206 lines · c
1// SPDX-License-Identifier: GPL-2.0-only2/*3 * drivers/hwmon/nsa320-hwmon.c4 *5 * ZyXEL NSA320 Media Servers6 * hardware monitoring7 *8 * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>9 * based on a board file driver10 * 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 0x5527 28/*29 * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed30 * to perform temperature and fan speed monitoring. It is read by taking31 * the active pin low. The 32 bit output word is then clocked onto the32 * data line. The MSB of the data word is a magic nuber to indicate it33 * has been read correctly, the next byte is the fan speed (in hundreds34 * of RPM) and the last two bytes are the temperature (in tenths of a35 * degree)36 */37 38struct 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 47enum nsa320_inputs {48 NSA320_TEMP = 0,49 NSA320_FAN = 1,50};51 52static 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 delay59 * between the active (aka chip select) signal and the shorter60 * 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 safety63 * margin. (The single device tested became unreliable if the64 * delay was reduced to 1/10th of this value.)65 */66static 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 107static 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 115static 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 126static 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 137static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);138static DEVICE_ATTR_RO(temp1_input);139static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);140static DEVICE_ATTR_RO(fan1_input);141 142static 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 NULL148};149 150ATTRIBUTE_GROUPS(nsa320);151 152static const struct of_device_id of_nsa320_hwmon_match[] = {153 { .compatible = "zyxel,nsa320-mcu", },154 { },155};156 157static 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 190static 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 198module_platform_driver(nsa320_hwmon_driver);199 200MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);201MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");202MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");203MODULE_DESCRIPTION("NSA320 Hardware Monitoring");204MODULE_LICENSE("GPL v2");205MODULE_ALIAS("platform:nsa320-hwmon");206