[PATCH v4 2/5] nvme: add get_ams for nvme_ctrl_ops

[Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>]

The get_ams() will return the AMS(Arbitration Mechanism Selected)
from the driver.

Signed-off-by: Weiping Zhang <zhangweiping@xxxxxxxxxxxxxx>
---
 drivers/nvme/host/core.c | 9 ++++++++-
 drivers/nvme/host/nvme.h | 1 +
 drivers/nvme/host/pci.c  | 6 ++++++
 include/linux/nvme.h     | 1 +
 4 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 6ec03507da68..2275f1756369 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -2119,6 +2119,7 @@ int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
 	 */
 	unsigned dev_page_min, page_shift = 12;
 	int ret;
+	u32 ams = NVME_CC_AMS_RR;
 
 	ret = ctrl->ops->reg_read64(ctrl, NVME_REG_CAP, &ctrl->cap);
 	if (ret) {
@@ -2134,11 +2135,17 @@ int nvme_enable_ctrl(struct nvme_ctrl *ctrl)
 		return -ENODEV;
 	}
 
+	/* get Arbitration Mechanism Selected */
+	if (ctrl->ops->get_ams) {
+		ctrl->ops->get_ams(ctrl, &ams);
+		ams &= NVME_CC_AMS_MASK;
+	}
+
 	ctrl->page_size = 1 << page_shift;
 
 	ctrl->ctrl_config = NVME_CC_CSS_NVM;
 	ctrl->ctrl_config |= (page_shift - 12) << NVME_CC_MPS_SHIFT;
-	ctrl->ctrl_config |= NVME_CC_AMS_RR | NVME_CC_SHN_NONE;
+	ctrl->ctrl_config |= ams | NVME_CC_SHN_NONE;
 	ctrl->ctrl_config |= NVME_CC_IOSQES | NVME_CC_IOCQES;
 	ctrl->ctrl_config |= NVME_CC_ENABLE;
 
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 1024fec7914c..a1df74f2eed3 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -407,6 +407,7 @@ struct nvme_ctrl_ops {
 	void (*submit_async_event)(struct nvme_ctrl *ctrl);
 	void (*delete_ctrl)(struct nvme_ctrl *ctrl);
 	int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size);
+	void (*get_ams)(struct nvme_ctrl *ctrl, u32 *ams);
 };
 
 #ifdef CONFIG_FAULT_INJECTION_DEBUG_FS
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 445c2ee2a01d..e460c7310187 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2688,6 +2688,11 @@ static int nvme_pci_get_address(struct nvme_ctrl *ctrl, char *buf, int size)
 	return snprintf(buf, size, "%s", dev_name(&pdev->dev));
 }
 
+static void nvme_pci_get_ams(struct nvme_ctrl *ctrl, u32 *ams)
+{
+	*ams = NVME_CC_AMS_RR;
+}
+
 static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
 	.name			= "pcie",
 	.module			= THIS_MODULE,
@@ -2699,6 +2704,7 @@ static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
 	.free_ctrl		= nvme_pci_free_ctrl,
 	.submit_async_event	= nvme_pci_submit_async_event,
 	.get_address		= nvme_pci_get_address,
+	.get_ams		= nvme_pci_get_ams,
 };
 
 static int nvme_dev_map(struct nvme_dev *dev)
diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 3d5189f46cb1..6fe9121e4d27 100644
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -171,6 +171,7 @@ enum {
 	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,
+	NVME_CC_AMS_MASK	= 7 << NVME_CC_AMS_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,
-- 
2.14.1