linux/drivers/hwmon/nsa320-hwmon.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * drivers/hwmon/nsa320-hwmon.c
 *
 * ZyXEL NSA320 Media Servers
 * hardware monitoring
 *
 * Copyright (C) 2016 Adam Baker <[email protected]>
 * based on a board file driver
 * Copyright (C) 2012 Peter Schildmann <[email protected]>
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio/consumer.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/mutex.h>
#include <linux/of.h>
#include <linux/platform_device.h>

/* Tests for error return values rely upon this value being < 0x80 */
#define MAGIC_NUMBER …

/*
 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
 * to perform temperature and fan speed monitoring. It is read by taking
 * the active pin low. The 32 bit output word is then clocked onto the
 * data line. The MSB of the data word is a magic nuber to indicate it
 * has been read correctly, the next byte is the fan speed (in hundreds
 * of RPM) and the last two bytes are the temperature (in tenths of a
 * degree)
 */

struct nsa320_hwmon { … };

enum nsa320_inputs { … };

static const char * const nsa320_input_names[] = …;

/*
 * Although this protocol looks similar to SPI the long delay
 * between the active (aka chip select) signal and the shorter
 * delay between clock pulses are needed for reliable operation.
 * The delays provided are taken from the manufacturer kernel,
 * testing suggest they probably incorporate a reasonable safety
 * margin. (The single device tested became unreliable if the
 * delay was reduced to 1/10th of this value.)
 */
static s32 nsa320_hwmon_update(struct device *dev)
{ … }

static ssize_t label_show(struct device *dev, struct device_attribute *attr,
			  char *buf)
{ … }

static ssize_t temp1_input_show(struct device *dev,
				struct device_attribute *attr, char *buf)
{ … }

static ssize_t fan1_input_show(struct device *dev,
			       struct device_attribute *attr, char *buf)
{ … }

static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
static DEVICE_ATTR_RO(temp1_input);
static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
static DEVICE_ATTR_RO(fan1_input);

static struct attribute *nsa320_attrs[] = …;

ATTRIBUTE_GROUPS(…);

static const struct of_device_id of_nsa320_hwmon_match[] = …;

static int nsa320_hwmon_probe(struct platform_device *pdev)
{ … }

/* All allocations use devres so remove() is not needed. */

static struct platform_driver nsa320_hwmon_driver = …;

module_platform_driver(…) …;

MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
MODULE_AUTHOR(…) …;
MODULE_AUTHOR(…) …;
MODULE_DESCRIPTION(…) …;
MODULE_LICENSE(…) …;
MODULE_ALIAS(…) …;