// 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);