hwmon: lochnagar: Add Lochnagar 2 hardware monitoring driver

Lochnagar is an evaluation and development board for Cirrus
Logic Smart CODEC and Amp devices. It allows the connection of
most Cirrus Logic devices on mini-cards, as well as allowing
connection of various application processor systems to provide a
full evaluation platform.

This driver adds support for the hardware monitoring features of
the Lochnagar 2 to the hwmon API. Monitoring is provided for
the board voltages, currents and temperature supported by the
board controller chip.

Signed-off-by: Lucas Tanure <tanureal@opensource.cirrus.com>
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

5 files changed, 506 insertions, 0 deletions

diff --git a/Documentation/hwmon/lochnagar b/Documentation/hwmon/lochnagar
new file mode 100644
index 000000000000..e9686fb3eb40
--- /dev/null
+++ b/Documentation/hwmon/lochnagar
@@ -0,0 +1,80 @@
+Kernel Driver Lochnagar
+========================
+
+Supported systems:
+  * Cirrus Logic : Lochnagar 2
+
+Author: Lucas A. Tanure Alves
+
+Description
+-----------
+
+Lochnagar 2 features built-in Current Monitor circuitry that allows for the
+measurement of both voltage and current on up to eight of the supply voltage
+rails provided to the minicards. The Current Monitor does not require any
+hardware modifications or external circuitry to operate.
+
+The current and voltage measurements are obtained through the standard register
+map interface to the Lochnagar board controller, and can therefore be monitored
+by software.
+
+Sysfs attributes
+----------------
+
+temp1_input             The Lochnagar board temperature (milliCelsius)
+in0_input               Measured voltage for DBVDD1 (milliVolts)
+in0_label               "DBVDD1"
+curr1_input             Measured current for DBVDD1 (milliAmps)
+curr1_label             "DBVDD1"
+power1_average          Measured average power for DBVDD1 (microWatts)
+power1_average_interval Power averaging time input valid from 1 to 1708mS
+power1_label            "DBVDD1"
+in1_input               Measured voltage for 1V8 DSP (milliVolts)
+in1_label               "1V8 DSP"
+curr2_input             Measured current for 1V8 DSP (milliAmps)
+curr2_label             "1V8 DSP"
+power2_average          Measured average power for 1V8 DSP (microWatts)
+power2_average_interval Power averaging time input valid from 1 to 1708mS
+power2_label            "1V8 DSP"
+in2_input               Measured voltage for 1V8 CDC (milliVolts)
+in2_label               "1V8 CDC"
+curr3_input             Measured current for 1V8 CDC (milliAmps)
+curr3_label             "1V8 CDC"
+power3_average          Measured average power for 1V8 CDC (microWatts)
+power3_average_interval Power averaging time input valid from 1 to 1708mS
+power3_label            "1V8 CDC"
+in3_input               Measured voltage for VDDCORE DSP (milliVolts)
+in3_label               "VDDCORE DSP"
+curr4_input             Measured current for VDDCORE DSP (milliAmps)
+curr4_label             "VDDCORE DSP"
+power4_average          Measured average power for VDDCORE DSP (microWatts)
+power4_average_interval Power averaging time input valid from 1 to 1708mS
+power4_label            "VDDCORE DSP"
+in4_input               Measured voltage for AVDD 1V8 (milliVolts)
+in4_label               "AVDD 1V8"
+curr5_input             Measured current for AVDD 1V8 (milliAmps)
+curr5_label             "AVDD 1V8"
+power5_average          Measured average power for AVDD 1V8 (microWatts)
+power5_average_interval Power averaging time input valid from 1 to 1708mS
+power5_label            "AVDD 1V8"
+curr6_input             Measured current for SYSVDD (milliAmps)
+curr6_label             "SYSVDD"
+power6_average          Measured average power for SYSVDD (microWatts)
+power6_average_interval Power averaging time input valid from 1 to 1708mS
+power6_label            "SYSVDD"
+in6_input               Measured voltage for VDDCORE CDC (milliVolts)
+in6_label               "VDDCORE CDC"
+curr7_input             Measured current for VDDCORE CDC (milliAmps)
+curr7_label             "VDDCORE CDC"
+power7_average          Measured average power for VDDCORE CDC (microWatts)
+power7_average_interval Power averaging time input valid from 1 to 1708mS
+power7_label            "VDDCORE CDC"
+in7_input               Measured voltage for MICVDD (milliVolts)
+in7_label               "MICVDD"
+curr8_input             Measured current for MICVDD (milliAmps)
+curr8_label             "MICVDD"
+power8_average          Measured average power for MICVDD (microWatts)
+power8_average_interval Power averaging time input valid from 1 to 1708mS
+power8_label            "MICVDD"
+
+Note: It is not possible to measure voltage on the SYSVDD rail.
