1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers 4 * 5 * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com> 6 */ 7 #include <linux/module.h> 8 #include <linux/mod_devicetable.h> 9 #include <linux/spi/spi.h> 10 11 #include <linux/iio/sysfs.h> 12 #include <linux/iio/iio.h> 13 14 #define MAX5487_WRITE_WIPER_A (0x01 << 8) 15 #define MAX5487_WRITE_WIPER_B (0x02 << 8) 16 17 /* copy both wiper regs to NV regs */ 18 #define MAX5487_COPY_AB_TO_NV (0x23 << 8) 19 /* copy both NV regs to wiper regs */ 20 #define MAX5487_COPY_NV_TO_AB (0x33 << 8) 21 22 #define MAX5487_MAX_POS 255 23 24 struct max5487_data { 25 struct spi_device *spi; 26 int kohms; 27 }; 28 29 #define MAX5487_CHANNEL(ch, addr) { \ 30 .type = IIO_RESISTANCE, \ 31 .indexed = 1, \ 32 .output = 1, \ 33 .channel = ch, \ 34 .address = addr, \ 35 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 36 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 37 } 38 39 static const struct iio_chan_spec max5487_channels[] = { 40 MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A), 41 MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B), 42 }; 43 44 static int max5487_write_cmd(struct spi_device *spi, u16 cmd) 45 { 46 return spi_write(spi, (const void *) &cmd, sizeof(u16)); 47 } 48 49 static int max5487_read_raw(struct iio_dev *indio_dev, 50 struct iio_chan_spec const *chan, 51 int *val, int *val2, long mask) 52 { 53 struct max5487_data *data = iio_priv(indio_dev); 54 55 if (mask != IIO_CHAN_INFO_SCALE) 56 return -EINVAL; 57 58 *val = 1000 * data->kohms; 59 *val2 = MAX5487_MAX_POS; 60 61 return IIO_VAL_FRACTIONAL; 62 } 63 64 static int max5487_write_raw(struct iio_dev *indio_dev, 65 struct iio_chan_spec const *chan, 66 int val, int val2, long mask) 67 { 68 struct max5487_data *data = iio_priv(indio_dev); 69 70 if (mask != IIO_CHAN_INFO_RAW) 71 return -EINVAL; 72 73 if (val < 0 || val > MAX5487_MAX_POS) 74 return -EINVAL; 75 76 return max5487_write_cmd(data->spi, chan->address | val); 77 } 78 79 static const struct iio_info max5487_info = { 80 .read_raw = max5487_read_raw, 81 .write_raw = max5487_write_raw, 82 }; 83 84 static int max5487_spi_probe(struct spi_device *spi) 85 { 86 struct iio_dev *indio_dev; 87 struct max5487_data *data; 88 const struct spi_device_id *id = spi_get_device_id(spi); 89 int ret; 90 91 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); 92 if (!indio_dev) 93 return -ENOMEM; 94 95 spi_set_drvdata(spi, indio_dev); 96 data = iio_priv(indio_dev); 97 98 data->spi = spi; 99 data->kohms = id->driver_data; 100 101 indio_dev->info = &max5487_info; 102 indio_dev->name = id->name; 103 indio_dev->modes = INDIO_DIRECT_MODE; 104 indio_dev->channels = max5487_channels; 105 indio_dev->num_channels = ARRAY_SIZE(max5487_channels); 106 107 /* restore both wiper regs from NV regs */ 108 ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB); 109 if (ret < 0) 110 return ret; 111 112 return iio_device_register(indio_dev); 113 } 114 115 static void max5487_spi_remove(struct spi_device *spi) 116 { 117 struct iio_dev *indio_dev = spi_get_drvdata(spi); 118 int ret; 119 120 iio_device_unregister(indio_dev); 121 122 /* save both wiper regs to NV regs */ 123 ret = max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV); 124 if (ret) 125 dev_warn(&spi->dev, "Failed to save wiper regs to NV regs\n"); 126 } 127 128 static const struct spi_device_id max5487_id[] = { 129 { "MAX5487", 10 }, 130 { "MAX5488", 50 }, 131 { "MAX5489", 100 }, 132 { } 133 }; 134 MODULE_DEVICE_TABLE(spi, max5487_id); 135 136 static const struct acpi_device_id max5487_acpi_match[] = { 137 { "MAX5487", 10 }, 138 { "MAX5488", 50 }, 139 { "MAX5489", 100 }, 140 { }, 141 }; 142 MODULE_DEVICE_TABLE(acpi, max5487_acpi_match); 143 144 static struct spi_driver max5487_driver = { 145 .driver = { 146 .name = "max5487", 147 .acpi_match_table = max5487_acpi_match, 148 }, 149 .id_table = max5487_id, 150 .probe = max5487_spi_probe, 151 .remove = max5487_spi_remove 152 }; 153 module_spi_driver(max5487_driver); 154 155 MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>"); 156 MODULE_DESCRIPTION("max5487 SPI driver"); 157 MODULE_LICENSE("GPL v2"); 158