cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sl28cpld-hwmon.c (3136B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * sl28cpld hardware monitoring driver
      4 *
      5 * Copyright 2020 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 FAN_INPUT		0x00
     18#define   FAN_SCALE_X8		BIT(7)
     19#define   FAN_VALUE_MASK	GENMASK(6, 0)
     20
     21struct sl28cpld_hwmon {
     22	struct regmap *regmap;
     23	u32 offset;
     24};
     25
     26static umode_t sl28cpld_hwmon_is_visible(const void *data,
     27					 enum hwmon_sensor_types type,
     28					 u32 attr, int channel)
     29{
     30	return 0444;
     31}
     32
     33static int sl28cpld_hwmon_read(struct device *dev,
     34			       enum hwmon_sensor_types type, u32 attr,
     35			       int channel, long *input)
     36{
     37	struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev);
     38	unsigned int value;
     39	int ret;
     40
     41	switch (attr) {
     42	case hwmon_fan_input:
     43		ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT,
     44				  &value);
     45		if (ret)
     46			return ret;
     47		/*
     48		 * The register has a 7 bit value and 1 bit which indicates the
     49		 * scale. If the MSB is set, then the lower 7 bit has to be
     50		 * multiplied by 8, to get the correct reading.
     51		 */
     52		if (value & FAN_SCALE_X8)
     53			value = FIELD_GET(FAN_VALUE_MASK, value) << 3;
     54
     55		/*
     56		 * The counter period is 1000ms and the sysfs specification
     57		 * says we should assume 2 pulses per revolution.
     58		 */
     59		value *= 60 / 2;
     60
     61		break;
     62	default:
     63		return -EOPNOTSUPP;
     64	}
     65
     66	*input = value;
     67	return 0;
     68}
     69
     70static const struct hwmon_channel_info *sl28cpld_hwmon_info[] = {
     71	HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
     72	NULL
     73};
     74
     75static const struct hwmon_ops sl28cpld_hwmon_ops = {
     76	.is_visible = sl28cpld_hwmon_is_visible,
     77	.read = sl28cpld_hwmon_read,
     78};
     79
     80static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = {
     81	.ops = &sl28cpld_hwmon_ops,
     82	.info = sl28cpld_hwmon_info,
     83};
     84
     85static int sl28cpld_hwmon_probe(struct platform_device *pdev)
     86{
     87	struct sl28cpld_hwmon *hwmon;
     88	struct device *hwmon_dev;
     89	int ret;
     90
     91	if (!pdev->dev.parent)
     92		return -ENODEV;
     93
     94	hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
     95	if (!hwmon)
     96		return -ENOMEM;
     97
     98	hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL);
     99	if (!hwmon->regmap)
    100		return -ENODEV;
    101
    102	ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset);
    103	if (ret)
    104		return -EINVAL;
    105
    106	hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev,
    107				"sl28cpld_hwmon", hwmon,
    108				&sl28cpld_hwmon_chip_info, NULL);
    109	if (IS_ERR(hwmon_dev))
    110		dev_err(&pdev->dev, "failed to register as hwmon device");
    111
    112	return PTR_ERR_OR_ZERO(hwmon_dev);
    113}
    114
    115static const struct of_device_id sl28cpld_hwmon_of_match[] = {
    116	{ .compatible = "kontron,sl28cpld-fan" },
    117	{}
    118};
    119MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match);
    120
    121static struct platform_driver sl28cpld_hwmon_driver = {
    122	.probe = sl28cpld_hwmon_probe,
    123	.driver = {
    124		.name = "sl28cpld-fan",
    125		.of_match_table = sl28cpld_hwmon_of_match,
    126	},
    127};
    128module_platform_driver(sl28cpld_hwmon_driver);
    129
    130MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver");
    131MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
    132MODULE_LICENSE("GPL");