[PATCH 0/8] CXL Port Enumeration

[PATCH 0/8] CXL Port Enumeration

[Dan Williams]

This series is a preview of the proposed infrastructure for enabling
dynamic mapping of Host-managed Device Memory (HDM) Decoders. It
includes a not-for-upstream hack at the tail of the series to stand-in
for the in-flight ACPICA enabling. The goal is to get review of the
proposal in parallel with other in-flight dependencies. The next step
after this is to add dynamic enumeration and assignment of HDM Decoders
in coordination with per-cxl_port driver instances.

---

The enumeration starts with the ACPI0017 driver registering a 'struct
cxl_root' object to establish the top of a cxl_port topology. It then
scans the ACPI bus looking for ACPI0016 instances. The cxl_root object
is a singleton* anchor to hang "address-space" objects and be a parent
device for the downstream 'struct cxl_port' instances. An address-space
has a 1:1 relationship with a platform defined memory resource range,
like _CRS for PCIE Host Bridges. Use module parameters to model a
root-level HDM decoder that all downstream ports further decode, to be
replaced with a Code First ECN to do the same.

Each address space is modeled as a sysfs object that also shows up in
/proc/iomem as "CXL Address Space". That iomem resource is functionally
equivalent to the root-level 'PCI Bus' resources for PCIE.mmio while
'CXL Address Space' indicates space for CXL.mem to be mapped. "System
RAM" and "Persistent Memory", when mapped by HDM decoders, will appear
as child CXL.mem resources.

Once a 'struct cxl_root' is established the host bridge is modeled as 1
upstream 'struct cxl_port' and N downstream 'struct cxl_port' instances
(one per Root Port), just like a PCIE switch. The host-bridge upstream
port optionally has the HDM decoder registers from the CHBCR if the
host-bridge has multiple PCIE/CXL root ports. Single-ported host bridges
will not have HDM decoders in the CHBCR space (see CHBCR note in
8.2.5.12 CXL HDM Decoder Capability Structure), but the 'struct
cxl_port' object is still needed to represent other CXL capabilities and
access port-specific component registers outside of HDM decoders.

Each 'struct cxl_port' has a 'target_id' attribute that answers the
question "what port am I in my upstream port's HDM decoder target
list?". For the host-bridge struct cxl_port, the first tier of ports
below cxl_root.port, the id is derived from the ordinal mapping of the
ACPI0016 id (instance id, _UID, or other handle TBD), for all other
ports the id is the PCIE Root Port ID from the Link Capabilities
register [1]. The mapping of ordinal port identifiers relative to their
parent may change once libcxl and cxl-cli prove out region creation, or
a better option is found to establish a static device path / persistent
naming scheme. System software must not assume that 'struct cxl_port'
device names will be static from one boot to the next.

See patch7 for a tree(1) topology picture of what QEMU is producing
today with this enabling.

* cxl_root is singleton only by convention. A given cxl_root could
  represent 1 to N address spaces, this patch set chooses to implement 1
  cxl_root for all address spaces.

[1]: CXL 2.0 8.2.5.12.8 CXL HDM Decoder 0 Target List Low Register
     (Offset 24h) ...The Target Port Identifier for a given Downstream Port
     is reported via Port Number field in Link Capabilities Register. (See
     PCI Express Base Specification).

---

Dan Williams (8):
      cxl/mem: Move some definitions to mem.h
      cxl/mem: Introduce 'struct cxl_regs'
      cxl/core: Rename bus.c to core.c
      cxl/core: Refactor CXL register lookup for bridge reuse
      cxl/acpi: Introduce ACPI0017 driver and cxl_root
      cxl/Kconfig: Default drivers to CONFIG_CXL_BUS
      cxl/port: Introduce cxl_port objects
      cxl/acpi: Add module parameters to stand in for ACPI tables


 Documentation/driver-api/cxl/memory-devices.rst |    6 
 drivers/cxl/Kconfig                             |   16 +
 drivers/cxl/Makefile                            |    6 
 drivers/cxl/acpi.c                              |  215 +++++++++++
 drivers/cxl/bus.c                               |   29 -
 drivers/cxl/core.c                              |  468 +++++++++++++++++++++++
 drivers/cxl/cxl.h                               |  146 +++++--
 drivers/cxl/mem.c                               |   97 +----
 drivers/cxl/mem.h                               |   82 ++++
 9 files changed, 905 insertions(+), 160 deletions(-)
 create mode 100644 drivers/cxl/acpi.c
 delete mode 100644 drivers/cxl/bus.c
 create mode 100644 drivers/cxl/core.c
 create mode 100644 drivers/cxl/mem.h

Pre-release review notes:
- s/HDM/HDM decoder/ in cover letter (Ben)
- clarify whether cxl_root is a singleton (Ben)
- call out _UID as an ACPI0016 id for the target list (Ben)
- add a spec reference for the claim about pcie root port number (Ben)
- s/regs.dev/regs.device_regs/ (Ben)
- add spec reference for @base arg to cxl_setup_device_regs()
- convert CXL_ADDRSPACE_* to BIT() and GENMASK() (Ben)
- document struct cxl_port (Ben)
- fixup the original copyright date for acpi.c (Ben)
- change the link name for the hosting port_dev from its device-name to
  "host"
- fix a regression introduced by the CXL_DEVICE_REGS() trickery (Vishal)
- add a patch to default enable the critical sub-drivers based on the
  CXL_BUS option.
- rename cxl registers to cxl device registers (Ben)
- introduce cxl_device_regs as a subset of cxl_regs, but let them be
  referenced anonymously from cxlm->regs.
- rename cxl_setup_regs() to cxl_setup_device_regs() (Ben)
- add documentation to 'struct cxl_root' to make it clear what it is
  relative to PCIE/CXL Root Ports. (Ben)
- fixup the cover letter to remove cxl_root vs root-port confusion (Ben)

base-commit: a38fd8748464831584a19438cbb3082b5a2dab15

[PATCH 1/8] cxl/mem: Move some definitions to mem.h

[Dan Williams]

In preparation for sharing cxl.h with other generic CXL consumers,
move / consolidate some of the memory device specifics to mem.h.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/cxl.h |   57 ------------------------------------
 drivers/cxl/mem.c |   25 +---------------
 drivers/cxl/mem.h |   85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 81 deletions(-)
 create mode 100644 drivers/cxl/mem.h

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 6f14838c2d25..2e3bdacb32e7 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -34,62 +34,5 @@
 #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
 #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
 
-/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
-#define CXLMDEV_STATUS_OFFSET 0x0
-#define   CXLMDEV_DEV_FATAL BIT(0)
-#define   CXLMDEV_FW_HALT BIT(1)
-#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
-#define     CXLMDEV_MS_NOT_READY 0
-#define     CXLMDEV_MS_READY 1
-#define     CXLMDEV_MS_ERROR 2
-#define     CXLMDEV_MS_DISABLED 3
-#define CXLMDEV_READY(status)                                                  \
-	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
-	 CXLMDEV_MS_READY)
-#define   CXLMDEV_MBOX_IF_READY BIT(4)
-#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
-#define     CXLMDEV_RESET_NEEDED_NOT 0
-#define     CXLMDEV_RESET_NEEDED_COLD 1
-#define     CXLMDEV_RESET_NEEDED_WARM 2
-#define     CXLMDEV_RESET_NEEDED_HOT 3
-#define     CXLMDEV_RESET_NEEDED_CXL 4
-#define CXLMDEV_RESET_NEEDED(status)                                           \
-	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
-	 CXLMDEV_RESET_NEEDED_NOT)
-
-struct cxl_memdev;
-/**
- * struct cxl_mem - A CXL memory device
- * @pdev: The PCI device associated with this CXL device.
- * @regs: IO mappings to the device's MMIO
- * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
- * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
- * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
- * @payload_size: Size of space for payload
- *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
- * @mbox_mutex: Mutex to synchronize mailbox access.
- * @firmware_version: Firmware version for the memory device.
- * @enabled_commands: Hardware commands found enabled in CEL.
- * @pmem_range: Persistent memory capacity information.
- * @ram_range: Volatile memory capacity information.
- */
-struct cxl_mem {
-	struct pci_dev *pdev;
-	void __iomem *regs;
-	struct cxl_memdev *cxlmd;
-
-	void __iomem *status_regs;
-	void __iomem *mbox_regs;
-	void __iomem *memdev_regs;
-
-	size_t payload_size;
-	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
-	char firmware_version[0x10];
-	unsigned long *enabled_cmds;
-
-	struct range pmem_range;
-	struct range ram_range;
-};
-
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 244cb7d89678..45871ef65152 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -12,6 +12,7 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include "pci.h"
 #include "cxl.h"
+#include "mem.h"
 
