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linux/drivers/cpufreq/gx-suspmod.c
Rafael J. Wysocki 1e4f63aecb cpufreq: Avoid creating excessively large stack frames 
In the process of modifying a cpufreq policy, the cpufreq core makes
a copy of it including all of the internals which is stored on the
CPU stack.  Because struct cpufreq_policy is relatively large, this
may cause the size of the stack frame to exceed the 2 KB limit and
so the GCC complains when -Wframe-larger-than= is used.

In fact, it is not necessary to copy the entire policy structure
in order to modify it, however.

First, because cpufreq_set_policy() obtains the min and max policy
limits from frequency QoS now, it is not necessary to pass the limits
to it from the callers.  The only things that need to be passed to it
from there are the new governor pointer or (if there is a built-in
governor in the driver) the "policy" value representing the governor
choice.  They both can be passed as individual arguments, though, so
make cpufreq_set_policy() take them this way and rework its callers
accordingly.  This avoids making copies of cpufreq policies in the
callers of cpufreq_set_policy().

Second, cpufreq_set_policy() still needs to pass the new policy
data to the ->verify() callback of the cpufreq driver whose task
is to sanitize the min and max policy limits.  It still does not
need to make a full copy of struct cpufreq_policy for this purpose,
but it needs to pass a few items from it to the driver in case they
are needed (different drivers have different needs in that respect
and all of them have to be covered).  For this reason, introduce
struct cpufreq_policy_data to hold copies of the members of
struct cpufreq_policy used by the existing ->verify() driver
callbacks and pass a pointer to a temporary structure of that
type to ->verify() (instead of passing a pointer to full struct
cpufreq_policy to it).

While at it, notice that intel_pstate and longrun don't really need
to verify the "policy" value in struct cpufreq_policy, so drop those
check from them to avoid copying "policy" into struct
cpufreq_policy_data (which allows it to be slightly smaller).

Also while at it fix up white space in a couple of places and make
cpufreq_set_policy() static (as it can be so).

Fixes: 3000ce3c52 ("cpufreq: Use per-policy frequency QoS")
Link: https://lore.kernel.org/linux-pm/CAMuHMdX6-jb1W8uC2_237m8ctCpsnGp=JCxqt8pCWVqNXHmkVg@mail.gmail.com
Reported-by: kbuild test robot <lkp@intel.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: 5.4+ <stable@vger.kernel.org> # 5.4+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
2020-01-27 10:33:33 +01:00

