[PATCH] ARM: ptrace: Use bitfield helpers

[PATCH] ARM: ptrace: Use bitfield helpers

[Geert Uytterhoeven]

The isa_mode() macro extracts two fields, and recombines them into a
single value.  The shift value of the J-bit may look off-by-one to the
casual reader, as it is the net result of the extraction and
recombination steps.

Make this more obvious by using the FIELD_GET() helper, and shifting the
result into its final resting place.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
No changes in generated assembler code.

See "[PATCH 00/17] Non-const bitfield helper conversions"
(https://lore.kernel.org/r/cover.1637592133.git.geert+renesas@glider.be)
for background and more conversions.
---
 arch/arm/include/asm/ptrace.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm/include/asm/ptrace.h b/arch/arm/include/asm/ptrace.h
index 93051e2f402c8452..982514aa83c1f459 100644
--- a/arch/arm/include/asm/ptrace.h
+++ b/arch/arm/include/asm/ptrace.h
@@ -10,6 +10,7 @@
 #include <uapi/asm/ptrace.h>
 
 #ifndef __ASSEMBLY__
+#include <linux/bitfield.h>
 #include <linux/types.h>
 
 struct pt_regs {
@@ -35,8 +36,8 @@ struct svc_pt_regs {
 
 #ifndef CONFIG_CPU_V7M
 #define isa_mode(regs) \
-	((((regs)->ARM_cpsr & PSR_J_BIT) >> (__ffs(PSR_J_BIT) - 1)) | \
-	 (((regs)->ARM_cpsr & PSR_T_BIT) >> (__ffs(PSR_T_BIT))))
+	((FIELD_GET(PSR_J_BIT, (regs)->ARM_cpsr) << 1) | \
+	 FIELD_GET(PSR_T_BIT, (regs)->ARM_cpsr))
 #else
 #define isa_mode(regs) 1 /* Thumb */
 #endif
-- 
2.25.1


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[PATCH] dmaengine: stm32-mdma: Use bitfield helpers

[Geert Uytterhoeven]

Use the FIELD_{GET,PREP}() helpers, instead of defining custom macros
implementing the same operations.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Compile-tested only.

See "[PATCH 00/17] Non-const bitfield helper conversions"
(https://lore.kernel.org/r/cover.1637592133.git.geert+renesas@glider.be)
for background and more conversions.
---
 drivers/dma/stm32-mdma.c | 74 +++++++++++++---------------------------
 1 file changed, 23 insertions(+), 51 deletions(-)

diff --git a/drivers/dma/stm32-mdma.c b/drivers/dma/stm32-mdma.c
index d30a4a28d3bfd585..03ff64ff34bf594e 100644
--- a/drivers/dma/stm32-mdma.c
+++ b/drivers/dma/stm32-mdma.c
@@ -10,6 +10,7 @@
  * Inspired by stm32-dma.c and dma-jz4780.c
  */
 
+#include <linux/bitfield.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/dmaengine.h>
@@ -32,13 +33,6 @@
 
 #include "virt-dma.h"
 
-/*  MDMA Generic getter/setter */
-#define STM32_MDMA_SHIFT(n)		(ffs(n) - 1)
-#define STM32_MDMA_SET(n, mask)		(((n) << STM32_MDMA_SHIFT(mask)) & \
-					 (mask))
-#define STM32_MDMA_GET(n, mask)		(((n) & (mask)) >> \
-					 STM32_MDMA_SHIFT(mask))
-
 #define STM32_MDMA_GISR0		0x0000 /* MDMA Int Status Reg 1 */
 #define STM32_MDMA_GISR1		0x0004 /* MDMA Int Status Reg 2 */
 