 /**
  * DOC: cxl mem
@@ -29,12 +30,6 @@
  *  - Handle and manage error conditions.
  */
 
-/*
- * An entire PCI topology full of devices should be enough for any
- * config
- */
-#define CXL_MEM_MAX_DEVS 65536
-
 #define cxl_doorbell_busy(cxlm)                                                \
 	(readl((cxlm)->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET) &                  \
 	 CXLDEV_MBOX_CTRL_DOORBELL)
@@ -91,24 +86,6 @@ struct mbox_cmd {
 #define CXL_MBOX_SUCCESS 0
 };
 
-/**
- * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
- * @dev: driver core device object
- * @cdev: char dev core object for ioctl operations
- * @cxlm: pointer to the parent device driver data
- * @ops_active: active user of @cxlm in ops handlers
- * @ops_dead: completion when all @cxlm ops users have exited
- * @id: id number of this memdev instance.
- */
-struct cxl_memdev {
-	struct device dev;
-	struct cdev cdev;
-	struct cxl_mem *cxlm;
-	struct percpu_ref ops_active;
-	struct completion ops_dead;
-	int id;
-};
-
 static int cxl_mem_major;
 static DEFINE_IDA(cxl_memdev_ida);
 static struct dentry *cxl_debugfs;
diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
new file mode 100644
index 000000000000..daa9aba0e218
--- /dev/null
+++ b/drivers/cxl/mem.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2020-2021 Intel Corporation. */
+#ifndef __CXL_MEM_H__
+#define __CXL_MEM_H__
+
+/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
+#define CXLMDEV_STATUS_OFFSET 0x0
+#define   CXLMDEV_DEV_FATAL BIT(0)
+#define   CXLMDEV_FW_HALT BIT(1)
+#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
+#define     CXLMDEV_MS_NOT_READY 0
+#define     CXLMDEV_MS_READY 1
+#define     CXLMDEV_MS_ERROR 2
+#define     CXLMDEV_MS_DISABLED 3
+#define CXLMDEV_READY(status)                                                  \
+	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
+	 CXLMDEV_MS_READY)
+#define   CXLMDEV_MBOX_IF_READY BIT(4)
+#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
+#define     CXLMDEV_RESET_NEEDED_NOT 0
+#define     CXLMDEV_RESET_NEEDED_COLD 1
+#define     CXLMDEV_RESET_NEEDED_WARM 2
+#define     CXLMDEV_RESET_NEEDED_HOT 3
+#define     CXLMDEV_RESET_NEEDED_CXL 4
+#define CXLMDEV_RESET_NEEDED(status)                                           \
+	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
+	 CXLMDEV_RESET_NEEDED_NOT)
+
+/*
+ * An entire PCI topology full of devices should be enough for any
+ * config
+ */
+#define CXL_MEM_MAX_DEVS 65536
+
+/**
+ * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
+ * @dev: driver core device object
+ * @cdev: char dev core object for ioctl operations
+ * @cxlm: pointer to the parent device driver data
+ * @ops_active: active user of @cxlm in ops handlers
+ * @ops_dead: completion when all @cxlm ops users have exited
+ * @id: id number of this memdev instance.
+ */
+struct cxl_memdev {
+	struct device dev;
+	struct cdev cdev;
+	struct cxl_mem *cxlm;
+	struct percpu_ref ops_active;
+	struct completion ops_dead;
+	int id;
+};
+
+/**
+ * struct cxl_mem - A CXL memory device
+ * @pdev: The PCI device associated with this CXL device.
+ * @regs: IO mappings to the device's MMIO
+ * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
+ * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
+ * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
+ * @payload_size: Size of space for payload
+ *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
+ * @mbox_mutex: Mutex to synchronize mailbox access.
+ * @firmware_version: Firmware version for the memory device.
+ * @enabled_commands: Hardware commands found enabled in CEL.
+ * @pmem_range: Persistent memory capacity information.
+ * @ram_range: Volatile memory capacity information.
+ */
+struct cxl_mem {
+	struct pci_dev *pdev;
+	void __iomem *regs;
+	struct cxl_memdev *cxlmd;
+
+	void __iomem *status_regs;
+	void __iomem *mbox_regs;
+	void __iomem *memdev_regs;
+
+	size_t payload_size;
+	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
+	char firmware_version[0x10];
+	unsigned long *enabled_cmds;
+
+	struct range pmem_range;
+	struct range ram_range;
+};
+#endif /* __CXL_MEM_H__ */

[PATCH 2/8] cxl/mem: Introduce 'struct cxl_regs'

[Dan Williams]

In preparation for common register mapping facility, introduce a generic
container, 'struct cxl_regs', for CXL device register and later
component register block base pointers. Some CXL device types implement
both.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/cxl.h |   33 +++++++++++++++++++++++++++++++++
 drivers/cxl/mem.c |   44 ++++++++++++++++++++++++--------------------
 drivers/cxl/mem.h |   13 +++++--------
 3 files changed, 62 insertions(+), 28 deletions(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 2e3bdacb32e7..37325e504fb7 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -34,5 +34,38 @@
 #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
 #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
 
+/* See note for 'struct cxl_regs' for the rationale of this organization */
+#define CXL_DEVICE_REGS() \
+	void __iomem *status; \
+	void __iomem *mbox; \
+	void __iomem *memdev
+
+/**
+ * struct cxl_device_regs - Common container of CXL Device register
+ * 			    block base pointers
+ * @status: CXL 2.0 8.2.8.3 Device Status Registers
+ * @mbox: CXL 2.0 8.2.8.4 Mailbox Registers
+ * @memdev: CXL 2.0 8.2.8.5 Memory Device Registers
+ */
+struct cxl_device_regs {
+	CXL_DEVICE_REGS();
+};
+
+/*
+ * Note, the anonymous union organization allows for per
+ * register-block-type helper routines, without requiring block-type
+ * agnostic code to include the prefix. I.e.
+ * cxl_setup_device_regs(&cxlm->regs.dev) vs readl(cxlm->regs.mbox).
+ * The specificity reads naturally from left-to-right.
+ */
+struct cxl_regs {
+	union {
+		struct {
+			CXL_DEVICE_REGS();
+		};
+		struct cxl_device_regs device_regs;
+	};
+};
+
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 45871ef65152..6951243d128e 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -31,7 +31,7 @@
  */
 
 #define cxl_doorbell_busy(cxlm)                                                \
-	(readl((cxlm)->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET) &                  \
+	(readl((cxlm)->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET) &                  \
 	 CXLDEV_MBOX_CTRL_DOORBELL)
 
 /* CXL 2.0 - 8.2.8.4 */
@@ -271,7 +271,7 @@ static void cxl_mem_mbox_timeout(struct cxl_mem *cxlm,
 static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 				   struct mbox_cmd *mbox_cmd)
 {
-	void __iomem *payload = cxlm->mbox_regs + CXLDEV_MBOX_PAYLOAD_OFFSET;
+	void __iomem *payload = cxlm->regs.mbox + CXLDEV_MBOX_PAYLOAD_OFFSET;
 	u64 cmd_reg, status_reg;
 	size_t out_len;
 	int rc;
@@ -314,12 +314,12 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #2, #3 */
-	writeq(cmd_reg, cxlm->mbox_regs + CXLDEV_MBOX_CMD_OFFSET);
+	writeq(cmd_reg, cxlm->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
 
 	/* #4 */
 	dev_dbg(&cxlm->pdev->dev, "Sending command\n");
 	writel(CXLDEV_MBOX_CTRL_DOORBELL,
-	       cxlm->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET);
+	       cxlm->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);
 
 	/* #5 */
 	rc = cxl_mem_wait_for_doorbell(cxlm);
@@ -329,7 +329,7 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #6 */
-	status_reg = readq(cxlm->mbox_regs + CXLDEV_MBOX_STATUS_OFFSET);
+	status_reg = readq(cxlm->regs.mbox + CXLDEV_MBOX_STATUS_OFFSET);
 	mbox_cmd->return_code =
 		FIELD_GET(CXLDEV_MBOX_STATUS_RET_CODE_MASK, status_reg);
 
