All the necessary bits are initialized in order to find and map the
register space for CXL Memory Devices. This is accomplished by using the
Register Locator DVSEC (CXL 2.0 - 8.1.9.1) to determine which PCI BAR to
use, and how much of an offset from that BAR should be added.
If the memory device registers are found and mapped a new internal data
structure tracking device state is allocated.
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
---
drivers/cxl/cxl.h | 17 ++++++++++
drivers/cxl/mem.c | 83 +++++++++++++++++++++++++++++++++++++++++++++--
drivers/cxl/pci.h | 14 ++++++++
3 files changed, 112 insertions(+), 2 deletions(-)
create mode 100644 drivers/cxl/cxl.h
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
new file mode 100644
index 000000000000..d81d0ba4617c
--- /dev/null
+++ b/drivers/cxl/cxl.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2020 Intel Corporation. */
+
+#ifndef __CXL_H__
+#define __CXL_H__
+
+/**
+ * struct cxl_mem - A CXL memory device
+ * @pdev: The PCI device associated with this CXL device.
+ * @regs: IO mappings to the device's MMIO
+ */
+struct cxl_mem {
+ struct pci_dev *pdev;
+ void __iomem *regs;
+};
+
+#endif
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index f4ee9a507ac9..a869c8dc24cc 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -4,6 +4,58 @@
#include <linux/pci.h>
#include <linux/io.h>
#include "pci.h"
+#include "cxl.h"
+
+/**
+ * cxl_mem_create() - Create a new &struct cxl_mem.
+ * @pdev: The pci device associated with the new &struct cxl_mem.
+ * @reg_lo: Lower 32b of the register locator
+ * @reg_hi: Upper 32b of the register locator.
+ *
+ * Return: The new &struct cxl_mem on success, NULL on failure.
+ *
+ * Map the BAR for a CXL memory device. This BAR has the memory device's
+ * registers for the device as specified in CXL specification.
+ */
+static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev, u32 reg_lo,
+ u32 reg_hi)
+{
+ struct device *dev = &pdev->dev;
+ struct cxl_mem *cxlm;
+ void __iomem *regs;
+ u64 offset;
+ u8 bar;
+ int rc;
+
+ offset = ((u64)reg_hi << 32) | (reg_lo & CXL_REGLOC_ADDR_MASK);
+ bar = (reg_lo >> CXL_REGLOC_BIR_SHIFT) & CXL_REGLOC_BIR_MASK;
+
+ /* Basic sanity check that BAR is big enough */
+ if (pci_resource_len(pdev, bar) < offset) {
+ dev_err(dev, "BAR%d: %pr: too small (offset: %#llx)\n", bar,
+ &pdev->resource[bar], (unsigned long long)offset);
+ return NULL;
+ }
+
+ rc = pcim_iomap_regions(pdev, BIT(bar), pci_name(pdev));
+ if (rc != 0) {
+ dev_err(dev, "failed to map registers\n");
+ return NULL;
+ }
+
+ cxlm = devm_kzalloc(&pdev->dev, sizeof(*cxlm), GFP_KERNEL);
+ if (!cxlm) {
+ dev_err(dev, "No memory available\n");
+ return NULL;
+ }
+
+ regs = pcim_iomap_table(pdev)[bar];
+ cxlm->pdev = pdev;
+ cxlm->regs = regs + offset;
+
+ dev_dbg(dev, "Mapped CXL Memory Device resource\n");
+ return cxlm;
+}
static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
{
@@ -32,15 +84,42 @@ static int cxl_mem_dvsec(struct pci_dev *pdev, int dvsec)
static int cxl_mem_probe(struct pci_dev *pdev, const struct pci_device_id *id)
{
struct device *dev = &pdev->dev;
- int regloc;
+ struct cxl_mem *cxlm;
+ int rc, regloc, i;
+
+ rc = pcim_enable_device(pdev);
+ if (rc)
+ return rc;
regloc = cxl_mem_dvsec(pdev, PCI_DVSEC_ID_CXL_REGLOC);
if (!regloc) {
dev_err(dev, "register location dvsec not found\n");
return -ENXIO;
}
+ regloc += 0xc; /* Skip DVSEC + reserved fields */
- return 0;
+ rc = -ENXIO;
+ for (i = regloc; i < regloc + 0x24; i += 8) {
+ u32 reg_lo, reg_hi;
+ u8 reg_type;
+
+ /* "register low and high" contain other bits */
+ pci_read_config_dword(pdev, i, ®_lo);
+ pci_read_config_dword(pdev, i + 4, ®_hi);
+
+ reg_type =
+ (reg_lo >> CXL_REGLOC_RBI_SHIFT) & CXL_REGLOC_RBI_MASK;
+
+ if (reg_type == CXL_REGLOC_RBI_MEMDEV) {
+ rc = 0;
+ cxlm = cxl_mem_create(pdev, reg_lo, reg_hi);
+ if (!cxlm)
+ rc = -ENODEV;
+ break;
+ }
+ }
+
+ return rc;
}
static const struct pci_device_id cxl_mem_pci_tbl[] = {
diff --git a/drivers/cxl/pci.h b/drivers/cxl/pci.h
index a8a9935fa90b..df222edb6ac3 100644
--- a/drivers/cxl/pci.h
+++ b/drivers/cxl/pci.h
@@ -17,4 +17,18 @@
#define PCI_DVSEC_ID_CXL_REGLOC 0x8
+/* BAR Indicator Register (BIR) */
+#define CXL_REGLOC_BIR_SHIFT 0
+#define CXL_REGLOC_BIR_MASK 0x7
+
+/* Register Block Identifier (RBI) */
+#define CXL_REGLOC_RBI_SHIFT 8
+#define CXL_REGLOC_RBI_MASK 0xff
+#define CXL_REGLOC_RBI_EMPTY 0
+#define CXL_REGLOC_RBI_COMPONENT 1
+#define CXL_REGLOC_RBI_VIRT 2
+#define CXL_REGLOC_RBI_MEMDEV 3
+
+#define CXL_REGLOC_ADDR_MASK 0xffff0000
+
#endif /* __CXL_PCI_H__ */
--
2.30.0
