[PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Vasileios Amoiridis]

According to the datasheet of BMP38x and BMP390 devices, in SPI
operation, the first byte that returns after a read operation is
garbage and it needs to be dropped and return the rest of the
bytes.

Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
---
 drivers/iio/pressure/bmp280-spi.c | 47 ++++++++++++++++++++++++++++++-
 drivers/iio/pressure/bmp280.h     |  2 ++
 2 files changed, 48 insertions(+), 1 deletion(-)

diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
index 433d6fac83c4..c4b4a5d67f94 100644
--- a/drivers/iio/pressure/bmp280-spi.c
+++ b/drivers/iio/pressure/bmp280-spi.c
@@ -35,6 +35,32 @@ static int bmp280_regmap_spi_read(void *context, const void *reg,
 	return spi_write_then_read(spi, reg, reg_size, val, val_size);
 }
 
+static int bmp380_regmap_spi_read(void *context, const void *reg,
+				  size_t reg_size, void *val, size_t val_size)
+{
+	struct spi_device *spi = to_spi_device(context);
+	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
+	ssize_t status;
+	u8 buf;
+
+	memcpy(&buf, reg, reg_size);
+	buf |= 0x80;
+
+	/*
+	 * According to the BMP380, BMP388, BMP390 datasheets, for a basic
+	 * read operation, after the write is done, 2 bytes are received and
+	 * the first one has to be dropped. The 2nd one is the requested
+	 * value.
+	 */
+	status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);
+	if (status)
+		return status;
+
+	memcpy(val, ret + 1, val_size);
+
+	return 0;
+}
+
 static struct regmap_bus bmp280_regmap_bus = {
 	.write = bmp280_regmap_spi_write,
 	.read = bmp280_regmap_spi_read,
@@ -42,10 +68,18 @@ static struct regmap_bus bmp280_regmap_bus = {
 	.val_format_endian_default = REGMAP_ENDIAN_BIG,
 };
 
+static struct regmap_bus bmp380_regmap_bus = {
+	.write = bmp280_regmap_spi_write,
+	.read = bmp380_regmap_spi_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
+	.val_format_endian_default = REGMAP_ENDIAN_BIG,
+};
+
 static int bmp280_spi_probe(struct spi_device *spi)
 {
 	const struct spi_device_id *id = spi_get_device_id(spi);
 	const struct bmp280_chip_info *chip_info;
+	struct regmap_bus *bmp_regmap_bus;
 	struct regmap *regmap;
 	int ret;
 
@@ -58,8 +92,19 @@ static int bmp280_spi_probe(struct spi_device *spi)
 
 	chip_info = spi_get_device_match_data(spi);
 
+	switch (chip_info->chip_id[0]) {
+	case BMP380_CHIP_ID:
+	case BMP390_CHIP_ID:
+		bmp_regmap_bus = &bmp380_regmap_bus;
+		break;
+	default:
+		bmp_regmap_bus = &bmp280_regmap_bus;
+		break;
+	}
+
+
 	regmap = devm_regmap_init(&spi->dev,
-				  &bmp280_regmap_bus,
+				  bmp_regmap_bus,
 				  &spi->dev,
 				  chip_info->regmap_config);
 	if (IS_ERR(regmap)) {
diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
index 4012387d7956..ca482b7e4295 100644
--- a/drivers/iio/pressure/bmp280.h
+++ b/drivers/iio/pressure/bmp280.h
@@ -191,6 +191,8 @@
 #define BMP380_TEMP_SKIPPED		0x800000
 #define BMP380_PRESS_SKIPPED		0x800000
 
+#define BMP380_SPI_MAX_REG_COUNT_READ   3
+
 /* BMP280 specific registers */
 #define BMP280_REG_HUMIDITY_LSB		0xFE
 #define BMP280_REG_HUMIDITY_MSB		0xFD
-- 
2.25.1

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Andy Shevchenko]

On Thu, Feb 15, 2024 at 05:43:32PM +0100, Vasileios Amoiridis wrote:
> According to the datasheet of BMP38x and BMP390 devices, in SPI
> operation, the first byte that returns after a read operation is
> garbage and it needs to be dropped and return the rest of the
> bytes.