diff --git a/MAINTAINERS b/MAINTAINERS
index 2359e12e4c41..cfd9884256af 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3797,6 +3797,7 @@ M:	Richard Fitzgerald <rf@opensource.cirrus.com>
 L:	patches@opensource.cirrus.com
 S:	Supported
 F:	drivers/clk/clk-lochnagar.c
+F:	drivers/hwmon/lochnagar-hwmon.c
 F:	drivers/mfd/lochnagar-i2c.c
 F:	drivers/pinctrl/cirrus/pinctrl-lochnagar.c
 F:	drivers/regulator/lochnagar-regulator.c
@@ -3805,8 +3806,10 @@ F:	include/dt-bindings/pinctrl/lochnagar.h
 F:	include/linux/mfd/lochnagar*
 F:	Documentation/devicetree/bindings/mfd/cirrus,lochnagar.txt
 F:	Documentation/devicetree/bindings/clock/cirrus,lochnagar.txt
+F:	Documentation/devicetree/bindings/hwmon/cirrus,lochnagar.txt
 F:	Documentation/devicetree/bindings/pinctrl/cirrus,lochnagar.txt
 F:	Documentation/devicetree/bindings/regulator/cirrus,lochnagar.txt
+F:	Documentation/hwmon/lochnagar
 
 CISCO FCOE HBA DRIVER
 M:	Satish Kharat <satishkh@cisco.com>
diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index d0f1dfe2bcbb..dedd5febd3aa 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -705,6 +705,16 @@ config SENSORS_LINEAGE
 	  This driver can also be built as a module. If so, the module
 	  will be called lineage-pem.
 
+config SENSORS_LOCHNAGAR
+	tristate "Lochnagar Hardware Monitor"
+	depends on MFD_LOCHNAGAR
+	help
+	  If you say yes here you get support for Lochnagar 2 temperature,
+	  voltage and current sensors abilities.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called lochnagar-hwmon.
+
 config SENSORS_LTC2945
 	tristate "Linear Technology LTC2945"
 	depends on I2C
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index f5c7b442e69e..8db472ea04f0 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_SENSORS_JZ4740)	+= jz4740-hwmon.o
 obj-$(CONFIG_SENSORS_K8TEMP)	+= k8temp.o
 obj-$(CONFIG_SENSORS_K10TEMP)	+= k10temp.o
 obj-$(CONFIG_SENSORS_LINEAGE)	+= lineage-pem.o
+obj-$(CONFIG_SENSORS_LOCHNAGAR)	+= lochnagar-hwmon.o
 obj-$(CONFIG_SENSORS_LM63)	+= lm63.o
 obj-$(CONFIG_SENSORS_LM70)	+= lm70.o
 obj-$(CONFIG_SENSORS_LM73)	+= lm73.o
diff --git a/drivers/hwmon/lochnagar-hwmon.c b/drivers/hwmon/lochnagar-hwmon.c
new file mode 100644
index 000000000000..8b19adf2eeb0
--- /dev/null
+++ b/drivers/hwmon/lochnagar-hwmon.c
@@ -0,0 +1,412 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Lochnagar hardware monitoring features
+ *
+ * Copyright (c) 2016-2019 Cirrus Logic, Inc. and
+ *                         Cirrus Logic International Semiconductor Ltd.
