| Message ID | 20210708235618.1541335-3-liambeguin@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | AD7949 Fixes | expand |
> -----Original Message----- > From: Liam Beguin <liambeguin@gmail.com> > Sent: Friday, July 9, 2021 1:56 AM > To: liambeguin@gmail.com; lars@metafoo.de; Hennerich, Michael > <Michael.Hennerich@analog.com>; jic23@kernel.org; charles- > antoine.couret@essensium.com > Cc: linux-kernel@vger.kernel.org; linux-iio@vger.kernel.org; > devicetree@vger.kernel.org; robh+dt@kernel.org > Subject: [PATCH v1 2/4] iio: adc: ad7949: fix spi messages on non 14-bit > controllers > > [External] > > 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> > --- > drivers/iio/adc/ad7949.c | 67 > ++++++++++++++++++++++++++++++++++------ > 1 file changed, 58 insertions(+), 9 deletions(-) > > diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c > index 93aacf4f680b..bbc6b56330a3 100644 > --- a/drivers/iio/adc/ad7949.c > +++ b/drivers/iio/adc/ad7949.c > @@ -11,6 +11,7 @@ > #include <linux/module.h> > #include <linux/regulator/consumer.h> > #include <linux/spi/spi.h> > +#include <linux/bitfield.h> > > #define AD7949_MASK_TOTAL GENMASK(13, 0) > #define AD7949_CFG_REG_SIZE_BITS 14 > @@ -57,6 +58,7 @@ 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 > @@ -67,28 +69,59 @@ 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; > + union { > + __be16 buffer; > + u8 buf8[2]; > + } ____cacheline_aligned; > }; > > +static void ad7949_set_bits_per_word(struct ad7949_adc_chip > *ad7949_adc) > +{ > + u32 adc_mask = SPI_BPW_MASK(ad7949_adc->resolution); > + u32 bpw = adc_mask & ad7949_adc->spi->controller- > >bits_per_word_mask; > + > + if (bpw == adc_mask) > + ad7949_adc->bits_per_word = ad7949_adc- > >resolution; > + else if (bpw == SPI_BPW_MASK(16)) > + ad7949_adc->bits_per_word = 16; > + else > + ad7949_adc->bits_per_word = 8; > +} > + > 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; > 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 */ > + ad7949_adc->buf8[0] = FIELD_GET(GENMASK(13, 6), > ad7949_adc->cfg); > + ad7949_adc->buf8[1] = FIELD_GET(GENMASK(5, 0), > ad7949_adc->cfg); > + ad7949_adc->buf8[1] = ad7949_adc->buf8[1] << 2; > + break; > + } Honestly I didn't went through the driver but just a question... Are we sure that 'ad7949_adc->resolution' will have something valid (8, 14, 16)? A default statement is always a nice to have :). > spi_message_init_with_transfers(&msg, tx, 1); > ret = spi_sync(ad7949_adc->spi, &msg); > > @@ -105,14 +138,12 @@ 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); > 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, > }, > }; > > @@ -147,7 +178,24 @@ 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 */ > + if (ad7949_adc->resolution == 14) > + *val = *val >> 2; > + break; > + case 14: > + *val = ad7949_adc->buffer & GENMASK(13, 0); > + break; > + case 8: > + /* Convert byte array to u16, MSB first */ > + *val = (ad7949_adc->buf8[0] << 8) | ad7949_adc- > >buf8[1]; > + /* Shift-out padding bits */ > + if (ad7949_adc->resolution == 14) > + *val = *val >> 2; > + break; > + } > > return 0; > } > @@ -280,6 +328,7 @@ static int ad7949_spi_probe(struct spi_device > *spi) > spec = &ad7949_adc_spec[spi_get_device_id(spi)- > >driver_data]; > indio_dev->num_channels = spec->num_channels; > ad7949_adc->resolution = spec->resolution; > + ad7949_set_bits_per_word(ad7949_adc); > > ad7949_adc->vref = devm_regulator_get(dev, "vref"); > if (IS_ERR(ad7949_adc->vref)) { > -- > 2.30.1.489.g328c10930387
On Fri Jul 9, 2021 at 4:19 AM EDT, Sa, Nuno wrote: > > > > -----Original Message----- > > From: Liam Beguin <liambeguin@gmail.com> > > Sent: Friday, July 9, 2021 1:56 AM > > To: liambeguin@gmail.com; lars@metafoo.de; Hennerich, Michael > > <Michael.Hennerich@analog.com>; jic23@kernel.org; charles- > > antoine.couret@essensium.com > > Cc: linux-kernel@vger.kernel.org; linux-iio@vger.kernel.org; > > devicetree@vger.kernel.org; robh+dt@kernel.org > > Subject: [PATCH v1 2/4] iio: adc: ad7949: fix spi messages on non 14-bit > > controllers > > > > [External] > > > > 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> > > --- > > drivers/iio/adc/ad7949.c | 67 > > ++++++++++++++++++++++++++++++++++------ > > 1 file changed, 58 insertions(+), 9 deletions(-) > > > > diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c > > index 93aacf4f680b..bbc6b56330a3 100644 > > --- a/drivers/iio/adc/ad7949.c > > +++ b/drivers/iio/adc/ad7949.c > > @@ -11,6 +11,7 @@ > > #include <linux/module.h> > > #include <linux/regulator/consumer.h> > > #include <linux/spi/spi.h> > > +#include <linux/bitfield.h> > > > > #define AD7949_MASK_TOTAL GENMASK(13, 0) > > #define AD7949_CFG_REG_SIZE_BITS 14 > > @@ -57,6 +58,7 @@ 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 > > @@ -67,28 +69,59 @@ 