[PATCH v2 0/2] Cleanup controller configuration register handling

[PATCH v2 0/2] Cleanup controller configuration register handling

[Damien Le Moal]

A couple of patches to cleanup the definition and handling of the CC
register. No functional changes.

Changes from v1:
 - Added comments to describe the CC enum and its fields (patch 1)
 - Added review tags to patch 2

Damien Le Moal (2):
  nvme: Cleanup the definition of the controller config register fields
  nvmet: Use enum definitions instead of hardcoded values

 drivers/nvme/target/nvmet.h | 14 ++++++-------
 include/linux/nvme.h        | 40 ++++++++++++++++++++++++++++++-------
 2 files changed, 40 insertions(+), 14 deletions(-)

-- 
2.48.1

[PATCH v2 1/2] nvme: Cleanup the definition of the controller config register fields

[Damien Le Moal]

Reorganized the enum used to define the fields of the contrller
configuration (CC) register in include/linux/nvme.h to:
1) Group together all the values defined for each field.
2) Add the missing field masks definitions.
3) Add comments to describe the enum and each field.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
---
 include/linux/nvme.h | 40 +++++++++++++++++++++++++++++++++-------
 1 file changed, 33 insertions(+), 7 deletions(-)

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index fe3b60818fdc..2dc05b1c3283 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -199,28 +199,54 @@ enum {
 #define NVME_NVM_IOSQES		6
 #define NVME_NVM_IOCQES		4
 
+/*
+ * Controller Configuration (CC) register (Offset 14h)
+ */
 enum {
+	/* Enable (EN): bit 0 */
 	NVME_CC_ENABLE		= 1 << 0,
 	NVME_CC_EN_SHIFT	= 0,
+
+	/* Bits 03:01 are reserved (NVMe Base Specification rev 2.1) */
+
+	/* I/O Command Set Selected (CSS): bits 06:04 */
 	NVME_CC_CSS_SHIFT	= 4,
-	NVME_CC_MPS_SHIFT	= 7,
-	NVME_CC_AMS_SHIFT	= 11,
-	NVME_CC_SHN_SHIFT	= 14,
-	NVME_CC_IOSQES_SHIFT	= 16,
-	NVME_CC_IOCQES_SHIFT	= 20,
+	NVME_CC_CSS_MASK	= 7 << NVME_CC_CSS_SHIFT,
 	NVME_CC_CSS_NVM		= 0 << NVME_CC_CSS_SHIFT,
 	NVME_CC_CSS_CSI		= 6 << NVME_CC_CSS_SHIFT,
-	NVME_CC_CSS_MASK	= 7 << NVME_CC_CSS_SHIFT,
+
+	/* Memory Page Size (MPS): bits 10:07 */
+	NVME_CC_MPS_SHIFT	= 7,
+	NVME_CC_MPS_MASK	= 0xf << NVME_CC_MPS_SHIFT,
+
+	/* Arbitration Mechanism Selected (AMS): bits 13:11 */
+	NVME_CC_AMS_SHIFT	= 11,
+	NVME_CC_AMS_MASK	= 7 << NVME_CC_AMS_SHIFT,
 	NVME_CC_AMS_RR		= 0 << NVME_CC_AMS_SHIFT,
 	NVME_CC_AMS_WRRU	= 1 << NVME_CC_AMS_SHIFT,
 	NVME_CC_AMS_VS		= 7 << NVME_CC_AMS_SHIFT,
+
+	/* Shutdown Notification (SHN): bits 15:14 */
+	NVME_CC_SHN_SHIFT	= 14,
+	NVME_CC_SHN_MASK	= 3 << NVME_CC_SHN_SHIFT,
 	NVME_CC_SHN_NONE	= 0 << NVME_CC_SHN_SHIFT,
 	NVME_CC_SHN_NORMAL	= 1 << NVME_CC_SHN_SHIFT,
 	NVME_CC_SHN_ABRUPT	= 2 << NVME_CC_SHN_SHIFT,
-	NVME_CC_SHN_MASK	= 3 << NVME_CC_SHN_SHIFT,
+
+	/* I/O Submission Queue Entry Size (IOSQES): bits 19:16 */
+	NVME_CC_IOSQES_SHIFT	= 16,
+	NVME_CC_IOSQES_MASK	= 0xf << NVME_CC_IOSQES_SHIFT,
 	NVME_CC_IOSQES		= NVME_NVM_IOSQES << NVME_CC_IOSQES_SHIFT,
+
+	/* I/O Completion Queue Entry Size (IOCQES): bits 23:20 */
+	NVME_CC_IOCQES_SHIFT	= 20,
+	NVME_CC_IOCQES_MASK	= 0xf << NVME_CC_IOCQES_SHIFT,
 	NVME_CC_IOCQES		= NVME_NVM_IOCQES << NVME_CC_IOCQES_SHIFT,
+
+	/* Controller Ready Independent of Media Enable (CRIME): bit 24 */
 	NVME_CC_CRIME		= 1 << 24,
+
+	/* Bits 25:31 are reserved (NVMe Base Specification rev 2.1) */
 };
 
