drivers/hwmon/nsa320-hwmon.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * drivers/hwmon/nsa320-hwmon.c
0004  *
0005  * ZyXEL NSA320 Media Servers
0006  * hardware monitoring
0007  *
0008  * Copyright (C) 2016 Adam Baker <linux@baker-net.org.uk>
0009  * based on a board file driver
0010  * Copyright (C) 2012 Peter Schildmann <linux@schildmann.info>
0011  */
0012
0013 #include <linux/bitops.h>
0014 #include <linux/delay.h>
0015 #include <linux/err.h>
0016 #include <linux/gpio/consumer.h>
0017 #include <linux/hwmon.h>
0018 #include <linux/hwmon-sysfs.h>
0019 #include <linux/jiffies.h>
0020 #include <linux/module.h>
0021 #include <linux/mutex.h>
0022 #include <linux/of.h>
0023 #include <linux/of_device.h>
0024 #include <linux/of_platform.h>
0025 #include <linux/platform_device.h>
0026
0027 /* Tests for error return values rely upon this value being < 0x80 */
0028 #define MAGIC_NUMBER 0x55
0029
0030 /*
0031  * The Zyxel hwmon MCU is a Holtek HT46R065 that is factory programmed
0032  * to perform temperature and fan speed monitoring. It is read by taking
0033  * the active pin low. The 32 bit output word is then clocked onto the
0034  * data line. The MSB of the data word is a magic nuber to indicate it
0035  * has been read correctly, the next byte is the fan speed (in hundreds
0036  * of RPM) and the last two bytes are the temperature (in tenths of a
0037  * degree)
0038  */
0039
0040 struct nsa320_hwmon {
0041     struct mutex        update_lock;    /* lock GPIO operations */
0042     unsigned long       last_updated;   /* jiffies */
0043     unsigned long       mcu_data;
0044     struct gpio_desc    *act;
0045     struct gpio_desc    *clk;
0046     struct gpio_desc    *data;
0047 };
0048
0049 enum nsa320_inputs {
0050     NSA320_TEMP = 0,
0051     NSA320_FAN = 1,
0052 };
0053
0054 static const char * const nsa320_input_names[] = {
0055     [NSA320_TEMP] = "System Temperature",
0056     [NSA320_FAN] = "Chassis Fan",
0057 };
0058
0059 /*
0060  * Although this protocol looks similar to SPI the long delay
0061  * between the active (aka chip select) signal and the shorter
0062  * delay between clock pulses are needed for reliable operation.
0063  * The delays provided are taken from the manufacturer kernel,
0064  * testing suggest they probably incorporate a reasonable safety
0065  * margin. (The single device tested became unreliable if the
0066  * delay was reduced to 1/10th of this value.)
0067  */
0068 static s32 nsa320_hwmon_update(struct device *dev)
0069 {
0070     u32 mcu_data;
0071     u32 mask;
0072     struct nsa320_hwmon *hwmon = dev_get_drvdata(dev);
0073
0074     mutex_lock(&hwmon->update_lock);
0075
0076     mcu_data = hwmon->mcu_data;
0077
0078     if (time_after(jiffies, hwmon->last_updated + HZ) || mcu_data == 0) {
0079         gpiod_set_value(hwmon->act, 1);
0080         msleep(100);
0081
0082         mcu_data = 0;
0083         for (mask = BIT(31); mask; mask >>= 1) {
0084             gpiod_set_value(hwmon->clk, 0);
0085             usleep_range(100, 200);
0086             gpiod_set_value(hwmon->clk, 1);
0087             usleep_range(100, 200);
0088             if (gpiod_get_value(hwmon->data))
0089                 mcu_data |= mask;
0090         }
0091
0092         gpiod_set_value(hwmon->act, 0);
0093         dev_dbg(dev, "Read raw MCU data %08x\n", mcu_data);
0094
0095         if ((mcu_data >> 24) != MAGIC_NUMBER) {
0096             dev_dbg(dev, "Read invalid MCU data %08x\n", mcu_data);
0097             mcu_data = -EIO;
