The LTC2499 is a 16-channel (eight differential), 24-bit, ADC with Easy Drive technology and a 2-wire, I2C interface. Implement support for the LTC2499 ADC by extending the LTC2497 driver. A new chip_info struct is added to differentiate between chip types and resolutions when reading data from the device. Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/2499fe.pdf Signed-off-by: Ciprian Regus <ciprian.regus@xxxxxxxxxx> --- changes in v2: - removed the bitfield.h and bitops.h includes, since they were not needed. - removed a blank line. - replaced the data buffer for the ltc2497_driverdata with a union. - depending on frame size, i2c transfers use either 3 or 4 byte buffers, instead of always using a __be32. - added a comment which explains the output data format and how does sign extension. happen. - added the const modifier for the chip_info structs. - renamed the chip_info struct to ltc2497_chip_info. - renamed the chip_type enum to ltc2497_chip_type - added probe fallback to using i2c_device_id in case OF fails. - used BITS_TO_BYTES() instead of dividing by 8. - used a tab instead of a space in a struct field declaration, which in v1 appeared as if the line was deleted and added back. - added back a trailing comma. - rearranged variable declaration lines so that longer ones would be first. - used pointers to a chip info struct in the i2c_device_id table, instead of enums. drivers/iio/adc/ltc2496.c | 8 ++++- drivers/iio/adc/ltc2497-core.c | 2 +- drivers/iio/adc/ltc2497.c | 56 +++++++++++++++++++++++++++++++--- drivers/iio/adc/ltc2497.h | 11 +++++++ 4 files changed, 70 insertions(+), 7 deletions(-) diff --git a/drivers/iio/adc/ltc2496.c b/drivers/iio/adc/ltc2496.c index dfb3bb5997e5..bf89d5ae19af 100644 --- a/drivers/iio/adc/ltc2496.c +++ b/drivers/iio/adc/ltc2496.c @@ -15,6 +15,7 @@ #include <linux/iio/driver.h> #include <linux/module.h> #include <linux/mod_devicetable.h> +#include <linux/property.h> #include "ltc2497.h" @@ -74,6 +75,7 @@ static int ltc2496_probe(struct spi_device *spi) spi_set_drvdata(spi, indio_dev); st->spi = spi; st->common_ddata.result_and_measure = ltc2496_result_and_measure; + st->common_ddata.chip_info = device_get_match_data(dev); return ltc2497core_probe(dev, indio_dev); } @@ -85,8 +87,12 @@ static void ltc2496_remove(struct spi_device *spi) ltc2497core_remove(indio_dev); } +static const struct ltc2497_chip_info ltc2496_info = { + .resolution = 16, +}; + static const struct of_device_id ltc2496_of_match[] = { - { .compatible = "lltc,ltc2496", }, + { .compatible = "lltc,ltc2496", .data = <c2496_info, }, {}, }; MODULE_DEVICE_TABLE(of, ltc2496_of_match); diff --git a/drivers/iio/adc/ltc2497-core.c b/drivers/iio/adc/ltc2497-core.c index 2a485c8a1940..b2752399402c 100644 --- a/drivers/iio/adc/ltc2497-core.c +++ b/drivers/iio/adc/ltc2497-core.c @@ -95,7 +95,7 @@ static int ltc2497core_read_raw(struct iio_dev *indio_dev, return ret; *val = ret / 1000; - *val2 = 17; + *val2 = ddata->chip_info->resolution + 1; return IIO_VAL_FRACTIONAL_LOG2; diff --git a/drivers/iio/adc/ltc2497.c b/drivers/iio/adc/ltc2497.c index f7c786f37ceb..2f660015f34b 100644 --- a/drivers/iio/adc/ltc2497.c +++ b/drivers/iio/adc/ltc2497.c @@ -12,6 +12,7 @@ #include <linux/iio/driver.h> #include <linux/module.h> #include <linux/mod_devicetable.h> +#include <linux/property.h> #include "ltc2497.h" @@ -19,11 +20,16 @@ struct ltc2497_driverdata { /* this must be the first member */ struct ltc2497core_driverdata common_ddata; struct i2c_client *client; + u32 recv_size; + u32 sub_lsb; /* * DMA (thus cache coherency maintenance) may require the * transfer buffers