[PATCH v2 09/10] nvme-pci: Add a quirk for a pseudo CMB

[Logan Gunthorpe]

Introduce a quirk to use CMB-like memory on older devices that have
an exposed BAR but do not advertise support for using CMBLOC and
CMBSIZE.

We'd like to use some of these older cards to test P2P memory.

Signed-off-by: Logan Gunthorpe <logang@xxxxxxxxxxxx>
---
 drivers/nvme/host/nvme.h |  7 +++++++
 drivers/nvme/host/pci.c  | 24 ++++++++++++++++++++----
 2 files changed, 27 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index e38beb1917e2..c84a1b9580c8 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -83,6 +83,13 @@ enum nvme_quirks {
 	 * Supports the LighNVM command set if indicated in vs[1].
 	 */
 	NVME_QUIRK_LIGHTNVM			= (1 << 6),
+
+	/*
+	 * Pseudo CMB Support on BAR 4. For adapters like the Microsemi
+	 * NVRAM that have CMB-like memory on a BAR but does not set
+	 * CMBLOC or CMBSZ.
+	 */
+	NVME_QUIRK_PSEUDO_CMB_BAR4		= (1 << 7),
 };
 
 /*
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index b896a78225cb..2ad20fb9f05d 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1679,6 +1679,13 @@ static ssize_t nvme_cmb_show(struct device *dev,
 }
 static DEVICE_ATTR(cmb, S_IRUGO, nvme_cmb_show, NULL);
 
+static u32 nvme_pseudo_cmbsz(struct pci_dev *pdev, int bar)
+{
+	return NVME_CMBSZ_WDS | NVME_CMBSZ_RDS |
+		(((ilog2(SZ_16M) - 12) / 4) << NVME_CMBSZ_SZU_SHIFT) |
+		((pci_resource_len(pdev, bar) / SZ_16M) << NVME_CMBSZ_SZ_SHIFT);
+}
+
 static u64 nvme_cmb_size_unit(struct nvme_dev *dev)
 {
 	u8 szu = (dev->cmbsz >> NVME_CMBSZ_SZU_SHIFT) & NVME_CMBSZ_SZU_MASK;
@@ -1698,10 +1705,15 @@ static void nvme_map_cmb(struct nvme_dev *dev)
 	struct pci_dev *pdev = to_pci_dev(dev->dev);
 	int bar;
 
-	dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
-	if (!dev->cmbsz)
-		return;
-	dev->cmbloc = readl(dev->bar + NVME_REG_CMBLOC);
+	if (dev->ctrl.quirks & NVME_QUIRK_PSEUDO_CMB_BAR4) {
+		dev->cmbsz = nvme_pseudo_cmbsz(pdev, 4);
+		dev->cmbloc = 4;
+	} else {
+		dev->cmbsz = readl(dev->bar + NVME_REG_CMBSZ);
+		if (!dev->cmbsz)
+			return;
+		dev->cmbloc = readl(dev->bar + NVME_REG_CMBLOC);
+	}
 
 	size = nvme_cmb_size_unit(dev) * nvme_cmb_size(dev);
 	offset = nvme_cmb_size_unit(dev) * NVME_CMB_OFST(dev->cmbloc);
@@ -2715,6 +2727,10 @@ static const struct pci_device_id nvme_id_table[] = {
 		.driver_data = NVME_QUIRK_LIGHTNVM, },
 	{ PCI_DEVICE(0x1d1d, 0x2807),	/* CNEX WL */
 		.driver_data = NVME_QUIRK_LIGHTNVM, },
+	{ PCI_DEVICE(0x11f8, 0xf117),	/* Microsemi NVRAM adaptor */
+		.driver_data = NVME_QUIRK_PSEUDO_CMB_BAR4, },
+	{ PCI_DEVICE(0x1db1, 0x0002),	/* Everspin nvNitro adaptor */
+		.driver_data = NVME_QUIRK_PSEUDO_CMB_BAR4,  },
 	{ PCI_DEVICE_CLASS(PCI_CLASS_STORAGE_EXPRESS, 0xffffff) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2001) },
 	{ PCI_DEVICE(PCI_VENDOR_ID_APPLE, 0x2003) },
-- 
2.11.0