iio: adc: add Versal SysMon driver

Add the core driver and MMIO platform driver for the AMD/Xilinx Versal
System Monitor (SysMon) block.

The SysMon block resides in the platform management controller (PMC) and
provides on-chip voltage and temperature monitoring through a 10-bit,
200 kSPS ADC. It can monitor up to 160 voltage channels and 64
temperature satellites distributed across the SoC, with a consistent
sample rate of 8 kSPS per channel regardless of how many channels are
enabled.

The hardware also provides four aggregate temperature registers that
are always present regardless of the device tree configuration: the
current max and min across all active satellites, and the peak and
trough values recorded since the last hardware reset.

The driver is split into two compilation units:
  - versal-sysmon-core: Channel parsing, IIO registration, read_raw
  - versal-sysmon: MMIO platform driver with custom regmap accessors

Voltage results are stored in a 19-bit modified floating-point format
and converted to millivolts. Temperature results are stored in Q8.7
signed fixed-point Celsius format and converted to millicelsius.

The MMIO regmap backend uses a custom reg_write accessor that
automatically unlocks the NPI (NoC programming interface) lock
register before each write, as required by the hardware. The regmap
is configured with fast_io since the underlying MMIO accessors are
safe to call from atomic context.

Co-developed-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Signed-off-by: Salih Erim <salih.erim@amd.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

6 files changed, 481 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index c401a3ff5994..0b46a74d74bb 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -29627,6 +29627,14 @@ F:	Documentation/devicetree/bindings/memory-controllers/xlnx,versal-net-ddrmc5.y
 F:	drivers/edac/versalnet_edac.c
 F:	include/linux/cdx/edac_cdx_pcol.h
 
+XILINX VERSAL SYSMON DRIVER
+M:	Salih Erim <salih.erim@amd.com>
+M:	Sai Krishna Potthuri <sai.krishna.potthuri@amd.com>
+L:	linux-iio@vger.kernel.org
+S:	Maintained
+F:	Documentation/devicetree/bindings/iio/adc/xlnx,versal-sysmon.yaml
+F:	drivers/iio/adc/versal-sysmon*
+
 XILINX WATCHDOG DRIVER
 M:	Srinivas Neeli <srinivas.neeli@amd.com>
 R:	Shubhrajyoti Datta <shubhrajyoti.datta@amd.com>
diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 441e5c660716..d1d776a7a9ba 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -1973,6 +1973,26 @@ config TWL6030_GPADC
 	  This driver can also be built as a module. If so, the module will be
 	  called twl6030-gpadc.
 