@@ -80,8 +74,7 @@
 #define STM32_MDMA_CCR_HEX		BIT(13)
 #define STM32_MDMA_CCR_BEX		BIT(12)
 #define STM32_MDMA_CCR_PL_MASK		GENMASK(7, 6)
-#define STM32_MDMA_CCR_PL(n)		STM32_MDMA_SET(n, \
-						       STM32_MDMA_CCR_PL_MASK)
+#define STM32_MDMA_CCR_PL(n)		FIELD_PREP(STM32_MDMA_CCR_PL_MASK, (n))
 #define STM32_MDMA_CCR_TCIE		BIT(5)
 #define STM32_MDMA_CCR_BTIE		BIT(4)
 #define STM32_MDMA_CCR_BRTIE		BIT(3)
@@ -99,48 +92,33 @@
 #define STM32_MDMA_CTCR_BWM		BIT(31)
 #define STM32_MDMA_CTCR_SWRM		BIT(30)
 #define STM32_MDMA_CTCR_TRGM_MSK	GENMASK(29, 28)
-#define STM32_MDMA_CTCR_TRGM(n)		STM32_MDMA_SET((n), \
-						       STM32_MDMA_CTCR_TRGM_MSK)
-#define STM32_MDMA_CTCR_TRGM_GET(n)	STM32_MDMA_GET((n), \
-						       STM32_MDMA_CTCR_TRGM_MSK)
+#define STM32_MDMA_CTCR_TRGM(n)		FIELD_PREP(STM32_MDMA_CTCR_TRGM_MSK, (n))
+#define STM32_MDMA_CTCR_TRGM_GET(n)	FIELD_GET(STM32_MDMA_CTCR_TRGM_MSK, (n))
 #define STM32_MDMA_CTCR_PAM_MASK	GENMASK(27, 26)
-#define STM32_MDMA_CTCR_PAM(n)		STM32_MDMA_SET(n, \
-						       STM32_MDMA_CTCR_PAM_MASK)
+#define STM32_MDMA_CTCR_PAM(n)		FIELD_PREP(STM32_MDMA_CTCR_PAM_MASK, (n))
 #define STM32_MDMA_CTCR_PKE		BIT(25)
 #define STM32_MDMA_CTCR_TLEN_MSK	GENMASK(24, 18)
-#define STM32_MDMA_CTCR_TLEN(n)		STM32_MDMA_SET((n), \
-						       STM32_MDMA_CTCR_TLEN_MSK)
-#define STM32_MDMA_CTCR_TLEN_GET(n)	STM32_MDMA_GET((n), \
-						       STM32_MDMA_CTCR_TLEN_MSK)
+#define STM32_MDMA_CTCR_TLEN(n)		FIELD_PREP(STM32_MDMA_CTCR_TLEN_MSK, (n))
+#define STM32_MDMA_CTCR_TLEN_GET(n)	FIELD_GET(STM32_MDMA_CTCR_TLEN_MSK, (n))
 #define STM32_MDMA_CTCR_LEN2_MSK	GENMASK(25, 18)
-#define STM32_MDMA_CTCR_LEN2(n)		STM32_MDMA_SET((n), \
-						       STM32_MDMA_CTCR_LEN2_MSK)
-#define STM32_MDMA_CTCR_LEN2_GET(n)	STM32_MDMA_GET((n), \
-						       STM32_MDMA_CTCR_LEN2_MSK)
+#define STM32_MDMA_CTCR_LEN2(n)		FIELD_PREP(STM32_MDMA_CTCR_LEN2_MSK, (n))
+#define STM32_MDMA_CTCR_LEN2_GET(n)	FIELD_GET(STM32_MDMA_CTCR_LEN2_MSK, (n))
 #define STM32_MDMA_CTCR_DBURST_MASK	GENMASK(17, 15)
-#define STM32_MDMA_CTCR_DBURST(n)	STM32_MDMA_SET(n, \
-						    STM32_MDMA_CTCR_DBURST_MASK)
+#define STM32_MDMA_CTCR_DBURST(n)	FIELD_PREP(STM32_MDMA_CTCR_DBURST_MASK, (n))