@@ -339,7 +339,7 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #7 */
-	cmd_reg = readq(cxlm->mbox_regs + CXLDEV_MBOX_CMD_OFFSET);
+	cmd_reg = readq(cxlm->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
 	out_len = FIELD_GET(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK, cmd_reg);
 
 	/* #8 */
@@ -400,7 +400,7 @@ static int cxl_mem_mbox_get(struct cxl_mem *cxlm)
 		goto out;
 	}
 
-	md_status = readq(cxlm->memdev_regs + CXLMDEV_STATUS_OFFSET);
+	md_status = readq(cxlm->regs.memdev + CXLMDEV_STATUS_OFFSET);
 	if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
 		dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
 		rc = -EBUSY;
@@ -868,7 +868,7 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 	int cap, cap_count;
 	u64 cap_array;
 
-	cap_array = readq(cxlm->regs + CXLDEV_CAP_ARRAY_OFFSET);
+	cap_array = readq(cxlm->base + CXLDEV_CAP_ARRAY_OFFSET);
 	if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
 	    CXLDEV_CAP_ARRAY_CAP_ID)
 		return -ENODEV;
@@ -881,25 +881,25 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		u16 cap_id;
 
 		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
-				   readl(cxlm->regs + cap * 0x10));
-		offset = readl(cxlm->regs + cap * 0x10 + 0x4);
-		register_block = cxlm->regs + offset;
+				   readl(cxlm->base + cap * 0x10));
+		offset = readl(cxlm->base + cap * 0x10 + 0x4);
+		register_block = cxlm->base + offset;
 
 		switch (cap_id) {
 		case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
 			dev_dbg(dev, "found Status capability (0x%x)\n", offset);
-			cxlm->status_regs = register_block;
+			cxlm->regs.status = register_block;
 			break;
 		case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
 			dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
-			cxlm->mbox_regs = register_block;
+			cxlm->regs.mbox = register_block;
 			break;
 		case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
 			dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
 			break;
 		case CXLDEV_CAP_CAP_ID_MEMDEV:
 			dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
-			cxlm->memdev_regs = register_block;
+			cxlm->regs.memdev = register_block;
 			break;
 		default:
 			dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
@@ -907,11 +907,11 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		}
 	}
 
-	if (!cxlm->status_regs || !cxlm->mbox_regs || !cxlm->memdev_regs) {
+	if (!cxlm->regs.status || !cxlm->regs.mbox || !cxlm->regs.memdev) {
 		dev_err(dev, "registers not found: %s%s%s\n",
-			!cxlm->status_regs ? "status " : "",
-			!cxlm->mbox_regs ? "mbox " : "",
-			!cxlm->memdev_regs ? "memdev" : "");
+			!cxlm->regs.status ? "status " : "",
+			!cxlm->regs.mbox ? "mbox " : "",
+			!cxlm->regs.memdev ? "memdev" : "");
 		return -ENXIO;
 	}
 
@@ -920,7 +920,7 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 
 static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm)
 {
-	const int cap = readl(cxlm->mbox_regs + CXLDEV_MBOX_CAPS_OFFSET);
+	const int cap = readl(cxlm->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET);
 
 	cxlm->payload_size =
 		1 << FIELD_GET(CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK, cap);
@@ -980,7 +980,7 @@ static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev, u32 reg_lo,
 
 	mutex_init(&cxlm->mbox_mutex);
 	cxlm->pdev = pdev;
-	cxlm->regs = regs + offset;
+	cxlm->base = regs + offset;
 	cxlm->enabled_cmds =
 		devm_kmalloc_array(dev, BITS_TO_LONGS(cxl_cmd_count),
 				   sizeof(unsigned long),
@@ -1495,6 +1495,10 @@ static __init int cxl_mem_init(void)
 	dev_t devt;
 	int rc;
 
+	/* Double check the anonymous union trickery in struct cxl_regs */
+	BUILD_BUG_ON(offsetof(struct cxl_regs, memdev) !=
+		     offsetof(struct cxl_regs, device_regs.memdev));
+
 	rc = alloc_chrdev_region(&devt, 0, CXL_MEM_MAX_DEVS, "cxl");
 	if (rc)
 		return rc;
diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
index daa9aba0e218..c247cf9c71af 100644
--- a/drivers/cxl/mem.h
+++ b/drivers/cxl/mem.h
@@ -53,10 +53,9 @@ struct cxl_memdev {
 /**
  * struct cxl_mem - A CXL memory device
  * @pdev: The PCI device associated with this CXL device.
- * @regs: IO mappings to the device's MMIO
- * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
- * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
- * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
+ * @base: IO mappings to the device's MMIO
+ * @cxlmd: Logical memory device chardev / interface
+ * @regs: Parsed register blocks
  * @payload_size: Size of space for payload
  *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
  * @mbox_mutex: Mutex to synchronize mailbox access.
@@ -67,12 +66,10 @@ struct cxl_memdev {
  */
 struct cxl_mem {
 	struct pci_dev *pdev;
-	void __iomem *regs;
+	void __iomem *base;
 	struct cxl_memdev *cxlmd;
 
-	void __iomem *status_regs;
-	void __iomem *mbox_regs;
-	void __iomem *memdev_regs;
+	struct cxl_regs regs;
 
 	size_t payload_size;
 	struct mutex mbox_mutex; /* Protects device mailbox and firmware */

Re: [PATCH 2/8] cxl/mem: Introduce 'struct cxl_regs'

[Christoph Hellwig]

On Wed, Mar 24, 2021 at 02:30:35PM -0700, Dan Williams wrote:
> In preparation for common register mapping facility, introduce a generic
> container, 'struct cxl_regs', for CXL device register and later
> component register block base pointers. Some CXL device types implement
> both.

The code looks like complete gibberish to me with a struct of a union of
a struct declaring members in a macro.  This needs a much more detailed
explanation and rationale.

Re: [PATCH 2/8] cxl/mem: Introduce 'struct cxl_regs'

[Williams, Dan J]

On Thu, 2021-03-25 at 08:15 +0000, Christoph Hellwig wrote:
> On Wed, Mar 24, 2021 at 02:30:35PM -0700, Dan Williams wrote:
> > In preparation for common register mapping facility, introduce a
> > generic
> > container, 'struct cxl_regs', for CXL device register and later
> > component register block base pointers. Some CXL device types
> > implement
> > both.
> 
> The code looks like complete gibberish to me with a struct of a union of
> a struct declaring members in a macro.  This needs a much more detailed
> explanation and rationale.

Ok, let me know if this makes the rationale clearer and lets this move
ahead. Ben has some follow-on patches that double-down on this
organization, so we want to get this question answered first.

Ben, I kept your reviewed-by, but if the new changelog does not look
quite right feel free to holler.

---

From a5618df78d28a9be6a75d4c1b1cd4e50f6e43297 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@intel.com>
Date: Tue, 9 Feb 2021 00:05:22 -0800
Subject: [PATCH] cxl/mem: Introduce 'struct cxl_regs' for "composable" CXL
 devices

CXL MMIO register blocks are organized by device type and capabilities.
There are Component registers, Device registers (yes, an ambiguous
name), and Memory Device registers (a specific extension of Device
registers).

It is possible for a given device instance (endpoint or port) to
implement register sets from multiple of the above categories.

The driver code that enumerates and maps the registers is type specific
so it is useful to have a dedicated type and helpers for each block
type.

At the same time, once the registers are mapped the origin type does not
matter. It is overly pedantic to reference the register block type in
code that is using the registers.

In preparation for the endpoint driver to incorporate Component registers
into its MMIO operations reorganize the registers to allow typed
enumeration + mapping, but anonymous usage. With the end state of
'struct cxl_regs' to be:

struct cxl_regs {
	union {
		struct {
			CXL_DEVICE_REGS();
		};
		struct cxl_device_regs device_regs;
	};
	union {
		struct {
			CXL_COMPONENT_REGS();
		};
		struct cxl_component_regs component_regs;
	};
};

With this arrangement the driver can share component init code with
ports, but when using the registers it can directly reference the
component register block type by name without the 'component_regs'
prefix.