 enum {
-- 
2.48.1

Re: [PATCH v2 1/2] nvme: Cleanup the definition of the controller config register fields

[Christoph Hellwig]

Looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH v2 1/2] nvme: Cleanup the definition of the controller config register fields

[Chaitanya Kulkarni]

On 2/12/2025 10:49 PM, Damien Le Moal wrote:
> Reorganized the enum used to define the fields of the contrller
> configuration (CC) register in include/linux/nvme.h to:
> 1) Group together all the values defined for each field.
> 2) Add the missing field masks definitions.
> 3) Add comments to describe the enum and each field.
> 
> Signed-off-by: Damien Le Moal<dlemoal@kernel.org>

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck

[PATCH v2 2/2] nvmet: Use enum definitions instead of hardcoded values

[Damien Le Moal]

Change the definition of the inline functions nvmet_cc_en(),
nvmet_cc_css(), nvmet_cc_mps(), nvmet_cc_ams(), nvmet_cc_shn(),
nvmet_cc_iosqes(), and nvmet_cc_iocqes() to use the enum difinitions in
include/linux/nvme.h instead of hardcoded values.

Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
---
 drivers/nvme/target/nvmet.h | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/nvme/target/nvmet.h b/drivers/nvme/target/nvmet.h
index 4be8d22d2d8d..d2c1233981e1 100644
--- a/drivers/nvme/target/nvmet.h
+++ b/drivers/nvme/target/nvmet.h
@@ -784,37 +784,37 @@ u16 nvmet_report_invalid_opcode(struct nvmet_req *req);
 
 static inline bool nvmet_cc_en(u32 cc)
 {
-	return (cc >> NVME_CC_EN_SHIFT) & 0x1;
+	return (cc & NVME_CC_ENABLE) >> NVME_CC_EN_SHIFT;
 }
 
 static inline u8 nvmet_cc_css(u32 cc)
 {
-	return (cc >> NVME_CC_CSS_SHIFT) & 0x7;
+	return (cc & NVME_CC_CSS_MASK) >> NVME_CC_CSS_SHIFT;
 }
 
 static inline u8 nvmet_cc_mps(u32 cc)
 {
-	return (cc >> NVME_CC_MPS_SHIFT) & 0xf;
+	return (cc & NVME_CC_MPS_MASK) >> NVME_CC_MPS_SHIFT;
 }
 
 static inline u8 nvmet_cc_ams(u32 cc)
 {
-	return (cc >> NVME_CC_AMS_SHIFT) & 0x7;
+	return (cc & NVME_CC_AMS_MASK) >> NVME_CC_AMS_SHIFT;
 }
 
 static inline u8 nvmet_cc_shn(u32 cc)
 {
-	return (cc >> NVME_CC_SHN_SHIFT) & 0x3;
+	return (cc & NVME_CC_SHN_MASK) >> NVME_CC_SHN_SHIFT;
 }
 
 static inline u8 nvmet_cc_iosqes(u32 cc)
 {
-	return (cc >> NVME_CC_IOSQES_SHIFT) & 0xf;
+	return (cc & NVME_CC_IOSQES_MASK) >> NVME_CC_IOSQES_SHIFT;
 }
 
 static inline u8 nvmet_cc_iocqes(u32 cc)
 {
-	return (cc >> NVME_CC_IOCQES_SHIFT) & 0xf;
+	return (cc & NVME_CC_IOCQES_MASK) >> NVME_CC_IOCQES_SHIFT;
 }
 
 /* Convert a 32-bit number to a 16-bit 0's based number */
-- 
2.48.1

Re: [PATCH v2 0/2] Cleanup controller configuration register handling

[Keith Busch]

On Thu, Feb 13, 2025 at 03:49:58PM +0900, Damien Le Moal wrote:
> A couple of patches to cleanup the definition and handling of the CC
> register. No functional changes.

Thanks, applied to nvme-6.14.