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 u32 sub_lsb; 32 /* 33 * DMA (thus cache coherency maintenance) may require the 34 * transfer buffers to live in their own cache lines. 35 */ 36 union { 37 __be32 d32; 38 u8 d8[3]; 39 } data __aligned(IIO_DMA_MINALIGN); 40 }; 41 42 static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, 43 u8 address, int *val) 44 { 45 struct ltc2497_driverdata *st = 46 container_of(ddata, struct ltc2497_driverdata, common_ddata); 47 int ret; 48 49 if (val) { 50 if (st->recv_size == 3) 51 ret = i2c_master_recv(st->client, (char *)&st->data.d8, 52 st->recv_size); 53 else 54 ret = i2c_master_recv(st->client, (char *)&st->data.d32, 55 st->recv_size); 56 if (ret < 0) { 57 dev_err(&st->client->dev, "i2c_master_recv failed\n"); 58 return ret; 59 } 60 61 /* 62 * The data format is 16/24 bit 2s complement, but with an upper sign bit on the 63 * resolution + 1 position, which is set for positive values only. Given this 64 * bit's value, subtracting BIT(resolution + 1) from the ADC's result is 65 * equivalent to a sign extension. 66 */ 67 if (st->recv_size == 3) { 68 *val = (get_unaligned_be24(st->data.d8) >> st->sub_lsb) 69 - BIT(ddata->chip_info->resolution + 1); 70 } else { 71 *val = (be32_to_cpu(st->data.d32) >> st->sub_lsb) 72 - BIT(ddata->chip_info->resolution + 1); 73 } 74 75 /* 76 * The part started a new conversion at the end of the above i2c 77 * transfer, so if the address didn't change since the last call 78 * everything is fine and we can return early. 79 * If not (which should only happen when some sort of bulk 80 * conversion is implemented) we have to program the new 81 * address. Note that this probably fails as the conversion that 82 * was triggered above is like not complete yet and the two 83 * operations have to be done in a single transfer. 84 */ 85 if (ddata->addr_prev == address) 86 return 0; 87 } 88 89 ret = i2c_smbus_write_byte(st->client, 90 LTC2497_ENABLE | address); 91 if (ret) 92 dev_err(&st->client->dev, "i2c transfer failed: %pe\n", 93 ERR_PTR(ret)); 94 return ret; 95 } 96 97 static int ltc2497_probe(struct i2c_client *client, 98 const struct i2c_device_id *id) 99 { 100 const struct ltc2497_chip_info *chip_info; 101 struct iio_dev *indio_dev; 102 struct ltc2497_driverdata *st; 103 struct device *dev = &client->dev; 104 u32 resolution; 105 106 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 107 I2C_FUNC_SMBUS_WRITE_BYTE)) 108 return -EOPNOTSUPP; 109 110 indio_dev = devm_iio_device_alloc(dev, sizeof(*st)); 111 if (!indio_dev) 112 return -ENOMEM; 113 114 st = iio_priv(indio_dev); 115 i2c_set_clientdata(client, indio_dev); 116 st->client = client; 117 st->common_ddata.result_and_measure = ltc2497_result_and_measure; 118 119 chip_info = device_get_match_data(dev); 120 if (!chip_info) 121 chip_info = (const struct ltc2497_chip_info *)id->driver_data; 122 st->common_ddata.chip_info = chip_info; 123 124 resolution = chip_info->resolution; 125 st->sub_lsb = 31 - (resolution + 1); 126 st->recv_size = BITS_TO_BYTES(resolution) + 1; 127 128 return ltc2497core_probe(dev, indio_dev); 129 } 130 131 static void ltc2497_remove(struct i2c_client *client) 132 { 133 struct iio_dev *indio_dev = i2c_get_clientdata(client); 134 135 ltc2497core_remove(indio_dev); 136 } 137 138 static const struct ltc2497_chip_info ltc2497_info[] = { 139 [TYPE_LTC2497] = { 140 .resolution = 16, 141 .name = NULL, 142 }, 143 [TYPE_LTC2499] = { 144 .resolution = 24, 145 .name = "ltc2499", 146 }, 147 }; 148 149 static const struct i2c_device_id ltc2497_id[] = { 150 { "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] }, 151 { "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2499] }, 152 { } 153 }; 154 MODULE_DEVICE_TABLE(i2c, ltc2497_id); 155 156 static const struct of_device_id ltc2497_of_match[] = { 157 { .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] }, 158 { .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] }, 159 {}, 160 }; 161 MODULE_DEVICE_TABLE(of, ltc2497_of_match); 162 163 static struct i2c_driver ltc2497_driver = { 164 .driver = { 165 .name = "ltc2497", 166 .of_match_table = ltc2497_of_match, 167 }, 168 .probe = ltc2497_probe, 169 .remove = ltc2497_remove, 170 .id_table = ltc2497_id, 171 }; 172 module_i2c_driver(ltc2497_driver); 173 174 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>"); 175 MODULE_DESCRIPTION("Linear Technology LTC2497 ADC driver"); 176 MODULE_LICENSE("GPL v2"); 177