+config VERSAL_SYSMON_CORE
+	tristate
+	select REGMAP
+
+config VERSAL_SYSMON
+	tristate "AMD Versal SysMon driver"
+	depends on ARCH_ZYNQMP || COMPILE_TEST
+	depends on HAS_IOMEM
+	select VERSAL_SYSMON_CORE
+	help
+	  Say yes here to have support for the AMD/Xilinx Versal System
+	  Monitor (SysMon). This driver provides voltage and temperature
+	  monitoring through the IIO subsystem.
+
+	  The SysMon measures up to 160 supply voltages and reads up to
+	  64 temperature satellites distributed across the SoC.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called versal-sysmon.
+
 config VF610_ADC
 	tristate "Freescale vf610 ADC driver"
 	depends on HAS_IOMEM
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index dc24d0ae76a5..667f7e18506e 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -169,6 +169,8 @@ obj-$(CONFIG_TI_TLC4541) += ti-tlc4541.o
 obj-$(CONFIG_TI_TSC2046) += ti-tsc2046.o
 obj-$(CONFIG_TWL4030_MADC) += twl4030-madc.o
 obj-$(CONFIG_TWL6030_GPADC) += twl6030-gpadc.o
+obj-$(CONFIG_VERSAL_SYSMON_CORE) += versal-sysmon-core.o
+obj-$(CONFIG_VERSAL_SYSMON) += versal-sysmon.o
 obj-$(CONFIG_VF610_ADC) += vf610_adc.o
 obj-$(CONFIG_VIPERBOARD_ADC) += viperboard_adc.o
 obj-$(CONFIG_XILINX_AMS) += xilinx-ams.o
diff --git a/drivers/iio/adc/versal-sysmon-core.c b/drivers/iio/adc/versal-sysmon-core.c
new file mode 100644
index 000000000000..03a745d3fb4f
--- /dev/null
+++ b/drivers/iio/adc/versal-sysmon-core.c
@@ -0,0 +1,292 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD Versal SysMon core driver
+ *
+ * Copyright (C) 2019 - 2022, Xilinx, Inc.
+ * Copyright (C) 2022 - 2026, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/array_size.h>
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/cleanup.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/overflow.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/string.h>
+#include <linux/sysfs.h>
+#include <linux/units.h>
+
+#include <linux/iio/iio.h>
+
+#include "versal-sysmon.h"
+
+#define SYSMON_CHAN_TEMP(_chan, _address, _name)		\
+{								\
+	.type = IIO_TEMP,					\
+	.indexed = 1,						\
+	.address = _address,					\
+	.channel = _chan,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+	.datasheet_name = _name,				\
+}
+
+/*
+ * Static temperature channels (always present).
+ *
+ * These are hardware-computed aggregate registers across all active
+ * temperature satellites:
+ *   temp:     current max temperature across all active satellites
+ *   min:      current min temperature across all active satellites
+ *   max_max:  highest peak recorded since last hardware reset
+ *   min_min:  lowest trough recorded since last hardware reset
+ */
+static const struct iio_chan_spec temp_channels[] = {
+	SYSMON_CHAN_TEMP(0, SYSMON_TEMP_MAX, "temp"),
+	SYSMON_CHAN_TEMP(1, SYSMON_TEMP_MIN, "min"),
+	SYSMON_CHAN_TEMP(2, SYSMON_TEMP_MAX_MAX, "max_max"),
+	SYSMON_CHAN_TEMP(3, SYSMON_TEMP_MIN_MIN, "min_min"),
+};
+
+static void sysmon_supply_rawtoprocessed(int raw_data, int *val)
+{
+	int mantissa, format, exponent;
+
+	mantissa = FIELD_GET(SYSMON_MANTISSA_MASK, raw_data);
+	exponent = SYSMON_SUPPLY_MANTISSA_BITS - FIELD_GET(SYSMON_MODE_MASK, raw_data);
+	format = FIELD_GET(SYSMON_FMT_MASK, raw_data);
+	/*
+	 * When format bit is set the mantissa is two's complement
+	 * (per hardware spec); sign-extend to int for correct arithmetic.
+	 */
+	if (format)
+		mantissa = sign_extend32(mantissa, 15);
+
+	*val = (mantissa * (int)MILLI) >> exponent;
+}
+
+static int sysmon_read_raw(struct iio_dev *indio_dev,
+			   struct iio_chan_spec const *chan,
