--- /dev/null
+/*
+ * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ *
+ * Licensed under the terms of the GNU GPL License version 2.
+ *
+ * BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/init.h>
+#include <linux/cpufreq.h>
+#include <linux/timex.h>
+
+#include <asm/msr.h>
+#include <asm/processor.h>
+#include <asm/cpu_device_id.h>
+
+static struct cpufreq_driver longrun_driver;
+
+/**
+ * longrun_{low,high}_freq is needed for the conversion of cpufreq kHz
+ * values into per cent values. In TMTA microcode, the following is valid:
+ * performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
+ */
+static unsigned int longrun_low_freq, longrun_high_freq;
+
+
+/**
+ * longrun_get_policy - get the current LongRun policy
+ * @policy: struct cpufreq_policy where current policy is written into
+ *
+ * Reads the current LongRun policy by access to MSR_TMTA_LONGRUN_FLAGS
+ * and MSR_TMTA_LONGRUN_CTRL
+ */
+static void longrun_get_policy(struct cpufreq_policy *policy)
+{
+ u32 msr_lo, msr_hi;
+
+ rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
+ pr_debug("longrun flags are %x - %x\n", msr_lo, msr_hi);
+ if (msr_lo & 0x01)
+ policy->policy = CPUFREQ_POLICY_PERFORMANCE;
+ else
+ policy->policy = CPUFREQ_POLICY_POWERSAVE;
+
+ rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
+ pr_debug("longrun ctrl is %x - %x\n", msr_lo, msr_hi);
+ msr_lo &= 0x0000007F;
+ msr_hi &= 0x0000007F;
+
+ if (longrun_high_freq <= longrun_low_freq) {
+ /* Assume degenerate Longrun table */
+ policy->min = policy->max = longrun_high_freq;
+ } else {
+ policy->min = longrun_low_freq + msr_lo *
+ ((longrun_high_freq - longrun_low_freq) / 100);
+ policy->max = longrun_low_freq + msr_hi *
+ ((longrun_high_freq - longrun_low_freq) / 100);
+ }
+ policy->cpu = 0;
+}
+
+
+/**
+ * longrun_set_policy - sets a new CPUFreq policy
+ * @policy: new policy
+ *
+ * Sets a new CPUFreq policy on LongRun-capable processors. This function
+ * has to be called with cpufreq_driver locked.
+ */
+static int longrun_set_policy(struct cpufreq_policy *policy)
+{
+ u32 msr_lo, msr_hi;
+ u32 pctg_lo, pctg_hi;
+
+ if (!policy)
+ return -EINVAL;
+
+ if (longrun_high_freq <= longrun_low_freq) {
+ /* Assume degenerate Longrun table */
+ pctg_lo = pctg_hi = 100;
+ } else {
+ pctg_lo = (policy->min - longrun_low_freq) /
+ ((longrun_high_freq - longrun_low_freq) / 100);
+ pctg_hi = (policy->max - longrun_low_freq) /
+ ((longrun_high_freq - longrun_low_freq) / 100);
+ }
+
+ if (pctg_hi > 100)
+ pctg_hi = 100;
+ if (pctg_lo > pctg_hi)
+ pctg_lo = pctg_hi;
+
+ /* performance or economy mode */
+ rdmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
+ msr_lo &= 0xFFFFFFFE;
+ switch (policy->policy) {
+ case CPUFREQ_POLICY_PERFORMANCE:
+ msr_lo |= 0x00000001;
+ break;
+ case CPUFREQ_POLICY_POWERSAVE:
+ break;
+ }
+ wrmsr(MSR_TMTA_LONGRUN_FLAGS, msr_lo, msr_hi);
+
+ /* lower and upper boundary */
+ rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
+ msr_lo &= 0xFFFFFF80;
+ msr_hi &= 0xFFFFFF80;
+ msr_lo |= pctg_lo;
+ msr_hi |= pctg_hi;
+ wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
+
+ return 0;
+}
+
+
+/**
+ * longrun_verify_poliy - verifies a new CPUFreq policy
+ * @policy: the policy to verify
+ *
+ * Validates a new CPUFreq policy. This function has to be called with
+ * cpufreq_driver locked.
+ */
+static int longrun_verify_policy(struct cpufreq_policy *policy)
+{
+ if (!policy)
+ return -EINVAL;
+
+ policy->cpu = 0;
+ cpufreq_verify_within_cpu_limits(policy);
+
+ if ((policy->policy != CPUFREQ_POLICY_POWERSAVE) &&
+ (policy->policy != CPUFREQ_POLICY_PERFORMANCE))
+ return -EINVAL;
+
+ return 0;
+}
+
+static unsigned int longrun_get(unsigned int cpu)
+{
+ u32 eax, ebx, ecx, edx;
+
+ if (cpu)
+ return 0;
+
+ cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
+ pr_debug("cpuid eax is %u\n", eax);
+
+ return eax * 1000;
+}
+
+/**
+ * longrun_determine_freqs - determines the lowest and highest possible core frequency
+ * @low_freq: an int to put the lowest frequency into
+ * @high_freq: an int to put the highest frequency into
+ *
+ * Determines the lowest and highest possible core frequencies on this CPU.
+ * This is necessary to calculate the performance percentage according to
+ * TMTA rules:
+ * performance_pctg = (target_freq - low_freq)/(high_freq - low_freq)
+ */
+static int longrun_determine_freqs(unsigned int *low_freq,
+ unsigned int *high_freq)
+{
+ u32 msr_lo, msr_hi;
+ u32 save_lo, save_hi;
+ u32 eax, ebx, ecx, edx;
+ u32 try_hi;
+ struct cpuinfo_x86 *c = &cpu_data(0);
+
+ if (!low_freq || !high_freq)
+ return -EINVAL;
+
+ if (cpu_has(c, X86_FEATURE_LRTI)) {
+ /* if the LongRun Table Interface is present, the
+ * detection is a bit easier:
+ * For minimum frequency, read out the maximum
+ * level (msr_hi), write that into "currently
+ * selected level", and read out the frequency.
