This driver detects a chipset and does thing that suitable for chip.
I test it on MediaGXm 200MHz with CS5520 and Geode GX1 with CS5520.
My code based on Zwane Mwaikambo's patch. I re-write almost.
Please merge this driver into cpufreq project patchset.
A patch for 2.5.53 is attatched and you can download driver file only from
http://www.da-cha.org/geode/gx-suspmod.c
diff -uNr -X kernel-patches/dontdiff linux-2.5.53/arch/i386/Kconfig edited/linux-2.5.53/arch/i386/Kconfig
--- linux-2.5.53/arch/i386/Kconfig 2002-12-26 02:33:08.000000000 +0900
+++ edited/linux-2.5.53/arch/i386/Kconfig 2002-12-25 16:37:01.000000000 +0900
@@ -985,6 +1003,17 @@
If in doubt, say N.
+config X86_GX_SUSPMOD
+ tristate "Cyrix MediaGX/NatSemi Geode Suspend Modulation"
+ depends on CPU_FREQ
+ help
+ This add the CPUFreq driver for NatSemi Geode processors which
+ support suspend modulation.
+
+ For details, take a look at linux/Documentation/cpufreq.
+
+ If in doubt, say N.
+
endmenu
diff -uNr -X kernel-patches/dontdiff linux-2.5.53/arch/i386/defconfig edited/linux-2.5.53/arch/i386/defconfig
--- linux-2.5.53/arch/i386/defconfig 2002-12-03 07:55:46.000000000 +0900
+++ edited/linux-2.5.53/arch/i386/defconfig 2002-12-25 16:37:01.000000000 +0900
@@ -65,6 +65,7 @@
CONFIG_X86_MCE=y
# CONFIG_X86_MCE_NONFATAL is not set
CONFIG_X86_MCE_P4THERMAL=y
+# CONFIG_X86_GX_SUSPMOD is not set
# CONFIG_TOSHIBA is not set
# CONFIG_I8K is not set
# CONFIG_MICROCODE is not set
diff -uNr -X kernel-patches/dontdiff linux-2.5.53/arch/i386/kernel/cpu/cpufreq/Makefile edited/linux-2.5.53/arch/i386/kernel/cpu/cpufreq/Makefile
--- linux-2.5.53/arch/i386/kernel/cpu/cpufreq/Makefile 2002-12-17 23:28:28.000000000 +0900
+++ edited/linux-2.5.53/arch/i386/kernel/cpu/cpufreq/Makefile 2002-12-25 16:37:01.000000000 +0900
@@ -4,3 +4,5 @@
obj-$(CONFIG_X86_P4_CLOCKMOD) += p4-clockmod.o
obj-$(CONFIG_ELAN_CPUFREQ) += elanfreq.o
obj-$(CONFIG_X86_LONGRUN) += longrun.o
+obj-$(CONFIG_X86_GX_SUSPMOD) += gx-suspmod.o
+
diff -uNr -X kernel-patches/dontdiff linux-2.5.53/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c edited/linux-2.5.53/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c
--- linux-2.5.53/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c 1970-01-01 09:00:00.000000000 +0900
+++ edited/linux-2.5.53/arch/i386/kernel/cpu/cpufreq/gx-suspmod.c 2002-12-25 16:37:01.000000000 +0900
@@ -0,0 +1,467 @@
+/*
+ * 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 * MAX_DURAION) / stock_freq
+ * off_duration = MAX_DURAION - 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 <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>
+
+/* 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 cpufreq_driver *gx_driver;
+static struct gxfreq_params *gx_params;
+static int stock_freq;
+MODULE_PARM(stock_freq, "i");
+
+/* 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
+};
+
+#define PCI_BUSCLK (30000)
+#define MIN_CPUFREQ_DIV (10)
+
+/****************************************************************
+ * 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 struct pci_dev *gx_detect_chipset(void)
+{
+ struct pci_dev *gx_pci;
+
+ /* check if CPU is a MediaGX or a Geode. */
+ if ((current_cpu_data.x86_vendor != X86_VENDOR_NSC) &&
+ (current_cpu_data.x86_vendor != X86_VENDOR_CYRIX)) {
+ printk(KERN_INFO "gx-suspmod: error: no MediaGX/Geode processor found!\n");
+ return NULL;
+ }
+
+ /* detect which companion chip is used */
+#if 1
+ pci_for_each_dev(gx_pci) {
+ if ((pci_match_device (gx_chipset_tbl, gx_pci)) != NULL) {
+ return gx_pci;
+ }
+ }
+#else
+ gx_pci = pci_find_subsys(PCI_VENDOR_ID_CYRIX,
+ PCI_DEVICE_ID_CYRIX_5530_LEGACY,
+ PCI_ANY_ID,
+ PCI_ANY_ID,
+ NULL);
+ if (gx_pci) return gx_pci;
+ gx_pci = pci_find_subsys(PCI_VENDOR_ID_CYRIX,
+ PCI_DEVICE_ID_CYRIX_5520,
+ PCI_ANY_ID,
+ PCI_ANY_ID,
+ NULL);
+ if (gx_pci) return gx_pci;
+ gx_pci = pci_find_subsys(PCI_VENDOR_ID_CYRIX,
+ PCI_DEVICE_ID_CYRIX_5510,
+ PCI_ANY_ID,
+ PCI_ANY_ID,
+ NULL);
+ if (gx_pci) return gx_pci;
+#endif
+
+ printk(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
+ *
+**/
+
+#define MAX_DURATION 20
+
+static unsigned int gx_validate_speed(unsigned int khz)
+{
+
+ gx_params->on_duration = ((khz*MAX_DURATION) / stock_freq) & 0xff;
+ gx_params->off_duration = MAX_DURATION - gx_params->on_duration;
+
+ while ((gx_params->on_duration & 1)&&(gx_params->off_duration & 1)) {
+ gx_params->on_duration = (gx_params->on_duration >> 1) & 0xff;
+ gx_params->off_duration = (gx_params->off_duration >> 1) & 0xff;
+ }
+
+ /* off_duration = (gx_params->on_duration * (stock_freq - khz))/khz; */
+
+ return (stock_freq * gx_params->on_duration) / (gx_params->on_duration + gx_params->off_duration);
+}
+
+
+/**
+ * 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);
+
+#ifdef CONFIG_CPU_FREQ_24_API
+ gx_driver->cpu_cur_freq[0] = new_khz;
+#endif
+ 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;
+ freqs.new= gx_get_cpuspeed();
+
+ 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.