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; > > + union { > > + __be16 buffer; > > + u8 buf8[2]; > > + } ____cacheline_aligned; > > }; > > > > +static void ad7949_set_bits_per_word(struct ad7949_adc_chip > > *ad7949_adc) > > +{ > > + u32 adc_mask = SPI_BPW_MASK(ad7949_adc->resolution); > > + u32 bpw = adc_mask & ad7949_adc->spi->controller- > > >bits_per_word_mask; > > + > > + if (bpw == adc_mask) > > + ad7949_adc->bits_per_word = ad7949_adc- > > >resolution; > > + else if (bpw == SPI_BPW_MASK(16)) > > + ad7949_adc->bits_per_word = 16; > > + else > > + ad7949_adc->bits_per_word = 8; > > +} > > + > > 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; > > 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 */ > > + ad7949_adc->buf8[0] = FIELD_GET(GENMASK(13, 6), > > ad7949_adc->cfg); > > + ad7949_adc->buf8[1] = FIELD_GET(GENMASK(5, 0), > > ad7949_adc->cfg); > > + ad7949_adc->buf8[1] = ad7949_adc->buf8[1] << 2; > > + break; > > + } > > Honestly I didn't went through the driver but just a question... Are we > sure that 'ad7949_adc->resolution' will have something valid (8, 14, > 16)? > A default statement is always a nice to have :). > Thanks for pointing that out. You're right that based on this driver there's no guaranty that `ad7949_adc->resolution` will have a valid value. I'll add a default to 8-bit. Thanks, Liam > > spi_message_init_with_transfers(&msg, tx, 1); > > ret = spi_sync(ad7949_adc->spi, &msg); > > > > @@ -105,14 +138,12 @@ 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); > > 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, > > }, > > }; > > > > @@ -147,7 +178,24 @@ 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 */ > > + if (ad7949_adc->resolution == 14) > > + *val = *val >> 2; > > + break; > > + case 14: > > + *val = ad7949_adc->buffer & GENMASK(13, 0); > > + break; > > + case 8: > > + /* Convert byte array to u16, MSB first */ > > + *val = (ad7949_adc->buf8[0] << 8) | ad7949_adc- > > >buf8[1]; > > + /* Shift-out padding bits */ > > + if (ad7949_adc->resolution == 14) > > + *val = *val >> 2; > > + break; > > + } > > > > return 0; > > } > > @@ -280,6 +328,7 @@ static int ad7949_spi_probe(struct spi_device > > *spi) > > spec = &ad7949_adc_spec[spi_get_device_id(spi)- > > >driver_data]; > > indio_dev->num_channels = spec->num_channels; > > ad7949_adc->resolution = spec->resolution; > > + ad7949_set_bits_per_word(ad7949_adc); > > > > ad7949_adc->vref = devm_regulator_get(dev, "vref"); > > if (IS_ERR(ad7949_adc->vref)) { > > -- > > 2.30.1.489.g328c10930387
diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index 93aacf4f680b..bbc6b56330a3 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -11,6 +11,7 @@ #include <linux/module.h> #include <linux/regulator/consumer.h> #include <linux/spi/spi.h> +#include <linux/bitfield.h> #define AD7949_MASK_TOTAL GENMASK(13, 0) #define AD7949_CFG_REG_SIZE_BITS 14 @@ -57,6 +58,7 @@ 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 @@ -67,28 +69,59 @@ 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; + union { + __be16 buffer; + u8 buf8[2]; + } ____cacheline_aligned; }; +static void ad7949_set_bits_per_word(struct ad7949_adc_chip *ad7949_adc) +{ + u32 adc_mask = SPI_BPW_MASK(ad7949_adc->resolution); + u32 bpw = adc_mask & ad7949_adc->spi->controller->bits_per_word_mask; + + if (bpw == adc_mask) + ad7949_adc->bits_per_word = ad7949_adc->resolution; + else if (bpw == SPI_BPW_MASK(16)) + ad7949_adc->bits_per_word = 16; + else + ad7949_adc->bits_per_word = 8; +} + 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; 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 */ + ad7949_adc->buf8[0] = FIELD_GET(GENMASK(13, 6), ad7949_adc->cfg); + ad7949_adc->buf8[1] = FIELD_GET(GENMASK(5, 0), ad7949_adc->cfg); + ad7949_adc->buf8[1] = ad7949_adc->buf8[1] << 2; + break; + } + spi_message_init_with_transfers(&msg, tx, 1); ret = spi_sync(ad7949_adc->spi, &msg); @@ -105,14 +138,12 @@ 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); 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, }, }; @@ -147,7 +178,24 @@ 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 */ + if (ad7949_adc->resolution == 14) + *val = *val >> 2; + break; + case 14: + *val = ad7949_adc->buffer & GENMASK(13, 0); + break; + case 8: + /* Convert byte array to u16, MSB first */ + *val = (ad7949_adc->buf8[0] << 8) | ad7949_adc->buf8[1]; + /* Shift-out padding bits */ + if (ad7949_adc->resolution == 14) + *val = *val >> 2; + break; + } return 0; } @@ -280,6 +328,7 @@ static int ad7949_spi_probe(struct spi_device *spi) spec = &ad7949_adc_spec[spi_get_device_id(spi)->driver_data]; indio_dev->num_channels = spec->num_channels; ad7949_adc->resolution = spec->resolution; + ad7949_set_bits_per_word(ad7949_adc); ad7949_adc->vref = devm_regulator_get(dev, "vref"); if (IS_ERR(ad7949_adc->vref)) {