+ * For maximum frequency, read out level zero.
+ */
+ /* minimum */
+ rdmsr(MSR_TMTA_LRTI_READOUT, msr_lo, msr_hi);
+ wrmsr(MSR_TMTA_LRTI_READOUT, msr_hi, msr_hi);
+ rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
+ *low_freq = msr_lo * 1000; /* to kHz */
+
+ /* maximum */
+ wrmsr(MSR_TMTA_LRTI_READOUT, 0, msr_hi);
+ rdmsr(MSR_TMTA_LRTI_VOLT_MHZ, msr_lo, msr_hi);
+ *high_freq = msr_lo * 1000; /* to kHz */
+
+ pr_debug("longrun table interface told %u - %u kHz\n",
+ *low_freq, *high_freq);
+
+ if (*low_freq > *high_freq)
+ *low_freq = *high_freq;
+ return 0;
+ }
+
+ /* set the upper border to the value determined during TSC init */
+ *high_freq = (cpu_khz / 1000);
+ *high_freq = *high_freq * 1000;
+ pr_debug("high frequency is %u kHz\n", *high_freq);
+
+ /* get current borders */
+ rdmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
+ save_lo = msr_lo & 0x0000007F;
+ save_hi = msr_hi & 0x0000007F;
+
+ /* if current perf_pctg is larger than 90%, we need to decrease the
+ * upper limit to make the calculation more accurate.
+ */
+ cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
+ /* try decreasing in 10% steps, some processors react only
+ * on some barrier values */
+ for (try_hi = 80; try_hi > 0 && ecx > 90; try_hi -= 10) {
+ /* set to 0 to try_hi perf_pctg */
+ msr_lo &= 0xFFFFFF80;
+ msr_hi &= 0xFFFFFF80;
+ msr_hi |= try_hi;
+ wrmsr(MSR_TMTA_LONGRUN_CTRL, msr_lo, msr_hi);
+
+ /* read out current core MHz and current perf_pctg */
+ cpuid(0x80860007, &eax, &ebx, &ecx, &edx);
+
+ /* restore values */
+ wrmsr(MSR_TMTA_LONGRUN_CTRL, save_lo, save_hi);
+ }
+ pr_debug("percentage is %u %%, freq is %u MHz\n", ecx, eax);
+
+ /* performance_pctg = (current_freq - low_freq)/(high_freq - low_freq)
+ * eqals
+ * low_freq * (1 - perf_pctg) = (cur_freq - high_freq * perf_pctg)
+ *
+ * high_freq * perf_pctg is stored tempoarily into "ebx".
+ */
+ ebx = (((cpu_khz / 1000) * ecx) / 100); /* to MHz */
+
+ if ((ecx > 95) || (ecx == 0) || (eax < ebx))
+ return -EIO;
+
+ edx = ((eax - ebx) * 100) / (100 - ecx);
+ *low_freq = edx * 1000; /* back to kHz */
+
+ pr_debug("low frequency is %u kHz\n", *low_freq);
+
+ if (*low_freq > *high_freq)
+ *low_freq = *high_freq;
+
+ return 0;
+}
+
+
+static int longrun_cpu_init(struct cpufreq_policy *policy)
+{
+ int result = 0;
+
+ /* capability check */
+ if (policy->cpu != 0)
+ return -ENODEV;
+
+ /* detect low and high frequency */
+ result = longrun_determine_freqs(&longrun_low_freq, &longrun_high_freq);
+ if (result)
+ return result;
+
+ /* cpuinfo and default policy values */
+ policy->cpuinfo.min_freq = longrun_low_freq;
+ policy->cpuinfo.max_freq = longrun_high_freq;
+ policy->cpuinfo.transition_latency = CPUFREQ_ETERNAL;
+ longrun_get_policy(policy);
+
+ return 0;
+}
+
+
+static struct cpufreq_driver longrun_driver = {
+ .flags = CPUFREQ_CONST_LOOPS,
+ .verify = longrun_verify_policy,
+ .setpolicy = longrun_set_policy,
+ .get = longrun_get,
+ .init = longrun_cpu_init,
+ .name = "longrun",
+};
+
+static const struct x86_cpu_id longrun_ids[] = {
+ { X86_VENDOR_TRANSMETA, X86_FAMILY_ANY, X86_MODEL_ANY,
+ X86_FEATURE_LONGRUN },
+ {}
+};
+MODULE_DEVICE_TABLE(x86cpu, longrun_ids);
+
+/**
+ * longrun_init - initializes the Transmeta Crusoe LongRun CPUFreq driver
+ *
+ * Initializes the LongRun support.
+ */
+static int __init longrun_init(void)
+{
+ if (!x86_match_cpu(longrun_ids))
+ return -ENODEV;
+ return cpufreq_register_driver(&longrun_driver);
+}
+
+
+/**
+ * longrun_exit - unregisters LongRun support
+ */
+static void __exit longrun_exit(void)
+{
+ cpufreq_unregister_driver(&longrun_driver);
+}
+
+
+MODULE_AUTHOR("Dominik Brodowski <linux@brodo.de>");
+MODULE_DESCRIPTION("LongRun driver for Transmeta Crusoe and "
+ "Efficeon processors.");
+MODULE_LICENSE("GPL");
+
+module_init(longrun_init);
+module_exit(longrun_exit);
Code Review / kvmfornfv.git / blobdiff