1 files changed, 436 insertions, 0 deletions
diff --git a/drivers/cpufreq/cppc_cpufreq.c b/drivers/cpufreq/cppc_cpufreq.c
new file mode 100644
index 000000000..30f302149
--- /dev/null
+++ b/drivers/cpufreq/cppc_cpufreq.c
@@ -0,0 +1,436 @@
+/*
+ * CPPC (Collaborative Processor Performance Control) driver for
+ * interfacing with the CPUfreq layer and governors. See
+ * cppc_acpi.c for CPPC specific methods.
+ *
+ * (C) Copyright 2014, 2015 Linaro Ltd.
+ * Author: Ashwin Chaugule <ashwin.chaugule@linaro.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2
+ * of the License.
+ */
+
+#define pr_fmt(fmt)	"CPPC Cpufreq:"	fmt
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/dmi.h>
+#include <linux/time.h>
+#include <linux/vmalloc.h>
+
+#include <asm/unaligned.h>
+
+#include <acpi/cppc_acpi.h>
+
+/* Minimum struct length needed for the DMI processor entry we want */
+#define DMI_ENTRY_PROCESSOR_MIN_LENGTH	48
+
+/* Offest in the DMI processor structure for the max frequency */
+#define DMI_PROCESSOR_MAX_SPEED  0x14
+
+/*
+ * These structs contain information parsed from per CPU
+ * ACPI _CPC structures.
+ * e.g. For each CPU the highest, lowest supported
+ * performance capabilities, desired performance level
+ * requested etc.
+ */
+static struct cppc_cpudata **all_cpu_data;
+
+/* Callback function used to retrieve the max frequency from DMI */
+static void cppc_find_dmi_mhz(const struct dmi_header *dm, void *private)
+{
+	const u8 *dmi_data = (const u8 *)dm;
+	u16 *mhz = (u16 *)private;
+
+	if (dm->type == DMI_ENTRY_PROCESSOR &&
+	    dm->length >= DMI_ENTRY_PROCESSOR_MIN_LENGTH) {
+		u16 val = (u16)get_unaligned((const u16 *)
+				(dmi_data + DMI_PROCESSOR_MAX_SPEED));
+		*mhz = val > *mhz ? val : *mhz;
+	}
+}
+
+/* Look up the max frequency in DMI */
+static u64 cppc_get_dmi_max_khz(void)
+{
+	u16 mhz = 0;
+
+	dmi_walk(cppc_find_dmi_mhz, &mhz);
+
+	/*
+	 * Real stupid fallback value, just in case there is no
+	 * actual value set.
+	 */
+	mhz = mhz ? mhz : 1;
+
+	return (1000 * mhz);
+}
+
+/*
+ * If CPPC lowest_freq and nominal_freq registers are exposed then we can
+ * use them to convert perf to freq and vice versa
+ *
+ * If the perf/freq point lies between Nominal and Lowest, we can treat
+ * (Low perf, Low freq) and (Nom Perf, Nom freq) as 2D co-ordinates of a line
+ * and extrapolate the rest
+ * For perf/freq > Nominal, we use the ratio perf:freq at Nominal for conversion
+ */
+static unsigned int cppc_cpufreq_perf_to_khz(struct cppc_cpudata *cpu,
+					unsigned int perf)
+{
+	static u64 max_khz;
+	struct cppc_perf_caps *caps = &cpu->perf_caps;
+	u64 mul, div;
+
+	if (caps->lowest_freq && caps->nominal_freq) {
+		if (perf >= caps->nominal_perf) {
+			mul = caps->nominal_freq;
+			div = caps->nominal_perf;
+		} else {
+			mul = caps->nominal_freq - caps->lowest_freq;
+			div = caps->nominal_perf - caps->lowest_perf;
