hwmon: Add amd_energy driver to report energy counters

This patch adds hwmon based amd_energy driver support for
family 17h processors from AMD.

The driver provides following interface to the userspace
1. Reports the per core consumption
	* file: "energy%d_input", label: "Ecore%03d"
2. Reports per socket energy consumption
	* file: "energy%d_input", label: "Esocket%d"
3. To, increase the wrap around time of the socket energy
   counters, a 64bit accumultor is implemented.
4. Reports scaled energy value in Joules.

Cc: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: NNaveen Krishna Chatradhi <nchatrad@amd.com>
Link: https://lore.kernel.org/r/20200519155011.56184-1-nchatrad@amd.comSigned-off-by: NGuenter Roeck <linux@roeck-us.net>

drivers/hwmon/Kconfig

@@ -324,6 +324,16 @@ config SENSORS_FAM15H_POWER
 	  This driver can also be built as a module. If so, the module
 	  will be called fam15h_power.
 
+config SENSORS_AMD_ENERGY
+	tristate "AMD RAPL MSR based Energy driver"
+	depends on X86
+	help
+	  If you say yes here you get support for core and package energy
+	  sensors, based on RAPL MSR for AMD family 17h and above CPUs.
+
+	  This driver can also be built as a module. If so, the module
+	  will be called as amd_energy.
+
 config SENSORS_APPLESMC
 	tristate "Apple SMC (Motion sensor, light sensor, keyboard backlight)"
 	depends on INPUT && X86

drivers/hwmon/Makefile

@@ -45,6 +45,7 @@ obj-$(CONFIG_SENSORS_ADT7411)	+= adt7411.o
 obj-$(CONFIG_SENSORS_ADT7462)	+= adt7462.o
 obj-$(CONFIG_SENSORS_ADT7470)	+= adt7470.o
 obj-$(CONFIG_SENSORS_ADT7475)	+= adt7475.o
+obj-$(CONFIG_SENSORS_AMD_ENERGY) += amd_energy.o
 obj-$(CONFIG_SENSORS_APPLESMC)	+= applesmc.o
 obj-$(CONFIG_SENSORS_ARM_SCMI)	+= scmi-hwmon.o
 obj-$(CONFIG_SENSORS_ARM_SCPI)	+= scpi-hwmon.o

