1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * ltc2497.c - Driver for Analog Devices/Linear Technology LTC2497 ADC 4 * 5 * Copyright (C) 2017 Analog Devices Inc. 6 * 7 * Datasheet: http://cds.linear.com/docs/en/datasheet/2497fd.pdf 8 */ 9 10 #include <linux/i2c.h> 11 #include <linux/iio/iio.h> 12 #include <linux/iio/driver.h> 13 #include <linux/module.h> 14 #include <linux/mod_devicetable.h> 15 #include <linux/property.h> 16 17 #include <asm/unaligned.h> 18 19 #include "ltc2497.h" 20 21 enum ltc2497_chip_type { 22 TYPE_LTC2497, 23 TYPE_LTC2499, 24 }; 25 26 struct ltc2497_driverdata { 27 /* this must be the first member */ 28 struct ltc2497core_driverdata common_ddata; 29 struct i2c_client *client; 30 u32 recv_size; 31 /* 32 * DMA (thus cache coherency maintenance) may require the 33 * transfer buffers to live in their own cache lines. 34 */ 35 union { 36 __be32 d32; 37 u8 d8[3]; 38 } data __aligned(IIO_DMA_MINALIGN); 39 }; 40 41 static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, 42 u8 address, int *val) 43 { 44 struct ltc2497_driverdata *st = 45 container_of(ddata, struct ltc2497_driverdata, common_ddata); 46 int ret; 47 48 if (val) { 49 if (st->recv_size == 3) 50 ret = i2c_master_recv(st->client, (char *)&st->data.d8, 51 st->recv_size); 52 else 53 ret = i2c_master_recv(st->client, (char *)&st->data.d32, 54 st->recv_size); 55 if (ret < 0) { 56 dev_err(&st->client->dev, "i2c_master_recv failed\n"); 57 return ret; 58 } 59 60 /* 61 * The data format is 16/24 bit 2s complement, but with an upper sign bit on the 62 * resolution + 1 position, which is set for positive values only. Given this 63 * bit's value, subtracting BIT(resolution + 1) from the ADC's result is 64 * equivalent to a sign extension. 65 */ 66 if (st->recv_size == 3) { 67 *val = (get_unaligned_be24(st->data.d8) >> 6) 68 - BIT(ddata->chip_info->resolution + 1); 69 } else { 70 *val = (be32_to_cpu(st->data.d32) >> 6) 71 - BIT(ddata->chip_info->resolution + 1); 72 } 73 74 /* 75 * The part started a new conversion at the end of the above i2c 76 * transfer, so if the address didn't change since the last call 77 * everything is fine and we can return early. 78 * If not (which should only happen when some sort of bulk 79 * conversion is implemented) we have to program the new 80 * address. Note that this probably fails as the conversion that 81 * was triggered above is like not complete yet and the two 82 * operations have to be done in a single transfer. 83 */ 84 if (ddata->addr_prev == address) 85 return 0; 86 } 87 88 ret = i2c_smbus_write_byte(st->client, 89 LTC2497_ENABLE | address); 90 if (ret) 91 dev_err(&st->client->dev, "i2c transfer failed: %pe\n", 92 ERR_PTR(ret)); 93 return ret; 94 } 95 96 static int ltc2497_probe(struct i2c_client *client) 97 { 98 const struct ltc2497_chip_info *chip_info; 99 struct iio_dev *indio_dev; 100 struct ltc2497_driverdata *st; 101 struct device *dev = &client->dev; 102 u32 resolution; 103 104 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 105 I2C_FUNC_SMBUS_WRITE_BYTE)) 106 return -EOPNOTSUPP; 107 108 indio_dev = devm_iio_device_alloc(dev, sizeof(*st)); 109 if (!indio_dev) 110 return -ENOMEM; 111 112 st = iio_priv(indio_dev); 113 i2c_set_clientdata(client, indio_dev); 114 st->client = client; 115 st->common_ddata.result_and_measure = ltc2497_result_and_measure; 116 117 chip_info = i2c_get_match_data(client); 118 st->common_ddata.chip_info = chip_info; 119 120 resolution = chip_info->resolution; 121 st->recv_size = BITS_TO_BYTES(resolution) + 1; 122 123 return ltc2497core_probe(dev, indio_dev); 124 } 125 126 static void ltc2497_remove(struct i2c_client *client) 127 { 128 struct iio_dev *indio_dev = i2c_get_clientdata(client); 129 130 ltc2497core_remove(indio_dev); 131 } 132 133 static const struct ltc2497_chip_info ltc2497_info[] = { 134 [TYPE_LTC2497] = { 135 .resolution = 16, 136 .name = NULL, 137 }, 138 [TYPE_LTC2499] = { 139 .resolution = 24, 140 .name = "ltc2499", 141 }, 142 }; 143 144 static const struct i2c_device_id ltc2497_id[] = { 145 { "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] }, 146 { "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2499] }, 147 { } 148 }; 149 MODULE_DEVICE_TABLE(i2c, ltc2497_id); 150 151 static const struct of_device_id ltc2497_of_match[] = { 152 { .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] }, 153 { .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] }, 154 {}, 155 }; 156 MODULE_DEVICE_TABLE(of, ltc2497_of_match); 157 158 static struct i2c_driver ltc2497_driver = { 159 .driver = { 160 .name = "ltc2497", 161 .of_match_table = ltc2497_of_match, 162 }, 163 .probe = ltc2497_probe, 164 .remove = ltc2497_remove, 165 .id_table = ltc2497_id, 166 }; 167 module_i2c_driver(ltc2497_driver); 168 169 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>"); 170 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); 171 MODULE_LICENSE("GPL v2"); 172