+		}
+	} else {
+		if (!max_khz)
+			max_khz = cppc_get_dmi_max_khz();
+		mul = max_khz;
+		div = cpu->perf_caps.highest_perf;
+	}
+	return (u64)perf * mul / div;
+}
+
+static unsigned int cppc_cpufreq_khz_to_perf(struct cppc_cpudata *cpu,
+					unsigned int freq)
+{
+	static u64 max_khz;
+	struct cppc_perf_caps *caps = &cpu->perf_caps;
+	u64  mul, div;
+
+	if (caps->lowest_freq && caps->nominal_freq) {
+		if (freq >= caps->nominal_freq) {
+			mul = caps->nominal_perf;
+			div = caps->nominal_freq;
+		} else {
+			mul = caps->lowest_perf;
+			div = caps->lowest_freq;
+		}
+	} else {
+		if (!max_khz)
+			max_khz = cppc_get_dmi_max_khz();
+		mul = cpu->perf_caps.highest_perf;
+		div = max_khz;
+	}
+
+	return (u64)freq * mul / div;
+}
+
+static int cppc_cpufreq_set_target(struct cpufreq_policy *policy,
+		unsigned int target_freq,
+		unsigned int relation)
+{
+	struct cppc_cpudata *cpu;
+	struct cpufreq_freqs freqs;
+	u32 desired_perf;
+	int ret = 0;
+
+	cpu = all_cpu_data[policy->cpu];
+
+	desired_perf = cppc_cpufreq_khz_to_perf(cpu, target_freq);
+	/* Return if it is exactly the same perf */
+	if (desired_perf == cpu->perf_ctrls.desired_perf)
+		return ret;
+
+	cpu->perf_ctrls.desired_perf = desired_perf;
+	freqs.old = policy->cur;
+	freqs.new = target_freq;
+
+	cpufreq_freq_transition_begin(policy, &freqs);
+	ret = cppc_set_perf(cpu->cpu, &cpu->perf_ctrls);
+	cpufreq_freq_transition_end(policy, &freqs, ret != 0);
+
+	if (ret)
+		pr_debug("Failed to set target on CPU:%d. ret:%d\n",
+				cpu->cpu, ret);
+
+	return ret;
+}
+
+static int cppc_verify_policy(struct cpufreq_policy *policy)
+{
+	cpufreq_verify_within_cpu_limits(policy);
+	return 0;
+}
+
+static void cppc_cpufreq_stop_cpu(struct cpufreq_policy *policy)
+{
+	int cpu_num = policy->cpu;
+	struct cppc_cpudata *cpu = all_cpu_data[cpu_num];
+	int ret;
+
+	cpu->perf_ctrls.desired_perf = cpu->perf_caps.lowest_perf;
+
+	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
+	if (ret)
+		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
+				cpu->perf_caps.lowest_perf, cpu_num, ret);
+}
+
+/*
+ * The PCC subspace describes the rate at which platform can accept commands
+ * on the shared PCC channel (including READs which do not count towards freq
+ * trasition requests), so ideally we need to use the PCC values as a fallback
+ * if we don't have a platform specific transition_delay_us
+ */
+#ifdef CONFIG_ARM64
+#include <asm/cputype.h>
+
+static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
+{
+	unsigned long implementor = read_cpuid_implementor();
+	unsigned long part_num = read_cpuid_part_number();
+	unsigned int delay_us = 0;
+
+	switch (implementor) {
+	case ARM_CPU_IMP_QCOM:
+		switch (part_num) {
+		case QCOM_CPU_PART_FALKOR_V1:
+		case QCOM_CPU_PART_FALKOR:
+			delay_us = 10000;
+			break;
+		default:
+			delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