499 lines
14 KiB
C
Raw Blame History

// SPDX-License-Identifier: GPL-2.0-only
/*
* Cyrix MediaGX and NatSemi Geode Suspend Modulation
* (C) 2002 Zwane Mwaikambo <zwane@commfireservices.com>
* (C) 2002 Hiroshi Miura <miura@da-cha.org>
* All Rights Reserved
*
* The author(s) of this software shall not be held liable for damages
* of any nature resulting due to the use of this software. This
* software is provided AS-IS with no warranties.
*
* Theoretical note:
*
* (see Geode(tm) CS5530 manual (rev.4.1) page.56)
*
* CPU frequency control on NatSemi Geode GX1/GXLV processor and CS55x0
* are based on Suspend Modulation.
*
* Suspend Modulation works by asserting and de-asserting the SUSP# pin
* to CPU(GX1/GXLV) for configurable durations. When asserting SUSP#
* the CPU enters an idle state. GX1 stops its core clock when SUSP# is
* asserted then power consumption is reduced.
*
* Suspend Modulation's OFF/ON duration are configurable
* with 'Suspend Modulation OFF Count Register'
* and 'Suspend Modulation ON Count Register'.
* These registers are 8bit counters that represent the number of
* 32us intervals which the SUSP# pin is asserted(ON)/de-asserted(OFF)
* to the processor.
*
* These counters define a ratio which is the effective frequency
* of operation of the system.
*
* OFF Count
* F_eff = Fgx * ----------------------
* OFF Count + ON Count
*
* 0 <= On Count, Off Count <= 255
*
* From these limits, we can get register values
*
* off_duration + on_duration <= MAX_DURATION
* on_duration = off_duration * (stock_freq - freq) / freq
*
* off_duration = (freq * DURATION) / stock_freq
* on_duration = DURATION - off_duration
*
*---------------------------------------------------------------------------
*
* ChangeLog:
* Dec. 12, 2003 Hiroshi Miura <miura@da-cha.org>
* - fix on/off register mistake
* - fix cpu_khz calc when it stops cpu modulation.
*
* Dec. 11, 2002 Hiroshi Miura <miura@da-cha.org>
* - rewrite for Cyrix MediaGX Cx5510/5520 and
* NatSemi Geode Cs5530(A).
*
* Jul. ??, 2002 Zwane Mwaikambo <zwane@commfireservices.com>
* - cs5530_mod patch for 2.4.19-rc1.
*
*---------------------------------------------------------------------------
*
* Todo
* Test on machines with 5510, 5530, 5530A
*/
/************************************************************************
* Suspend Modulation - Definitions *
************************************************************************/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/cpufreq.h>
#include <linux/pci.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <asm/cpu_device_id.h>
#include <asm/processor-cyrix.h>
/* PCI config registers, all at F0 */
#define PCI_PMER1 0x80 /* power management enable register 1 */
#define PCI_PMER2 0x81 /* power management enable register 2 */
#define PCI_PMER3 0x82 /* power management enable register 3 */
#define PCI_IRQTC 0x8c /* irq speedup timer counter register:typical 2 to 4ms */
#define PCI_VIDTC 0x8d /* video speedup timer counter register: typical 50 to 100ms */
#define PCI_MODOFF 0x94 /* suspend modulation OFF counter register, 1 = 32us */
#define PCI_MODON 0x95 /* suspend modulation ON counter register */
#define PCI_SUSCFG 0x96 /* suspend configuration register */
/* PMER1 bits */
#define GPM (1<<0) /* global power management */
#define GIT (1<<1) /* globally enable PM device idle timers */
#define GTR (1<<2) /* globally enable IO traps */
#define IRQ_SPDUP (1<<3) /* disable clock throttle during interrupt handling */
#define VID_SPDUP (1<<4) /* disable clock throttle during vga video handling */
/* SUSCFG bits */
#define SUSMOD (1<<0) /* enable/disable suspend modulation */
/* the below is supported only with cs5530 (after rev.1.2)/cs5530A */
#define SMISPDUP (1<<1) /* select how SMI re-enable suspend modulation: */
/* IRQTC timer or read SMI speedup disable reg.(F1BAR[08-09h]) */
#define SUSCFG (1<<2) /* enable powering down a GXLV processor. "Special 3Volt Suspend" mode */
/* the below is supported only with cs5530A */
#define PWRSVE_ISA (1<<3) /* stop ISA clock */
#define PWRSVE (1<<4) /* active idle */
struct gxfreq_params {
u8 on_duration;
u8 off_duration;
u8 pci_suscfg;
u8 pci_pmer1;
u8 pci_pmer2;
struct pci_dev *cs55x0;
};
static struct gxfreq_params *gx_params;
static int stock_freq;
/* PCI bus clock - defaults to 30.000 if cpu_khz is not available */
static int pci_busclk;
module_param(pci_busclk, int, 0444);
/* maximum duration for which the cpu may be suspended
* (32us * MAX_DURATION). If no parameter is given, this defaults
* to 255.
