| Message ID | 20210713043425.3321230-3-liambeguin@gmail.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Jonathan Cameron |
| Headers | show |
| Series | AD7949 Fixes | expand |
On Tue, 13 Jul 2021 00:34:23 -0400 Liam Beguin <liambeguin@gmail.com> wrote: > From: Liam Beguin <lvb@xiphos.com> > > This driver supports devices with 14-bit and 16-bit sample sizes. > This is not always handled properly by spi controllers and can fail. To > work around this limitation, pad samples to 16-bit and split the sample > into two 8-bit messages in the event that only 8-bit messages are > supported by the controller. > > Signed-off-by: Liam Beguin <lvb@xiphos.com> A small tidy up below that will make this even neater... > --- > drivers/iio/adc/ad7949.c | 68 +++++++++++++++++++++++++++++++++++----- > 1 file changed, 60 insertions(+), 8 deletions(-) > > diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c > index 0b549b8bd7a9..65f78751225b 100644 > --- a/drivers/iio/adc/ad7949.c > +++ b/drivers/iio/adc/ad7949.c > @@ -12,6 +12,7 @@ > #include <linux/regulator/consumer.h> > #include <linux/spi/spi.h> > #include <linux/bitfield.h> > +#include <asm/unaligned.h> > > #define AD7949_MASK_TOTAL GENMASK(13, 0) > > @@ -67,6 +68,7 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { > * @indio_dev: reference to iio structure > * @spi: reference to spi structure > * @resolution: resolution of the chip > + * @bits_per_word: number of bits per SPI word > * @cfg: copy of the configuration register > * @current_channel: current channel in use > * @buffer: buffer to send / receive data to / from device > @@ -77,6 +79,7 @@ struct ad7949_adc_chip { > struct iio_dev *indio_dev; > struct spi_device *spi; > u8 resolution; > + u8 bits_per_word; > u16 cfg; > unsigned int current_channel; > u16 buffer ____cacheline_aligned; > @@ -86,19 +89,37 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, > u16 mask) > { > int ret; > - int bits_per_word = ad7949_adc->resolution; > - int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS; > + u8 buf8[2]; > struct spi_message msg; > struct spi_transfer tx[] = { > { > .tx_buf = &ad7949_adc->buffer, > .len = 2, > - .bits_per_word = bits_per_word, > + .bits_per_word = ad7949_adc->bits_per_word, > }, > }; > > + ad7949_adc->buffer = 0; > ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask); > - ad7949_adc->buffer = ad7949_adc->cfg << shift; > + > + switch (ad7949_adc->bits_per_word) { > + case 16: > + ad7949_adc->buffer = ad7949_adc->cfg << 2; > + break; > + case 14: > + ad7949_adc->buffer = ad7949_adc->cfg; > + break; > + case 8: > + /* Pack 14-bit value into 2 bytes, MSB first */ > + buf8[0] = FIELD_GET(GENMASK(13, 6), ad7949_adc->cfg); > + buf8[1] = FIELD_GET(GENMASK(5, 0), ad7949_adc->cfg) << 2; > + memcpy(&ad7949_adc->buffer, buf8, 2); Can probably tidy this up given the form - all we actually need to do is ensure the value ends up big endian. /* Type is only big endian for this case as must be done as two transfers */ ad7949_adc->buffer = (u16)cpu_to_be16(ad7959_adc->cfg << 2); > + break; > + default: > + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); > + return -EINVAL; > + } > + > spi_message_init_with_transfers(&msg, tx, 1); > ret = spi_sync(ad7949_adc->spi, &msg); > > @@ -115,14 +136,13 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, > { > int ret; > int i; > - int bits_per_word = ad7949_adc->resolution; > - int mask = GENMASK(ad7949_adc->resolution - 1, 0); > + u8 buf8[2]; As below, not needed that I can see. > struct spi_message msg; > struct spi_transfer tx[] = { > { > .rx_buf = &ad7949_adc->buffer, > .len = 2, > - .bits_per_word = bits_per_word, > + .bits_per_word = ad7949_adc->bits_per_word, > }, > }; > > @@ -157,7 +177,26 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, > > ad7949_adc->current_channel = channel; > > - *val = ad7949_adc->buffer & mask; > + switch (ad7949_adc->bits_per_word) { > + case 16: > + *val = ad7949_adc->buffer; > + /* Shift-out