So, map + enumerate can be shared across drivers of different CXL
classes e.g.:

void cxl_setup_device_regs(struct device *dev, void __iomem *base,
			   struct cxl_device_regs *regs);

void cxl_setup_component_regs(struct device *dev, void __iomem *base,
			      struct cxl_component_regs *regs);

...while inline usage in the driver need not indicate where the
registers came from:

readl(cxlm->regs.mbox + MBOX_OFFSET);
readl(cxlm->regs.hdm + HDM_OFFSET);

...instead of:

readl(cxlm->regs.device_regs.mbox + MBOX_OFFSET);
readl(cxlm->regs.component_regs.hdm + HDM_OFFSET);

This complexity of the definition in .h yields improvement in code
readability in .c while maintaining type-safety for organization of
setup code. It prepares the implementation to maintain organization in
the face of CXL devices that compose register interfaces consisting of
multiple types.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/cxl.h | 33 +++++++++++++++++++++++++++++++++
 drivers/cxl/mem.c | 44 ++++++++++++++++++++++++--------------------
 drivers/cxl/mem.h | 13 +++++--------
 3 files changed, 62 insertions(+), 28 deletions(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 2e3bdacb32e7..37325e504fb7 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -34,5 +34,38 @@
 #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
 #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
 
+/* See note for 'struct cxl_regs' for the rationale of this organization */
+#define CXL_DEVICE_REGS() \
+	void __iomem *status; \
+	void __iomem *mbox; \
+	void __iomem *memdev
+
+/**
+ * struct cxl_device_regs - Common container of CXL Device register
+ * 			    block base pointers
+ * @status: CXL 2.0 8.2.8.3 Device Status Registers
+ * @mbox: CXL 2.0 8.2.8.4 Mailbox Registers
+ * @memdev: CXL 2.0 8.2.8.5 Memory Device Registers
+ */
+struct cxl_device_regs {
+	CXL_DEVICE_REGS();
+};
+
+/*
+ * Note, the anonymous union organization allows for per
+ * register-block-type helper routines, without requiring block-type
+ * agnostic code to include the prefix. I.e.
+ * cxl_setup_device_regs(&cxlm->regs.dev) vs readl(cxlm->regs.mbox).
+ * The specificity reads naturally from left-to-right.
+ */
+struct cxl_regs {
+	union {
+		struct {
+			CXL_DEVICE_REGS();
+		};
+		struct cxl_device_regs device_regs;
+	};
+};
+
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 45871ef65152..6951243d128e 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -31,7 +31,7 @@
  */
 
 #define cxl_doorbell_busy(cxlm)                                                \
-	(readl((cxlm)->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET) &                  \
+	(readl((cxlm)->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET) &                  \
 	 CXLDEV_MBOX_CTRL_DOORBELL)
 
 /* CXL 2.0 - 8.2.8.4 */
@@ -271,7 +271,7 @@ static void cxl_mem_mbox_timeout(struct cxl_mem *cxlm,
 static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 				   struct mbox_cmd *mbox_cmd)
 {
-	void __iomem *payload = cxlm->mbox_regs + CXLDEV_MBOX_PAYLOAD_OFFSET;
+	void __iomem *payload = cxlm->regs.mbox + CXLDEV_MBOX_PAYLOAD_OFFSET;
 	u64 cmd_reg, status_reg;
 	size_t out_len;
 	int rc;
@@ -314,12 +314,12 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #2, #3 */
-	writeq(cmd_reg, cxlm->mbox_regs + CXLDEV_MBOX_CMD_OFFSET);
+	writeq(cmd_reg, cxlm->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
 
 	/* #4 */
 	dev_dbg(&cxlm->pdev->dev, "Sending command\n");
 	writel(CXLDEV_MBOX_CTRL_DOORBELL,
-	       cxlm->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET);
+	       cxlm->regs.mbox + CXLDEV_MBOX_CTRL_OFFSET);
 
 	/* #5 */
 	rc = cxl_mem_wait_for_doorbell(cxlm);
@@ -329,7 +329,7 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #6 */
-	status_reg = readq(cxlm->mbox_regs + CXLDEV_MBOX_STATUS_OFFSET);
+	status_reg = readq(cxlm->regs.mbox + CXLDEV_MBOX_STATUS_OFFSET);
 	mbox_cmd->return_code =
 		FIELD_GET(CXLDEV_MBOX_STATUS_RET_CODE_MASK, status_reg);
 
@@ -339,7 +339,7 @@ static int __cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm,
 	}
 
 	/* #7 */
-	cmd_reg = readq(cxlm->mbox_regs + CXLDEV_MBOX_CMD_OFFSET);
+	cmd_reg = readq(cxlm->regs.mbox + CXLDEV_MBOX_CMD_OFFSET);
 	out_len = FIELD_GET(CXLDEV_MBOX_CMD_PAYLOAD_LENGTH_MASK, cmd_reg);
 
 	/* #8 */
@@ -400,7 +400,7 @@ static int cxl_mem_mbox_get(struct cxl_mem *cxlm)
 		goto out;
 	}
 
-	md_status = readq(cxlm->memdev_regs + CXLMDEV_STATUS_OFFSET);
+	md_status = readq(cxlm->regs.memdev + CXLMDEV_STATUS_OFFSET);
 	if (!(md_status & CXLMDEV_MBOX_IF_READY && CXLMDEV_READY(md_status))) {
 		dev_err(dev, "mbox: reported doorbell ready, but not mbox ready\n");
 		rc = -EBUSY;
@@ -868,7 +868,7 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 	int cap, cap_count;
 	u64 cap_array;
 
-	cap_array = readq(cxlm->regs + CXLDEV_CAP_ARRAY_OFFSET);
+	cap_array = readq(cxlm->base + CXLDEV_CAP_ARRAY_OFFSET);
 	if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
 	    CXLDEV_CAP_ARRAY_CAP_ID)
 		return -ENODEV;
@@ -881,25 +881,25 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		u16 cap_id;
 
 		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
-				   readl(cxlm->regs + cap * 0x10));
-		offset = readl(cxlm->regs + cap * 0x10 + 0x4);
-		register_block = cxlm->regs + offset;
+				   readl(cxlm->base + cap * 0x10));
+		offset = readl(cxlm->base + cap * 0x10 + 0x4);
+		register_block = cxlm->base + offset;
 
 		switch (cap_id) {
 		case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
 			dev_dbg(dev, "found Status capability (0x%x)\n", offset);
-			cxlm->status_regs = register_block;
+			cxlm->regs.status = register_block;
 			break;
 		case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
 			dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
-			cxlm->mbox_regs = register_block;
+			cxlm->regs.mbox = register_block;
 			break;
 		case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
 			dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
 			break;
 		case CXLDEV_CAP_CAP_ID_MEMDEV:
 			dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
-			cxlm->memdev_regs = register_block;
+			cxlm->regs.memdev = register_block;
 			break;
 		default:
 			dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
@@ -907,11 +907,11 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 		}
 	}
 
-	if (!cxlm->status_regs || !cxlm->mbox_regs || !cxlm->memdev_regs) {
+	if (!cxlm->regs.status || !cxlm->regs.mbox || !cxlm->regs.memdev) {
 		dev_err(dev, "registers not found: %s%s%s\n",
-			!cxlm->status_regs ? "status " : "",
-			!cxlm->mbox_regs ? "mbox " : "",
-			!cxlm->memdev_regs ? "memdev" : "");
+			!cxlm->regs.status ? "status " : "",
+			!cxlm->regs.mbox ? "mbox " : "",
+			!cxlm->regs.memdev ? "memdev" : "");
 		return -ENXIO;
 	}
 
@@ -920,7 +920,7 @@ static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 
 static int cxl_mem_setup_mailbox(struct cxl_mem *cxlm)
 {
-	const int cap = readl(cxlm->mbox_regs + CXLDEV_MBOX_CAPS_OFFSET);
+	const int cap = readl(cxlm->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET);
 
 	cxlm->payload_size =
 		1 << FIELD_GET(CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK, cap);
@@ -980,7 +980,7 @@ static struct cxl_mem *cxl_mem_create(struct pci_dev *pdev, u32 reg_lo,
 
 	mutex_init(&cxlm->mbox_mutex);
 	cxlm->pdev = pdev;
-	cxlm->regs = regs + offset;
+	cxlm->base = regs + offset;
 	cxlm->enabled_cmds =
 		devm_kmalloc_array(dev, BITS_TO_LONGS(cxl_cmd_count),
 				   sizeof(unsigned long),
@@ -1495,6 +1495,10 @@ static __init int cxl_mem_init(void)
 	dev_t devt;
 	int rc;
 