+ */
+
+int cpufreq_gx_verify(struct cpufreq_policy *policy)
+{
+
+ if (!gx_driver || !stock_freq || !policy)
+ return -EINVAL;
+
+ policy->cpu = 0;
+ cpufreq_verify_within_limits(policy, (stock_freq / MIN_CPUFREQ_DIV), stock_freq);
+
+ return 0;
+}
+
+/*
+ * cpufreq_gx_setpolicy:
+ *
+ */
+int cpufreq_gx_setpolicy(struct cpufreq_policy *policy)
+{
+
+ if (!gx_driver || !stock_freq || !policy)
+ return -EINVAL;
+
+ policy->cpu = 0;
+
+ if (policy->policy == CPUFREQ_POLICY_POWERSAVE) {
+ gx_set_cpuspeed(policy->min);
+ } else {
+ gx_set_cpuspeed(policy->max);
+ }
+ return 0;
+}
+
+/*
+ * cpufreq_gx_init:
+ * MediaGX/Geode GX initilize cpufreq driver
+ */
+
+int __init cpufreq_gx_init(void)
+{
+ int maxfreq,ret,curfreq;
+ struct cpufreq_driver *driver;
+ 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;
+
+ dprintk("geode suspend modulation available.\n");
+
+ driver = kmalloc(sizeof(struct cpufreq_driver) + NR_CPUS * sizeof(struct cpufreq_policy), GFP_KERNEL);
+ if (driver == NULL)
+ return -ENOMEM;
+ params = kmalloc(sizeof(struct gxfreq_params), GFP_KERNEL);
+ if (params == NULL) {
+ kfree(driver);
+ return -ENOMEM;
+ }
+
+ driver->policy = (struct cpufreq_policy *)(driver + 1);
+ params->cs55x0 = gx_pci;
+
+ /* 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;
+
+ gx_params = params;
+
+ maxfreq = stock_freq?stock_freq
+ :(stock_freq = PCI_BUSCLK * gx_freq_mult[getCx86(CX86_DIR1) & 0x0f]);
+ 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 */
+#ifdef CONFIG_CPU_FREQ_24_API
+ driver->cpu_cur_freq[0] = curfreq;
+#endif
+ driver->policy[0].cpu = 0;
+ driver->policy[0].min = maxfreq/MIN_CPUFREQ_DIV;
+ driver->policy[0].max = maxfreq;
+ driver->policy[0].policy = CPUFREQ_POLICY_PERFORMANCE;
+ driver->policy[0].cpuinfo.min_freq = maxfreq/MIN_CPUFREQ_DIV;
+ driver->policy[0].cpuinfo.max_freq = maxfreq;
+ driver->policy[0].cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+ driver->verify = &cpufreq_gx_verify;
+ driver->setpolicy = &cpufreq_gx_setpolicy;
+
+ gx_driver = driver;
+
+ if ((ret = cpufreq_register(driver))) {
+ kfree(driver);
+ kfree(params);
+ return ret; /* register error! */
+ }
+
+ return 0;
+}
+
+void __exit cpufreq_gx_exit(void)
+{
+ if (gx_driver) {
+// pci_write_config_byte(gx_params->cs55x0, PCI_SUSCFG, gx_params->pci_suscfg);
+// pci_write_config_byte(gx_params->cs55x0, PCI_PMER1, gx_params->pci_pmer1);
+// pci_write_config_byte(gx_params->cs55x0, PCI_PMER2, gx_params->pci_pmer2);
+ cpufreq_unregister();
+ kfree(gx_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);
+
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