+			break;
+		}
+		break;
+	default:
+		delay_us = cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
+		break;
+	}
+
+	return delay_us;
+}
+
+#else
+
+static unsigned int cppc_cpufreq_get_transition_delay_us(int cpu)
+{
+	return cppc_get_transition_latency(cpu) / NSEC_PER_USEC;
+}
+#endif
+
+static int cppc_cpufreq_cpu_init(struct cpufreq_policy *policy)
+{
+	struct cppc_cpudata *cpu;
+	unsigned int cpu_num = policy->cpu;
+	int ret = 0;
+
+	cpu = all_cpu_data[policy->cpu];
+
+	cpu->cpu = cpu_num;
+	ret = cppc_get_perf_caps(policy->cpu, &cpu->perf_caps);
+
+	if (ret) {
+		pr_debug("Err reading CPU%d perf capabilities. ret:%d\n",
+				cpu_num, ret);
+		return ret;
+	}
+
+	/* Convert the lowest and nominal freq from MHz to KHz */
+	cpu->perf_caps.lowest_freq *= 1000;
+	cpu->perf_caps.nominal_freq *= 1000;
+
+	/*
+	 * Set min to lowest nonlinear perf to avoid any efficiency penalty (see
+	 * Section 8.4.7.1.1.5 of ACPI 6.1 spec)
+	 */
+	policy->min = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_nonlinear_perf);
+	policy->max = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
+
+	/*
+	 * Set cpuinfo.min_freq to Lowest to make the full range of performance
+	 * available if userspace wants to use any perf between lowest & lowest
+	 * nonlinear perf
+	 */
+	policy->cpuinfo.min_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.lowest_perf);
+	policy->cpuinfo.max_freq = cppc_cpufreq_perf_to_khz(cpu, cpu->perf_caps.highest_perf);
+
+	policy->transition_delay_us = cppc_cpufreq_get_transition_delay_us(cpu_num);
+	policy->shared_type = cpu->shared_type;
+
+	if (policy->shared_type == CPUFREQ_SHARED_TYPE_ANY) {
+		int i;
+
+		cpumask_copy(policy->cpus, cpu->shared_cpu_map);
+
+		for_each_cpu(i, policy->cpus) {
+			if (unlikely(i == policy->cpu))
+				continue;
+
+			memcpy(&all_cpu_data[i]->perf_caps, &cpu->perf_caps,
+			       sizeof(cpu->perf_caps));
+		}
+	} else if (policy->shared_type == CPUFREQ_SHARED_TYPE_ALL) {
+		/* Support only SW_ANY for now. */
+		pr_debug("Unsupported CPU co-ord type\n");
+		return -EFAULT;
+	}
+
+	cpu->cur_policy = policy;
+
+	/* Set policy->cur to max now. The governors will adjust later. */
+	policy->cur = cppc_cpufreq_perf_to_khz(cpu,
+					cpu->perf_caps.highest_perf);
+	cpu->perf_ctrls.desired_perf = cpu->perf_caps.highest_perf;
+
+	ret = cppc_set_perf(cpu_num, &cpu->perf_ctrls);
+	if (ret)
+		pr_debug("Err setting perf value:%d on CPU:%d. ret:%d\n",
+				cpu->perf_caps.highest_perf, cpu_num, ret);
+
+	return ret;
+}
+
+static inline u64 get_delta(u64 t1, u64 t0)
+{
+	if (t1 > t0 || t0 > ~(u32)0)
+		return t1 - t0;
+
+	return (u32)t1 - (u32)t0;
+}
+
+static int cppc_get_rate_from_fbctrs(struct cppc_cpudata *cpu,
+				     struct cppc_perf_fb_ctrs fb_ctrs_t0,
+				     struct cppc_perf_fb_ctrs fb_ctrs_t1)
+{
+	u64 delta_reference, delta_delivered;
