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

[Klaus Jensen]

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

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

Signed-off-by: Klaus Jensen <k.jen...@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