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