drivers/hwmon/amd_energy.c

+// SPDX-License-Identifier: GPL-2.0-only
+
+/*
+ * Copyright (C) 2020 Advanced Micro Devices, Inc.
+ */
+#include <asm/cpu_device_id.h>
+
+#include <linux/bits.h>
+#include <linux/cpu.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/hwmon.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/list.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/processor.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
+#include <linux/topology.h>
+#include <linux/types.h>
+
+#define DRVNAME			"amd_energy"
+
+#define ENERGY_PWR_UNIT_MSR	0xC0010299
+#define ENERGY_CORE_MSR		0xC001029A
+#define ENERGY_PKG_MSR		0xC001029B
+
+#define AMD_ENERGY_UNIT_MASK	0x01F00
+#define AMD_ENERGY_MASK		0xFFFFFFFF
+
+struct sensor_accumulator {
+	u64 energy_ctr;
+	u64 prev_value;
+	char label[10];
+};
+
+struct amd_energy_data {
+	struct hwmon_channel_info energy_info;
+	const struct hwmon_channel_info *info[2];
+	struct hwmon_chip_info chip;
+	struct task_struct *wrap_accumulate;
+	/* Lock around the accumulator */
+	struct mutex lock;
+	/* An accumulator for each core and socket */
+	struct sensor_accumulator *accums;
+	/* Energy Status Units */
+	u64 energy_units;
+	int nr_cpus;
+	int nr_socks;
+	int core_id;
+};
+
+static int amd_energy_read_labels(struct device *dev,
+				  enum hwmon_sensor_types type,
+				  u32 attr, int channel,
+				  const char **str)
+{
+	struct amd_energy_data *data = dev_get_drvdata(dev);
+
+	*str = data->accums[channel].label;
+	return 0;
+}
+
+static void get_energy_units(struct amd_energy_data *data)
+{
+	u64 rapl_units;
+
+	rdmsrl_safe(ENERGY_PWR_UNIT_MSR, &rapl_units);
+	data->energy_units = (rapl_units & AMD_ENERGY_UNIT_MASK) >> 8;
+}
+
+static void accumulate_socket_delta(struct amd_energy_data *data,
+				    int sock, int cpu)
+{
+	struct sensor_accumulator *s_accum;
+	u64 input;
+
+	mutex_lock(&data->lock);
+	rdmsrl_safe_on_cpu(cpu, ENERGY_PKG_MSR, &input);
+	input &= AMD_ENERGY_MASK;
+
+	s_accum = &data->accums[data->nr_cpus + sock];
+	if (input >= s_accum->prev_value)
+		s_accum->energy_ctr +=
+			input - s_accum->prev_value;
+	else
+		s_accum->energy_ctr += UINT_MAX -
+			s_accum->prev_value + input;
+
+	s_accum->prev_value = input;
+	mutex_unlock(&data->lock);
+}
+
+static void accumulate_core_delta(struct amd_energy_data *data)
+{
+	struct sensor_accumulator *c_accum;
+	u64 input;
+	int cpu;
+
+	mutex_lock(&data->lock);
+	if (data->core_id >= data->nr_cpus)
+		data->core_id = 0;
+
+	cpu = data->core_id;
+
+	if (!cpu_online(cpu))
+		goto out;
+
+	rdmsrl_safe_on_cpu(cpu, ENERGY_CORE_MSR, &input);
+	input &= AMD_ENERGY_MASK;
+
+	c_accum = &data->accums[cpu];
+
+	if (input >= c_accum->prev_value)
+		c_accum->energy_ctr +=
+			input - c_accum->prev_value;
+	else
+		c_accum->energy_ctr += UINT_MAX -
+			c_accum->prev_value + input;
+
+	c_accum->prev_value = input;
+
+out:
+	data->core_id++;
+	mutex_unlock(&data->lock);
+}
+
+static void read_accumulate(struct amd_energy_data *data)
+{
+	int sock;
+
+	for (sock = 0; sock < data->nr_socks; sock++) {
+		int cpu;
+
+		cpu = cpumask_first_and(cpu_online_mask,
+					cpumask_of_node(sock));
+
+		accumulate_socket_delta(data, sock, cpu);
+	}
+
+	accumulate_core_delta(data);
+}
+
+static void amd_add_delta(struct amd_energy_data *data, int ch,
+			  int cpu, long *val, bool is_core)
+{
+	struct sensor_accumulator *s_accum, *c_accum;
+	u64 input;
+
+	mutex_lock(&data->lock);
+	if (!is_core) {
+		rdmsrl_safe_on_cpu(cpu, ENERGY_PKG_MSR, &input);
+		input &= AMD_ENERGY_MASK;
+
+		s_accum = &data->accums[ch];
+		if (input >= s_accum->prev_value)
+			input += s_accum->energy_ctr -
+				  s_accum->prev_value;
+		else
+			input += UINT_MAX - s_accum->prev_value +
+				  s_accum->energy_ctr;
+	} else {
+		rdmsrl_safe_on_cpu(cpu, ENERGY_CORE_MSR, &input);
+		input &= AMD_ENERGY_MASK;
+
+		c_accum = &data->accums[ch];
+		if (input >= c_accum->prev_value)
+			input += c_accum->energy_ctr -
+				 c_accum->prev_value;
+		else
+			input += UINT_MAX - c_accum->prev_value +
+				 c_accum->energy_ctr;
+	}
+
+	/* Energy consumed = (1/(2^ESU) * RAW * 1000000UL) μJoules */
+	*val = div64_ul(input * 1000000UL, BIT(data->energy_units));
+
+	mutex_unlock(&data->lock);
+}
+
+static int amd_energy_read(struct device *dev,
+			   enum hwmon_sensor_types type,
+			   u32 attr, int channel, long *val)
+{
+	struct amd_energy_data *data = dev_get_drvdata(dev);
+	int cpu;
+
+	if (channel >= data->nr_cpus) {
+		cpu = cpumask_first_and(cpu_online_mask,
+					cpumask_of_node
+					(channel - data->nr_cpus));
+		amd_add_delta(data, channel, cpu, val, false);
+	} else {
+		cpu = channel;
+		if (!cpu_online(cpu))
+			return -ENODEV;
+
+		amd_add_delta(data, channel, cpu, val, true);
+	}
+
+	return 0;
+}
+
