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"); 208