpu)
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return -ENODEV;
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return speedstep_get_frequency(speedstep_processor);
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}
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static int speedstep_resume(struct cpufreq_policy *policy)
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{
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int result = speedstep_smi_ownership();
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if (result)
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pr_debug("fails in re-acquiring ownership of a SMI interface.\n");
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return result;
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}
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static struct cpufreq_driver speedstep_driver = {
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.name = "speedstep-smi",
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = speedstep_target,
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.init = speedstep_cpu_init,
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.get = speedstep_get,
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.resume = speedstep_resume,
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.attr = cpufreq_generic_attr,
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};
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static const struct x86_cpu_id ss_smi_ids[] = {
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{ X86_VENDOR_INTEL, 6, 0xb, },
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{ X86_VENDOR_INTEL, 6, 0x8, },
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{ X86_VENDOR_INTEL, 15, 2 },
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{}
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};
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#if 0
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/* Not auto loaded currently */
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MODULE_DEVICE_TABLE(x86cpu, ss_smi_ids);
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#endif
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/**
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* speedstep_init - initializes the SpeedStep CPUFreq driver
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*
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* Initializes the SpeedStep support. Returns -ENODEV on unsupported
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* BIOS, -EINVAL on problems during initiatization, and zero on
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* success.
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*/
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static int __init speedstep_init(void)
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{
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if (!x86_match_cpu(ss_smi_ids))
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return -ENODEV;
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speedstep_processor = speedstep_detect_processor();
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switch (speedstep_processor) {
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case SPEEDSTEP_CPU_PIII_T:
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case SPEEDSTEP_CPU_PIII_C:
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case SPEEDSTEP_CPU_PIII_C_EARLY:
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break;
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default:
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speedstep_processor = 0;
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}
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if (!speedstep_processor) {
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pr_debug("No supported Intel CPU detected.\n");
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return -ENODEV;
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}
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pr_debug("signature:0x%.8x, command:0x%.8x, "
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"event:0x%.8x, perf_level:0x%.8x.\n",
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ist_info.signature, ist_info.command,
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ist_info.event, ist_info.perf_level);
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/* Error if no IST-SMI BIOS or no PARM
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sig= 'ISGE' aka 'Intel Speedstep Gate E' */
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if ((ist_info.signature != 0x47534943) && (
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(smi_port == 0) || (smi_cmd == 0)))
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return -ENODEV;
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if (smi_sig == 1)
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smi_sig = 0x47534943;
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else
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smi_sig = ist_info.signature;
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/* setup smi_port from MODLULE_PARM or BIOS */
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if ((smi_port > 0xff) || (smi_port < 0))
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return -EINVAL;
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else if (smi_port == 0)
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smi_port = ist_info.command & 0xff;
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if ((smi_cmd > 0xff) || (smi_cmd < 0))
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return -EINVAL;
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else if (smi_cmd == 0)
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smi_cmd = (ist_info.command >> 16) & 0xff;
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return cpufreq_register_driver(&speedstep_driver);
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}
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/**
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* speedstep_exit - unregisters SpeedStep support
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*
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* Unregisters SpeedStep support.
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*/
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static void __exit speedstep_exit(void)
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{
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cpufreq_unregister_driver(&speedstep_driver);
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}
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module_param_hw(smi_port, int, ioport, 0444);
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module_param(smi_cmd, int, 0444);
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module_param(smi_sig, uint, 0444);
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MODULE_PARM_DESC(smi_port, "Override the BIOS-given IST port with this value "
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"-- Intel's default setting is 0xb2");
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MODULE_PARM_DESC(smi_cmd, "Override the BIOS-given IST command with this value "
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"-- Intel's default setting is 0x82");
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MODULE_PARM_DESC(smi_sig, "Set to 1 to fake the IST signature when using the "
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"SMI interface.");
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MODULE_AUTHOR("Hiroshi Miura");
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MODULE_DESCRIPTION("Speedstep driver for IST applet SMI interface.");
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MODULE_LICENSE("GPL");
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module_init(speedstep_init);
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module_exit(speedstep_exit);
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