From 05071aa864e84000759191438a4a9ff7ba2c360e Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Fri, 27 Sep 2013 16:34:27 +0200 Subject: [PATCH 1/3] spi: Add a spi_w8r16be() helper This patch adds a new spi_w8r16be() helper, which is similar to spi_w8r16() except that it converts the read data word from big endian to native endianness before returning it. The reason for introducing this new helper is that for SPI slave devices it is quite common that the read 16 bit data word is in big endian. So users of spi_w8r16() have to convert the result to native endianness manually. A second reason is that in this case the endianness of the return value of spi_w8r16() depends on its sign. If it is negative (i.e. a error code) it is already in native endianness, if it is positive it is in big endian. The sparse code checker doesn't like this kind of mixed endianness and special annotations are necessary to keep it quiet (E.g. casting to be16 using __force). Doing the conversion to native endianness in the helper function does not require such annotations since we are not mixing different endiannesses in the same variable. Signed-off-by: Lars-Peter Clausen Signed-off-by: Mark Brown --- include/linux/spi/spi.h | 27 +++++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 887116dbce2c..0e0aebdeb56b 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -823,6 +823,33 @@ static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd) return (status < 0) ? status : result; } +/** + * spi_w8r16be - SPI synchronous 8 bit write followed by 16 bit big-endian read + * @spi: device with which data will be exchanged + * @cmd: command to be written before data is read back + * Context: can sleep + * + * This returns the (unsigned) sixteen bit number returned by the device in cpu + * endianness, or else a negative error code. Callable only from contexts that + * can sleep. + * + * This function is similar to spi_w8r16, with the exception that it will + * convert the read 16 bit data word from big-endian to native endianness. + * + */ +static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd) + +{ + ssize_t status; + __be16 result; + + status = spi_write_then_read(spi, &cmd, 1, &result, 2); + if (status < 0) + return status; + + return be16_to_cpu(result); +} + /*---------------------------------------------------------------------------*/ /* From 600ba98bff438510dc81fc1ba9048420479bbded Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Fri, 27 Sep 2013 16:34:28 +0200 Subject: [PATCH 2/3] hwmon: (adt7310) Use spi_w8r16be() instead spi_w8r16() Using spi_w8r16be() instead of spi_w8r16() in this driver makes a code a bit shorter and cleaner. Signed-off-by: Lars-Peter Clausen Acked-by: Guenter Roeck Signed-off-by: Mark Brown --- drivers/hwmon/adt7310.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-) diff --git a/drivers/hwmon/adt7310.c b/drivers/hwmon/adt7310.c index da5f0789fb97..5994cf68e0a4 100644 --- a/drivers/hwmon/adt7310.c +++ b/drivers/hwmon/adt7310.c @@ -42,13 +42,8 @@ static const u8 adt7310_reg_table[] = { static int adt7310_spi_read_word(struct device *dev, u8 reg) { struct spi_device *spi = to_spi_device(dev); - int ret; - ret = spi_w8r16(spi, AD7310_COMMAND(reg) | ADT7310_CMD_READ); - if (ret < 0) - return ret; - - return be16_to_cpu((__force __be16)ret); + return spi_w8r16be(spi, AD7310_COMMAND(reg) | ADT7310_CMD_READ); } static int adt7310_spi_write_word(struct device *dev, u8 reg, u16 data) From 235907422548aae38d03a545f20fceb728b70ddd Mon Sep 17 00:00:00 