padding bits */ > + *val >>= 16 - ad7949_adc->resolution; > + break; > + case 14: > + *val = ad7949_adc->buffer & GENMASK(13, 0); > + break; > + case 8: > + memcpy(buf8, &ad7949_adc->buffer, 2); > + /* Convert byte array to u16, MSB first */ > + *val = get_unaligned_be16(buf8); Why the local copy first? *val = get_unaligned_be16(ad7949_adc->buffer); should get what you want, it doesn't care about the type. Even better, that buffer is aligned, so we can do be16_to_cpu() safely I think... > + /* Shift-out padding bits */ > + *val >>= 16 - ad7949_adc->resolution; > + break; > + default: > + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); > + return -EINVAL; > + } > > return 0; > } > @@ -265,6 +304,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) > > static int ad7949_spi_probe(struct spi_device *spi) > { > + u32 spi_ctrl_mask = spi->controller->bits_per_word_mask; > struct device *dev = &spi->dev; > const struct ad7949_adc_spec *spec; > struct ad7949_adc_chip *ad7949_adc; > @@ -291,6 +331,18 @@ static int ad7949_spi_probe(struct spi_device *spi) > indio_dev->num_channels = spec->num_channels; > ad7949_adc->resolution = spec->resolution; > > + /* Set SPI bits per word */ > + if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) { > + ad7949_adc->bits_per_word = ad7949_adc->resolution; > + } else if (spi_ctrl_mask == SPI_BPW_MASK(16)) { > + ad7949_adc->bits_per_word = 16; > + } else if (spi_ctrl_mask == SPI_BPW_MASK(8)) { > + ad7949_adc->bits_per_word = 8; > + } else { > + dev_err(dev, "unable to find common BPW with spi controller\n"); > + return -EINVAL; > + } > + > ad7949_adc->vref = devm_regulator_get(dev, "vref"); > if (IS_ERR(ad7949_adc->vref)) { > dev_err(dev, "fail to request regulator\n");
On Sat Jul 17, 2021 at 1:23 PM EDT, Jonathan Cameron wrote: > On Tue, 13 Jul 2021 00:34:23 -0400 > Liam Beguin <liambeguin@gmail.com> wrote: > > > From: Liam Beguin <lvb@xiphos.com> > > > > This driver supports devices with 14-bit and 16-bit sample sizes. > > This is not always handled properly by spi controllers and can fail. To > > work around this limitation, pad samples to 16-bit and split the sample > > into two 8-bit messages in the event that only 8-bit messages are > > supported by the controller. > > > > Signed-off-by: Liam Beguin <lvb@xiphos.com> > > A small tidy up below that will make this even neater... > > > --- > > drivers/iio/adc/ad7949.c | 68 +++++++++++++++++++++++++++++++++++----- > > 1 file changed, 60 insertions(+), 8 deletions(-) > > > > diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c > > index 0b549b8bd7a9..65f78751225b 100644 > > --- a/drivers/iio/adc/ad7949.c > > +++ b/drivers/iio/adc/ad7949.c > > @@ -12,6 +12,7 @@ > > #include <linux/regulator/consumer.h> > > #include <linux/spi/spi.h> > > #include <linux/bitfield.h> > > +#include <asm/unaligned.h> > > > > #define AD7949_MASK_TOTAL GENMASK(13, 0) > > > > @@ -67,6 +68,7 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { > > * @indio_dev: reference to iio structure > > * @spi: reference to spi structure > > * @resolution: resolution of the chip > > + * @bits_per_word: number of bits per SPI word > > * @cfg: copy of the configuration register > > * @current_channel: current channel in use > > * @buffer: buffer to send / receive data to / from device > > @@ -77,6 +79,7 @@ struct ad7949_adc_chip { > > struct iio_dev *indio_dev; > > struct spi_device *spi; > > u8 resolution; > > + u8 bits_per_word; > > u16 cfg; > > unsigned int current_channel; > > u16 buffer ____cacheline_aligned; > > @@ -86,19 +89,37 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, > > u16 mask) > > { > > int ret; > > - int bits_per_word = ad7949_adc->resolution; > > - int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS; > > + u8 buf8[2]; > > struct spi_message msg; > > struct spi_transfer tx[] = { > > { > > .tx_buf = &ad7949_adc->buffer, > > .len = 2, > > - .bits_per_word = bits_per_word, > > + .bits_per_word = ad7949_adc->bits_per_word, > > }, > > }; > > > > + ad7949_adc->buffer = 0; > > ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask); > > - ad7949_adc->buffer = ad7949_adc->cfg << shift; > > + > > + switch (ad7949_adc->bits_per_word) { > > + case 16: > > + ad7949_adc->buffer = ad7949_adc->cfg << 2; > > + break; > > + case 14: > > + ad7949_adc->buffer = ad7949_adc->cfg; > > + break; > > + case 8: > > + /* Pack 14-bit value into 2 bytes, MSB first */ > > + buf8[0] = FIELD_GET(GENMASK(13, 6), ad7949_adc->cfg); > > + buf8[1] = FIELD_GET(GENMASK(5, 0), ad7949_adc->cfg) << 2; > > + memcpy(&ad7949_adc->buffer, buf8, 2); Hi Jonathan, Apologies for the delay on this. > > Can probably tidy this up given the form - all we actually need to do is > ensure the > value ends up big endian. > > /* Type is only big endian for this case as must be done as two > transfers */ > ad7949_adc->buffer = (u16)cpu_to_be16(ad7959_adc->cfg << 2); That's much nicer, I'll rework the patch using this. Thanks, Liam > > > + break; > > + default: > > + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); > > + return -EINVAL; > > + } > > + > > spi_message_init_with_transfers(&msg, tx, 1); > > ret = spi_sync(ad7949_adc->spi, &msg); > > > > @@ -115,14 +136,13 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, > > { > > int ret; > > int i; > > - int bits_per_word = ad7949_adc->resolution; > > - int mask = GENMASK(ad7949_adc->resolution - 1, 0); > > + u8 buf8[2]; > > As below, not needed that I can see. > > > struct spi_message msg; > > struct spi_transfer tx[] = { > > { > > .rx_buf = &ad7949_adc->buffer, > > .len = 2, > > - .bits_per_word = bits_per_word, > > + .bits_per_word = ad7949_adc->bits_per_word, > > }, > > }; > > > > @@ -157,7 +177,26 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, > > > > ad7949_adc->current_channel = channel; > > > > - *val = ad7949_adc->buffer & mask; > > + switch (ad7949_adc->bits_per_word) { > > + case 16: > > + *val = ad7949_adc->buffer; > > + /* Shift-out padding bits */ > > + *val >>= 16 - ad7949_adc->resolution; > > + break; > > + case 14: > > + *val = ad7949_adc->buffer & GENMASK(13, 0); > > + break; > > + case 8: > > + memcpy(buf8, &ad7949_adc->buffer, 2); > > + /* Convert byte array to u16, MSB first */ > > + *val = get_unaligned_be16(buf8); > > Why the local copy first? > > *val = get_unaligned_be16(ad7949_adc->buffer); > > should get what you want, it doesn't care about the type. > Even better, that buffer is aligned, so we can do > be16_to_cpu() safely I think... > > > + /* Shift-out padding bits */ > > + *val >>= 16 - ad7949_adc->resolution; > > + break; > > + default: > > + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); > > + return -EINVAL; > > + } > > > > return 0; > > } > > @@ -265,6 +304,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) > > > > static int ad7949_spi_probe(struct spi_device *spi) > > { > > + u32 spi_ctrl_mask = spi->controller->bits_per_word_mask; > > struct device *dev = &spi->dev; > > const struct ad7949_adc_spec *spec; > > struct ad7949_adc_chip *ad7949_adc; > > @@ -291,6 +331,18 @@ static int ad7949_spi_probe(struct spi_device *spi) > > indio_dev->num_channels = spec->num_channels; > > ad7949_adc->resolution = spec->resolution; > > > > + /* Set SPI bits per word */ > > + if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) { > > + ad7949_adc->bits_per_word = ad7949_adc->resolution; > > + } else if (spi_ctrl_mask == SPI_BPW_MASK(16)) { > > + ad7949_adc->bits_per_word = 16; > > + } else if (spi_ctrl_mask == SPI_BPW_MASK(8)) { > > + ad7949_adc->bits_per_word = 8; > > + } else { > > + dev_err(dev, "unable to find common BPW with spi controller\n"); > > + return -EINVAL; > > + } > > + > > ad7949_adc->vref = devm_regulator_get(dev, "vref"); > > if (IS_ERR(ad7949_adc->vref)) { > > dev_err(dev, "fail to request regulator\n");
diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index 0b549b8bd7a9..65f78751225b 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -12,6 +12,7 @@ #include <linux/regulator/consumer.h> #include <linux/spi/spi.h> #include <linux/bitfield.h> +#include <asm/unaligned.h> #define AD7949_MASK_TOTAL GENMASK(13, 0) @@ -67,6 +68,7 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { * @indio_dev: reference to iio structure * @spi: reference to spi structure * @resolution: resolution of the chip + * @bits_per_word: number of bits per SPI word * @cfg: copy of the configuration register * @current_channel: current channel in use * @buffer: buffer to send / receive data to / from device @@ -77,6 +79,7 @@ struct ad7949_adc_chip { struct iio_dev *indio_dev; struct spi_device *spi; u8 resolution; + u8 bits_per_word; u16 cfg; unsigned int current_channel; u16 buffer ____cacheline_aligned; @@ -86,19 +89,37 @@ static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, u16 mask) { int ret; - int bits_per_word = ad7949_adc->resolution; - int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS; + u8 buf8[2]; struct spi_message msg; struct spi_transfer tx[] = { { .tx_buf = &ad7949_adc->buffer, .len = 2, - .bits_per_word = bits_per_word, + .bits_per_word = ad7949_adc->bits_per_word, }, }; + ad7949_adc->buffer = 0; ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask); - ad7949_adc->buffer = ad7949_adc->cfg << shift; + + switch (ad7949_adc->bits_per_word) { + case 16: + ad7949_adc->buffer = ad7949_adc->cfg << 2; + break; + case 14: + ad7949_adc->buffer = ad7949_adc->cfg; + break; + case 8: + /* Pack 14-bit value into 2 bytes, MSB first */ + buf8[0] = FIELD_GET(GENMASK(13, 6), ad7949_adc->cfg); + buf8[1] = FIELD_GET(GENMASK(5, 0), ad7949_adc->cfg) << 2; + memcpy(&ad7949_adc->buffer, buf8, 2); + break; + default: + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); + return -EINVAL; + } + spi_message_init_with_transfers(&msg, tx, 1); ret = spi_sync(ad7949_adc->spi, &msg); @@ -115,14 +136,13 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, { int ret; int i; - int bits_per_word = ad7949_adc->resolution; - int mask = GENMASK(ad7949_adc->resolution - 1, 0); + u8 buf8[2]; struct spi_message msg; struct spi_transfer tx[] = { { .rx_buf = &ad7949_adc->buffer, .len = 2, - .bits_per_word = bits_per_word, + .bits_per_word = ad7949_adc->bits_per_word, }, }; @@ -157,7 +177,26 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, ad7949_adc->current_channel = channel; - *val = ad7949_adc->buffer & mask; + switch (ad7949_adc->bits_per_word) { + case 16: + *val = ad7949_adc->buffer; + /* Shift-out padding bits */ + *val >>= 16 - ad7949_adc->resolution; + break; + case 14: + *val = ad7949_adc->buffer & GENMASK(13, 0); + break; + case 8: + memcpy(buf8, &ad7949_adc->buffer, 2); + /* Convert byte array to u16, MSB first */ + *val = get_unaligned_be16(buf8); + /* Shift-out padding bits */ + *val >>= 16 - ad7949_adc->resolution; + break; + default: + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); + return -EINVAL; + } return 0; } @@ -265,6 +304,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) static int ad7949_spi_probe(struct spi_device *spi) { + u32 spi_ctrl_mask = spi->controller->bits_per_word_mask; struct device *dev = &spi->dev; const struct ad7949_adc_spec *spec; struct ad7949_adc_chip *ad7949_adc; @@ -291,6 +331,18 @@ static int ad7949_spi_probe(struct spi_device *spi) indio_dev->num_channels = spec->num_channels; ad7949_adc->resolution = spec->resolution; + /* Set SPI bits per word */ + if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) { + ad7949_adc->bits_per_word = ad7949_adc->resolution; + } else if (spi_ctrl_mask == SPI_BPW_MASK(16)) { + ad7949_adc->bits_per_word = 16; + } else if (spi_ctrl_mask == SPI_BPW_MASK(8)) { + ad7949_adc->bits_per_word = 8; + } else { + dev_err(dev, "unable to find common BPW with spi controller\n"); + return -EINVAL; + } + ad7949_adc->vref = devm_regulator_get(dev, "vref"); if (IS_ERR(ad7949_adc->vref)) { dev_err(dev, "fail to request regulator\n");