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/*

 *      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

 *

 *      This program is free software; you can redistribute it and/or

 *      modify it under the terms of the GNU General Public License

 *      version 2 as published by the Free Software Foundation

 *

 *      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.

 *     

 * Theoritical 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 Moduration.

 *

 *      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/de-asserted to the

 *      processor.

 *

 *      These counters define a ratio which is the effective frequency

 *      of operation of the system.

 *

 *                             On Count

 *      F_eff = Fgx * ----------------------

 *                      On Count + Off Count

 *

 *      0 <= On Count, Off Count <= 255

 *

 *      From these limits, we can get register values

 *

 *      on_duration + off_duration <= MAX_DURATION

 *      off_duration = on_duration * (stock_freq - freq) / freq

 *

 *      on_duration  =  (freq * DURATION) / stock_freq

 *      off_duration = DURATION - on_duration

 *

 *

 *---------------------------------------------------------------------------

 *

 * ChangeLog:

 *      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 <linuxcomp.h>

#include <linux/kernel.h>

#include <linux/module.h> 

#include <linux/sched.h>

#include <linux/init.h>

#include <linux/smp.h>

#include <linux/cpufreq.h>

#include <linux/pci.h>

#include <asm/processor.h> 

#include <asm/errno.h>

extern struct cpuinfo_x86 new_cpu_data;

extern unsigned long cpu_khz;

/* 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 belows support 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 belows support 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;

        u8 pci_rev;

        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 = 0;

MODULE_PARM(pci_busclk, "i");

/* 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_PARM(max_duration, "i");

/* 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

/* DEBUG

 *   Define it if you want verbose debug output

 */

//#define SUSPMOD_DEBUG 1

#ifdef SUSPMOD_DEBUG

#define dprintk(msg...) printk(KERN_DEBUG "cpufreq:" msg)

#else

#define dprintk(msg...) do { } while(0)

#endif

/**

 *      we can detect a core multipiler 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_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5530_LEGACY, PCI_ANY_ID, PCI_ANY_ID },

        { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5520, PCI_ANY_ID, PCI_ANY_ID },

        { PCI_VENDOR_ID_CYRIX, PCI_DEVICE_ID_CYRIX_5510, PCI_ANY_ID, PCI_ANY_ID },

        { 0, },

};

/**

 *     gx_detect_chipset:

 *

 **/

static __init struct pci_dev *gx_detect_chipset(void)

{

        struct pci_dev *gx_pci = NULL;

        /* check if CPU is a MediaGX or a Geode. */

        if ((new_cpu_data.x86_vendor != X86_VENDOR_NSC) &&

            (new_cpu_data.x86_vendor != X86_VENDOR_CYRIX)) {

                dprintk(KERN_INFO "gx-suspmod: error: no MediaGX/Geode processor found!\n");

                return NULL;           

        }

        /* detect which companion chip is used */

        while ((gx_pci = pci_find_device(PCI_ANY_ID, PCI_ANY_ID, gx_pci)) != NULL) {

                if ((pci_match_device (gx_chipset_tbl, gx_pci)) != NULL) {

                        return gx_pci;

                }

        }

        dprintk(KERN_INFO "gx-suspmod: 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 int gx_get_cpuspeed(void)

{

        if ((gx_params->pci_suscfg & SUSMOD) == 0)

                return stock_freq;

        return (stock_freq * gx_params->on_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;

        *on_duration=1;

        *off_duration=0;

        for (i=max_duration; i>0; i--) {

                tmp_on = ((khz * i) / stock_freq) & 0xff;

                tmp_off = i - tmp_on;

                tmp_freq = (stock_freq * tmp_on) / 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(unsigned int khz)

{

        u8 suscfg, pmer1;

        unsigned int new_khz;

        unsigned long flags;

        struct cpufreq_freqs freqs;

        freqs.cpu = 0;

        freqs.old = gx_get_cpuspeed();

        new_khz = gx_validate_speed(khz, &gx_params->on_duration, &gx_params->off_duration);

        freqs.new = new_khz;

        if (new_khz == stock_freq) {  /* if new khz == 100% of CPU speed, it is special case */

                local_irq_save(flags);

