sa67mcu-hwmon.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * sl67mcu hardware monitoring driver
  4 *
  5 * Copyright 2025 Kontron Europe GmbH
  6 */
  7
  8#include <linux/bitfield.h>
  9#include <linux/hwmon.h>
 10#include <linux/kernel.h>
 11#include <linux/mod_devicetable.h>
 12#include <linux/module.h>
 13#include <linux/platform_device.h>
 14#include <linux/property.h>
 15#include <linux/regmap.h>
 16
 17#define SA67MCU_VOLTAGE(n)	(0x00 + ((n) * 2))
 18#define SA67MCU_TEMP(n)		(0x04 + ((n) * 2))
 19
 20struct sa67mcu_hwmon {
 21	struct regmap *regmap;
 22	u32 offset;
 23};
 24
 25static int sa67mcu_hwmon_read(struct device *dev,
 26			      enum hwmon_sensor_types type, u32 attr,
 27			      int channel, long *input)
 28{
 29	struct sa67mcu_hwmon *hwmon = dev_get_drvdata(dev);
 30	unsigned int offset;
 31	u8 reg[2];
 32	int ret;
 33
 34	switch (type) {
 35	case hwmon_in:
 36		switch (attr) {
 37		case hwmon_in_input:
 38			offset = hwmon->offset + SA67MCU_VOLTAGE(channel);
 39			break;
 40		default:
 41			return -EOPNOTSUPP;
 42		}
 43		break;
 44	case hwmon_temp:
 45		switch (attr) {
 46		case hwmon_temp_input:
 47			offset = hwmon->offset + SA67MCU_TEMP(channel);
 48			break;
 49		default:
 50			return -EOPNOTSUPP;
 51		}
 52		break;
 53	default:
 54		return -EOPNOTSUPP;
 55	}
 56
 57	/* Reading the low byte will capture the value */
 58	ret = regmap_bulk_read(hwmon->regmap, offset, reg, ARRAY_SIZE(reg));
 59	if (ret)
 60		return ret;
 61
 62	*input = reg[1] << 8 | reg[0];
 63
 64	/* Temperatures are s16 and in 0.1degC steps. */
 65	if (type == hwmon_temp)
 66		*input = sign_extend32(*input, 15) * 100;
 67
 68	return 0;
 69}
 70
 71static const struct hwmon_channel_info * const sa67mcu_hwmon_info[] = {
 72	HWMON_CHANNEL_INFO(in,
 73			   HWMON_I_INPUT | HWMON_I_LABEL,
 74			   HWMON_I_INPUT | HWMON_I_LABEL),
 75	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
 76	NULL
 77};
 78
 79static const char *const sa67mcu_hwmon_in_labels[] = {
 80	"VDDIN",
 81	"VDD_RTC",
 82};
 83
 84static int sa67mcu_hwmon_read_string(struct device *dev,
 85				     enum hwmon_sensor_types type, u32 attr,
 86				     int channel, const char **str)
 87{
 88	switch (type) {
 89	case hwmon_in:
 90		switch (attr) {
 91		case hwmon_in_label:
 92			*str = sa67mcu_hwmon_in_labels[channel];
 93			return 0;
 94		default:
 95			return -EOPNOTSUPP;
 96		}
 97	default:
 98		return -EOPNOTSUPP;
 99	}
100}
101
102static const struct hwmon_ops sa67mcu_hwmon_ops = {
103	.visible = 0444,
104	.read = sa67mcu_hwmon_read,
105	.read_string = sa67mcu_hwmon_read_string,
106};
107
108static const struct hwmon_chip_info sa67mcu_hwmon_chip_info = {
109	.ops = &sa67mcu_hwmon_ops,
110	.info = sa67mcu_hwmon_info,
111};
112
113static int sa67mcu_hwmon_probe(struct platform_device *pdev)
114{
115	struct sa67mcu_hwmon *hwmon;
116	struct device *hwmon_dev;
117	int ret;
118
119	if (!pdev->dev.parent)
120		return -ENODEV;
121
122	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
123	if (!hwmon)
124		return -ENOMEM;
125
126	hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
127	if (!hwmon->regmap)
128		return -ENODEV;
129
130	ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
131	if (ret)
132		return -EINVAL;
133
134	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
135							 "sa67mcu_hwmon", hwmon,
136							 &sa67mcu_hwmon_chip_info,
137							 NULL);
138	if (IS_ERR(hwmon_dev))
139		dev_err(&pdev->dev, "failed to register as hwmon device");
140
141	return PTR_ERR_OR_ZERO(hwmon_dev);
142}
143
144static const struct of_device_id sa67mcu_hwmon_of_match[] = {
145	{ .compatible = "kontron,sa67mcu-hwmon", },
146	{}
147};
148MODULE_DEVICE_TABLE(of, sa67mcu_hwmon_of_match);
149
150static struct platform_driver sa67mcu_hwmon_driver = {
151	.probe = sa67mcu_hwmon_probe,
152	.driver = {
153		.name = "sa67mcu-hwmon",
154		.of_match_table = sa67mcu_hwmon_of_match,
155	},
156};
157module_platform_driver(sa67mcu_hwmon_driver);
158
159MODULE_DESCRIPTION("sa67mcu Hardware Monitoring Driver");
160MODULE_AUTHOR("Michael Walle <mwalle@kernel.org>");
161MODULE_LICENSE("GPL");