0098         } else {
0099             hwmon->mcu_data = mcu_data;
0100             hwmon->last_updated = jiffies;
0101         }
0102     }
0103
0104     mutex_unlock(&hwmon->update_lock);
0105
0106     return mcu_data;
0107 }
0108
0109 static ssize_t label_show(struct device *dev, struct device_attribute *attr,
0110               char *buf)
0111 {
0112     int channel = to_sensor_dev_attr(attr)->index;
0113
0114     return sprintf(buf, "%s\n", nsa320_input_names[channel]);
0115 }
0116
0117 static ssize_t temp1_input_show(struct device *dev,
0118                 struct device_attribute *attr, char *buf)
0119 {
0120     s32 mcu_data = nsa320_hwmon_update(dev);
0121
0122     if (mcu_data < 0)
0123         return mcu_data;
0124
0125     return sprintf(buf, "%d\n", (mcu_data & 0xffff) * 100);
0126 }
0127
0128 static ssize_t fan1_input_show(struct device *dev,
0129                    struct device_attribute *attr, char *buf)
0130 {
0131     s32 mcu_data = nsa320_hwmon_update(dev);
0132
0133     if (mcu_data < 0)
0134         return mcu_data;
0135
0136     return sprintf(buf, "%d\n", ((mcu_data & 0xff0000) >> 16) * 100);
0137 }
0138
0139 static SENSOR_DEVICE_ATTR_RO(temp1_label, label, NSA320_TEMP);
0140 static DEVICE_ATTR_RO(temp1_input);
0141 static SENSOR_DEVICE_ATTR_RO(fan1_label, label, NSA320_FAN);
0142 static DEVICE_ATTR_RO(fan1_input);
0143
0144 static struct attribute *nsa320_attrs[] = {
0145     &sensor_dev_attr_temp1_label.dev_attr.attr,
0146     &dev_attr_temp1_input.attr,
0147     &sensor_dev_attr_fan1_label.dev_attr.attr,
0148     &dev_attr_fan1_input.attr,
0149     NULL
0150 };
0151
0152 ATTRIBUTE_GROUPS(nsa320);
0153
0154 static const struct of_device_id of_nsa320_hwmon_match[] = {
0155     { .compatible = "zyxel,nsa320-mcu", },
0156     { },
0157 };
0158
0159 static int nsa320_hwmon_probe(struct platform_device *pdev)
0160 {
0161     struct nsa320_hwmon *hwmon;
0162     struct device       *classdev;
0163
0164     hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL);
0165     if (!hwmon)
0166         return -ENOMEM;
0167
0168     /* Look up the GPIO pins to use */
0169     hwmon->act = devm_gpiod_get(&pdev->dev, "act", GPIOD_OUT_LOW);
0170     if (IS_ERR(hwmon->act))
0171         return PTR_ERR(hwmon->act);
0172
0173     hwmon->clk = devm_gpiod_get(&pdev->dev, "clk", GPIOD_OUT_HIGH);
0174     if (IS_ERR(hwmon->clk))
0175         return PTR_ERR(hwmon->clk);
0176
0177     hwmon->data = devm_gpiod_get(&pdev->dev, "data", GPIOD_IN);
0178     if (IS_ERR(hwmon->data))
0179         return PTR_ERR(hwmon->data);
0180
0181     mutex_init(&hwmon->update_lock);
0182
0183     classdev = devm_hwmon_device_register_with_groups(&pdev->dev,
0184                     "nsa320", hwmon, nsa320_groups);
0185
0186     return PTR_ERR_OR_ZERO(classdev);
0187
0188 }
0189
0190 /* All allocations use devres so remove() is not needed. */
0191
0192 static struct platform_driver nsa320_hwmon_driver = {
0193     .probe = nsa320_hwmon_probe,
0194     .driver = {
0195         .name = "nsa320-hwmon",
0196         .of_match_table = of_match_ptr(of_nsa320_hwmon_match),
0197     },
0198 };
0199
0200 module_platform_driver(nsa320_hwmon_driver);
0201
0202 MODULE_DEVICE_TABLE(of, of_nsa320_hwmon_match);
0203 MODULE_AUTHOR("Peter Schildmann <linux@schildmann.info>");
0204 MODULE_AUTHOR("Adam Baker <linux@baker-net.org.uk>");
0205 MODULE_DESCRIPTION("NSA320 Hardware Monitoring");
0206 MODULE_LICENSE("GPL v2");
0207 MODULE_ALIAS("platform:nsa320-hwmon");