Add a custom implementation of regmap read/write callbacks using the SPI bus. This allows them to be performed at a lower SCLK rate than data reads. Previously, all SPI transfers were being performed at a lower speed, but with this change sample data is read at the max bus speed while the register reads/writes remain at the lower rate. Also remove .can_multi_write from the AD4695 driver's regmap_configs, as this isn't implemented or needed. For some background context, see: https://lore.kernel.org/linux-iio/20241028163907.00007e12@xxxxxxxxxx/ Suggested-by: David Lechner <dlechner@xxxxxxxxxxxx> Signed-off-by: Trevor Gamblin <tgamblin@xxxxxxxxxxxx> --- drivers/iio/adc/Kconfig | 2 +- drivers/iio/adc/ad4695.c | 74 +++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 68 insertions(+), 8 deletions(-) diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig index 6c4e74420fd2..e0f9d01ce37d 100644 --- a/drivers/iio/adc/Kconfig +++ b/drivers/iio/adc/Kconfig @@ -51,9 +51,9 @@ config AD4130 config AD4695 tristate "Analog Device AD4695 ADC Driver" depends on SPI - select REGMAP_SPI select IIO_BUFFER select IIO_TRIGGERED_BUFFER + select REGMAP help Say yes here to build support for Analog Devices AD4695 and similar analog to digital converters (ADC). diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c index 4bc800293e60..921d996fff79 100644 --- a/drivers/iio/adc/ad4695.c +++ b/drivers/iio/adc/ad4695.c @@ -150,6 +150,8 @@ struct ad4695_state { /* Commands to send for single conversion. */ u16 cnv_cmd; u8 cnv_cmd2; + /* Buffer for storing data from regmap bus reads/writes */ + u8 regmap_bus_data[4]; }; static const struct regmap_range ad4695_regmap_rd_ranges[] = { @@ -194,7 +196,6 @@ static const struct regmap_config ad4695_regmap_config = { .max_register = AD4695_REG_AS_SLOT(127), .rd_table = &ad4695_regmap_rd_table, .wr_table = &ad4695_regmap_wr_table, - .can_multi_write = true, }; static const struct regmap_range ad4695_regmap16_rd_ranges[] = { @@ -226,7 +227,67 @@ static const struct regmap_config ad4695_regmap16_config = { .max_register = AD4695_REG_GAIN_IN(15), .rd_table = &ad4695_regmap16_rd_table, .wr_table = &ad4695_regmap16_wr_table, - .can_multi_write = true, +}; + +static int ad4695_regmap_bus_reg_write(void *context, const void *data, + size_t count) +{ + struct ad4695_state *st = context; + struct spi_transfer xfer = { + .speed_hz = AD4695_REG_ACCESS_SCLK_HZ, + .len = count, + .tx_buf = st->regmap_bus_data, + }; + + if (count > ARRAY_SIZE(st->regmap_bus_data)) + return -EINVAL; + + memcpy(st->regmap_bus_data, data, count); + + return spi_sync_transfer(st->spi, &xfer, 1); +} + +static int ad4695_regmap_bus_reg_read(void *context, const void *reg, + size_t reg_size, void *val, + size_t val_size) +{ + struct ad4695_state *st = context; + struct spi_transfer xfers[] = { + { + .speed_hz = AD4695_REG_ACCESS_SCLK_HZ, + .len = reg_size, + .tx_buf = &st->regmap_bus_data[0], + }, { + .speed_hz = AD4695_REG_ACCESS_SCLK_HZ, + .len = val_size, + .rx_buf = &st->regmap_bus_data[2], + }, + }; + int ret; + + if (reg_size > 2) + return -EINVAL; + + if (val_size > 2) + return -EINVAL; + + memcpy(&st->regmap_bus_data[0], reg, reg_size); + + ret = spi_sync_transfer(st->spi, xfers, ARRAY_SIZE(xfers)); + if (ret) + return ret; + + memcpy(val, &st->regmap_bus_data[2], val_size); + + return 0; +} + +static const struct regmap_bus ad4695_regmap_bus = { + .write = ad4695_regmap_bus_reg_write, + .read = ad4695_regmap_bus_reg_read, + .read_flag_mask = 0x80, + .reg_format_endian_default = REGMAP_ENDIAN_BIG, + .val_format_endian_default = REGMAP_ENDIAN_BIG, }; static const struct iio_chan_spec ad4695_channel_template = { @@ -1061,15 +1122,14 @@ static int ad4695_probe(struct spi_device *spi) if (!st->chip_info) return -EINVAL; - /* Registers cannot be read at the max allowable speed */ - spi->max_speed_hz = AD4695_REG_ACCESS_SCLK_HZ; - - st->regmap = devm_regmap_init_spi(spi, &ad4695_regmap_config); + st->regmap = devm_regmap_init(dev, &ad4695_regmap_bus, st, + &ad4695_regmap_config); if (IS_ERR(st->regmap)) return dev_err_probe(dev, PTR_ERR(st->regmap), "Failed to initialize regmap\n"); - st->regmap16 = devm_regmap_init_spi(spi, &ad4695_regmap16_config); + st->regmap16 = devm_regmap_init(dev, &ad4695_regmap_bus, st, + &ad4695_regmap16_config); if (IS_ERR(st->regmap16)) return dev_err_probe(dev, PTR_ERR(st->regmap16), "Failed to initialize regmap16\n"); -- 2.39.5
