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
  40 struct 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
  49 enum nsa320_inputs {
  50         NSA320_TEMP = 0,
  51         NSA320_FAN = 1,
  52 };
  53
  54 static 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  */
  68 static 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
 109 static 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
 117 static 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
 128 static 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
 139 static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
 140 static DEVICE_ATTR_RO(temp1_input);
 141 static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
 142 static DEVICE_ATTR_RO(fan1_input);
 143
 144 static 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
 152 ATTRIBUTE_GROUPS(nsa320);
 153
 154 static const struct of_device_id of_nsa320_hwmon_match[] = {
 155         { .compatible = "zyxel,nsa320-mcu", },
 156         { },
 157 };
 158
 159 static 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
 192 static 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
 200 module_platform_driver(nsa320_hwmon_driver);
 201
 202 MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
 203 MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
 204 MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
 205 MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
 206 MODULE_LICENSE("GPL v2");
 207 MODULE_ALIAS("platform:nsa320-hwmon");