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