[PATCH 2/3] nvme-pci: Add controller memory buffer supported macro

[Baolin Wang <baolin.wang@linux.alibaba.com>]

Introduce a new capability macro to indicate if the controller
supports the memory buffer or not, instead of reading the
NVME_REG_CMBSZ register.

Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
---
 drivers/nvme/host/pci.c | 2 +-
 include/linux/nvme.h    | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4b4b7b7..00c2701 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1760,7 +1760,7 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int bar;
 
-	if (dev->cmb_size)
+	if (!NVME_CAP_CMBS(dev->ctrl.cap) || dev->cmb_size)
 		return;
 
 	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 5ce51ab..e3726be 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -134,6 +134,7 @@ enum {
 #define NVME_CAP_NSSRC(cap)	(((cap) >> 36) & 0x1)
 #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)
-- 
1.8.3.1