+ *
+ * Author: Lucas Tanure <tanureal@opensource.cirrus.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>
+#include <linux/i2c.h>
+#include <linux/math64.h>
+#include <linux/mfd/lochnagar.h>
+#include <linux/mfd/lochnagar2_regs.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define LN2_MAX_NSAMPLE 1023
+#define LN2_SAMPLE_US   1670
+
+#define LN2_CURR_UNITS  1000
+#define LN2_VOLT_UNITS  1000
+#define LN2_TEMP_UNITS  1000
+#define LN2_PWR_UNITS   1000000
+
+static const char * const lochnagar_chan_names[] = {
+	"DBVDD1",
+	"1V8 DSP",
+	"1V8 CDC",
+	"VDDCORE DSP",
+	"AVDD 1V8",
+	"SYSVDD",
+	"VDDCORE CDC",
+	"MICVDD",
+};
+
+struct lochnagar_hwmon {
+	struct regmap *regmap;
+
+	long power_nsamples[ARRAY_SIZE(lochnagar_chan_names)];
+
+	/* Lock to ensure only a single sensor is read at a time */
+	struct mutex sensor_lock;
+};
+
+enum lochnagar_measure_mode {
+	LN2_CURR = 0,
+	LN2_VOLT,
+	LN2_TEMP,
+};
+
+/**
+ * float_to_long - Convert ieee754 reading from hardware to an integer
+ *
+ * @data: Value read from the hardware
+ * @precision: Units to multiply up to eg. 1000 = milli, 1000000 = micro
+ *
+ * Return: Converted integer reading
+ *
+ * Depending on the measurement type the hardware returns an ieee754
+ * floating point value in either volts, amps or celsius. This function
+ * will convert that into an integer in a smaller unit such as micro-amps
+ * or milli-celsius. The hardware does not return NaN, so consideration of
+ * that is not required.
+ */
+static long float_to_long(u32 data, u32 precision)
+{
+	u64 man = data & 0x007FFFFF;
+	int exp = ((data & 0x7F800000) >> 23) - 127 - 23;
+	bool negative = data & 0x80000000;
+	long result;
+
+	man = (man + (1 << 23)) * precision;
+
+	if (fls64(man) + exp > (int)sizeof(long) * 8 - 1)
+		result = LONG_MAX;
+	else if (exp < 0)
+		result = (man + (1ull << (-exp - 1))) >> -exp;
+	else
+		result = man << exp;
+
+	return negative ? -result : result;
+}
+
+static int do_measurement(struct regmap *regmap, int chan,
+			  enum lochnagar_measure_mode mode, int nsamples)
+{
+	unsigned int val;
+	int ret;
+
+	chan = 1 << (chan + LOCHNAGAR2_IMON_MEASURED_CHANNELS_SHIFT);
+
+	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL1,
+			   LOCHNAGAR2_IMON_ENA_MASK | chan | mode);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL2, nsamples);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
+			   LOCHNAGAR2_IMON_CONFIGURE_MASK);
+	if (ret < 0)
+		return ret;
+
+	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
+					val & LOCHNAGAR2_IMON_DONE_MASK,
+					1000, 10000);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3,
+			   LOCHNAGAR2_IMON_MEASURE_MASK);
+	if (ret < 0)
+		return ret;
+
+	/*
+	 * Actual measurement time is ~1.67mS per sample, approximate this
+	 * with a 1.5mS per sample msleep and then poll for success up to
+	 * ~0.17mS * 1023 (LN2_MAX_NSAMPLES). Normally for smaller values
+	 * of nsamples the poll will complete on the first loop due to
+	 * other latency in the system.