+			   int *val, int *val2, long mask)
+{
+	struct sysmon *sysmon = iio_priv(indio_dev);
+	unsigned int regval;
+	int ret;
+
+	guard(mutex)(&sysmon->lock);
+
+	switch (chan->type) {
+	case IIO_TEMP:
+		if (mask == IIO_CHAN_INFO_SCALE) {
+			/* Q8.7 to millicelsius: raw * 1000 / 128 */
+			*val = MILLIDEGREE_PER_DEGREE;
+			*val2 = BIT(SYSMON_FRACTIONAL_SHIFT);
+			return IIO_VAL_FRACTIONAL;
+		}
+		if (mask != IIO_CHAN_INFO_RAW)
+			return -EINVAL;
+
+		ret = regmap_read(sysmon->regmap, chan->address, &regval);
+		if (ret)
+			return ret;
+
+		*val = sign_extend32(regval, 15);
+		return IIO_VAL_INT;
+
+	case IIO_VOLTAGE:
+		if (mask != IIO_CHAN_INFO_PROCESSED)
+			return -EINVAL;
+
+		ret = regmap_read(sysmon->regmap,
+				  chan->address * SYSMON_REG_STRIDE +
+				  SYSMON_SUPPLY_BASE, &regval);
+		if (ret)
+			return ret;
+
+		sysmon_supply_rawtoprocessed(regval, val);
+		return IIO_VAL_INT;
+
+	default:
+		return -EINVAL;
+	}
+}
+
+static int sysmon_read_label(struct iio_dev *indio_dev,
+			     struct iio_chan_spec const *chan,
+			     char *label)
+{
+	if (chan->datasheet_name)
+		return sysfs_emit(label, "%s\n", chan->datasheet_name);
+
+	return -EINVAL;
+}
+
+static const struct iio_info sysmon_iio_info = {
+	.read_raw = sysmon_read_raw,
+	.read_label = sysmon_read_label,
+};
+
+/**
+ * sysmon_parse_fw() - Parse firmware nodes and configure IIO channels.
+ * @indio_dev: IIO device instance
+ * @dev: Parent device
+ *
+ * Reads voltage-channels and temperature-channels container nodes from
+ * firmware and builds the IIO channel array. Static temperature channels
+ * are prepended, followed by supply and satellite channels from DT.
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+static int sysmon_parse_fw(struct iio_dev *indio_dev, struct device *dev)
+{
+	unsigned int num_chan, num_static, num_supply, num_temp;
+	unsigned int idx, temp_chan_idx, volt_chan_idx;
+	struct iio_chan_spec *sysmon_channels;
+	const char *label;
+	u32 reg;
+	int ret;
+
+	struct fwnode_handle *supply_node __free(fwnode_handle) =
+		device_get_named_child_node(dev, "voltage-channels");
+	num_supply = fwnode_get_child_node_count(supply_node);
+
+	struct fwnode_handle *temp_node __free(fwnode_handle) =
+		device_get_named_child_node(dev, "temperature-channels");
+	num_temp = fwnode_get_child_node_count(temp_node);
+
+	num_static = ARRAY_SIZE(temp_channels);
+	num_chan = size_add(num_temp, size_add(num_static, num_supply));
+	sysmon_channels = devm_kcalloc(dev, num_chan, sizeof(*sysmon_channels), GFP_KERNEL);
+	if (!sysmon_channels)
+		return -ENOMEM;
+
+	/* Static temperature channels first */
+	memcpy(sysmon_channels, temp_channels, sizeof(temp_channels));
+	idx = num_static;
+
+	/* Supply channels from DT */
+	fwnode_for_each_child_node_scoped(supply_node, child) {
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing reg for supply channel\n");
+
+		if (reg > SYSMON_SUPPLY_IDX_MAX)
+			return dev_err_probe(dev, -EINVAL,
+					     "supply reg %u exceeds max %u\n",
+					     reg, SYSMON_SUPPLY_IDX_MAX);
+
+		ret = fwnode_property_read_string(child, "label", &label);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing label for supply channel\n");
+
+		sysmon_channels[idx++] = (struct iio_chan_spec) {
+			.type = IIO_VOLTAGE,
+			.indexed = 1,
+			.address = reg,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
+			.datasheet_name = label,
+		};
+	}
+
+	/* Temperature satellite channels from DT */
+	fwnode_for_each_child_node_scoped(temp_node, child) {