* Note that this leads to a maximum of 8 ms(!) where the CPU clock
* is suspended -- processing power is just 0.39% of what it used to be,
* though. 781.25 kHz(!) for a 200 MHz processor -- wow. */
static int max_duration = 255;
module_param(max_duration, int, 0444);
/* For the default policy, we want at least some processing power
* - let's say 5%. (min = maxfreq / POLICY_MIN_DIV)
*/
#define POLICY_MIN_DIV 20
/**
* we can detect a core multiplier from dir0_lsb
* from GX1 datasheet p.56,
* MULT[3:0]:
* 0000 = SYSCLK multiplied by 4 (test only)
* 0001 = SYSCLK multiplied by 10
* 0010 = SYSCLK multiplied by 4
* 0011 = SYSCLK multiplied by 6
* 0100 = SYSCLK multiplied by 9
* 0101 = SYSCLK multiplied by 5
* 0110 = SYSCLK multiplied by 7
* 0111 = SYSCLK multiplied by 8
* of 33.3MHz
**/
static int gx_freq_mult[16] = {
4, 10, 4, 6, 9, 5, 7, 8,
0, 0, 0, 0, 0, 0, 0, 0
};
/****************************************************************
* Low Level chipset interface *
****************************************************************/
static struct pci_device_id gx_chipset_tbl[] __initdata = {
{ PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY), },
{ PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5520), },
{ PCI_VDEVICE(CYRIX, PCI_DEVICE_ID_CYRIX_5510), },
{ 0, },
};
MODULE_DEVICE_TABLE(pci, gx_chipset_tbl);
static void gx_write_byte(int reg, int value)
{
pci_write_config_byte(gx_params->cs55x0, reg, value);
}
/**
* gx_detect_chipset:
*
**/
static struct pci_dev * __init gx_detect_chipset(void)
{
struct pci_dev *gx_pci = NULL;
/* detect which companion chip is used */
for_each_pci_dev(gx_pci) {
if ((pci_match_id(gx_chipset_tbl, gx_pci)) != NULL)
return gx_pci;
}
pr_debug("error: no supported chipset found!\n");
return NULL;
}
/**
* gx_get_cpuspeed:
*
* Finds out at which efficient frequency the Cyrix MediaGX/NatSemi
* Geode CPU runs.
*/
static unsigned int gx_get_cpuspeed(unsigned int cpu)
{
if ((gx_params->pci_suscfg & SUSMOD) == 0)
return stock_freq;
return (stock_freq * gx_params->off_duration)
/ (gx_params->on_duration + gx_params->off_duration);
}
/**
* gx_validate_speed:
* determine current cpu speed
*
**/
static unsigned int gx_validate_speed(unsigned int khz, u8 *on_duration,
u8 *off_duration)
{
unsigned int i;
u8 tmp_on, tmp_off;
int old_tmp_freq = stock_freq;
int tmp_freq;
*off_duration = 1;
*on_duration = 0;
for (i = max_duration; i > 0; i--) {
tmp_off = ((khz * i) / stock_freq) & 0xff;
tmp_on = i - tmp_off;
tmp_freq = (stock_freq * tmp_off) / i;
/* if this relation is closer to khz, use this. If it's equal,
* prefer it, too - lower latency */
if (abs(tmp_freq - khz) <= abs(old_tmp_freq - khz)) {
*on_duration = tmp_on;
*off_duration = tmp_off;
old_tmp_freq = tmp_freq;
}
}
return old_tmp_freq;
}
/**
* gx_set_cpuspeed:
* set cpu speed in khz.
**/
static void gx_set_cpuspeed(struct cpufreq_policy *policy, unsigned int khz)
{
u8 suscfg, pmer1;
unsigned int new_khz;
unsigned long flags;
struct cpufreq_freqs freqs;
freqs.old = gx_get_cpuspeed(0);
new_khz = gx_validate_speed(khz, &gx_params->on_duration,
&gx_params->off_duration);
freqs.new = new_khz;
cpufreq_freq_transition_begin(policy, &freqs);
local_irq_save(flags);
if (new_khz != stock_freq) {
/* if new khz == 100% of CPU speed, it is special case */
switch (gx_params->cs55x0->device) {
case PCI_DEVICE_ID_CYRIX_5530_LEGACY:
pmer1 = gx_params->pci_pmer1 | IRQ_SPDUP | VID_SPDUP;
/* FIXME: need to test other values -- Zwane,Miura */
/* typical 2 to 4ms */
gx_write_byte(PCI_IRQTC, 4);
/* typical 50 to 100ms */
gx_write_byte(PCI_VIDTC, 100);
gx_write_byte(PCI_PMER1, pmer1);
if (gx_params->cs55x0->revision < 0x10) {
/* CS5530(rev 1.2, 1.3) */
suscfg = gx_params->pci_suscfg|SUSMOD;
} else {
/* CS5530A,B.. */
suscfg = gx_params->pci_suscfg|SUSMOD|PWRSVE;
}
break;
case PCI_DEVICE_ID_CYRIX_5520:
case PCI_DEVICE_ID_CYRIX_5510:
suscfg = gx_params->pci_suscfg | SUSMOD;
break;
default:
local_irq_restore(flags);
pr_debug("fatal: try to set unknown chipset.\n");
return;
}
} else {
suscfg = gx_params->pci_suscfg & ~(SUSMOD);
gx_params->off_duration = 0;
gx_params->on_duration = 0;
pr_debug("suspend modulation disabled: cpu runs 100%% speed.\n");
}
gx_write_byte(PCI_MODOFF, gx_params->off_duration);
gx_write_byte(PCI_MODON, gx_params->on_duration);
gx_write_byte(PCI_SUSCFG, suscfg);
pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &suscfg);
local_irq_restore(flags);
gx_params->pci_suscfg = suscfg;
cpufreq_freq_transition_end(policy, &freqs, 0);
pr_debug("suspend modulation w/ duration of ON:%d us, OFF:%d us\n",