+	 */
+	msleep((nsamples * 3) / 2);
+
+	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL3, val,
+					val & LOCHNAGAR2_IMON_DONE_MASK,
+					5000, 200000);
+	if (ret < 0)
+		return ret;
+
+	return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL3, 0);
+}
+
+static int request_data(struct regmap *regmap, int chan, u32 *data)
+{
+	unsigned int val;
+	int ret;
+
+	ret = regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4,
+			   LOCHNAGAR2_IMON_DATA_REQ_MASK |
+			   chan << LOCHNAGAR2_IMON_CH_SEL_SHIFT);
+	if (ret < 0)
+		return ret;
+
+	ret =  regmap_read_poll_timeout(regmap, LOCHNAGAR2_IMON_CTRL4, val,
+					val & LOCHNAGAR2_IMON_DATA_RDY_MASK,
+					1000, 10000);
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA1, &val);
+	if (ret < 0)
+		return ret;
+
+	*data = val << 16;
+
+	ret = regmap_read(regmap, LOCHNAGAR2_IMON_DATA2, &val);
+	if (ret < 0)
+		return ret;
+
+	*data |= val;
+
+	return regmap_write(regmap, LOCHNAGAR2_IMON_CTRL4, 0);
+}
+
+static int read_sensor(struct device *dev, int chan,
+		       enum lochnagar_measure_mode mode, int nsamples,
+		       unsigned int precision, long *val)
+{
+	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
+	struct regmap *regmap = priv->regmap;
+	u32 data;
+	int ret;
+
+	mutex_lock(&priv->sensor_lock);
+
+	ret = do_measurement(regmap, chan, mode, nsamples);
+	if (ret < 0) {
+		dev_err(dev, "Failed to perform measurement: %d\n", ret);
+		goto error;
+	}
+
+	ret = request_data(regmap, chan, &data);
+	if (ret < 0) {
+		dev_err(dev, "Failed to read measurement: %d\n", ret);
+		goto error;
+	}
+
+	*val = float_to_long(data, precision);
+
+error:
+	mutex_unlock(&priv->sensor_lock);
+
+	return ret;
+}
+
+static int read_power(struct device *dev, int chan, long *val)
+{
+	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
+	int nsamples = priv->power_nsamples[chan];
+	u64 power;
+	int ret;
+
+	if (!strcmp("SYSVDD", lochnagar_chan_names[chan])) {
+		power = 5 * LN2_PWR_UNITS;
+	} else {
+		ret = read_sensor(dev, chan, LN2_VOLT, 1, LN2_PWR_UNITS, val);
+		if (ret < 0)
+			return ret;
+
+		power = abs(*val);
+	}
+
+	ret = read_sensor(dev, chan, LN2_CURR, nsamples, LN2_PWR_UNITS, val);
+	if (ret < 0)
+		return ret;
+
+	power *= abs(*val);
+	power = DIV_ROUND_CLOSEST_ULL(power, LN2_PWR_UNITS);
+
+	if (power > LONG_MAX)
+		*val = LONG_MAX;
+	else
+		*val = power;
+
+	return 0;
+}
+
+static umode_t lochnagar_is_visible(const void *drvdata,
+				    enum hwmon_sensor_types type,
+				    u32 attr, int chan)
+{
+	switch (type) {
+	case hwmon_in:
+		if (!strcmp("SYSVDD", lochnagar_chan_names[chan]))
+			return 0;
+		break;
+	case hwmon_power:
+		if (attr == hwmon_power_average_interval)
+			return 0644;
+		break;
+	default:
+		break;
+	}
+
+	return 0444;
+}
+
+static int lochnagar_read(struct device *dev, enum hwmon_sensor_types type,
+			  u32 attr, int chan, long *val)
+{
+	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
+	int interval;
+
+	switch (type) {
+	case hwmon_in:
+		return read_sensor(dev, chan, LN2_VOLT, 1, LN2_VOLT_UNITS, val);
+	case hwmon_curr:
+		return read_sensor(dev, chan, LN2_CURR, 1, LN2_CURR_UNITS, val);
+	case hwmon_temp:
