[PATCH] cpufreq: add driver for NatSemi Geode / Cyrix MediaGX

This patch by Hiroshi Miura adds a cpufreq driver for Cyrix MediaGX and
National Semiconductor Geode processors using "Suspend Modulation". It's
partly based on Zwane Mwaikambo's work.

arch/i386/Kconfig

@@ -1047,6 +1047,18 @@ config X86_LONGRUN
 
 	  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
 
 

arch/i386/kernel/cpu/cpufreq/Makefile

@@ -4,3 +4,4 @@ obj-$(CONFIG_X86_SPEEDSTEP)	+= speedstep.o
 obj-$(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

arch/i386/kernel/cpu/cpufreq/gx-suspmod.c

+/*
+ *	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 <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;
+
+/* 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;
+
+	/* 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 */
+	pci_for_each_dev(gx_pci) {
+		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 (!gx_driver || !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_setpolicy:  
+ *
+ */
+static 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) {
+		/* here we need to make sure that we don't set the
+		 * frequency below policy->min (see comment in
+		 * cpufreq_gx_verify() - guarantee of processing 
+		 * capacity.
+		 */
+		u8 tmp1, tmp2;
+		unsigned int tmp_freq = gx_validate_speed(policy->min, &tmp1, &tmp2);
+		while (tmp_freq < policy->min) {
+			tmp_freq += stock_freq / max_duration;
+			tmp_freq = gx_validate_speed(tmp_freq, &tmp1, &tmp2);
+		}
+		gx_set_cpuspeed(tmp_freq);
+	} else {
+		gx_set_cpuspeed(policy->max);
+	}
+	return 0;
+}
+
+/* 
+ * cpufreq_gx_init:
+ *   MediaGX/Geode GX initilize cpufreq driver
+ */
+
+static 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;
+
+	/* check whether module parameters are sane */
+	if (max_duration > 0xff)
+		max_duration = 0xff;
+
+	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;
+
+	/* 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 */
+#ifdef CONFIG_CPU_FREQ_24_API
+	driver->cpu_cur_freq[0] = curfreq;
+#endif
+	driver->policy[0].cpu = 0;
+
+	if (max_duration < POLICY_MIN_DIV)
+		driver->policy[0].min = maxfreq / max_duration;
+	else
+		driver->policy[0].min = maxfreq / POLICY_MIN_DIV;
+	driver->policy[0].max = maxfreq;
+	driver->policy[0].policy = CPUFREQ_POLICY_PERFORMANCE;
+	driver->policy[0].cpuinfo.min_freq = maxfreq / max_duration;
+	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;
+}
+
+static void __exit cpufreq_gx_exit(void)
+{
+	if (gx_driver) {
+		/* disable throttling */
+		gx_set_cpuspeed(stock_freq);
+		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);
+