1 files changed, 317 insertions, 0 deletions
diff --git a/drivers/cpufreq/longrun.c b/drivers/cpufreq/longrun.c
new file mode 100644
index 0000000000..1caaec7c28
--- /dev/null
+++ b/drivers/cpufreq/longrun.c
@@ -0,0 +1,317 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * (C) 2002 - 2003  Dominik Brodowski <linux@brodo.de>
+ *
+ *  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_data *policy)
+{
+	if (!policy)
+		return -EINVAL;
+
+	policy->cpu = 0;
+	cpufreq_verify_within_cpu_limits(policy);
+
+	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;
+	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_MATCH_VENDOR_FEATURE(TRANSMETA, X86_FEATURE_LONGRUN, NULL),
+	{}
+};
+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);