2001 From: Lars-Peter Clausen Date: Fri, 27 Sep 2013 16:34:29 +0200 Subject: [PATCH 3/3] staging:iio:ade7753/ade7754/ade7759: Use spi_w8r16be() instead of spi_w8r16() Using spi_w8r16be() will do the conversion of the result from big endian to native endian in the helper function. This makes the code a bit smaller and also keeps sparse happy. Fixes the following sparse warnings: drivers/staging/iio/meter/ade7753.c:97:29: warning: incorrect type in argument 1 (different base types) drivers/staging/iio/meter/ade7753.c:97:29: expected restricted __be16 const [usertype] *p drivers/staging/iio/meter/ade7753.c:97:29: got unsigned short [usertype] *val drivers/staging/iio/meter/ade7754.c:97:29: warning: incorrect type in argument 1 (different base types) drivers/staging/iio/meter/ade7754.c:97:29: expected restricted __be16 const [usertype] *p drivers/staging/iio/meter/ade7754.c:97:29: got unsigned short [usertype] *val drivers/staging/iio/meter/ade7759.c:97:29: warning: incorrect type in argument 1 (different base types) drivers/staging/iio/meter/ade7759.c:97:29: expected restricted __be16 const [usertype] *p drivers/staging/iio/meter/ade7759.c:97:29: got unsigned short [usertype] *val Signed-off-by: Lars-Peter Clausen Acked-by: Jonathan Cameron Signed-off-by: Mark Brown --- drivers/staging/iio/meter/ade7753.c | 3 +-- drivers/staging/iio/meter/ade7754.c | 3 +-- drivers/staging/iio/meter/ade7759.c | 3 +-- 3 files changed, 3 insertions(+), 6 deletions(-) diff --git a/drivers/staging/iio/meter/ade7753.c b/drivers/staging/iio/meter/ade7753.c index 74025fbae679..abfc8bd1794d 100644 --- a/drivers/staging/iio/meter/ade7753.c +++ b/drivers/staging/iio/meter/ade7753.c @@ -86,7 +86,7 @@ static int ade7753_spi_read_reg_16(struct device *dev, struct ade7753_state *st = iio_priv(indio_dev); ssize_t ret; - ret = spi_w8r16(st->us, ADE7753_READ_REG(reg_address)); + ret = spi_w8r16be(st->us, ADE7753_READ_REG(reg_address)); if (ret < 0) { dev_err(&st->us->dev, "problem when reading 16 bit register 0x%02X", reg_address); @@ -94,7 +94,6 @@ static int ade7753_spi_read_reg_16(struct device *dev, } *val = ret; - *val = be16_to_cpup(val); return 0; } diff --git a/drivers/staging/iio/meter/ade7754.c b/drivers/staging/iio/meter/ade7754.c index f649ebe55a04..3d1c02cd6538 100644 --- a/drivers/staging/iio/meter/ade7754.c +++ b/drivers/staging/iio/meter/ade7754.c @@ -86,7 +86,7 @@ static int ade7754_spi_read_reg_16(struct device *dev, struct ade7754_state *st = iio_priv(indio_dev); int ret; - ret = spi_w8r16(st->us, ADE7754_READ_REG(reg_address)); + ret = spi_w8r16be(st->us, ADE7754_READ_REG(reg_address)); if (ret < 0) { dev_err(&st->us->dev, "problem when reading 16 bit register 0x%02X", reg_address); @@ -94,7 +94,6 @@ static int ade7754_spi_read_reg_16(struct device *dev, } *val = ret; - *val = be16_to_cpup(val); return 0; } diff --git a/drivers/staging/iio/meter/ade7759.c b/drivers/staging/iio/meter/ade7759.c index d214ac4932cb..7467e51fd424 100644 --- a/drivers/staging/iio/meter/ade7759.c +++ b/drivers/staging/iio/meter/ade7759.c @@ -86,7 +86,7 @@ static int ade7759_spi_read_reg_16(struct device *dev, struct ade7759_state *st = iio_priv(indio_dev); int ret; - ret = spi_w8r16(st->us, ADE7759_READ_REG(reg_address)); + ret = spi_w8r16be(st->us, ADE7759_READ_REG(reg_address)); if (ret < 0) { dev_err(&st->us->dev, "problem when reading 16 bit register 0x%02X", reg_address); @@ -94,7 +94,6 @@ static int ade7759_spi_read_reg_16(struct device *dev, } *val = ret; - *val = be16_to_cpup(val); return 0; }