Thank you for the patch, my comments below.

...

> +static int bmp380_regmap_spi_read(void *context, const void *reg,
> +				  size_t reg_size, void *val, size_t val_size)
> +{
> +	struct spi_device *spi = to_spi_device(context);
> +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
> +	ssize_t status;
> +	u8 buf;

AFAIU this buffer is not DMA-capable.

> +	memcpy(&buf, reg, reg_size);

I prefer to see a switch case with cases based on allowed sizes and proper
endianess accessors.

> +	buf |= 0x80;

This is done by regmap, no?

> +	/*
> +	 * According to the BMP380, BMP388, BMP390 datasheets, for a basic
> +	 * read operation, after the write is done, 2 bytes are received and
> +	 * the first one has to be dropped. The 2nd one is the requested
> +	 * value.
> +	 */
> +	status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);

sizeof() ?

> +	if (status)
> +		return status;

> +	memcpy(val, ret + 1, val_size);

As per above.

> +	return 0;
> +}

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Angel Iglesias]

On Thu, 2024-02-15 at 17:43 +0100, Vasileios Amoiridis wrote:
> According to the datasheet of BMP38x and BMP390 devices, in SPI
> operation, the first byte that returns after a read operation is
> garbage and it needs to be dropped and return the rest of the
> bytes.

Hey good catch! It flew past me when I added this devices because I tested only
on i2c at the time.

Kind regards,
Angel

> Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
> ---
>  drivers/iio/pressure/bmp280-spi.c | 47 ++++++++++++++++++++++++++++++-
>  drivers/iio/pressure/bmp280.h     |  2 ++
>  2 files changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-
> spi.c
> index 433d6fac83c4..c4b4a5d67f94 100644
> --- a/drivers/iio/pressure/bmp280-spi.c
> +++ b/drivers/iio/pressure/bmp280-spi.c
> @@ -35,6 +35,32 @@ static int bmp280_regmap_spi_read(void *context, const void
> *reg,
>  	return spi_write_then_read(spi, reg, reg_size, val, val_size);
>  }
>  
> +static int bmp380_regmap_spi_read(void *context, const void *reg,
> +				  size_t reg_size, void *val, size_t
> val_size)
> +{
> +	struct spi_device *spi = to_spi_device(context);
> +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
> +	ssize_t status;
> +	u8 buf;
> +
> +	memcpy(&buf, reg, reg_size);
> +	buf |= 0x80;
> +
> +	/*
> +	 * According to the BMP380, BMP388, BMP390 datasheets, for a basic
> +	 * read operation, after the write is done, 2 bytes are received and
> +	 * the first one has to be dropped. The 2nd one is the requested
> +	 * value.
> +	 */
> +	status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);
> +	if (status)
> +		return status;
> +
> +	memcpy(val, ret + 1, val_size);
> +
> +	return 0;
> +}
> +
>  static struct regmap_bus bmp280_regmap_bus = {
>  	.write = bmp280_regmap_spi_write,
>  	.read = bmp280_regmap_spi_read,
> @@ -42,10 +68,18 @@ static struct regmap_bus bmp280_regmap_bus = {
>  	.val_format_endian_default = REGMAP_ENDIAN_BIG,
>  };
>  
> +static struct regmap_bus bmp380_regmap_bus = {
> +	.write = bmp280_regmap_spi_write,
> +	.read = bmp380_regmap_spi_read,
> +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> +};
> +
>  static int bmp280_spi_probe(struct spi_device *spi)
>  {
>  	const struct spi_device_id *id = spi_get_device_id(spi);
>  	const struct bmp280_chip_info *chip_info;
> +	struct regmap_bus *bmp_regmap_bus;
>  	struct regmap *regmap;
>  	int ret;
>  
> @@ -58,8 +92,19 @@ static int bmp280_spi_probe(struct spi_device *spi)
>  
>  	chip_info = spi_get_device_match_data(spi);
>  
> +	switch (chip_info->chip_id[0]) {
> +	case BMP380_CHIP_ID:
> +	case BMP390_CHIP_ID:
> +		bmp_regmap_bus = &bmp380_regmap_bus;
> +		break;
> +	default:
> +		bmp_regmap_bus = &bmp280_regmap_bus;
> +		break;
> +	}
> +
> +
>  	regmap = devm_regmap_init(&spi->dev,
> -				  &bmp280_regmap_bus,
> +				  bmp_regmap_bus,
>  				  &spi->dev,
>  				  chip_info->regmap_config);
>  	if (IS_ERR(regmap)) {
> diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> index 4012387d7956..ca482b7e4295 100644
> --- a/drivers/iio/pressure/bmp280.h
> +++ b/drivers/iio/pressure/bmp280.h
> @@ -191,6 +191,8 @@
>  #define BMP380_TEMP_SKIPPED		0x800000
>  #define BMP380_PRESS_SKIPPED		0x800000
>  
> +#define BMP380_SPI_MAX_REG_COUNT_READ   3
> +
>  /* BMP280 specific registers */
>  #define BMP280_REG_HUMIDITY_LSB		0xFE
>  #define BMP280_REG_HUMIDITY_MSB		0xFD