+		return read_sensor(dev, chan, LN2_TEMP, 1, LN2_TEMP_UNITS, val);
+	case hwmon_power:
+		switch (attr) {
+		case hwmon_power_average:
+			return read_power(dev, chan, val);
+		case hwmon_power_average_interval:
+			interval = priv->power_nsamples[chan] * LN2_SAMPLE_US;
+			*val = DIV_ROUND_CLOSEST(interval, 1000);
+			return 0;
+		default:
+			return -EOPNOTSUPP;
+		}
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int lochnagar_read_string(struct device *dev,
+				 enum hwmon_sensor_types type, u32 attr,
+				 int chan, const char **str)
+{
+	switch (type) {
+	case hwmon_in:
+	case hwmon_curr:
+	case hwmon_power:
+		*str = lochnagar_chan_names[chan];
+		return 0;
+	default:
+		return -EOPNOTSUPP;
+	}
+}
+
+static int lochnagar_write(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int chan, long val)
+{
+	struct lochnagar_hwmon *priv = dev_get_drvdata(dev);
+
+	if (type != hwmon_power || attr != hwmon_power_average_interval)
+		return -EOPNOTSUPP;
+
+	val = clamp_t(long, val, 1, (LN2_MAX_NSAMPLE * LN2_SAMPLE_US) / 1000);
+	val = DIV_ROUND_CLOSEST(val * 1000, LN2_SAMPLE_US);
+
+	priv->power_nsamples[chan] = val;
+
+	return 0;
+}
+
+static const struct hwmon_ops lochnagar_ops = {
+	.is_visible = lochnagar_is_visible,
+	.read = lochnagar_read,
+	.read_string = lochnagar_read_string,
+	.write = lochnagar_write,
+};
+
+static const struct hwmon_channel_info *lochnagar_info[] = {
+	HWMON_CHANNEL_INFO(temp,  HWMON_T_INPUT),
+	HWMON_CHANNEL_INFO(in,    HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL,
+				  HWMON_I_INPUT | HWMON_I_LABEL),
+	HWMON_CHANNEL_INFO(curr,  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL,
+				  HWMON_C_INPUT | HWMON_C_LABEL),
+	HWMON_CHANNEL_INFO(power, HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL,
+				  HWMON_P_AVERAGE | HWMON_P_AVERAGE_INTERVAL |
+				  HWMON_P_LABEL),
+	NULL
+};
+
+static const struct hwmon_chip_info lochnagar_chip_info = {
+	.ops = &lochnagar_ops,
+	.info = lochnagar_info,
+};
+
+static const struct of_device_id lochnagar_of_match[] = {
+	{ .compatible = "cirrus,lochnagar2-hwmon" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, lochnagar_of_match);
+
+static int lochnagar_hwmon_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device *hwmon_dev;
+	struct lochnagar_hwmon *priv;
+	int i;
+
+	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	mutex_init(&priv->sensor_lock);
+
+	priv->regmap = dev_get_regmap(dev->parent, NULL);
+	if (!priv->regmap) {
+		dev_err(dev, "No register map found\n");
+		return -EINVAL;
+	}
+
+	for (i = 0; i < ARRAY_SIZE(priv->power_nsamples); i++)
+		priv->power_nsamples[i] = 96;
+
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "Lochnagar", priv,
+							 &lochnagar_chip_info,
+							 NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static struct platform_driver lochnagar_hwmon_driver = {
+	.driver = {
+		.name = "lochnagar-hwmon",
+		.of_match_table = lochnagar_of_match,
+	},
+	.probe = lochnagar_hwmon_probe,
+};
+module_platform_driver(lochnagar_hwmon_driver);
+
+MODULE_AUTHOR("Lucas Tanure <tanureal@opensource.cirrus.com>");
+MODULE_DESCRIPTION("Lochnagar hardware monitoring features");
+MODULE_LICENSE("GPL");