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

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * drivers/hwmon/nsa320-hwmon.c
   4 *
   5 * ZyXEL NSA320 Media Servers
   6 * hardware monitoring
   7 *
   8 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
   9 * based on a board file driver
  10 * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
  11 */
  12
  13#include <linux/bitops.h>
  14#include <linux/delay.h>
  15#include <linux/err.h>
  16#include <linux/gpio/consumer.h>
  17#include <linux/hwmon.h>
  18#include <linux/hwmon-sysfs.h>
  19#include <linux/jiffies.h>
  20#include <linux/module.h>
  21#include <linux/mutex.h>
  22#include <linux/of.h>
  23#include <linux/of_device.h>
  24#include <linux/of_platform.h>
  25#include <linux/platform_device.h>
  26
  27/* Tests for error return values rely upon this value being < 0x80 */
  28#define MAGIC_NUMBER 0x55
  29
  30/*
  31 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
  32 * to perform temperature and fan speed monitoring. It is read by taking
  33 * the active pin low. The 32 bit output word is then clocked onto the
  34 * data line. The MSB of the data word is a magic nuber to indicate it
  35 * has been read correctly, the next byte is the fan speed (in hundreds
  36 * of RPM) and the last two bytes are the temperature (in tenths of a
  37 * degree)
  38 */
  39
  40struct nsa320_hwmon {
  41        struct mutex            update_lock;    /* lock GPIO operations */
  42        unsigned long           last_updated;   /* jiffies */
  43        unsigned long           mcu_data;
  44        struct gpio_desc        *act;
  45        struct gpio_desc        *clk;
  46        struct gpio_desc        *data;
  47};
  48
  49enum nsa320_inputs {
  50        NSA320_TEMP = 0,
  51        NSA320_FAN = 1,
  52};
  53
  54static const char * const nsa320_input_names[] = {
  55        [NSA320_TEMP] = "System Temperature",
  56        [NSA320_FAN] = "Chassis Fan",
  57};
  58
  59/*
  60 * Although this protocol looks similar to SPI the long delay
  61 * between the active (aka chip select) signal and the shorter
  62 * delay between clock pulses are needed for reliable operation.
  63 * The delays provided are taken from the manufacturer kernel,
  64 * testing suggest they probably incorporate a reasonable safety
  65 * margin. (The single device tested became unreliable if the
  66 * delay was reduced to 1/10th of this value.)
  67 */
  68static s32 nsa320_hwmon_update(struct device *dev)
  69{
  70        u32 mcu_data;
  71        u32 mask;
  72        struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
  73
  74        mutex_lock(&hwmon->update_lock);
  75
  76        mcu_data = hwmon->mcu_data;
  77
  78        if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
  79                gpiod_set_value(hwmon->act, 1);
  80                msleep(100);
  81
  82                mcu_data = 0;
  83                for (mask = BIT(31); mask; mask >>= 1) {
  84                        gpiod_set_value(hwmon->clk, 0);
  85                        usleep_range(100, 200);
  86                        gpiod_set_value(hwmon->clk, 1);
  87                        usleep_range(100, 200);
  88                        if (gpiod_get_value(hwmon->data))
  89                                mcu_data |= mask;
  90                }
  91
  92                gpiod_set_value(hwmon->act, 0);
  93                dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
  94
  95                if ((mcu_data >> 24) != MAGIC_NUMBER) {
  96                        dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
  97                        mcu_data = -EIO;
  98                } else {
  99                        hwmon->mcu_data = mcu_data;
 100                        hwmon->last_updated = jiffies;
 101                }
 102        }
 103
 104        mutex_unlock(&hwmon->update_lock);
 105
 106        return mcu_data;
 107}
 108
 109static ssize_t label_show(struct device *dev, struct device_attribute *attr,
 110                          char *buf)
 111{
 112        int channel = to_sensor_dev_attr(attr)->index;
 113
 114        return sprintf(buf, "%s\n", nsa320_input_names[channel]);
 115}
 116
 117static ssize_t temp1_input_show(struct device *dev,
 118                                struct device_attribute *attr, char *buf)
 119{
 120        s32 mcu_data = nsa320_hwmon_update(dev);
 121
 122        if (mcu_data < 0)
 123                return mcu_data;
 124
 125        return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
 126}
 127
 128static ssize_t fan1_input_show(struct device *dev,
 129                               struct device_attribute *attr, char *buf)
 130{
 131        s32 mcu_data = nsa320_hwmon_update(dev);
 132
 133        if (mcu_data < 0)
 134                return mcu_data;
 135
 136        return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
 137}
 138
 139static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
 140static DEVICE_ATTR_RO(temp1_input);
 141static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
 142static DEVICE_ATTR_RO(fan1_input);
 143
 144static struct attribute *nsa320_attrs[] = {
 145        &sensor_dev_attr_temp1_label.dev_attr.attr,
 146        &dev_attr_temp1_input.attr,
 147        &sensor_dev_attr_fan1_label.dev_attr.attr,
 148        &dev_attr_fan1_input.attr,
 149        NULL
 150};
 151
 152ATTRIBUTE_GROUPS(nsa320);
 153
 154static const struct of_device_id of_nsa320_hwmon_match[] = {
 155        { .compatible = "zyxel,nsa320-mcu", },
 156        { },
 157};
 158
 159static int nsa320_hwmon_probe(struct platform_device *pdev)
 160{
 161        struct nsa320_hwmon     *hwmon;
 162        struct device           *classdev;
 163
 164        hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
 165        if (!hwmon)
 166                return -ENOMEM;
 167
 168        /* Look up the GPIO pins to use */
 169        hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
 170        if (IS_ERR(hwmon->act))
 171                return PTR_ERR(hwmon->act);
 172
 173        hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
 174        if (IS_ERR(hwmon->clk))
 175                return PTR_ERR(hwmon->clk);
 176
 177        hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
 178        if (IS_ERR(hwmon->data))
 179                return PTR_ERR(hwmon->data);
 180
 181        mutex_init(&hwmon->update_lock);
 182
 183        classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
 184                                        "nsa320", hwmon, nsa320_groups);
 185
 186        return PTR_ERR_OR_ZERO(classdev);
 187
 188}
 189
 190/* All allocations use devres so remove() is not needed. */
 191
 192static struct platform_driver nsa320_hwmon_driver = {
 193        .probe = nsa320_hwmon_probe,
 194        .driver = {
 195                .name = "nsa320-hwmon",
 196                .of_match_table = of_match_ptr(of_nsa320_hwmon_match),
 197        },
 198};
 199
 200module_platform_driver(nsa320_hwmon_driver);
 201
 202MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
 203MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
 204MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
 205MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
 206MODULE_LICENSE("GPL v2");
 207MODULE_ALIAS("platform:nsa320-hwmon");
 208