LXR linux/drivers/hwmon/nsa320-hwmon.c

   1/*
   2 * drivers/hwmon/nsa320-hwmon.c
   3 *
   4 * ZyXEL NSA320 Media Servers
   5 * hardware monitoring
   6 *
   7 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
   8 * based on a board file driver
   9 * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
  10 *
  11 * This program is free software; you can redistribute it and/or modify it
  12 * under the terms of the GNU General Public License v2 as published by the
  13 * Free Software Foundation.
  14 *
  15 * This program is distributed in the hope that it will be useful, but WITHOUT
  16 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  17 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
  18 * more details.
  19 */
  20
  21#include <linux/bitops.h>
  22#include <linux/delay.h>
  23#include <linux/err.h>
  24#include <linux/gpio/consumer.h>
  25#include <linux/hwmon.h>
  26#include <linux/hwmon-sysfs.h>
  27#include <linux/jiffies.h>
  28#include <linux/module.h>
  29#include <linux/mutex.h>
  30#include <linux/of.h>
  31#include <linux/of_device.h>
  32#include <linux/of_platform.h>
  33#include <linux/platform_device.h>
  34
  35/* Tests for error return values rely upon this value being < 0x80 */
  36#define MAGIC_NUMBER 0x55
  37
  38/*
  39 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
  40 * to perform temperature and fan speed monitoring. It is read by taking
  41 * the active pin low. The 32 bit output word is then clocked onto the
  42 * data line. The MSB of the data word is a magic nuber to indicate it
  43 * has been read correctly, the next byte is the fan speed (in hundreds
  44 * of RPM) and the last two bytes are the temperature (in tenths of a
  45 * degree)
  46 */
  47
  48struct nsa320_hwmon {
  49        struct mutex            update_lock;    /* lock GPIO operations */
  50        unsigned long           last_updated;   /* jiffies */
  51        unsigned long           mcu_data;
  52        struct gpio_desc        *act;
  53        struct gpio_desc        *clk;
  54        struct gpio_desc        *data;
  55};
  56
  57enum nsa320_inputs {
  58        NSA320_TEMP = 0,
  59        NSA320_FAN = 1,
  60};
  61
  62static const char * const nsa320_input_names[] = {
  63        [NSA320_TEMP] = "System Temperature",
  64        [NSA320_FAN] = "Chassis Fan",
  65};
  66
  67/*
  68 * Although this protocol looks similar to SPI the long delay
  69 * between the active (aka chip select) signal and the shorter
  70 * delay between clock pulses are needed for reliable operation.
  71 * The delays provided are taken from the manufacturer kernel,
  72 * testing suggest they probably incorporate a reasonable safety
  73 * margin. (The single device tested became unreliable if the
  74 * delay was reduced to 1/10th of this value.)
  75 */
  76static s32 nsa320_hwmon_update(struct device *dev)
  77{
  78        u32 mcu_data;
  79        u32 mask;
  80        struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
  81
  82        mutex_lock(&hwmon->update_lock);
  83
  84        mcu_data = hwmon->mcu_data;
  85
  86        if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
  87                gpiod_set_value(hwmon->act, 1);
  88                msleep(100);
  89
  90                mcu_data = 0;
  91                for (mask = BIT(31); mask; mask >>= 1) {
  92                        gpiod_set_value(hwmon->clk, 0);
  93                        usleep_range(100, 200);
  94                        gpiod_set_value(hwmon->clk, 1);
  95                        usleep_range(100, 200);
  96                        if (gpiod_get_value(hwmon->data))
  97                                mcu_data |= mask;
  98                }
  99
 100                gpiod_set_value(hwmon->act, 0);
 101                dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
 102
 103                if ((mcu_data >> 24) != MAGIC_NUMBER) {
 104                        dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
 105                        mcu_data = -EIO;
 106                } else {
 107                        hwmon->mcu_data = mcu_data;
 108                        hwmon->last_updated = jiffies;
 109                }
 110        }
 111
 112        mutex_unlock(&hwmon->update_lock);
 113
 114        return mcu_data;
 115}
 116
 117static ssize_t show_label(struct device *dev,
 118                          struct device_attribute *attr, char *buf)
 119{
 120        int channel = to_sensor_dev_attr(attr)->index;
 121
 122        return sprintf(buf, "%s\n", nsa320_input_names[channel]);
 123}
 124
 125static ssize_t temp1_input_show(struct device *dev,
 126                                struct device_attribute *attr, char *buf)
 127{
 128        s32 mcu_data = nsa320_hwmon_update(dev);
 129
 130        if (mcu_data < 0)
 131                return mcu_data;
 132
 133        return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
 134}
 135
 136static ssize_t fan1_input_show(struct device *dev,
 137                               struct device_attribute *attr, char *buf)
 138{
 139        s32 mcu_data = nsa320_hwmon_update(dev);
 140
 141        if (mcu_data < 0)
 142                return mcu_data;
 143
 144        return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
 145}
 146
 147static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_label, NULL, NSA320_TEMP);
 148static DEVICE_ATTR_RO(temp1_input);
 149static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, show_label, NULL, NSA320_FAN);
 150static DEVICE_ATTR_RO(fan1_input);
 151
 152static struct attribute *nsa320_attrs[] = {
 153        &sensor_dev_attr_temp1_label.dev_attr.attr,
 154        &dev_attr_temp1_input.attr,
 155        &sensor_dev_attr_fan1_label.dev_attr.attr,
 156        &dev_attr_fan1_input.attr,
 157        NULL
 158};
 159
 160ATTRIBUTE_GROUPS(nsa320);
 161
 162static const struct of_device_id of_nsa320_hwmon_match[] = {
 163        { .compatible = "zyxel,nsa320-mcu", },
 164        { },
 165};
 166
 167static int nsa320_hwmon_probe(struct platform_device *pdev)
 168{
 169        struct nsa320_hwmon     *hwmon;
 170        struct device           *classdev;
 171
 172        hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
 173        if (!hwmon)
 174                return -ENOMEM;
 175
 176        /* Look up the GPIO pins to use */
 177        hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
 178        if (IS_ERR(hwmon->act))
 179                return PTR_ERR(hwmon->act);
 180
 181        hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
 182        if (IS_ERR(hwmon->clk))
 183                return PTR_ERR(hwmon->clk);
 184
 185        hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
 186        if (IS_ERR(hwmon->data))
 187                return PTR_ERR(hwmon->data);
 188
 189        mutex_init(&hwmon->update_lock);
 190
 191        classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
 192                                        "nsa320", hwmon, nsa320_groups);
 193
 194        return PTR_ERR_OR_ZERO(classdev);
 195
 196}
 197
 198/* All allocations use devres so remove() is not needed. */
 199
 200static struct platform_driver nsa320_hwmon_driver = {
 201        .probe = nsa320_hwmon_probe,
 202        .driver = {
 203                .name = "nsa320-hwmon",
 204                .of_match_table = of_match_ptr(of_nsa320_hwmon_match),
 205        },
 206};
 207
 208module_platform_driver(nsa320_hwmon_driver);
 209
 210MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
 211MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
 212MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
 213MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
 214MODULE_LICENSE("GPL v2");
 215MODULE_ALIAS("platform:nsa320-hwmon");
 216