1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ltc2496.c - Driver for Analog Devices/Linear Technology LTC2496 ADC 4 * 5 * Based on ltc2497.c which has 6 * Copyright (C) 2017 Analog Devices Inc. 7 * 8 * Licensed under the GPL-2. 9 * 10 * Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2496fc.pdf 11 */ 12 13 #include <linux/spi/spi.h> 14 #include <linux/iio/iio.h> 15 #include <linux/iio/driver.h> 16 #include <linux/module.h> 17 #include <linux/mod_devicetable.h> 18 19 #include "ltc2497.h" 20 21 struct ltc2496_driverdata { 22 /* this must be the first member */ 23 struct ltc2497core_driverdata common_ddata; 24 struct spi_device *spi; 25 26 /* 27 * DMA (thus cache coherency maintenance) requires the 28 * transfer buffers to live in their own cache lines. 29 */ 30 unsigned char rxbuf[3] ____cacheline_aligned; 31 unsigned char txbuf[3]; 32 }; 33 34 static int ltc2496_result_and_measure(struct ltc2497core_driverdata *ddata, 35 u8 address, int *val) 36 { 37 struct ltc2496_driverdata *st = 38 container_of(ddata, struct ltc2496_driverdata, common_ddata); 39 struct spi_transfer t = { 40 .tx_buf = st->txbuf, 41 .rx_buf = st->rxbuf, 42 .len = sizeof(st->txbuf), 43 }; 44 int ret; 45 46 st->txbuf[0] = LTC2497_ENABLE | address; 47 48 ret = spi_sync_transfer(st->spi, &t, 1); 49 if (ret < 0) { 50 dev_err(&st->spi->dev, "spi_sync_transfer failed: %pe\n", 51 ERR_PTR(ret)); 52 return ret; 53 } 54 55 if (val) 56 *val = ((st->rxbuf[0] & 0x3f) << 12 | 57 st->rxbuf[1] << 4 | st->rxbuf[2] >> 4) - 58 (1 << 17); 59 60 return 0; 61 } 62 63 static int ltc2496_probe(struct spi_device *spi) 64 { 65 struct iio_dev *indio_dev; 66 struct ltc2496_driverdata *st; 67 struct device *dev = &spi->dev; 68 69 indio_dev = devm_iio_device_alloc(dev, sizeof(*st)); 70 if (!indio_dev) 71 return -ENOMEM; 72 73 st = iio_priv(indio_dev); 74 spi_set_drvdata(spi, indio_dev); 75 st->spi = spi; 76 st->common_ddata.result_and_measure = ltc2496_result_and_measure; 77 78 return ltc2497core_probe(dev, indio_dev); 79 } 80 81 static void ltc2496_remove(struct spi_device *spi) 82 { 83 struct iio_dev *indio_dev = spi_get_drvdata(spi); 84 85 ltc2497core_remove(indio_dev); 86 } 87 88 static const struct of_device_id ltc2496_of_match[] = { 89 { .compatible = "lltc,ltc2496", }, 90 {}, 91 }; 92 MODULE_DEVICE_TABLE(of, ltc2496_of_match); 93 94 static struct spi_driver ltc2496_driver = { 95 .driver = { 96 .name = "ltc2496", 97 .of_match_table = ltc2496_of_match, 98 }, 99 .probe = ltc2496_probe, 100 .remove = ltc2496_remove, 101 }; 102 module_spi_driver(ltc2496_driver); 103 104 MODULE_AUTHOR("Uwe Kleine-König <u.kleine-könig@pengutronix.de>"); 105 MODULE_DESCRIPTION("Linear Technology LTC2496 ADC driver"); 106 MODULE_LICENSE("GPL v2"); 107