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
  48 struct 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
  57 enum nsa320_inputs {
  58         NSA320_TEMP = 0,
  59         NSA320_FAN = 1,
  60 };
  61
  62 static 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  */
  76 static 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
 117 static 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
 125 static ssize_t show_temp(struct device *dev, struct device_attribute *attr,
 126                          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
 136 static ssize_t show_fan(struct device *dev, struct device_attribute *attr,
 137                         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
 147 static SENSOR_DEVICE_ATTR(temp1_label, S_IRUGO, show_label, NULL, NSA320_TEMP);
 148 static DEVICE_ATTR(temp1_input, S_IRUGO, show_temp, NULL);
 149 static SENSOR_DEVICE_ATTR(fan1_label, S_IRUGO, show_label, NULL, NSA320_FAN);
 150 static DEVICE_ATTR(fan1_input, S_IRUGO, show_fan, NULL);
 151
 152 static 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
 160 ATTRIBUTE_GROUPS(nsa320);
 161
 162 static const struct of_device_id of_nsa320_hwmon_match[] = {
 163         { .compatible = "zyxel,nsa320-mcu", },
 164         { },
 165 };
 166
 167 static 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
 200 static 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
 208 module_platform_driver(nsa320_hwmon_driver);
 209
 210 MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
 211 MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
 212 MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
 213 MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
 214 MODULE_LICENSE("GPL v2");
 215 MODULE_ALIAS("platform:nsa320-hwmon");