[PATCH v2] nvme: allow use of cmb on v1.4 controllers

[PATCH v2] nvme: allow use of cmb on v1.4 controllers

[Klaus Jensen]

From: Klaus Jensen <k.jensen@samsung.com>

Since NVMe v1.4 the Controller Memory Buffer must be explicitly enabled
by the host.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 drivers/nvme/host/pci.c | 13 ++++++++++++-
 include/linux/nvme.h    |  6 ++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 50d9a20568a2..62eb83030a5a 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -23,6 +23,7 @@
 #include <linux/t10-pi.h>
 #include <linux/types.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
+#include <linux/io-64-nonatomic-hi-lo.h>
 #include <linux/sed-opal.h>
 #include <linux/pci-p2pdma.h>
 
@@ -1787,7 +1788,7 @@ static u32 nvme_cmb_size(struct nvme_dev *dev)
 
 static void nvme_map_cmb(struct nvme_dev *dev)
 {
-	u64 size, offset;
+	u64 size, offset, cmbmsc;
 	resource_size_t bar_size;
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int bar;
@@ -1795,6 +1796,9 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	if (dev->cmb_size)
 		return;
 
+	if (NVME_CAP_CMBS(dev->ctrl.cap))
+		writel(NVME_CMBMSC_CRE, dev->bar + NVME_REG_CMBMSC);
+
 	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
 	if (!dev->cmbsz)
 		return;
@@ -1808,6 +1812,13 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	if (offset > bar_size)
 		return;
 
+	if (NVME_CAP_CMBS(dev->ctrl.cap)) {
+		cmbmsc = pci_bus_address(pdev, bar) + offset;
+		cmbmsc |= (NVME_CMBMSC_CRE | NVME_CMBMSC_CMSE);
+
+		hi_lo_writeq(cmbmsc, dev->bar + NVME_REG_CMBMSC);
+	}
+
 	/*
 	 * Controllers may support a CMB size larger than their BAR,
 	 * for example, due to being behind a bridge. Reduce the CMB to
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index d92535997687..bfed36e342cc 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -116,6 +116,9 @@ enum {
 	NVME_REG_BPMBL	= 0x0048,	/* Boot Partition Memory Buffer
 					 * Location
 					 */
+	NVME_REG_CMBMSC = 0x0050,	/* Controller Memory Buffer Memory
+					 * Space Control
+					 */
 	NVME_REG_PMRCAP	= 0x0e00,	/* Persistent Memory Capabilities */
 	NVME_REG_PMRCTL	= 0x0e04,	/* Persistent Memory Region Control */
 	NVME_REG_PMRSTS	= 0x0e08,	/* Persistent Memory Region Status */
@@ -135,6 +138,7 @@ enum {
 #define NVME_CAP_CSS(cap)	(((cap) >> 37) & 0xff)
 #define NVME_CAP_MPSMIN(cap)	(((cap) >> 48) & 0xf)
 #define NVME_CAP_MPSMAX(cap)	(((cap) >> 52) & 0xf)
+#define NVME_CAP_CMBS(cap)	(((cap) >> 57) & 0x1)
 
 #define NVME_CMB_BIR(cmbloc)	((cmbloc) & 0x7)
 #define NVME_CMB_OFST(cmbloc)	(((cmbloc) >> 12) & 0xfffff)
@@ -192,6 +196,8 @@ enum {
 	NVME_CSTS_SHST_OCCUR	= 1 << 2,
 	NVME_CSTS_SHST_CMPLT	= 2 << 2,
 	NVME_CSTS_SHST_MASK	= 3 << 2,
+	NVME_CMBMSC_CRE		= 1 << 0,
+	NVME_CMBMSC_CMSE	= 1 << 1,
 };
 
 struct nvme_id_power_state {
-- 
2.30.0

Re: [PATCH v2] nvme: allow use of cmb on v1.4 controllers

[Klaus Jensen]

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On Jan 15 07:30, Klaus Jensen wrote:
> From: Klaus Jensen <k.jensen@samsung.com>
> 
> Since NVMe v1.4 the Controller Memory Buffer must be explicitly enabled
> by the host.
> 

Sorry, messed up and missed adding the changes for v2.

v2:
  - Do not explicitly check the NVMe version, rely on the presence of
    the new register instead. (Christoph)
  - Use hi_lo_writeq. (Christoph, Keith)
  - Fix missing offset and use pci_bus_address(). (Keith)

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Re: [PATCH v2] nvme: allow use of cmb on v1.4 controllers

[Christoph Hellwig]

Thanks,

applied to nvme-5.11 with a little tweak to remove the cmbmsc local
variable and a comment explaining what is going on.

Re: [PATCH v2] nvme: allow use of cmb on v1.4 controllers

[Klaus Jensen]

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On Jan 18 18:59, Christoph Hellwig wrote:
> Thanks,
> 
> applied to nvme-5.11 with a little tweak to remove the cmbmsc local
> variable and a comment explaining what is going on.
> 

Sweet. Thanks!

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