1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * ad2s90.c simple support for the ADI Resolver to Digital Converters: AD2S90 4 * 5 * Copyright (c) 2010-2010 Analog Devices Inc. 6 */ 7 #include <linux/types.h> 8 #include <linux/mutex.h> 9 #include <linux/device.h> 10 #include <linux/spi/spi.h> 11 #include <linux/slab.h> 12 #include <linux/sysfs.h> 13 #include <linux/module.h> 14 15 #include <linux/iio/iio.h> 16 #include <linux/iio/sysfs.h> 17 18 /* 19 * Although chip's max frequency is 2Mhz, it needs 600ns between CS and the 20 * first falling edge of SCLK, so frequency should be at most 1 / (2 * 6e-7) 21 */ 22 #define AD2S90_MAX_SPI_FREQ_HZ 830000 23 24 struct ad2s90_state { 25 struct mutex lock; /* lock to protect rx buffer */ 26 struct spi_device *sdev; 27 u8 rx[2] __aligned(IIO_DMA_MINALIGN); 28 }; 29 30 static int ad2s90_read_raw(struct iio_dev *indio_dev, 31 struct iio_chan_spec const *chan, 32 int *val, 33 int *val2, 34 long m) 35 { 36 int ret; 37 struct ad2s90_state *st = iio_priv(indio_dev); 38 39 if (chan->type != IIO_ANGL) 40 return -EINVAL; 41 42 switch (m) { 43 case IIO_CHAN_INFO_SCALE: 44 /* 2 * Pi / 2^12 */ 45 *val = 6283; /* mV */ 46 *val2 = 12; 47 return IIO_VAL_FRACTIONAL_LOG2; 48 case IIO_CHAN_INFO_RAW: 49 mutex_lock(&st->lock); 50 ret = spi_read(st->sdev, st->rx, 2); 51 if (ret < 0) { 52 mutex_unlock(&st->lock); 53 return ret; 54 } 55 *val = (((u16)(st->rx[0])) << 4) | ((st->rx[1] & 0xF0) >> 4); 56 57 mutex_unlock(&st->lock); 58 59 return IIO_VAL_INT; 60 default: 61 break; 62 } 63 64 return -EINVAL; 65 } 66 67 static const struct iio_info ad2s90_info = { 68 .read_raw = ad2s90_read_raw, 69 }; 70 71 static const struct iio_chan_spec ad2s90_chan = { 72 .type = IIO_ANGL, 73 .indexed = 1, 74 .channel = 0, 75 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), 76 }; 77 78 static int ad2s90_probe(struct spi_device *spi) 79 { 80 struct iio_dev *indio_dev; 81 struct ad2s90_state *st; 82 83 if (spi->max_speed_hz > AD2S90_MAX_SPI_FREQ_HZ) { 84 dev_err(&spi->dev, "SPI CLK, %d Hz exceeds %d Hz\n", 85 spi->max_speed_hz, AD2S90_MAX_SPI_FREQ_HZ); 86 return -EINVAL; 87 } 88 89 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st)); 90 if (!indio_dev) 91 return -ENOMEM; 92 st = iio_priv(indio_dev); 93 spi_set_drvdata(spi, indio_dev); 94 95 mutex_init(&st->lock); 96 st->sdev = spi; 97 indio_dev->info = &ad2s90_info; 98 indio_dev->modes = INDIO_DIRECT_MODE; 99 indio_dev->channels = &ad2s90_chan; 100 indio_dev->num_channels = 1; 101 indio_dev->name = spi_get_device_id(spi)->name; 102 103 return devm_iio_device_register(indio_dev->dev.parent, indio_dev); 104 } 105 106 static const struct of_device_id ad2s90_of_match[] = { 107 { .compatible = "adi,ad2s90", }, 108 {} 109 }; 110 MODULE_DEVICE_TABLE(of, ad2s90_of_match); 111 112 static const struct spi_device_id ad2s90_id[] = { 113 { "ad2s90" }, 114 {} 115 }; 116 MODULE_DEVICE_TABLE(spi, ad2s90_id); 117 118 static struct spi_driver ad2s90_driver = { 119 .driver = { 120 .name = "ad2s90", 121 .of_match_table = ad2s90_of_match, 122 }, 123 .probe = ad2s90_probe, 124 .id_table = ad2s90_id, 125 }; 126 module_spi_driver(ad2s90_driver); 127 128 MODULE_AUTHOR("Graff Yang <graff.yang@gmail.com>"); 129 MODULE_DESCRIPTION("Analog Devices AD2S90 Resolver to Digital SPI driver"); 130 MODULE_LICENSE("GPL v2"); 131