+	/* Double check the anonymous union trickery in struct cxl_regs */
+	BUILD_BUG_ON(offsetof(struct cxl_regs, memdev) !=
+		     offsetof(struct cxl_regs, device_regs.memdev));
+
 	rc = alloc_chrdev_region(&devt, 0, CXL_MEM_MAX_DEVS, "cxl");
 	if (rc)
 		return rc;
diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
index daa9aba0e218..c247cf9c71af 100644
--- a/drivers/cxl/mem.h
+++ b/drivers/cxl/mem.h
@@ -53,10 +53,9 @@ struct cxl_memdev {
 /**
  * struct cxl_mem - A CXL memory device
  * @pdev: The PCI device associated with this CXL device.
- * @regs: IO mappings to the device's MMIO
- * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
- * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
- * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
+ * @base: IO mappings to the device's MMIO
+ * @cxlmd: Logical memory device chardev / interface
+ * @regs: Parsed register blocks
  * @payload_size: Size of space for payload
  *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
  * @mbox_mutex: Mutex to synchronize mailbox access.
@@ -67,12 +66,10 @@ struct cxl_memdev {
  */
 struct cxl_mem {
 	struct pci_dev *pdev;
-	void __iomem *regs;
+	void __iomem *base;
 	struct cxl_memdev *cxlmd;
 
-	void __iomem *status_regs;
-	void __iomem *mbox_regs;
-	void __iomem *memdev_regs;
+	struct cxl_regs regs;
 
 	size_t payload_size;
 	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
-- 
2.26.2

[PATCH 3/8] cxl/core: Rename bus.c to core.c

[Dan Williams]

In preparation for more generic shared functionality across endpoint
consumers of core cxl resources, and platform-firmware producers of
those resources, rename bus.c to core.c. In addition to the central
rendezvous for interleave coordination, the core will also define common
routines like CXL register block mapping.

Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 Documentation/driver-api/cxl/memory-devices.rst |    6 ++---
 drivers/cxl/Makefile                            |    4 ++-
 drivers/cxl/bus.c                               |   29 ----------------------
 drivers/cxl/core.c                              |   30 +++++++++++++++++++++++
 4 files changed, 35 insertions(+), 34 deletions(-)
 delete mode 100644 drivers/cxl/bus.c
 create mode 100644 drivers/cxl/core.c

diff --git a/Documentation/driver-api/cxl/memory-devices.rst b/Documentation/driver-api/cxl/memory-devices.rst
index 1bad466f9167..71495ed77069 100644
--- a/Documentation/driver-api/cxl/memory-devices.rst
+++ b/Documentation/driver-api/cxl/memory-devices.rst
@@ -28,10 +28,10 @@ CXL Memory Device
 .. kernel-doc:: drivers/cxl/mem.c
    :internal:
 
-CXL Bus
+CXL Core
 -------
-.. kernel-doc:: drivers/cxl/bus.c
-   :doc: cxl bus
+.. kernel-doc:: drivers/cxl/core.c
+   :doc: cxl core
 
 External Interfaces
 ===================
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index a314a1891f4d..3808e39dd31f 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
-obj-$(CONFIG_CXL_BUS) += cxl_bus.o
+obj-$(CONFIG_CXL_BUS) += cxl_core.o
 obj-$(CONFIG_CXL_MEM) += cxl_mem.o
 
 ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=CXL
-cxl_bus-y := bus.o
+cxl_core-y := core.o
 cxl_mem-y := mem.o
diff --git a/drivers/cxl/bus.c b/drivers/cxl/bus.c
deleted file mode 100644
index 58f74796d525..000000000000
--- a/drivers/cxl/bus.c
+++ /dev/null
@@ -1,29 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
-#include <linux/device.h>
-#include <linux/module.h>
-
-/**
- * DOC: cxl bus
- *
- * The CXL bus provides namespace for control devices and a rendezvous
- * point for cross-device interleave coordination.
- */
-struct bus_type cxl_bus_type = {
-	.name = "cxl",
-};
-EXPORT_SYMBOL_GPL(cxl_bus_type);
-
-static __init int cxl_bus_init(void)
-{
-	return bus_register(&cxl_bus_type);
-}
-
-static void cxl_bus_exit(void)
-{
-	bus_unregister(&cxl_bus_type);
-}
-
-module_init(cxl_bus_init);
-module_exit(cxl_bus_exit);
-MODULE_LICENSE("GPL v2");
diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c
new file mode 100644
index 000000000000..7f8d2034038a
--- /dev/null
+++ b/drivers/cxl/core.c
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
+#include <linux/device.h>
+#include <linux/module.h>
+
+/**
+ * DOC: cxl core
+ *
+ * The CXL core provides a sysfs hierarchy for control devices and a rendezvous
+ * point for cross-device interleave coordination through cxl ports.
+ */
+
+struct bus_type cxl_bus_type = {
+	.name = "cxl",
+};
+EXPORT_SYMBOL_GPL(cxl_bus_type);
+
+static __init int cxl_core_init(void)
+{
+	return bus_register(&cxl_bus_type);
+}
+
+static void cxl_core_exit(void)
+{
+	bus_unregister(&cxl_bus_type);
+}
+
+module_init(cxl_core_init);
+module_exit(cxl_core_exit);
+MODULE_LICENSE("GPL v2");

[PATCH 4/8] cxl/core: Refactor CXL register lookup for bridge reuse

[Dan Williams]

While CXL Memory Device endpoints locate the CXL MMIO registers in a PCI
BAR, CXL root bridges have their MMIO base address described by platform
firmware. Refactor the existing register lookup into a generic facility
for endpoints and bridges to share.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/core.c |   57 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/cxl/cxl.h  |    3 +++
 drivers/cxl/mem.c  |   50 +++++-----------------------------------------
 3 files changed, 65 insertions(+), 45 deletions(-)

diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c
index 7f8d2034038a..2ab467ef9909 100644
--- a/drivers/cxl/core.c
+++ b/drivers/cxl/core.c
@@ -1,7 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0-only
-/* Copyright(c) 2020 Intel Corporation. All rights reserved. */
+/* Copyright(c) 2020-2021 Intel Corporation. All rights reserved. */
 #include <linux/device.h>
 #include <linux/module.h>
+#include "cxl.h"
 
 /**
  * DOC: cxl core
@@ -10,6 +11,60 @@
  * point for cross-device interleave coordination through cxl ports.
  */
 
+/*
+ * cxl_setup_device_regs() - Detect CXL Device register blocks
+ * @dev: Host device of the @base mapping
+ * @base: mapping of CXL 2.0 8.2.8 CXL Device Register Interface
+ */
+void cxl_setup_device_regs(struct device *dev, void __iomem *base,
+			   struct cxl_device_regs *regs)
+{
+	int cap, cap_count;
+	u64 cap_array;
+
+	*regs = (struct cxl_device_regs) { 0 };
+
+	cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
+	if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
+	    CXLDEV_CAP_ARRAY_CAP_ID)
+		return;
+
+	cap_count = FIELD_GET(CXLDEV_CAP_ARRAY_COUNT_MASK, cap_array);
+
+	for (cap = 1; cap <= cap_count; cap++) {
+		void __iomem *register_block;
+		u32 offset;
+		u16 cap_id;
+
+		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
+				   readl(base + cap * 0x10));
+		offset = readl(base + cap * 0x10 + 0x4);
+		register_block = base + offset;
+
+		switch (cap_id) {
+		case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
+			dev_dbg(dev, "found Status capability (0x%x)\n", offset);
+			regs->status = register_block;
+			break;
+		case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
+			dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
+			regs->mbox = register_block;
+			break;
+		case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
+			dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
+			break;
+		case CXLDEV_CAP_CAP_ID_MEMDEV:
+			dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
+			regs->memdev = register_block;
+			break;
+		default:
+			dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
+			break;
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(cxl_setup_device_regs);
+
 struct bus_type cxl_bus_type = {
 	.name = "cxl",
 };
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 37325e504fb7..cbd29650c4e2 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -67,5 +67,8 @@ struct cxl_regs {
 	};
 };
 
+void cxl_setup_device_regs(struct device *dev, void __iomem *base,
+			   struct cxl_device_regs *regs);
+
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 6951243d128e..ee55abfa147e 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -865,53 +865,15 @@ static int cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm, u16 opcode,
 static int cxl_mem_setup_regs(struct cxl_mem *cxlm)
 {
 	struct device *dev = &cxlm->pdev->dev;
-	int cap, cap_count;
-	u64 cap_array;
+	struct cxl_regs *regs = &cxlm->regs;
 
