| Message ID | 20241111-tgamblin-ad4695_improvements-v1-3-698af4512635@baylibre.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | iio: adc: ad4695: add new regmap callbacks, timing improvements | expand |
On 2024-11-11 10:59, Trevor Gamblin wrote: > 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@Huawei.com/ > > Suggested-by: David Lechner <dlechner@baylibre.com> > Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com> > --- > 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 f36c1a1db886..180a0fd4f03c 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 = { > @@ -1040,15 +1101,14 @@ 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_regmap_config); Note that there's a bug here - that should be + st->regmap16 = devm_regmap_init(dev, &ad4695_regmap_bus, st, + &ad4695_regmap16_config); I can fix this in v2, unless it would just be easier to fix during merge (assuming there is no other major feedback). > if (IS_ERR(st->regmap16)) > return dev_err_probe(dev, PTR_ERR(st->regmap16), > "Failed to initialize regmap16\n"); >
On 2024-11-11 10:59, Trevor Gamblin wrote: > 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@Huawei.com/ > > Suggested-by: David Lechner <dlechner@baylibre.com> > Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com> Found a couple more bugs after some testing. I'll wait until EOD on Wednesday to send a v2, in case there are any other review comments.
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 f36c1a1db886..180a0fd4f03c 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 = { @@ -1040,15 +1101,14 @@ 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_regmap_config); if (IS_ERR(st->regmap16)) return dev_err_probe(dev, PTR_ERR(st->regmap16), "Failed to initialize regmap16\n");
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@Huawei.com/ Suggested-by: David Lechner <dlechner@baylibre.com> Signed-off-by: Trevor Gamblin <tgamblin@baylibre.com> --- drivers/iio/adc/Kconfig | 2 +- drivers/iio/adc/ad4695.c | 74 +++++++++++++++++++++++++++++++++++++++++++----- 2 files changed, 68 insertions(+), 8 deletions(-)