1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * sl28cpld hardware monitoring driver 4 * 5 * Copyright 2020 Kontron Europe GmbH 6 */ 7 8 #include <linux/bitfield.h> 9 #include <linux/hwmon.h> 10 #include <linux/kernel.h> 11 #include <linux/mod_devicetable.h> 12 #include <linux/module.h> 13 #include <linux/platform_device.h> 14 #include <linux/property.h> 15 #include <linux/regmap.h> 16 17 #define FAN_INPUT 0x00 18 #define FAN_SCALE_X8 BIT(7) 19 #define FAN_VALUE_MASK GENMASK(6, 0) 20 21 struct sl28cpld_hwmon { 22 struct regmap *regmap; 23 u32 offset; 24 }; 25 26 static umode_t sl28cpld_hwmon_is_visible(const void *data, 27 enum hwmon_sensor_types type, 28 u32 attr, int channel) 29 { 30 return 0444; 31 } 32 33 static int sl28cpld_hwmon_read(struct device *dev, 34 enum hwmon_sensor_types type, u32 attr, 35 int channel, long *input) 36 { 37 struct sl28cpld_hwmon *hwmon = dev_get_drvdata(dev); 38 unsigned int value; 39 int ret; 40 41 switch (attr) { 42 case hwmon_fan_input: 43 ret = regmap_read(hwmon->regmap, hwmon->offset + FAN_INPUT, 44 &value); 45 if (ret) 46 return ret; 47 /* 48 * The register has a 7 bit value and 1 bit which indicates the 49 * scale. If the MSB is set, then the lower 7 bit has to be 50 * multiplied by 8, to get the correct reading. 51 */ 52 if (value & FAN_SCALE_X8) 53 value = FIELD_GET(FAN_VALUE_MASK, value) << 3; 54 55 /* 56 * The counter period is 1000ms and the sysfs specification 57 * says we should assume 2 pulses per revolution. 58 */ 59 value *= 60 / 2; 60 61 break; 62 default: 63 return -EOPNOTSUPP; 64 } 65 66 *input = value; 67 return 0; 68 } 69 70 static const struct hwmon_channel_info * const sl28cpld_hwmon_info[] = { 71 HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT), 72 NULL 73 }; 74 75 static const struct hwmon_ops sl28cpld_hwmon_ops = { 76 .is_visible = sl28cpld_hwmon_is_visible, 77 .read = sl28cpld_hwmon_read, 78 }; 79 80 static const struct hwmon_chip_info sl28cpld_hwmon_chip_info = { 81 .ops = &sl28cpld_hwmon_ops, 82 .info = sl28cpld_hwmon_info, 83 }; 84 85 static int sl28cpld_hwmon_probe(struct platform_device *pdev) 86 { 87 struct sl28cpld_hwmon *hwmon; 88 struct device *hwmon_dev; 89 int ret; 90 91 if (!pdev->dev.parent) 92 return -ENODEV; 93 94 hwmon = devm_kzalloc(&pdev->dev, sizeof(*hwmon), GFP_KERNEL); 95 if (!hwmon) 96 return -ENOMEM; 97 98 hwmon->regmap = dev_get_regmap(pdev->dev.parent, NULL); 99 if (!hwmon->regmap) 100 return -ENODEV; 101 102 ret = device_property_read_u32(&pdev->dev, "reg", &hwmon->offset); 103 if (ret) 104 return -EINVAL; 105 106 hwmon_dev = devm_hwmon_device_register_with_info(&pdev->dev, 107 "sl28cpld_hwmon", hwmon, 108 &sl28cpld_hwmon_chip_info, NULL); 109 if (IS_ERR(hwmon_dev)) 110 dev_err(&pdev->dev, "failed to register as hwmon device"); 111 112 return PTR_ERR_OR_ZERO(hwmon_dev); 113 } 114 115 static const struct of_device_id sl28cpld_hwmon_of_match[] = { 116 { .compatible = "kontron,sl28cpld-fan" }, 117 {} 118 }; 119 MODULE_DEVICE_TABLE(of, sl28cpld_hwmon_of_match); 120 121 static struct platform_driver sl28cpld_hwmon_driver = { 122 .probe = sl28cpld_hwmon_probe, 123 .driver = { 124 .name = "sl28cpld-fan", 125 .of_match_table = sl28cpld_hwmon_of_match, 126 }, 127 }; 128 module_platform_driver(sl28cpld_hwmon_driver); 129 130 MODULE_DESCRIPTION("sl28cpld Hardware Monitoring Driver"); 131 MODULE_AUTHOR("Michael Walle <michael@walle.cc>"); 132 MODULE_LICENSE("GPL"); 133