-	cap_array = readq(cxlm->base + CXLDEV_CAP_ARRAY_OFFSET);
-	if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
-	    CXLDEV_CAP_ARRAY_CAP_ID)
-		return -ENODEV;
-
-	cap_count = FIELD_GET(CXLDEV_CAP_ARRAY_COUNT_MASK, cap_array);
-
-	for (cap = 1; cap <= cap_count; cap++) {
-		void __iomem *register_block;
-		u32 offset;
-		u16 cap_id;
-
-		cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
-				   readl(cxlm->base + cap * 0x10));
-		offset = readl(cxlm->base + cap * 0x10 + 0x4);
-		register_block = cxlm->base + offset;
-
-		switch (cap_id) {
-		case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
-			dev_dbg(dev, "found Status capability (0x%x)\n", offset);
-			cxlm->regs.status = register_block;
-			break;
-		case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
-			dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
-			cxlm->regs.mbox = register_block;
-			break;
-		case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
-			dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
-			break;
-		case CXLDEV_CAP_CAP_ID_MEMDEV:
-			dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
-			cxlm->regs.memdev = register_block;
-			break;
-		default:
-			dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
-			break;
-		}
-	}
+	cxl_setup_device_regs(dev, cxlm->base, &regs->device_regs);
 
-	if (!cxlm->regs.status || !cxlm->regs.mbox || !cxlm->regs.memdev) {
+	if (!regs->status || !regs->mbox || !regs->memdev) {
 		dev_err(dev, "registers not found: %s%s%s\n",
-			!cxlm->regs.status ? "status " : "",
-			!cxlm->regs.mbox ? "mbox " : "",
-			!cxlm->regs.memdev ? "memdev" : "");
+			!regs->status ? "status " : "",
+			!regs->mbox ? "mbox " : "",
+			!regs->memdev ? "memdev" : "");
 		return -ENXIO;
 	}
 

Re: [PATCH 4/8] cxl/core: Refactor CXL register lookup for bridge reuse

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 3824 bytes --]

Hi Dan,

I love your patch! Yet something to improve:

[auto build test ERROR on a38fd8748464831584a19438cbb3082b5a2dab15]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/CXL-Port-Enumeration/20210325-053311
base:   a38fd8748464831584a19438cbb3082b5a2dab15
config: arc-randconfig-r014-20210325 (attached as .config)
compiler: arceb-elf-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/0day-ci/linux/commit/efa27967ffcd67a6109c23987e76b9ed2e97ae27
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Dan-Williams/CXL-Port-Enumeration/20210325-053311
        git checkout efa27967ffcd67a6109c23987e76b9ed2e97ae27
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=arc 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   drivers/cxl/core.c: In function 'cxl_setup_device_regs':
>> drivers/cxl/core.c:27:14: error: implicit declaration of function 'readq'; did you mean 'readb'? [-Werror=implicit-function-declaration]
      27 |  cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
         |              ^~~~~
         |              readb
   cc1: some warnings being treated as errors


vim +27 drivers/cxl/core.c

     6	
     7	/**
     8	 * DOC: cxl core
     9	 *
    10	 * The CXL core provides a sysfs hierarchy for control devices and a rendezvous
    11	 * point for cross-device interleave coordination through cxl ports.
    12	 */
    13	
    14	/*
    15	 * cxl_setup_device_regs() - Detect CXL Device register blocks
    16	 * @dev: Host device of the @base mapping
    17	 * @base: mapping of CXL 2.0 8.2.8 CXL Device Register Interface
    18	 */
    19	void cxl_setup_device_regs(struct device *dev, void __iomem *base,
    20				   struct cxl_device_regs *regs)
    21	{
    22		int cap, cap_count;
    23		u64 cap_array;
    24	
    25		*regs = (struct cxl_device_regs) { 0 };
    26	
  > 27		cap_array = readq(base + CXLDEV_CAP_ARRAY_OFFSET);
    28		if (FIELD_GET(CXLDEV_CAP_ARRAY_ID_MASK, cap_array) !=
    29		    CXLDEV_CAP_ARRAY_CAP_ID)
    30			return;
    31	
    32		cap_count = FIELD_GET(CXLDEV_CAP_ARRAY_COUNT_MASK, cap_array);
    33	
    34		for (cap = 1; cap <= cap_count; cap++) {
    35			void __iomem *register_block;
    36			u32 offset;
    37			u16 cap_id;
    38	
    39			cap_id = FIELD_GET(CXLDEV_CAP_HDR_CAP_ID_MASK,
    40					   readl(base + cap * 0x10));
    41			offset = readl(base + cap * 0x10 + 0x4);
    42			register_block = base + offset;
    43	
    44			switch (cap_id) {
    45			case CXLDEV_CAP_CAP_ID_DEVICE_STATUS:
    46				dev_dbg(dev, "found Status capability (0x%x)\n", offset);
    47				regs->status = register_block;
    48				break;
    49			case CXLDEV_CAP_CAP_ID_PRIMARY_MAILBOX:
    50				dev_dbg(dev, "found Mailbox capability (0x%x)\n", offset);
    51				regs->mbox = register_block;
    52				break;
    53			case CXLDEV_CAP_CAP_ID_SECONDARY_MAILBOX:
    54				dev_dbg(dev, "found Secondary Mailbox capability (0x%x)\n", offset);
    55				break;
    56			case CXLDEV_CAP_CAP_ID_MEMDEV:
    57				dev_dbg(dev, "found Memory Device capability (0x%x)\n", offset);
    58				regs->memdev = register_block;
    59				break;
    60			default:
    61				dev_dbg(dev, "Unknown cap ID: %d (0x%x)\n", cap_id, offset);
    62				break;
    63			}
    64		}
    65	}
    66	EXPORT_SYMBOL_GPL(cxl_setup_device_regs);
    67	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

[-- Attachment #2: .config.gz --]
[-- Type: application/gzip, Size: 34792 bytes --]

[PATCH 5/8] cxl/acpi: Introduce ACPI0017 driver and cxl_root

[Dan Williams]

While CXL builds upon the PCI software model for dynamic enumeration and
control, a static platform component is required to bootstrap the CXL
memory layout. In addition to identifying the host bridges ACPI is
responsible for enumerating the CXL memory space that can be addressed
by decoders. This is similar to the requirement for ACPI to publish
resources reported by _CRS for PCI host bridges.

Introduce the cxl_root object as an abstract "port" into the CXL.mem
address space described by HDM decoders identified by the ACPI
CEDT.CHBS.

For now just establish the initial boilerplate and sysfs attributes, to
be followed by enumeration of the ports within the host bridge.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/Kconfig  |   14 ++
 drivers/cxl/Makefile |    2 
 drivers/cxl/acpi.c   |   39 +++++++
 drivers/cxl/core.c   |  285 ++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/cxl.h    |   64 +++++++++++
 5 files changed, 404 insertions(+)
 create mode 100644 drivers/cxl/acpi.c

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index 97dc4d751651..fb282af84afd 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -50,4 +50,18 @@ config CXL_MEM_RAW_COMMANDS
 	  potential impact to memory currently in use by the kernel.
 
 	  If developing CXL hardware or the driver say Y, otherwise say N.
+
+config CXL_ACPI
+	tristate "CXL ACPI: Platform Support"
+	depends on ACPI
+	help
+	  Enable support for host managed device memory (HDM) resources
+	  published by a platform's ACPI CXL memory layout description.
+	  See Chapter 9.14.1 CXL Early Discovery Table (CEDT) in the CXL
+	  2.0 specification. The CXL core consumes these resource to
+	  publish port and address_space objects used to map regions
+	  that represent System RAM, or Persistent Memory regions to be
+	  managed by LIBNVDIMM.
+
+	  If unsure say 'm'.
 endif
diff --git a/drivers/cxl/Makefile b/drivers/cxl/Makefile
index 3808e39dd31f..f429ca6b59d9 100644
--- a/drivers/cxl/Makefile
+++ b/drivers/cxl/Makefile
@@ -1,7 +1,9 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_CXL_BUS) += cxl_core.o
 obj-$(CONFIG_CXL_MEM) += cxl_mem.o
+obj-$(CONFIG_CXL_ACPI) += cxl_acpi.o
 