+	u64 reference_perf, delivered_perf;
+
+	reference_perf = fb_ctrs_t0.reference_perf;
+
+	delta_reference = get_delta(fb_ctrs_t1.reference,
+				    fb_ctrs_t0.reference);
+	delta_delivered = get_delta(fb_ctrs_t1.delivered,
+				    fb_ctrs_t0.delivered);
+
+	/* Check to avoid divide-by zero */
+	if (delta_reference || delta_delivered)
+		delivered_perf = (reference_perf * delta_delivered) /
+					delta_reference;
+	else
+		delivered_perf = cpu->perf_ctrls.desired_perf;
+
+	return cppc_cpufreq_perf_to_khz(cpu, delivered_perf);
+}
+
+static unsigned int cppc_cpufreq_get_rate(unsigned int cpunum)
+{
+	struct cppc_perf_fb_ctrs fb_ctrs_t0 = {0}, fb_ctrs_t1 = {0};
+	struct cppc_cpudata *cpu = all_cpu_data[cpunum];
+	int ret;
+
+	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t0);
+	if (ret)
+		return ret;
+
+	udelay(2); /* 2usec delay between sampling */
+
+	ret = cppc_get_perf_ctrs(cpunum, &fb_ctrs_t1);
+	if (ret)
+		return ret;
+
+	return cppc_get_rate_from_fbctrs(cpu, fb_ctrs_t0, fb_ctrs_t1);
+}
+
+static struct cpufreq_driver cppc_cpufreq_driver = {
+	.flags = CPUFREQ_CONST_LOOPS,
+	.verify = cppc_verify_policy,
+	.target = cppc_cpufreq_set_target,
+	.get = cppc_cpufreq_get_rate,
+	.init = cppc_cpufreq_cpu_init,
+	.stop_cpu = cppc_cpufreq_stop_cpu,
+	.name = "cppc_cpufreq",
+};
+
+static int __init cppc_cpufreq_init(void)
+{
+	int i, ret = 0;
+	struct cppc_cpudata *cpu;
+
+	if (acpi_disabled)
+		return -ENODEV;
+
+	all_cpu_data = kcalloc(num_possible_cpus(), sizeof(void *),
+			       GFP_KERNEL);
+	if (!all_cpu_data)
+		return -ENOMEM;
+
+	for_each_possible_cpu(i) {
+		all_cpu_data[i] = kzalloc(sizeof(struct cppc_cpudata), GFP_KERNEL);
+		if (!all_cpu_data[i])
+			goto out;
+
+		cpu = all_cpu_data[i];
+		if (!zalloc_cpumask_var(&cpu->shared_cpu_map, GFP_KERNEL))
+			goto out;
+	}
+
+	ret = acpi_get_psd_map(all_cpu_data);
+	if (ret) {
+		pr_debug("Error parsing PSD data. Aborting cpufreq registration.\n");
+		goto out;
+	}
+
+	ret = cpufreq_register_driver(&cppc_cpufreq_driver);
+	if (ret)
+		goto out;
+
+	return ret;
+
+out:
+	for_each_possible_cpu(i) {
+		cpu = all_cpu_data[i];
+		if (!cpu)
+			break;
+		free_cpumask_var(cpu->shared_cpu_map);
+		kfree(cpu);
+	}
+
+	kfree(all_cpu_data);
+	return -ENODEV;
+}
+
+static void __exit cppc_cpufreq_exit(void)
+{
+	struct cppc_cpudata *cpu;
+	int i;
+
+	cpufreq_unregister_driver(&cppc_cpufreq_driver);
+
+	for_each_possible_cpu(i) {
+		cpu = all_cpu_data[i];
+		free_cpumask_var(cpu->shared_cpu_map);
+		kfree(cpu);
+	}
+
+	kfree(all_cpu_data);
+}
+
+module_exit(cppc_cpufreq_exit);
+MODULE_AUTHOR("Ashwin Chaugule");
+MODULE_DESCRIPTION("CPUFreq driver based on the ACPI CPPC v5.0+ spec");
+MODULE_LICENSE("GPL");
+
+late_initcall(cppc_cpufreq_init);
+
+static const struct acpi_device_id cppc_acpi_ids[] = {
+	{ACPI_PROCESSOR_DEVICE_HID, },
+	{}
+};
+
+MODULE_DEVICE_TABLE(acpi, cppc_acpi_ids);