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Jonathan Cameron]

On Thu, 15 Feb 2024 19:03:27 +0200
Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:

> On Thu, Feb 15, 2024 at 05:43:32PM +0100, Vasileios Amoiridis wrote:
> > According to the datasheet of BMP38x and BMP390 devices, in SPI
> > operation, the first byte that returns after a read operation is
> > garbage and it needs to be dropped and return the rest of the
> > bytes.  
> 
> Thank you for the patch, my comments below.
> 
> ...
> 
> > +static int bmp380_regmap_spi_read(void *context, const void *reg,
> > +				  size_t reg_size, void *val, size_t val_size)
> > +{
> > +	struct spi_device *spi = to_spi_device(context);
> > +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
> > +	ssize_t status;
> > +	u8 buf;  
> 
> AFAIU this buffer is not DMA-capable.

Doesn't matter in this case as spi_write_then_read() bounces anyway so you don't need
to provide it with a dma safe buffer. It's in the docs, so we can rely
on this not changing.

https://elixir.bootlin.com/linux/latest/source/drivers/spi/spi.c#L4391

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Jonathan Cameron]

On Thu, 15 Feb 2024 17:43:32 +0100
Vasileios Amoiridis <vassilisamir@gmail.com> wrote:

> According to the datasheet of BMP38x and BMP390 devices, in SPI
> operation, the first byte that returns after a read operation is
> garbage and it needs to be dropped and return the rest of the
> bytes.

Make it clear in the patch title that this is a fix and add a fixes tag.

> 
> Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
> ---
>  drivers/iio/pressure/bmp280-spi.c | 47 ++++++++++++++++++++++++++++++-
>  drivers/iio/pressure/bmp280.h     |  2 ++
>  2 files changed, 48 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
> index 433d6fac83c4..c4b4a5d67f94 100644
> --- a/drivers/iio/pressure/bmp280-spi.c
> +++ b/drivers/iio/pressure/bmp280-spi.c
> @@ -35,6 +35,32 @@ static int bmp280_regmap_spi_read(void *context, const void *reg,
>  	return spi_write_then_read(spi, reg, reg_size, val, val_size);
>  }
>  
> +static int bmp380_regmap_spi_read(void *context, const void *reg,
> +				  size_t reg_size, void *val, size_t val_size)
> +{
> +	struct spi_device *spi = to_spi_device(context);
> +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];

Given you rely on val_size < 3 you should check for that explcitly rather than
potentially overflowing the buffer.
ret is not a good naming choice for this variable as it's commonly used for
integer return values.  Call it read_buf or something like that.

> +	ssize_t status;
> +	u8 buf;
> +
> +	memcpy(&buf, reg, reg_size);
> +	buf |= 0x80;

Can you use regmap_bus read_flag_mask for this?  Seems to apply to 
all devices supported. + that's common for spi regmaps


Mind you I note the bmp280_regmap_spi_write() is masking the bit out which seems
backwards  - all the registers are defined with the bit set for that part
but not the 380.  Ah well - not part of this fix even if it's odd.


