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Message-ID: <20240216132644.GA4236@vamoiridPC>
Date: Fri, 16 Feb 2024 14:26:44 +0100
From: Vasileios Amoiridis <vassilisamir@...il.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Vasileios Amoiridis <vassilisamir@...il.com>, lars@...afoo.de,
ang.iglesiasg@...il.com, andriy.shevchenko@...ux.intel.com,
579lpy@...il.com, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drivers: iio: pressure: Add SPI support for BMP38x and
BMP390
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@...il.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@...il.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
>
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