 ccflags-y += -DDEFAULT_SYMBOL_NAMESPACE=CXL
 cxl_core-y := core.o
 cxl_mem-y := mem.o
+cxl_acpi-y := acpi.o
diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
new file mode 100644
index 000000000000..d54c2d5de730
--- /dev/null
+++ b/drivers/cxl/acpi.c
@@ -0,0 +1,39 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright(c) 2021 Intel Corporation. All rights reserved. */
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/acpi.h>
+#include "cxl.h"
+
+static int cxl_acpi_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct cxl_root *cxl_root;
+
+	cxl_root = devm_cxl_add_root(dev, NULL, 0);
+	if (IS_ERR(cxl_root))
+		return PTR_ERR(cxl_root);
+	dev_dbg(dev, "register: %s\n", dev_name(&cxl_root->port.dev));
+
+	return 0;
+}
+
+static const struct acpi_device_id cxl_acpi_ids[] = {
+	{ "ACPI0017", 0 },
+	{ "", 0 },
+};
+MODULE_DEVICE_TABLE(acpi, cxl_acpi_ids);
+
+static struct platform_driver cxl_acpi_driver = {
+	.probe = cxl_acpi_probe,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.acpi_match_table = cxl_acpi_ids,
+	},
+};
+
+module_platform_driver(cxl_acpi_driver);
+MODULE_LICENSE("GPL v2");
+MODULE_IMPORT_NS(CXL);
diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c
index 2ab467ef9909..07b58cfda392 100644
--- a/drivers/cxl/core.c
+++ b/drivers/cxl/core.c
@@ -2,6 +2,8 @@
 /* Copyright(c) 2020-2021 Intel Corporation. All rights reserved. */
 #include <linux/device.h>
 #include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/idr.h>
 #include "cxl.h"
 
 /**
@@ -11,6 +13,289 @@
  * point for cross-device interleave coordination through cxl ports.
  */
 
+static DEFINE_IDA(cxl_port_ida);
+
+static ssize_t devtype_show(struct device *dev, struct device_attribute *attr,
+			    char *buf)
+{
+	return sysfs_emit(buf, "%s\n", dev->type->name);
+}
+static DEVICE_ATTR_RO(devtype);
+
+static struct attribute *cxl_base_attributes[] = {
+	&dev_attr_devtype.attr,
+	NULL,
+};
+
+static struct attribute_group cxl_base_attribute_group = {
+	.attrs = cxl_base_attributes,
+};
+
+static struct cxl_address_space *dev_to_address_space(struct device *dev)
+{
+	struct cxl_address_space_dev *cxl_asd = to_cxl_address_space(dev);
+
+	return cxl_asd->address_space;
+}
+
+static ssize_t start_show(struct device *dev, struct device_attribute *attr,
+			  char *buf)
+{
+	struct cxl_address_space *space = dev_to_address_space(dev);
+
+	return sysfs_emit(buf, "%#llx\n", space->range.start);
+}
+static DEVICE_ATTR_RO(start);
+
+static ssize_t end_show(struct device *dev, struct device_attribute *attr,
+			char *buf)
+{
+	struct cxl_address_space *space = dev_to_address_space(dev);
+
+	return sysfs_emit(buf, "%#llx\n", space->range.end);
+}
+static DEVICE_ATTR_RO(end);
+
+#define CXL_ATTR_SUPPORTS(name, flag)                                  \
+static ssize_t supports_##name##_show(                                 \
+	struct device *dev, struct device_attribute *attr, char *buf)  \
+{                                                                      \
+	struct cxl_address_space *space = dev_to_address_space(dev);   \
+                                                                       \
+	return sysfs_emit(buf, "%s\n",                                 \
+			  (space->flags & (flag)) ? "1" : "0");        \
+}                                                                      \
+static DEVICE_ATTR_RO(supports_##name)
+
+CXL_ATTR_SUPPORTS(pmem, CXL_ADDRSPACE_PMEM);
+CXL_ATTR_SUPPORTS(ram, CXL_ADDRSPACE_RAM);
+CXL_ATTR_SUPPORTS(type2, CXL_ADDRSPACE_TYPE2);
+CXL_ATTR_SUPPORTS(type3, CXL_ADDRSPACE_TYPE3);
+
+static struct attribute *cxl_address_space_attributes[] = {
+	&dev_attr_start.attr,
+	&dev_attr_end.attr,
+	&dev_attr_supports_pmem.attr,
+	&dev_attr_supports_ram.attr,
+	&dev_attr_supports_type2.attr,
+	&dev_attr_supports_type3.attr,
+	NULL,
+};
+
+static umode_t cxl_address_space_visible(struct kobject *kobj,
+					 struct attribute *a, int n)
+{
+	struct device *dev = container_of(kobj, struct device, kobj);
+	struct cxl_address_space *space = dev_to_address_space(dev);
+
+	if (a == &dev_attr_supports_pmem.attr &&
+	    !(space->flags & CXL_ADDRSPACE_PMEM))
+		return 0;
+
+	if (a == &dev_attr_supports_ram.attr &&
+	    !(space->flags & CXL_ADDRSPACE_RAM))
+		return 0;
+
+	if (a == &dev_attr_supports_type2.attr &&
+	    !(space->flags & CXL_ADDRSPACE_TYPE2))
+		return 0;
+
+	if (a == &dev_attr_supports_type3.attr &&
+	    !(space->flags & CXL_ADDRSPACE_TYPE3))
+		return 0;
+
+	return a->mode;
+}
+
+static struct attribute_group cxl_address_space_attribute_group = {
+	.attrs = cxl_address_space_attributes,
+	.is_visible = cxl_address_space_visible,
+};
+
+static const struct attribute_group *cxl_address_space_attribute_groups[] = {
+	&cxl_address_space_attribute_group,
+	&cxl_base_attribute_group,
+	NULL,
+};
+
+static void cxl_address_space_release(struct device *dev)
+{
+	struct cxl_address_space_dev *cxl_asd = to_cxl_address_space(dev);
+
+	remove_resource(&cxl_asd->res);
+	kfree(cxl_asd);
+}
+
+static const struct device_type cxl_address_space_type = {
+	.name = "cxl_address_space",
+	.release = cxl_address_space_release,
+	.groups = cxl_address_space_attribute_groups,
+};
+
+struct cxl_address_space_dev *to_cxl_address_space(struct device *dev)
+{
+	if (dev_WARN_ONCE(dev, dev->type != &cxl_address_space_type,
+			  "not a cxl_address_space device\n"))
+		return NULL;
+	return container_of(dev, struct cxl_address_space_dev, dev);
+}
+
+static void cxl_root_release(struct device *dev)
+{
+	struct cxl_root *cxl_root = to_cxl_root(dev);
+
+	ida_free(&cxl_port_ida, cxl_root->port.id);
+	kfree(cxl_root);
+}
+
+static ssize_t target_id_show(struct device *dev, struct device_attribute *attr,
+			      char *buf)
+{
+	struct cxl_port *cxl_port = to_cxl_port(dev);
+
+	return sysfs_emit(buf, "%d\n", cxl_port->target_id);
+}
+static DEVICE_ATTR_RO(target_id);
+
+static struct attribute *cxl_port_attributes[] = {
+	&dev_attr_target_id.attr,
+	NULL,
+};
+
+static struct attribute_group cxl_port_attribute_group = {
+	.attrs = cxl_port_attributes,
+};
+
+static const struct attribute_group *cxl_port_attribute_groups[] = {
+	&cxl_port_attribute_group,
+	&cxl_base_attribute_group,
+	NULL,
+};
+
+static const struct device_type cxl_root_type = {
+	.name = "cxl_root",
+	.release = cxl_root_release,
+	.groups = cxl_port_attribute_groups,
+};
+
+struct cxl_root *to_cxl_root(struct device *dev)
+{
+	if (dev_WARN_ONCE(dev, dev->type != &cxl_root_type,
+			  "not a cxl_root device\n"))
+		return NULL;
+	return container_of(dev, struct cxl_root, port.dev);
+}
+
+struct cxl_port *to_cxl_port(struct device *dev)
+{
+	if (dev_WARN_ONCE(dev, dev->type != &cxl_root_type,
+			  "not a cxl_port device\n"))
+		return NULL;
+	return container_of(dev, struct cxl_port, dev);
+}
+
+static void unregister_dev(void *dev)
+{
+	device_unregister(dev);
+}
+
+struct cxl_root *devm_cxl_add_root(struct device *parent,
+				   struct cxl_address_space *cxl_space,
+				   int nr_spaces)
+{
+	struct cxl_root *cxl_root;
+	struct cxl_port *port;
+	struct device *dev;
+	int i, rc;
+
+	cxl_root = kzalloc(struct_size(cxl_root, address_space, nr_spaces),
+			   GFP_KERNEL);
+	if (!cxl_root)
+		return ERR_PTR(-ENOMEM);
+
+	memcpy(cxl_root->address_space, cxl_space,
+	       flex_array_size(cxl_root, address_space, nr_spaces));
+	cxl_root->nr_spaces = nr_spaces;
+
+	rc = ida_alloc(&cxl_port_ida, GFP_KERNEL);
+	if (rc < 0) {
+		kfree(cxl_root);
+		return ERR_PTR(rc);
+	}
+	port = &cxl_root->port;
+	port->id = rc;
+
+	dev = &port->dev;
+	device_initialize(dev);
+	device_set_pm_not_required(dev);
+	dev->parent = parent;
+	dev->bus = &cxl_bus_type;
+	dev->type = &cxl_root_type;
+
+	rc = dev_set_name(dev, "root%d", port->id);
+	if (rc == 0)
+		rc = device_add(dev);
+
+	if (rc) {
+		put_device(dev);
+		return ERR_PTR(rc);
+	}
+
+	rc = devm_add_action_or_reset(parent, unregister_dev, dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	for (i = 0; i < nr_spaces; i++) {
+		struct cxl_address_space *space = &cxl_root->address_space[i];
+		struct cxl_address_space_dev *cxl_asd;
+		struct resource *res;
+
+		if (!range_len(&space->range))
+			continue;
+
+		cxl_asd = kzalloc(sizeof(*cxl_asd), GFP_KERNEL);
+		if (!cxl_asd)
+			return ERR_PTR(-ENOMEM);
+
+		res = &cxl_asd->res;
+		res->name = "CXL Address Space";
+		res->start = space->range.start;
+		res->end = space->range.end;
+		res->flags = IORESOURCE_MEM;
+
+		rc = insert_resource(&iomem_resource, res);
+		if (rc) {
+			kfree(cxl_asd);
+			return ERR_PTR(rc);
+		}
+
+		cxl_asd->address_space = space;
+		dev = &cxl_asd->dev;
+		device_initialize(dev);
+		device_set_pm_not_required(dev);
+		dev->parent = &port->dev;
+		dev->type = &cxl_address_space_type;
+
+		rc = dev_set_name(dev, "address_space%d", i);
+		if (rc == 0)
+			rc = device_add(dev);
+
+		if (rc) {
+			put_device(dev);
+			return ERR_PTR(rc);
+		}
+		dev_dbg(parent, "%s: register %s\n", dev_name(&port->dev),
+			dev_name(dev));
+
+		rc = devm_add_action_or_reset(parent, unregister_dev, dev);
+		if (rc)
+			return ERR_PTR(rc);
+	}
+
+	return cxl_root;
+}
+EXPORT_SYMBOL_GPL(devm_cxl_add_root);
+
 /*
  * cxl_setup_device_regs() - Detect CXL Device register blocks
  * @dev: Host device of the @base mapping
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index cbd29650c4e2..f1a2271cfbb5 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -70,5 +70,69 @@ struct cxl_regs {
 void cxl_setup_device_regs(struct device *dev, void __iomem *base,
 			   struct cxl_device_regs *regs);
 