> +
> +	/*
> +	 * According to the BMP380, BMP388, BMP390 datasheets, for a basic
> +	 * read operation, after the write is done, 2 bytes are received and
> +	 * the first one has to be dropped. The 2nd one is the requested
> +	 * value.
> +	 */
> +	status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);
> +	if (status)
> +		return status;
> +
> +	memcpy(val, ret + 1, val_size);
> +
> +	return 0;
> +}
> +
>  static struct regmap_bus bmp280_regmap_bus = {
>  	.write = bmp280_regmap_spi_write,
>  	.read = bmp280_regmap_spi_read,
> @@ -42,10 +68,18 @@ static struct regmap_bus bmp280_regmap_bus = {
>  	.val_format_endian_default = REGMAP_ENDIAN_BIG,
>  };
>  
> +static struct regmap_bus bmp380_regmap_bus = {
> +	.write = bmp280_regmap_spi_write,
> +	.read = bmp380_regmap_spi_read,
> +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> +};
> +
>  static int bmp280_spi_probe(struct spi_device *spi)
>  {
>  	const struct spi_device_id *id = spi_get_device_id(spi);
>  	const struct bmp280_chip_info *chip_info;
> +	struct regmap_bus *bmp_regmap_bus;
>  	struct regmap *regmap;
>  	int ret;
>  
> @@ -58,8 +92,19 @@ static int bmp280_spi_probe(struct spi_device *spi)
>  
>  	chip_info = spi_get_device_match_data(spi);
>  
> +	switch (chip_info->chip_id[0]) {
> +	case BMP380_CHIP_ID:
> +	case BMP390_CHIP_ID:
> +		bmp_regmap_bus = &bmp380_regmap_bus;
> +		break;
> +	default:
> +		bmp_regmap_bus = &bmp280_regmap_bus;
> +		break;
> +	}
> +
> +
>  	regmap = devm_regmap_init(&spi->dev,
> -				  &bmp280_regmap_bus,
> +				  bmp_regmap_bus,
>  				  &spi->dev,
>  				  chip_info->regmap_config);
>  	if (IS_ERR(regmap)) {
> diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> index 4012387d7956..ca482b7e4295 100644
> --- a/drivers/iio/pressure/bmp280.h
> +++ b/drivers/iio/pressure/bmp280.h
> @@ -191,6 +191,8 @@
>  #define BMP380_TEMP_SKIPPED		0x800000
>  #define BMP380_PRESS_SKIPPED		0x800000
>  
> +#define BMP380_SPI_MAX_REG_COUNT_READ   3
This doesn't seem useful as only used in one place.
> +
>  /* BMP280 specific registers */
>  #define BMP280_REG_HUMIDITY_LSB		0xFE
>  #define BMP280_REG_HUMIDITY_MSB		0xFD

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Vasileios Amoiridis]

On Fri, Feb 16, 2024 at 11:18:34AM +0000, Jonathan Cameron wrote:
> On Thu, 15 Feb 2024 17:43:32 +0100
> Vasileios Amoiridis <vassilisamir@gmail.com> wrote:
> 
> > According to the datasheet of BMP38x and BMP390 devices, in SPI
> > operation, the first byte that returns after a read operation is
> > garbage and it needs to be dropped and return the rest of the
> > bytes.
> 
> Make it clear in the patch title that this is a fix and add a fixes tag.
> 

The original support for SPI was added 8 years ago. Should I include that commit
of 8 years ago in the fixes tag or just use a the word "fixes" with the rest of the
title?

> > 
> > Signed-off-by: Vasileios Amoiridis <vassilisamir@gmail.com>
> > ---
> >  drivers/iio/pressure/bmp280-spi.c | 47 ++++++++++++++++++++++++++++++-
> >  drivers/iio/pressure/bmp280.h     |  2 ++
> >  2 files changed, 48 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/iio/pressure/bmp280-spi.c b/drivers/iio/pressure/bmp280-spi.c
> > index 433d6fac83c4..c4b4a5d67f94 100644
> > --- a/drivers/iio/pressure/bmp280-spi.c
> > +++ b/drivers/iio/pressure/bmp280-spi.c
> > @@ -35,6 +35,32 @@ static int bmp280_regmap_spi_read(void *context, const void *reg,
> >  	return spi_write_then_read(spi, reg, reg_size, val, val_size);
> >  }
> >  
> > +static int bmp380_regmap_spi_read(void *context, const void *reg,
> > +				  size_t reg_size, void *val, size_t val_size)
> > +{
> > +	struct spi_device *spi = to_spi_device(context);
> > +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
> 
> Given you rely on val_size < 3 you should check for that explcitly rather than
> potentially overflowing the buffer.
> ret is not a good naming choice for this variable as it's commonly used for
> integer return values.  Call it read_buf or something like that.
> 

Thanks for pointing this out it makes a lot of sense.

