1 /* 2 * max5487.c - Support for MAX5487, MAX5488, MAX5489 digital potentiometers 3 * 4 * Copyright (C) 2016 Cristina-Gabriela Moraru <cristina.moraru09@gmail.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License version 2 as 8 * published by the Free Software Foundation. 9 * 10 */ 11 #include <linux/module.h> 12 #include <linux/spi/spi.h> 13 #include <linux/acpi.h> 14 15 #include <linux/iio/sysfs.h> 16 #include <linux/iio/iio.h> 17 18 #define MAX5487_WRITE_WIPER_A (0x01 << 8) 19 #define MAX5487_WRITE_WIPER_B (0x02 << 8) 20 21 /* copy both wiper regs to NV regs */ 22 #define MAX5487_COPY_AB_TO_NV (0x23 << 8) 23 /* copy both NV regs to wiper regs */ 24 #define MAX5487_COPY_NV_TO_AB (0x33 << 8) 25 26 #define MAX5487_MAX_POS 255 27 28 struct max5487_data { 29 struct spi_device *spi; 30 int kohms; 31 }; 32 33 #define MAX5487_CHANNEL(ch, addr) { \ 34 .type = IIO_RESISTANCE, \ 35 .indexed = 1, \ 36 .output = 1, \ 37 .channel = ch, \ 38 .address = addr, \ 39 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 40 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 41 } 42 43 static const struct iio_chan_spec max5487_channels[] = { 44 MAX5487_CHANNEL(0, MAX5487_WRITE_WIPER_A), 45 MAX5487_CHANNEL(1, MAX5487_WRITE_WIPER_B), 46 }; 47 48 static int max5487_write_cmd(struct spi_device *spi, u16 cmd) 49 { 50 return spi_write(spi, (const void *) &cmd, sizeof(u16)); 51 } 52 53 static int max5487_read_raw(struct iio_dev *indio_dev, 54 struct iio_chan_spec const *chan, 55 int *val, int *val2, long mask) 56 { 57 struct max5487_data *data = iio_priv(indio_dev); 58 59 if (mask != IIO_CHAN_INFO_SCALE) 60 return -EINVAL; 61 62 *val = 1000 * data->kohms; 63 *val2 = MAX5487_MAX_POS; 64 65 return IIO_VAL_FRACTIONAL; 66 } 67 68 static int max5487_write_raw(struct iio_dev *indio_dev, 69 struct iio_chan_spec const *chan, 70 int val, int val2, long mask) 71 { 72 struct max5487_data *data = iio_priv(indio_dev); 73 74 if (mask != IIO_CHAN_INFO_RAW) 75 return -EINVAL; 76 77 if (val < 0 || val > MAX5487_MAX_POS) 78 return -EINVAL; 79 80 return max5487_write_cmd(data->spi, chan->address | val); 81 } 82 83 static const struct iio_info max5487_info = { 84 .read_raw = max5487_read_raw, 85 .write_raw = max5487_write_raw, 86 .driver_module = THIS_MODULE, 87 }; 88 89 static int max5487_spi_probe(struct spi_device *spi) 90 { 91 struct iio_dev *indio_dev; 92 struct max5487_data *data; 93 const struct spi_device_id *id = spi_get_device_id(spi); 94 int ret; 95 96 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*data)); 97 if (!indio_dev) 98 return -ENOMEM; 99 100 dev_set_drvdata(&spi->dev, indio_dev); 101 data = iio_priv(indio_dev); 102 103 data->spi = spi; 104 data->kohms = id->driver_data; 105 106 indio_dev->info = &max5487_info; 107 indio_dev->name = id->name; 108 indio_dev->dev.parent = &spi->dev; 109 indio_dev->modes = INDIO_DIRECT_MODE; 110 indio_dev->channels = max5487_channels; 111 indio_dev->num_channels = ARRAY_SIZE(max5487_channels); 112 113 /* restore both wiper regs from NV regs */ 114 ret = max5487_write_cmd(data->spi, MAX5487_COPY_NV_TO_AB); 115 if (ret < 0) 116 return ret; 117 118 return iio_device_register(indio_dev); 119 } 120 121 static int max5487_spi_remove(struct spi_device *spi) 122 { 123 struct iio_dev *indio_dev = dev_get_drvdata(&spi->dev); 124 125 iio_device_unregister(indio_dev); 126 127 /* save both wiper regs to NV regs */ 128 return max5487_write_cmd(spi, MAX5487_COPY_AB_TO_NV); 129 } 130 131 static const struct spi_device_id max5487_id[] = { 132 { "MAX5487", 10 }, 133 { "MAX5488", 50 }, 134 { "MAX5489", 100 }, 135 { } 136 }; 137 MODULE_DEVICE_TABLE(spi, max5487_id); 138 139 static const struct acpi_device_id max5487_acpi_match[] = { 140 { "MAX5487", 10 }, 141 { "MAX5488", 50 }, 142 { "MAX5489", 100 }, 143 { }, 144 }; 145 MODULE_DEVICE_TABLE(acpi, max5487_acpi_match); 146 147 static struct spi_driver max5487_driver = { 148 .driver = { 149 .name = "max5487", 150 .owner = THIS_MODULE, 151 .acpi_match_table = ACPI_PTR(max5487_acpi_match), 152 }, 153 .id_table = max5487_id, 154 .probe = max5487_spi_probe, 155 .remove = max5487_spi_remove 156 }; 157 module_spi_driver(max5487_driver); 158 159 MODULE_AUTHOR("Cristina-Gabriela Moraru <cristina.moraru09@gmail.com>"); 160 MODULE_DESCRIPTION("max5487 SPI driver"); 161 MODULE_LICENSE("GPL v2"); 162