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

[Klaus Jensen]

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

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

Signed-off-by: Klaus Jensen <k.jensen at samsung.com>
---
 drivers/nvme/host/pci.c | 25 ++++++++++++++++++++++++-
 include/linux/nvme.h    |  6 ++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 50d9a20568a2..9c2bbb242994 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1787,7 +1787,8 @@ static u32 nvme_cmb_size(struct nvme_dev *dev)
 
 static void nvme_map_cmb(struct nvme_dev *dev)
 {
-	u64 size, offset;
+	u32 vs;
+	u64 size, offset, cmbmsc;
 	resource_size_t bar_size;
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int bar;
@@ -1795,6 +1796,15 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	if (dev->cmb_size)
 		return;
 
+	vs = readl(dev->bar + NVME_REG_VS);
+
+	if (vs >= NVME_VS(1, 4, 0)) {
+		if (!NVME_CAP_CMBS(dev->ctrl.cap))
+			return;
+
+		writel(NVME_CMBMSC_CRE, dev->bar + NVME_REG_CMBMSC);
+	}
+
 	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
 	if (!dev->cmbsz)
 		return;
@@ -1805,6 +1815,19 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	bar = NVME_CMB_BIR(dev->cmbloc);
 	bar_size = pci_resource_len(pdev, bar);
 
+	if (vs >= NVME_VS(1, 4, 0)) {
+		cmbmsc = pci_resource_start(pdev, bar);
+		cmbmsc |= (NVME_CMBMSC_CRE | NVME_CMBMSC_CMSE);
+
+		/*
+		 * Writing the low bits may cause the controller to check the
+		 * validity of the 52 bit controller base address in the CMBMSC
+		 * register, so write the high bits first.
+		 */
+		writel(cmbmsc >> 32, dev->bar + NVME_REG_CMBMSC + 4);
+		writel(cmbmsc, dev->bar + NVME_REG_CMBMSC);
+	}
+
 	if (offset > bar_size)
 		return;
 
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