+		ret = fwnode_property_read_u32(child, "reg", &reg);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing reg for temp channel\n");
+
+		if (reg < 1 || reg > SYSMON_TEMP_SAT_MAX)
+			return dev_err_probe(dev, -EINVAL,
+					     "temp reg %u out of range [1..%u]\n",
+					     reg, SYSMON_TEMP_SAT_MAX);
+
+		ret = fwnode_property_read_string(child, "label", &label);
+		if (ret)
+			return dev_err_probe(dev, ret,
+					     "missing label for temp channel\n");
+
+		sysmon_channels[idx++] = (struct iio_chan_spec) {
+			.type = IIO_TEMP,
+			.indexed = 1,
+			.address = SYSMON_TEMP_SAT_BASE +
+				   (reg - 1) * SYSMON_REG_STRIDE,
+			.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+			.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+			.datasheet_name = label,
+		};
+	}
+
+	indio_dev->num_channels = idx;
+	indio_dev->info = &sysmon_iio_info;
+
+	/*
+	 * Assign per-type sequential channel numbers.
+	 * IIO sysfs uses type prefix (in_tempN, in_voltageN)
+	 * so numbers only need to be unique within each type.
+	 */
+	temp_chan_idx = 0;
+	volt_chan_idx = 0;
+	for (unsigned int idx = 0; idx < indio_dev->num_channels; idx++) {
+		if (sysmon_channels[idx].type == IIO_TEMP)
+			sysmon_channels[idx].channel = temp_chan_idx++;
+		else
+			sysmon_channels[idx].channel = volt_chan_idx++;
+	}
+
+	indio_dev->channels = sysmon_channels;
+
+	return 0;
+}
+
+/**
+ * devm_versal_sysmon_core_probe() - Initialize Versal SysMon core
+ * @dev: Parent device
+ * @regmap: Register map for hardware access
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int devm_versal_sysmon_core_probe(struct device *dev, struct regmap *regmap)
+{
+	struct iio_dev *indio_dev;
+	struct sysmon *sysmon;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(dev, sizeof(*sysmon));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	sysmon = iio_priv(indio_dev);
+	sysmon->regmap = regmap;
+
+	ret = devm_mutex_init(dev, &sysmon->lock);
+	if (ret)
+		return ret;
+
+	/* Disable all interrupts and clear pending status */
+	ret = regmap_write(sysmon->regmap, SYSMON_IDR, SYSMON_INTR_ALL_MASK);
+	if (ret)
+		return ret;
+	ret = regmap_write(sysmon->regmap, SYSMON_ISR, SYSMON_INTR_ALL_MASK);
+	if (ret)
+		return ret;
+
+	indio_dev->name = "versal-sysmon";
+	indio_dev->modes = INDIO_DIRECT_MODE;
+
+	ret = sysmon_parse_fw(indio_dev, dev);
+	if (ret)
+		return ret;
+
+	return devm_iio_device_register(dev, indio_dev);
+}
+EXPORT_SYMBOL_NS_GPL(devm_versal_sysmon_core_probe, "VERSAL_SYSMON");
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("AMD Versal SysMon Core Driver");
+MODULE_AUTHOR("Salih Erim <salih.erim@amd.com>");
diff --git a/drivers/iio/adc/versal-sysmon.c b/drivers/iio/adc/versal-sysmon.c
new file mode 100644
index 000000000000..529d0486c9f9
--- /dev/null
+++ b/drivers/iio/adc/versal-sysmon.c
@@ -0,0 +1,92 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * AMD Versal SysMon MMIO platform driver
+ *
+ * Copyright (C) 2019 - 2022, Xilinx, Inc.
+ * Copyright (C) 2022 - 2026, Advanced Micro Devices, Inc.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/types.h>
+
+#include "versal-sysmon.h"
+
+struct sysmon_mmio {
+	void __iomem *base;
+};
+
+static int sysmon_mmio_reg_read(void *context, unsigned int reg, unsigned int *val)
+{
+	struct sysmon_mmio *mmio = context;
+
+	*val = readl(mmio->base + reg);
+	return 0;
+}
+
+static int sysmon_mmio_reg_write(void *context, unsigned int reg, unsigned int val)
+{
+	struct sysmon_mmio *mmio = context;
+
+	/* NPI must be unlocked before any register write except to NPI_LOCK */
+	if (reg != SYSMON_NPI_LOCK)
