linux-kernel - [PATCH 1/4] cxl/mem: Fully decode device capability header

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Date:   Thu,  6 May 2021 15:36:51 -0700
From:   ira.weiny@...el.com
To:     Ben Widawsky <ben.widawsky@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Cc:     Ira Weiny <ira.weiny@...el.com>,
        Alison Schofield <alison.schofield@...el.com>,
        Vishal Verma <vishal.l.verma@...el.com>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        linux-cxl@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 1/4] cxl/mem: Fully decode device capability header

From: Ira Weiny <ira.weiny@...el.com>

Previously only the capability ID and offset were decoded.

Create a version MASK and decode the additional version and length
fields of the header.

Signed-off-by: Ira Weiny <ira.weiny@...el.com>
---
 drivers/cxl/core.c | 15 ++++++++++++---
 drivers/cxl/cxl.h  |  1 +
 2 files changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c
index b3c3532b53f7..21553386e218 100644
--- a/drivers/cxl/core.c
+++ b/drivers/cxl/core.c
@@ -501,12 +501,21 @@ void cxl_setup_device_regs(struct device *dev, void __iomem *base,
 
 	for (cap = 1; cap <= cap_count; cap++) {
 		void __iomem *register_block;
-		u32 offset;
+		u32 hdr, offset, __maybe_unused length;
 		u16 cap_id;
+		u8 version;
+
+		hdr = readl(base + cap * 0x10);
+
+		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK, hdr);
+		version = FIELD_GET(CXLDEV_CAP_HDR_VERSION_MASK, hdr);
+		if (version != 1)
+			dev_err(dev, "Vendor cap ID: %x incorrect version (0x%x)\n",
+				cap_id, version);
 
-		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
-				   readl(base + cap * 0x10));
 		offset = readl(base + cap * 0x10 + 0x4);
+		length = readl(base + cap * 0x10 + 0x8);
+
 		register_block = base + offset;
 
 		switch (cap_id) {
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 0211f44c95a2..9b315c069557 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -15,6 +15,7 @@
 #define   CXLDEV_CAP_ARRAY_COUNT_MASK GENMASK_ULL(47, 32)
 /* CXL 2.0 8.2.8.2 CXL Device Capability Header Register */
 #define CXLDEV_CAP_HDR_CAP_ID_MASK GENMASK(15, 0)
+#define CXLDEV_CAP_HDR_VERSION_MASK GENMASK(23, 16)
 /* CXL 2.0 8.2.8.2.1 CXL Device Capabilities */
 #define CXLDEV_CAP_CAP_ID_DEVICE_STATUS 0x1
 #define CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX 0x2
-- 
2.28.0.rc0.12.gb6a658bd00c9