 #define STM32_MDMA_CTCR_SBURST_MASK	GENMASK(14, 12)
-#define STM32_MDMA_CTCR_SBURST(n)	STM32_MDMA_SET(n, \
-						    STM32_MDMA_CTCR_SBURST_MASK)
+#define STM32_MDMA_CTCR_SBURST(n)	FIELD_PREP(STM32_MDMA_CTCR_SBURST_MASK, (n))
 #define STM32_MDMA_CTCR_DINCOS_MASK	GENMASK(11, 10)
-#define STM32_MDMA_CTCR_DINCOS(n)	STM32_MDMA_SET((n), \
-						    STM32_MDMA_CTCR_DINCOS_MASK)
+#define STM32_MDMA_CTCR_DINCOS(n)	FIELD_PREP(STM32_MDMA_CTCR_DINCOS_MASK, (n))
 #define STM32_MDMA_CTCR_SINCOS_MASK	GENMASK(9, 8)
-#define STM32_MDMA_CTCR_SINCOS(n)	STM32_MDMA_SET((n), \
-						    STM32_MDMA_CTCR_SINCOS_MASK)
+#define STM32_MDMA_CTCR_SINCOS(n)	FIELD_PREP(STM32_MDMA_CTCR_SINCOS_MASK, (n))
 #define STM32_MDMA_CTCR_DSIZE_MASK	GENMASK(7, 6)
-#define STM32_MDMA_CTCR_DSIZE(n)	STM32_MDMA_SET(n, \
-						     STM32_MDMA_CTCR_DSIZE_MASK)
+#define STM32_MDMA_CTCR_DSIZE(n)	FIELD_PREP(STM32_MDMA_CTCR_DSIZE_MASK, (n))
 #define STM32_MDMA_CTCR_SSIZE_MASK	GENMASK(5, 4)
-#define STM32_MDMA_CTCR_SSIZE(n)	STM32_MDMA_SET(n, \
-						     STM32_MDMA_CTCR_SSIZE_MASK)
+#define STM32_MDMA_CTCR_SSIZE(n)	FIELD_PREP(STM32_MDMA_CTCR_SSIZE_MASK, (n))
 #define STM32_MDMA_CTCR_DINC_MASK	GENMASK(3, 2)
-#define STM32_MDMA_CTCR_DINC(n)		STM32_MDMA_SET((n), \
-						      STM32_MDMA_CTCR_DINC_MASK)
+#define STM32_MDMA_CTCR_DINC(n)		FIELD_PREP(STM32_MDMA_CTCR_DINC_MASK, (n))
 #define STM32_MDMA_CTCR_SINC_MASK	GENMASK(1, 0)
-#define STM32_MDMA_CTCR_SINC(n)		STM32_MDMA_SET((n), \
-						      STM32_MDMA_CTCR_SINC_MASK)
+#define STM32_MDMA_CTCR_SINC(n)		FIELD_PREP(STM32_MDMA_CTCR_SINC_MASK, (n))
 #define STM32_MDMA_CTCR_CFG_MASK	(STM32_MDMA_CTCR_SINC_MASK \
 					| STM32_MDMA_CTCR_DINC_MASK \
 					| STM32_MDMA_CTCR_SINCOS_MASK \
@@ -151,16 +129,13 @@
 /* MDMA Channel x block number of data register */
 #define STM32_MDMA_CBNDTR(x)		(0x54 + 0x40 * (x))
 #define STM32_MDMA_CBNDTR_BRC_MK	GENMASK(31, 20)
-#define STM32_MDMA_CBNDTR_BRC(n)	STM32_MDMA_SET(n, \
-						       STM32_MDMA_CBNDTR_BRC_MK)
-#define STM32_MDMA_CBNDTR_BRC_GET(n)	STM32_MDMA_GET((n), \
-						       STM32_MDMA_CBNDTR_BRC_MK)
+#define STM32_MDMA_CBNDTR_BRC(n)	FIELD_PREP(STM32_MDMA_CBNDTR_BRC_MK, (n))
+#define STM32_MDMA_CBNDTR_BRC_GET(n)	FIELD_GET(STM32_MDMA_CBNDTR_BRC_MK, (n))
 