> > +	ssize_t status;
> > +	u8 buf;
> > +
> > +	memcpy(&buf, reg, reg_size);
> > +	buf |= 0x80;
> 
> Can you use regmap_bus read_flag_mask for this?  Seems to apply to 
> all devices supported. + that's common for spi regmaps
>

Yes I noticed it yesterday in my tests that this was missing and it actually
applies to all the devices. So the read_flag_mask should be added to both
regmap_bus structs. 
> 
> Mind you I note the bmp280_regmap_spi_write() is masking the bit out which seems
> backwards  - all the registers are defined with the bit set for that part
> but not the 380.  Ah well - not part of this fix even if it's odd.
> 
> 
> > +
> > +	/*
> > +	 * According to the BMP380, BMP388, BMP390 datasheets, for a basic
> > +	 * read operation, after the write is done, 2 bytes are received and
> > +	 * the first one has to be dropped. The 2nd one is the requested
> > +	 * value.
> > +	 */
> > +	status = spi_write_then_read(spi, &buf, 1, ret, val_size + 1);
> > +	if (status)
> > +		return status;
> > +
> > +	memcpy(val, ret + 1, val_size);
> > +
> > +	return 0;
> > +}
> > +
> >  static struct regmap_bus bmp280_regmap_bus = {
> >  	.write = bmp280_regmap_spi_write,
> >  	.read = bmp280_regmap_spi_read,
> > @@ -42,10 +68,18 @@ static struct regmap_bus bmp280_regmap_bus = {
> >  	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> >  };
> >  
> > +static struct regmap_bus bmp380_regmap_bus = {
> > +	.write = bmp280_regmap_spi_write,
> > +	.read = bmp380_regmap_spi_read,
> > +	.reg_format_endian_default = REGMAP_ENDIAN_BIG,
> > +	.val_format_endian_default = REGMAP_ENDIAN_BIG,
> > +};
> > +
> >  static int bmp280_spi_probe(struct spi_device *spi)
> >  {
> >  	const struct spi_device_id *id = spi_get_device_id(spi);
> >  	const struct bmp280_chip_info *chip_info;
> > +	struct regmap_bus *bmp_regmap_bus;
> >  	struct regmap *regmap;
> >  	int ret;
> >  
> > @@ -58,8 +92,19 @@ static int bmp280_spi_probe(struct spi_device *spi)
> >  
> >  	chip_info = spi_get_device_match_data(spi);
> >  
> > +	switch (chip_info->chip_id[0]) {
> > +	case BMP380_CHIP_ID:
> > +	case BMP390_CHIP_ID:
> > +		bmp_regmap_bus = &bmp380_regmap_bus;
> > +		break;
> > +	default:
> > +		bmp_regmap_bus = &bmp280_regmap_bus;
> > +		break;
> > +	}
> > +
> > +
> >  	regmap = devm_regmap_init(&spi->dev,
> > -				  &bmp280_regmap_bus,
> > +				  bmp_regmap_bus,
> >  				  &spi->dev,
> >  				  chip_info->regmap_config);
> >  	if (IS_ERR(regmap)) {
> > diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> > index 4012387d7956..ca482b7e4295 100644
> > --- a/drivers/iio/pressure/bmp280.h
> > +++ b/drivers/iio/pressure/bmp280.h
> > @@ -191,6 +191,8 @@
> >  #define BMP380_TEMP_SKIPPED		0x800000
> >  #define BMP380_PRESS_SKIPPED		0x800000
> >  
> > +#define BMP380_SPI_MAX_REG_COUNT_READ   3
> This doesn't seem useful as only used in one place.

