summaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/gx-suspmod.c
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/cpufreq/gx-suspmod.c')
-rw-r--r--drivers/cpufreq/gx-suspmod.c498
1 files changed, 498 insertions, 0 deletions
diff --git a/drivers/cpufreq/gx-suspmod.c b/drivers/cpufreq/gx-suspmod.c
new file mode 100644
index 0000000000..75b3ef7ec6
--- /dev/null
+++ b/drivers/cpufreq/gx-suspmod.c
@@ -0,0 +1,498 @@
+// 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);
+
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 01:30:17 +0000