 #define STM32_MDMA_CBNDTR_BRDUM		BIT(19)
 #define STM32_MDMA_CBNDTR_BRSUM		BIT(18)
 #define STM32_MDMA_CBNDTR_BNDT_MASK	GENMASK(16, 0)
-#define STM32_MDMA_CBNDTR_BNDT(n)	STM32_MDMA_SET(n, \
-						    STM32_MDMA_CBNDTR_BNDT_MASK)
+#define STM32_MDMA_CBNDTR_BNDT(n)	FIELD_PREP(STM32_MDMA_CBNDTR_BNDT_MASK, (n))
 
 /* MDMA Channel x source address register */
 #define STM32_MDMA_CSAR(x)		(0x58 + 0x40 * (x))
@@ -171,11 +146,9 @@
 /* MDMA Channel x block repeat address update register */
 #define STM32_MDMA_CBRUR(x)		(0x60 + 0x40 * (x))
 #define STM32_MDMA_CBRUR_DUV_MASK	GENMASK(31, 16)
-#define STM32_MDMA_CBRUR_DUV(n)		STM32_MDMA_SET(n, \
-						      STM32_MDMA_CBRUR_DUV_MASK)
+#define STM32_MDMA_CBRUR_DUV(n)		FIELD_PREP(STM32_MDMA_CBRUR_DUV_MASK, (n))
 #define STM32_MDMA_CBRUR_SUV_MASK	GENMASK(15, 0)
-#define STM32_MDMA_CBRUR_SUV(n)		STM32_MDMA_SET(n, \
-						      STM32_MDMA_CBRUR_SUV_MASK)
+#define STM32_MDMA_CBRUR_SUV(n)		FIELD_PREP(STM32_MDMA_CBRUR_SUV_MASK, (n))
 
 /* MDMA Channel x link address register */
 #define STM32_MDMA_CLAR(x)		(0x64 + 0x40 * (x))
@@ -185,8 +158,7 @@
 #define STM32_MDMA_CTBR_DBUS		BIT(17)
 #define STM32_MDMA_CTBR_SBUS		BIT(16)
 #define STM32_MDMA_CTBR_TSEL_MASK	GENMASK(7, 0)
-#define STM32_MDMA_CTBR_TSEL(n)		STM32_MDMA_SET(n, \
-						      STM32_MDMA_CTBR_TSEL_MASK)
+#define STM32_MDMA_CTBR_TSEL(n)		FIELD_PREP(STM32_MDMA_CTBR_TSEL_MASK, (n))
 
 /* MDMA Channel x mask address register */
 #define STM32_MDMA_CMAR(x)		(0x70 + 0x40 * (x))
-- 
2.25.1


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Re: [PATCH] ARM: ptrace: Use bitfield helpers

[Russell King (Oracle)]

On Mon, Nov 22, 2021 at 04:53:41PM +0100, Geert Uytterhoeven wrote:
> The isa_mode() macro extracts two fields, and recombines them into a
> single value.  The shift value of the J-bit may look off-by-one to the
> casual reader, as it is the net result of the extraction and
> recombination steps.

I'd recommend avoiding the suggestion that the explicit "- 1" could
be misinterpreted as an off-by-one error.

>  #define isa_mode(regs) \
> -	((((regs)->ARM_cpsr & PSR_J_BIT) >> (__ffs(PSR_J_BIT) - 1)) | \
> -	 (((regs)->ARM_cpsr & PSR_T_BIT) >> (__ffs(PSR_T_BIT))))
> +	((FIELD_GET(PSR_J_BIT, (regs)->ARM_cpsr) << 1) | \

I'd suggest getting rid of the extra unnecessary parens there.
Too many parens leads to a decrease in readability.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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Re: [Linux-stm32] [PATCH] dmaengine: stm32-mdma: Use bitfield helpers

[Amelie DELAUNAY]

Hi Geert,

Thanks for your patch.

On 11/22/21 4:54 PM, Geert Uytterhoeven wrote:
> Use the FIELD_{GET,PREP}() helpers, instead of defining custom macros
> implementing the same operations.
> 
> Signed-off-by: Geert Uytterhoeven<geert+renesas@glider.be>


Reviewed-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Tested-by: Amelie Delaunay <amelie.delaunay@foss.st.com>

> ---
> Compile-tested only.
> 
> See "[PATCH 00/17] Non-const bitfield helper conversions"
> (https://lore.kernel.org/r/cover.1637592133.git.geert+renesas@glider.be)
> for background and more conversions.
> ---
>   drivers/dma/stm32-mdma.c | 74 +++++++++++++---------------------------
>   1 file changed, 23 insertions(+), 51 deletions(-)

Regards,
Amelie

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Re: [PATCH] dmaengine: stm32-mdma: Use bitfield helpers

[Vinod Koul]

On 22-11-21, 16:54, Geert Uytterhoeven wrote:
> Use the FIELD_{GET,PREP}() helpers, instead of defining custom macros
> implementing the same operations.

Applied, thanks

-- 
~Vinod

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