to live in their own cache lines. */ - __be32 buf __aligned(IIO_DMA_MINALIGN); + union { + __be32 d32; + u8 d8[3]; + } data __aligned(IIO_DMA_MINALIGN); }; static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, @@ -34,13 +40,29 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, int ret; if (val) { - ret = i2c_master_recv(st->client, (char *)&st->buf, 3); + if (st->recv_size == 3) + ret = i2c_master_recv(st->client, (char *)&st->data.d8, st->recv_size); + else + ret = i2c_master_recv(st->client, (char *)&st->data.d32, st->recv_size); + if (ret < 0) { dev_err(&st->client->dev, "i2c_master_recv failed\n"); return ret; } - *val = (be32_to_cpu(st->buf) >> 14) - (1 << 17); + /* + * The data format is 16/24 bit 2s complement, but with an upper sign bit on the + * resolution + 1 position, which is set for positive values only. Given this + * bit's value, subtracting BIT(resolution + 1) from the ADC's result is + * equivalent to a sign extension. + */ + if (st->recv_size == 3) { + *val = (get_unaligned_be24(st->data.d8) >> st->sub_lsb) + - BIT(ddata->chip_info->resolution + 1); + } else { + *val = (be32_to_cpu(st->data.d32) >> st->sub_lsb) + - BIT(ddata->chip_info->resolution + 1); + } } ret = i2c_smbus_write_byte(st->client, @@ -54,9 +76,11 @@ static int ltc2497_result_and_measure(struct ltc2497core_driverdata *ddata, static int ltc2497_probe(struct i2c_client *client, const struct i2c_device_id *id) { + const struct ltc2497_chip_info *chip_info; struct iio_dev *indio_dev; struct ltc2497_driverdata *st; struct device *dev = &client->dev; + u32 resolution; if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | I2C_FUNC_SMBUS_WRITE_BYTE)) @@ -71,6 +95,15 @@ static int ltc2497_probe(struct i2c_client *client, st->client = client; st->common_ddata.result_and_measure = ltc2497_result_and_measure; + chip_info = device_get_match_data(dev); + if (!chip_info) + chip_info = (const struct ltc2497_chip_info *)id->driver_data; + st->common_ddata.chip_info = chip_info; + + resolution = chip_info->resolution; + st->sub_lsb = 31 - (resolution + 1); + st->recv_size = BITS_TO_BYTES(resolution) + 1; + return ltc2497core_probe(dev, indio_dev); } @@ -83,14 +116,27 @@ static int ltc2497_remove(struct i2c_client *client) return 0; } +static const struct ltc2497_chip_info ltc2497_info[] = { + [TYPE_LTC2497] = { + .resolution = 16, + .name = NULL, + }, + [TYPE_LTC2499] = { + .resolution = 24, + .name = "ltc2499", + }, +}; + static const struct i2c_device_id ltc2497_id[] = { - { "ltc2497", 0 }, + { "ltc2497", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] }, + { "ltc2499", (kernel_ulong_t)<c2497_info[TYPE_LTC2497] }, { } }; MODULE_DEVICE_TABLE(i2c, ltc2497_id); static const struct of_device_id ltc2497_of_match[] = { - { .compatible = "lltc,ltc2497", }, + { .compatible = "lltc,ltc2497", .data = <c2497_info[TYPE_LTC2497] }, + { .compatible = "lltc,ltc2499", .data = <c2497_info[TYPE_LTC2499] }, {}, }; MODULE_DEVICE_TABLE(of, ltc2497_of_match); diff --git a/drivers/iio/adc/ltc2497.h b/drivers/iio/adc/ltc2497.h index d0b42dd6b8ad..95f6a5f4d4a6 100644 --- a/drivers/iio/adc/ltc2497.h +++ b/drivers/iio/adc/ltc2497.h @@ -4,9 +4,20 @@ #define LTC2497_CONFIG_DEFAULT LTC2497_ENABLE #define LTC2497_CONVERSION_TIME_MS 150ULL +enum ltc2497_chip_type { + TYPE_LTC2496, + TYPE_LTC2497, + TYPE_LTC2499, +}; + +struct ltc2497_chip_info { + u32 resolution; +}; + struct ltc2497core_driverdata { struct regulator *ref; ktime_t time_prev; + const struct ltc2497_chip_info *chip_info; u8 addr_prev; int (*result_and_measure)(struct ltc2497core_driverdata *ddata, u8 address, int *val); -- 2.30.2
