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"); 206