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