gx_params->on_duration * 32, gx_params->off_duration * 32);
pr_debug("suspend modulation w/ clock speed: %d kHz.\n", freqs.new);
}
/****************************************************************
* High level functions *
****************************************************************/
/*
* cpufreq_gx_verify: test if frequency range is valid
*
* This function checks if a given frequency range in kHz is valid
* for the hardware supported by the driver.
*/
static int cpufreq_gx_verify(struct cpufreq_policy_data *policy)
{
unsigned int tmp_freq = 0;
u8 tmp1, tmp2;
if (!stock_freq || !policy)
return -EINVAL;
policy->cpu = 0;
cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
stock_freq);
/* it needs to be assured that at least one supported frequency is
* within policy->min and policy->max. If it is not, policy->max
* needs to be increased until one frequency is supported.
* policy->min may not be decreased, though. This way we guarantee a
* specific processing capacity.
*/
tmp_freq = gx_validate_speed(policy->min, &tmp1, &tmp2);
if (tmp_freq < policy->min)
tmp_freq += stock_freq / max_duration;
policy->min = tmp_freq;
if (policy->min > policy->max)
policy->max = tmp_freq;
tmp_freq = gx_validate_speed(policy->max, &tmp1, &tmp2);
if (tmp_freq > policy->max)
tmp_freq -= stock_freq / max_duration;
policy->max = tmp_freq;
if (policy->max < policy->min)
policy->max = policy->min;
cpufreq_verify_within_limits(policy, (stock_freq / max_duration),
stock_freq);
return 0;
}
/*
* cpufreq_gx_target:
*
*/
static int cpufreq_gx_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
u8 tmp1, tmp2;
unsigned int tmp_freq;
if (!stock_freq || !policy)
return -EINVAL;
policy->cpu = 0;
tmp_freq = gx_validate_speed(target_freq, &tmp1, &tmp2);
while (tmp_freq < policy->min) {
tmp_freq += stock_freq / max_duration;
tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
}
while (tmp_freq > policy->max) {
tmp_freq -= stock_freq / max_duration;
tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
}
gx_set_cpuspeed(policy, tmp_freq);
return 0;
}
static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)
{
unsigned int maxfreq;
if (!policy || policy->cpu != 0)
return -ENODEV;
/* determine maximum frequency */
if (pci_busclk)
maxfreq = pci_busclk * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
else if (cpu_khz)
maxfreq = cpu_khz;
else
maxfreq = 30000 * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f];
stock_freq = maxfreq;
pr_debug("cpu max frequency is %d.\n", maxfreq);
/* setup basic struct for cpufreq API */
policy->cpu = 0;
if (max_duration < POLICY_MIN_DIV)
policy->min = maxfreq / max_duration;
else
policy->min = maxfreq / POLICY_MIN_DIV;
policy->max = maxfreq;
policy->cpuinfo.min_freq = maxfreq / max_duration;
policy->cpuinfo.max_freq = maxfreq;
return 0;
}
/*
* cpufreq_gx_init:
* MediaGX/Geode GX initialize cpufreq driver
*/
static struct cpufreq_driver gx_suspmod_driver = {
.flags = CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING,
.get = gx_get_cpuspeed,
.verify = cpufreq_gx_verify,
.target = cpufreq_gx_target,
.init = cpufreq_gx_cpu_init,
.name = "gx-suspmod",
};
static int __init cpufreq_gx_init(void)
{
int ret;
struct gxfreq_params *params;
struct pci_dev *gx_pci;
/* Test if we have the right hardware */
gx_pci = gx_detect_chipset();
if (gx_pci == NULL)
return -ENODEV;
/* check whether module parameters are sane */
if (max_duration > 0xff)
max_duration = 0xff;
pr_debug("geode suspend modulation available.\n");
params = kzalloc(sizeof(*params), GFP_KERNEL);
if (params == NULL)
return -ENOMEM;
params->cs55x0 = gx_pci;
gx_params = params;
/* keep cs55x0 configurations */
pci_read_config_byte(params->cs55x0, PCI_SUSCFG, &(params->pci_suscfg));
pci_read_config_byte(params->cs55x0, PCI_PMER1, &(params->pci_pmer1));
pci_read_config_byte(params->cs55x0, PCI_PMER2, &(params->pci_pmer2));
pci_read_config_byte(params->cs55x0, PCI_MODON, &(params->on_duration));
pci_read_config_byte(params->cs55x0, PCI_MODOFF,
&(params->off_duration));
ret = cpufreq_register_driver(&gx_suspmod_driver);
if (ret) {
kfree(params);
return ret; /* register error! */
}
return 0;
}
static void __exit cpufreq_gx_exit(void)
{
cpufreq_unregister_driver(&gx_suspmod_driver);
pci_dev_put(gx_params->cs55x0);
kfree(gx_params);
}
MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
MODULE_DESCRIPTION("Cpufreq driver for Cyrix MediaGX and NatSemi Geode");
MODULE_LICENSE("GPL");
module_init(cpufreq_gx_init);
module_exit(cpufreq_gx_exit);
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