+static umode_t amd_energy_is_visible(const void *_data,
+				     enum hwmon_sensor_types type,
+				     u32 attr, int channel)
+{
+	return 0444;
+}
+
+static int energy_accumulator(void *p)
+{
+	struct amd_energy_data *data = (struct amd_energy_data *)p;
+
+	while (!kthread_should_stop()) {
+		/*
+		 * Ignoring the conditions such as
+		 * cpu being offline or rdmsr failure
+		 */
+		read_accumulate(data);
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (kthread_should_stop())
+			break;
+
+		/*
+		 * On a 240W system, with default resolution the
+		 * Socket Energy status register may wrap around in
+		 * 2^32*15.3 e-6/240 = 273.8041 secs (~4.5 mins)
+		 *
+		 * let us accumulate for every 100secs
+		 */
+		schedule_timeout(msecs_to_jiffies(100000));
+	}
+	return 0;
+}
+
+static const struct hwmon_ops amd_energy_ops = {
+	.is_visible = amd_energy_is_visible,
+	.read = amd_energy_read,
+	.read_string = amd_energy_read_labels,
+};
+
+static int amd_create_sensor(struct device *dev,
+			     struct amd_energy_data *data,
+			     u8 type, u32 config)
+{
+	struct hwmon_channel_info *info = &data->energy_info;
+	struct sensor_accumulator *accums;
+	int i, num_siblings, cpus, sockets;
+	u32 *s_config;
+
+	/* Identify the number of siblings per core */
+	num_siblings = ((cpuid_ebx(0x8000001e) >> 8) & 0xff) + 1;
+
+	sockets = num_possible_nodes();
+
+	/*
+	 * Energy counter register is accessed at core level.
+	 * Hence, filterout the siblings.
+	 */
+	cpus = num_present_cpus() / num_siblings;
+
+	s_config = devm_kcalloc(dev, cpus + sockets,
+				sizeof(u32), GFP_KERNEL);
+	if (!s_config)
+		return -ENOMEM;
+
+	accums = devm_kcalloc(dev, cpus + sockets,
+			      sizeof(struct sensor_accumulator),
+			      GFP_KERNEL);
+	if (!accums)
+		return -ENOMEM;
+
+	info->type = type;
+	info->config = s_config;
+
+	data->nr_cpus = cpus;
+	data->nr_socks = sockets;
+	data->accums = accums;
+
+	for (i = 0; i < cpus + sockets; i++) {
+		s_config[i] = config;
+		if (i < cpus)
+			scnprintf(accums[i].label, 10,
+				  "Ecore%03u", i);
+		else
+			scnprintf(accums[i].label, 10,
+				  "Esocket%u", (i - cpus));
+	}
+
+	return 0;
+}
+
+static int amd_energy_probe(struct platform_device *pdev)
+{
+	struct device *hwmon_dev;
+	struct amd_energy_data *data;
+	struct device *dev = &pdev->dev;
+
+	data = devm_kzalloc(dev,
+			    sizeof(struct amd_energy_data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->chip.ops = &amd_energy_ops;
+	data->chip.info = data->info;
+
+	dev_set_drvdata(dev, data);
+	/* Populate per-core energy reporting */
+	data->info[0] = &data->energy_info;
+	amd_create_sensor(dev, data, hwmon_energy,
+			  HWMON_E_INPUT | HWMON_E_LABEL);
+
+	mutex_init(&data->lock);
+	get_energy_units(data);
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, DRVNAME,
+							 data,
+							 &data->chip,
+							 NULL);
+	if (IS_ERR(hwmon_dev))
+		return PTR_ERR(hwmon_dev);
+
+	data->wrap_accumulate = kthread_run(energy_accumulator, data,
+					    "%s", dev_name(hwmon_dev));
+	if (IS_ERR(data->wrap_accumulate))
+		return PTR_ERR(data->wrap_accumulate);
+
+	return PTR_ERR_OR_ZERO(data->wrap_accumulate);
+}
+
+static int amd_energy_remove(struct platform_device *pdev)
+{
+	struct amd_energy_data *data = dev_get_drvdata(&pdev->dev);
+
+	if (data && data->wrap_accumulate)
+		kthread_stop(data->wrap_accumulate);
+
+	return 0;
+}
+
+static const struct platform_device_id amd_energy_ids[] = {
+	{ .name = DRVNAME, },
+	{}
+};
+MODULE_DEVICE_TABLE(platform, amd_energy_ids);
+
+static struct platform_driver amd_energy_driver = {
+	.probe = amd_energy_probe,
+	.remove	= amd_energy_remove,
+	.id_table = amd_energy_ids,
+	.driver = {
+		.name = DRVNAME,
+	},
+};
+
+static struct platform_device *amd_energy_platdev;
+
+static const struct x86_cpu_id cpu_ids[] __initconst = {
+	X86_MATCH_VENDOR_FAM(AMD, 0x17, NULL),
+	{}
+};
+MODULE_DEVICE_TABLE(x86cpu, cpu_ids);
+
+static int __init amd_energy_init(void)
+{
+	int ret;
+
+	if (!x86_match_cpu(cpu_ids))
+		return -ENODEV;
+
+	ret = platform_driver_register(&amd_energy_driver);
+	if (ret)
+		return ret;
+
+	amd_energy_platdev = platform_device_alloc(DRVNAME, 0);
+	if (!amd_energy_platdev)
+		return -ENOMEM;
+
+	ret = platform_device_add(amd_energy_platdev);
+	if (ret) {
+		platform_device_put(amd_energy_platdev);
+		platform_driver_unregister(&amd_energy_driver);
+		return ret;
+	}
+
+	return ret;
+}
+
+static void __exit amd_energy_exit(void)
+{
+	platform_device_unregister(amd_energy_platdev);
+	platform_driver_unregister(&amd_energy_driver);
+}
+
+module_init(amd_energy_init);
+module_exit(amd_energy_exit);
+
+MODULE_DESCRIPTION("Driver for AMD Energy reporting from RAPL MSR via HWMON interface");
+MODULE_AUTHOR("Naveen Krishna Chatradhi <nchatrad@amd.com>");
+MODULE_LICENSE("GPL");