Could this define be moved in the bmp280-spi.c file or to not even use a define?

> > +
> >  /* BMP280 specific registers */
> >  #define BMP280_REG_HUMIDITY_LSB		0xFE
> >  #define BMP280_REG_HUMIDITY_MSB		0xFD
> 

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Vasileios Amoiridis]

On Fri, Feb 16, 2024 at 11:05:43AM +0000, Jonathan Cameron wrote:
> On Thu, 15 Feb 2024 19:03:27 +0200
> Andy Shevchenko <andriy.shevchenko@linux.intel.com> wrote:
> 
> > On Thu, Feb 15, 2024 at 05:43:32PM +0100, Vasileios Amoiridis wrote:
> > > According to the datasheet of BMP38x and BMP390 devices, in SPI
> > > operation, the first byte that returns after a read operation is
> > > garbage and it needs to be dropped and return the rest of the
> > > bytes.  
> > 
> > Thank you for the patch, my comments below.
> > 
> > ...
> > 
> > > +static int bmp380_regmap_spi_read(void *context, const void *reg,
> > > +				  size_t reg_size, void *val, size_t val_size)
> > > +{
> > > +	struct spi_device *spi = to_spi_device(context);
> > > +	u8 ret[BMP380_SPI_MAX_REG_COUNT_READ + 1];
> > > +	ssize_t status;
> > > +	u8 buf;  
> > 
> > AFAIU this buffer is not DMA-capable.
> 
> Doesn't matter in this case as spi_write_then_read() bounces anyway so you don't need
> to provide it with a dma safe buffer. It's in the docs, so we can rely
> on this not changing.
> 
> https://elixir.bootlin.com/linux/latest/source/drivers/spi/spi.c#L4391
> 

Since the read_flag_mask can be used in the struct regmap_bus, there is no need for an 
extra u8 buffer to manipulate the bits. Instead, the reg value from the function inputs 
can be used as in any other case.

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Jonathan Cameron]

On Fri, 16 Feb 2024 14:26:44 +0100
Vasileios Amoiridis <vassilisamir@gmail.com> wrote:

> On Fri, Feb 16, 2024 at 11:18:34AM +0000, Jonathan Cameron wrote:
> > On Thu, 15 Feb 2024 17:43:32 +0100
> > Vasileios Amoiridis <vassilisamir@gmail.com> wrote:
> >   
> > > According to the datasheet of BMP38x and BMP390 devices, in SPI
> > > operation, the first byte that returns after a read operation is
> > > garbage and it needs to be dropped and return the rest of the
> > > bytes.  
> > 
> > Make it clear in the patch title that this is a fix and add a fixes tag.
> >   
> 
> The original support for SPI was added 8 years ago. Should I include that commit
> of 8 years ago in the fixes tag or just use a the word "fixes" with the rest of the
> title?
> 
Original git commit for the fixes tag.  Lets us know this wants to go in all stable kernels.
Also fixes in the title.


> > > +	ssize_t status;
> > > +	u8 buf;
> > > +
> > > +	memcpy(&buf, reg, reg_size);
> > > +	buf |= 0x80;  
> > 
> > Can you use regmap_bus read_flag_mask for this?  Seems to apply to 
> > all devices supported. + that's common for spi regmaps
> >  
> 
> Yes I noticed it yesterday in my tests that this was missing and it actually
> applies to all the devices. So the read_flag_mask should be added to both
> regmap_bus structs. 

It's there sort of indirectly for the bmp280 - the register addresses all happen
to include that bit, then it is cleared explicitly for the other direction.