+		writel(SYSMON_NPI_UNLOCK_CODE, mmio->base + SYSMON_NPI_LOCK);
+	writel(val, mmio->base + reg);
+
+	return 0;
+}
+
+static const struct regmap_config sysmon_mmio_regmap_config = {
+	.reg_bits = 32,
+	.val_bits = 32,
+	.reg_stride = SYSMON_REG_STRIDE,
+	.max_register = SYSMON_MAX_REG,
+	.reg_read = sysmon_mmio_reg_read,
+	.reg_write = sysmon_mmio_reg_write,
+	.fast_io = true,
+};
+
+static int sysmon_platform_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct sysmon_mmio *mmio;
+	struct regmap *regmap;
+
+	mmio = devm_kzalloc(dev, sizeof(*mmio), GFP_KERNEL);
+	if (!mmio)
+		return -ENOMEM;
+
+	mmio->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(mmio->base))
+		return PTR_ERR(mmio->base);
+
+	regmap = devm_regmap_init(dev, NULL, mmio, &sysmon_mmio_regmap_config);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	return devm_versal_sysmon_core_probe(dev, regmap);
+}
+
+static const struct of_device_id sysmon_of_match_table[] = {
+	{ .compatible = "xlnx,versal-sysmon" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, sysmon_of_match_table);
+
+static struct platform_driver sysmon_platform_driver = {
+	.probe = sysmon_platform_probe,
+	.driver = {
+		.name = "versal-sysmon",
+		.of_match_table = sysmon_of_match_table,
+	},
+};
+module_platform_driver(sysmon_platform_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("AMD Versal SysMon Platform Driver");
+MODULE_IMPORT_NS("VERSAL_SYSMON");
+MODULE_AUTHOR("Salih Erim <salih.erim@amd.com>");
diff --git a/drivers/iio/adc/versal-sysmon.h b/drivers/iio/adc/versal-sysmon.h
new file mode 100644
index 000000000000..e27a53575752
--- /dev/null
+++ b/drivers/iio/adc/versal-sysmon.h
@@ -0,0 +1,67 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AMD Versal SysMon driver
+ *
+ * Copyright (C) 2019 - 2022, Xilinx, Inc.
+ * Copyright (C) 2022 - 2026, Advanced Micro Devices, Inc.
+ */
+
+#ifndef _VERSAL_SYSMON_H_
+#define _VERSAL_SYSMON_H_
+
+#include <linux/bits.h>
+#include <linux/mutex.h>
+
+struct device;
+struct regmap;
+
+/* Register offsets (sorted by address) */
+#define SYSMON_NPI_LOCK			0x000C
+#define SYSMON_ISR			0x0044
+#define SYSMON_IDR			0x0050
+#define SYSMON_TEMP_MAX			0x1030
+#define SYSMON_TEMP_MIN			0x1034
+#define SYSMON_SUPPLY_BASE		0x1040
+#define SYSMON_TEMP_MIN_MIN		0x1F8C
+#define SYSMON_TEMP_MAX_MAX		0x1F90
+#define SYSMON_TEMP_SAT_BASE		0x1FAC
+#define SYSMON_MAX_REG			0x24C0
+
+/* NPI unlock value written to SYSMON_NPI_LOCK */
+#define SYSMON_NPI_UNLOCK_CODE		0xF9E8D7C6
+
+/* Register stride: 4 bytes per 32-bit register */
+#define SYSMON_REG_STRIDE		4
+
+#define SYSMON_SUPPLY_IDX_MAX		159
+#define SYSMON_TEMP_SAT_MAX		64
+#define SYSMON_INTR_ALL_MASK		GENMASK(31, 0)
+
+/* Supply voltage conversion register fields */
+#define SYSMON_MANTISSA_MASK		GENMASK(15, 0)
+#define SYSMON_FMT_MASK			BIT(16)
+#define SYSMON_MODE_MASK		GENMASK(18, 17)
+
+/* Q8.7 fractional shift */
+#define SYSMON_FRACTIONAL_SHIFT		7U
+#define SYSMON_SUPPLY_MANTISSA_BITS	16
+
+/**
+ * struct sysmon - Driver data for Versal SysMon
+ * @regmap: register map for hardware access
+ * @lock: protects read-modify-write sequences on threshold registers
+ *        and cached state that spans multiple regmap calls
+ */
+struct sysmon {
+	struct regmap *regmap;
+	/*
+	 * Protects read-modify-write sequences on threshold registers
+	 * and cached state (oversampling ratios, hysteresis values)
+	 * that spans multiple regmap calls.
+	 */
+	struct mutex lock;
+};
+
+int devm_versal_sysmon_core_probe(struct device *dev, struct regmap *regmap);
+
+#endif /* _VERSAL_SYSMON_H_ */