From 2922a8de996956893bb98e4aa91be9774c958336 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Tue, 21 May 2013 20:36:34 -0600 Subject: spi: introduce macros to set bits_per_word_mask Introduce two macros to make setting up spi_master.bits_per_word_mask easier, and avoid mistakes like writing BIT(n) instead of BIT(n - 1). SPI_BPW_MASK is for a single supported value of bits_per_word_mask. SPI_BPW_RANGE_MASK represents a contiguous set of bit lengths. Signed-off-by: Stephen Warren Signed-off-by: Mark Brown --- include/linux/spi/spi.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include/linux/spi/spi.h') diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 6ff26c8db7b..17372562225 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -308,6 +308,8 @@ struct spi_master { /* bitmask of supported bits_per_word for transfers */ u32 bits_per_word_mask; +#define SPI_BPW_MASK(bits) BIT((bits) - 1) +#define SPI_BPW_RANGE_MASK(min, max) ((BIT(max) - 1) - (BIT(min) - 1)) /* other constraints relevant to this driver */ u16 flags; -- cgit v1.2.3-70-g09d2 From 4dd9572abc224019a042b662fb0eececca283cb9 Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Thu, 30 May 2013 09:59:39 -0600 Subject: spi: fix undefined behaviour in SPI_BPW_RANGE_MASK The parameters to SPI_BPW_RANGE_MASK() are in the range 1..32. If 32 is used as a parameter, part of the expression is "1 << 32". Since 32 is >= the size of the type in use, such a shift is undefined behaviour. Add macro SPI_BIT_MASK to Implement a special case and thus avoid undefined behaviour. Use this new macro rather than BIT() when implementing SPI_BPW_RANGE_MASK(). This fixes build warnings such as: drivers/spi/spi-gpio.c:446:2: warning: left shift count >= width of type [enabled by default] SPI_BPW_MASK() already avoids this, since its parameter is also in range 1..32, yet it only shifts by up to one less than the input parameter. Reported-by: Fengguang Wu Signed-off-by: Stephen Warren Signed-off-by: Mark Brown --- include/linux/spi/spi.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) (limited to 'include/linux/spi/spi.h') diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 17372562225..3e9479134d9 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -309,7 +309,8 @@ struct spi_master { /* bitmask of supported bits_per_word for transfers */ u32 bits_per_word_mask; #define SPI_BPW_MASK(bits) BIT((bits) - 1) -#define SPI_BPW_RANGE_MASK(min, max) ((BIT(max) - 1) - (BIT(min) - 1)) +#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0UL : (BIT(bits) - 1)) +#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min)) /* other constraints relevant to this driver */ u16 flags; -- cgit v1.2.3-70-g09d2 From eca8960a8e0f48dc62c1063bcc33a626455d766e Mon Sep 17 00:00:00 2001 From: Stephen Warren Date: Thu, 30 May 2013 09:59:40 -0600 Subject: spi: fix incorrect handling of min param in SPI_BPW_RANGE_MASK SPI_BPW_RANGE_MASK is intended to work by calculating two masks; one representing support for all bits up-to-and-including the "max" supported value, and one representing support for all bits up-to-but-not-including the "min" supported value, and then taking the difference between the two, resulting in a mask representing support for all bits between (inclusive) the min and max values. However, the second mask ended up representing all bits up-to-and- including rather up-to-but-not-including. Fix this bug. Signed-off-by: Stephen Warren Signed-off-by: Mark Brown --- include/linux/spi/spi.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'include/linux/spi/spi.h') diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h index 3e9479134d9..28e440be1c0 100644 --- a/include/linux/spi/spi.h +++ b/include/linux/spi/spi.h @@ -310,7 +310,7 @@ struct spi_master { u32 bits_per_word_mask; #define SPI_BPW_MASK(bits) BIT((bits) - 1) #define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0UL : (BIT(bits) - 1)) -#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min)) +#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1)) /* other constraints relevant to this driver */ u16 flags; -- cgit v1.2.3-70-g09d2