                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

                pci_write_config_byte(gx_params->cs55x0, PCI_SUSCFG, (gx_params->pci_suscfg & ~(SUSMOD)));

                pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &(gx_params->pci_suscfg));

                local_irq_restore(flags);

                dprintk("suspend modulation disabled: cpu runs 100 percent speed.\n");

                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

                return;

        }

        cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

        local_irq_save(flags);

        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 */

                pci_write_config_byte(gx_params->cs55x0, PCI_IRQTC, 4); /* typical 2 to 4ms */

                pci_write_config_byte(gx_params->cs55x0, PCI_VIDTC, 100);/* typical 50 to 100ms */

                pci_write_config_byte(gx_params->cs55x0, PCI_PMER1, pmer1);

                if (gx_params->pci_rev < 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);

                dprintk("fatal: try to set unknown chipset.\n");

                return;

        }

        pci_write_config_byte(gx_params->cs55x0, PCI_MODOFF, gx_params->off_duration);

        pci_write_config_byte(gx_params->cs55x0, PCI_MODON, gx_params->on_duration);

        pci_write_config_byte(gx_params->cs55x0, PCI_SUSCFG, suscfg);

        pci_read_config_byte(gx_params->cs55x0, PCI_SUSCFG, &suscfg);

        local_irq_restore(flags);

        gx_params->pci_suscfg = suscfg;

        cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);

        dprintk("suspend modulation w/ duration of ON:%d us, OFF:%d us\n",

                gx_params->on_duration * 32, gx_params->off_duration * 32);

        dprintk("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 *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 freuqency 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(tmp_freq);

        return 0;

}

static int cpufreq_gx_cpu_init(struct cpufreq_policy *policy)

{

        int maxfreq, curfreq;

        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;

        curfreq = gx_get_cpuspeed();

        dprintk("cpu max frequency is %d.\n", maxfreq);

        dprintk("cpu current frequency is %dkHz.\n",curfreq);

        /* 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->cur = curfreq;

        policy->governor = 0; //!!!CPUFREQ_DEFAULT_GOVERNOR;

        policy->cpuinfo.min_freq = maxfreq / max_duration;

        policy->cpuinfo.max_freq = maxfreq;

        policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;

        return 0;

}

/*

 * cpufreq_gx_init:

 *   MediaGX/Geode GX initialize cpufreq driver

 */

static struct cpufreq_driver gx_suspmod_driver = {

        .verify         = cpufreq_gx_verify,

        .target         = cpufreq_gx_target,

        .init           = cpufreq_gx_cpu_init,

        .name           = "gx-suspmod",

        .owner          = THIS_MODULE,

};

/*static*/ int __init cpufreq_gx_init(void)

{

        int ret;

        struct gxfreq_params *params;

        struct pci_dev *gx_pci;

        u32 class_rev;

        /* Test if we have the right hardware */

        if ((gx_pci = gx_detect_chipset()) == NULL)

                return -ENODEV;

        /* check whether module parameters are sane */

        if (max_duration > 0xff)

                max_duration = 0xff;

        dprintk("geode suspend modulation available.\n");

        params = kmalloc(sizeof(struct gxfreq_params), GFP_KERNEL);

        if (params == NULL)

                return -ENOMEM;

        memset(params, 0, sizeof(struct gxfreq_params));

        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));

        pci_read_config_dword(params->cs55x0, PCI_CLASS_REVISION, &class_rev);

        params->pci_rev = class_rev && 0xff;

        if ((ret = cpufreq_register_driver(&gx_suspmod_driver))) {

                kfree(params);

                return ret;                   /* register error! */

        }

        return 0;

}

/*static*/ void __exit cpufreq_gx_exit(void)

{

        cpufreq_unregister_driver(&gx_suspmod_driver);

        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);