> > 
> > Mind you I note the bmp280_regmap_spi_write() is masking the bit out which seems
> > backwards  - all the registers are defined with the bit set for that part
> > but not the 380.  Ah well - not part of this fix even if it's odd.
> > 

> > > diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> > > index 4012387d7956..ca482b7e4295 100644
> > > --- a/drivers/iio/pressure/bmp280.h
> > > +++ b/drivers/iio/pressure/bmp280.h
> > > @@ -191,6 +191,8 @@
> > >  #define BMP380_TEMP_SKIPPED		0x800000
> > >  #define BMP380_PRESS_SKIPPED		0x800000
> > >  
> > > +#define BMP380_SPI_MAX_REG_COUNT_READ   3  
> > This doesn't seem useful as only used in one place.  
> 
> Could this define be moved in the bmp280-spi.c file or to not even use a define?
Not use it. Don't see how it is helpful. Just check that the
thing will fit in the array using an ARRAY_SIZE()...
> 
> > > +
> > >  /* BMP280 specific registers */
> > >  #define BMP280_REG_HUMIDITY_LSB		0xFE
> > >  #define BMP280_REG_HUMIDITY_MSB		0xFD  
> >   

Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and BMP390

[Vasileios Amoiridis]

On Fri, Feb 16, 2024 at 03:47:42PM +0000, Jonathan Cameron wrote:
> On Fri, 16 Feb 2024 14:26:44 +0100
> Vasileios Amoiridis <vassilisamir@gmail.com> wrote:
> 
> > On Fri, Feb 16, 2024 at 11:18:34AM +0000, Jonathan Cameron wrote:
> > > On Thu, 15 Feb 2024 17:43:32 +0100
> > > Vasileios Amoiridis <vassilisamir@gmail.com> wrote:
> > >   
> > > > According to the datasheet of BMP38x and BMP390 devices, in SPI
> > > > operation, the first byte that returns after a read operation is
> > > > garbage and it needs to be dropped and return the rest of the
> > > > bytes.  
> > > 
> > > Make it clear in the patch title that this is a fix and add a fixes tag.
> > >   
> > 
> > The original support for SPI was added 8 years ago. Should I include that commit
> > of 8 years ago in the fixes tag or just use a the word "fixes" with the rest of the
> > title?
> > 
> Original git commit for the fixes tag.  Lets us know this wants to go in all stable kernels.
> Also fixes in the title.
 
Ok, will do that!
>
> 
> > > > +	ssize_t status;
> > > > +	u8 buf;
> > > > +
> > > > +	memcpy(&buf, reg, reg_size);
> > > > +	buf |= 0x80;  
> > > 
> > > Can you use regmap_bus read_flag_mask for this?  Seems to apply to 
> > > all devices supported. + that's common for spi regmaps
> > >  
> > 
> > Yes I noticed it yesterday in my tests that this was missing and it actually
> > applies to all the devices. So the read_flag_mask should be added to both
> > regmap_bus structs. 
> 
> It's there sort of indirectly for the bmp280 - the register addresses all happen
> to include that bit, then it is cleared explicitly for the other direction.

Oh okay, now I understand what you mean. Ok then I can also send a different patch
for this as well just to keep the code consistent.
> 
> 
> 
> > > 
> > > Mind you I note the bmp280_regmap_spi_write() is masking the bit out which seems
> > > backwards  - all the registers are defined with the bit set for that part
> > > but not the 380.  Ah well - not part of this fix even if it's odd.
> > > 
> 
> > > > diff --git a/drivers/iio/pressure/bmp280.h b/drivers/iio/pressure/bmp280.h
> > > > index 4012387d7956..ca482b7e4295 100644
> > > > --- a/drivers/iio/pressure/bmp280.h
> > > > +++ b/drivers/iio/pressure/bmp280.h
> > > > @@ -191,6 +191,8 @@
> > > >  #define BMP380_TEMP_SKIPPED		0x800000
> > > >  #define BMP380_PRESS_SKIPPED		0x800000
> > > >  
> > > > +#define BMP380_SPI_MAX_REG_COUNT_READ   3  
> > > This doesn't seem useful as only used in one place.  
> > 
> > Could this define be moved in the bmp280-spi.c file or to not even use a define?
> Not use it. Don't see how it is helpful. Just check that the
> thing will fit in the array using an ARRAY_SIZE()...

Understood.
> > 
> > > > +
> > > >  /* BMP280 specific registers */
> > > >  #define BMP280_REG_HUMIDITY_LSB		0xFE
> > > >  #define BMP280_REG_HUMIDITY_MSB		0xFD  
> > >   
> 

Thank you very much for the feedback, I'll work on the patches and submit them again.

Best regards,
Vasileios Amoiridis