+/*
+ * Address space properties derived from:
+ * CXL 2.0 8.2.5.12.7 CXL HDM Decoder 0 Control Register
+ */
+#define CXL_ADDRSPACE_RAM   BIT(0)
+#define CXL_ADDRSPACE_PMEM  BIT(1)
+#define CXL_ADDRSPACE_TYPE2 BIT(2)
+#define CXL_ADDRSPACE_TYPE3 BIT(3)
+#define CXL_ADDRSPACE_MASK  GENMASK(3, 0)
+
+struct cxl_address_space {
+	struct range range;
+	int interleave_size;
+	unsigned long flags;
+	unsigned long targets;
+};
+
+struct cxl_address_space_dev {
+	struct device dev;
+	struct resource res;
+	struct cxl_address_space *address_space;
+};
+
+/**
+ * struct cxl_port - object representing a root, upstream, or downstream port
+ * @dev: this port's device
+ * @port_dev: PCI or platform device host of the CXL capability
+ * @id: id for port device-name
+ * @target_id: this port's HDM decoder id in the parent port
+ * @regs: hardware registers
+ */
+struct cxl_port {
+	struct device dev;
+	struct device *port_dev;
+	int id;
+	int target_id;
+	struct cxl_regs *regs;
+};
+
+/*
+ * struct cxl_root - platform object parent of CXL host bridges
+ *
+ * A cxl_root object represents a set of address spaces that are
+ * interleaved across a set of child host bridges, but never interleaved
+ * to another cxl_root object. It contains a cxl_port that is a special
+ * case in that it does not have a parent port and related HDMs, instead
+ * its decode is derived from the root (platform firmware defined)
+ * address space description. Not to be confused with CXL Root Ports
+ * that are the PCIE Root Ports within PCIE Host Bridges that are
+ * flagged by platform firmware (ACPI0016 on ACPI platforms) as having
+ * CXL capabilities.
+ */
+struct cxl_root {
+	struct cxl_port port;
+	int nr_spaces;
+	struct cxl_address_space address_space[];
+};
+
+struct cxl_root *to_cxl_root(struct device *dev);
+struct cxl_port *to_cxl_port(struct device *dev);
+struct cxl_address_space_dev *to_cxl_address_space(struct device *dev);
+struct cxl_root *devm_cxl_add_root(struct device *parent,
+				   struct cxl_address_space *cxl_space,
+				   int nr_spaces);
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */

[PATCH 6/8] cxl/Kconfig: Default drivers to CONFIG_CXL_BUS

[Dan Williams]

CONFIG_CXL_BUS is default 'n' as expected for new functionality. When
that is enabled do not make the end user hunt for all the expected
sub-options to enable. For example CONFIG_CXL_BUS without CONFIG_CXL_MEM
is an odd/expert configuration, so is CONFIG_CXL_MEM without
CONFIG_CXL_ACPI (on ACPI capable platforms). Default CONFIG_CXL_MEM and
CONFIG_CXL_ACPI to CONFIG_CXL_BUS.

Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/Kconfig |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/cxl/Kconfig b/drivers/cxl/Kconfig
index fb282af84afd..1da7970a5e55 100644
--- a/drivers/cxl/Kconfig
+++ b/drivers/cxl/Kconfig
@@ -15,6 +15,7 @@ if CXL_BUS
 
 config CXL_MEM
 	tristate "CXL.mem: Memory Devices"
+	default CXL_BUS
 	help
 	  The CXL.mem protocol allows a device to act as a provider of
 	  "System RAM" and/or "Persistent Memory" that is fully coherent
@@ -54,6 +55,7 @@ config CXL_MEM_RAW_COMMANDS
 config CXL_ACPI
 	tristate "CXL ACPI: Platform Support"
 	depends on ACPI
+	default CXL_BUS
 	help
 	  Enable support for host managed device memory (HDM) resources
 	  published by a platform's ACPI CXL memory layout description.

[PATCH 7/8] cxl/port: Introduce cxl_port objects

[Dan Williams]

Once the cxl_root is established then other ports in the hierarchy can
be attached. The cxl_port object, unlike cxl_root that is associated
with host bridges, is associated with PCIE Root Ports or PCIE Switch
Ports. Add cxl_port instances for all PCIE Root Ports in an ACPI0016
host bridge. The cxl_port instances for PCIE Switch Ports are not
included here as those are to be modeled as another service device
registered on the pcie_port_bus_type.

A sample sysfs topology for a single-host-bridge with
single-PCIE/CXL-root-port:

/sys/bus/cxl/devices/root0
├── address_space0
│   ├── devtype
│   ├── end
│   ├── start
│   ├── supports_ram
│   ├── supports_type2
│   ├── supports_type3
│   └── uevent
├── address_space1
│   ├── devtype
│   ├── end
│   ├── start
│   ├── supports_pmem
│   ├── supports_type2
│   ├── supports_type3
│   └── uevent
├── devtype
├── port1
│   ├── devtype
│   ├── host -> ../../../../LNXSYSTM:00/LNXSYBUS:00/ACPI0016:00
│   ├── port2
│   │   ├── devtype
│   │   ├── host -> ../../../../../pci0000:34/0000:34:00.0
│   │   ├── subsystem -> ../../../../../../bus/cxl
│   │   ├── target_id
│   │   └── uevent
│   ├── subsystem -> ../../../../../bus/cxl
│   ├── target_id
│   └── uevent
├── subsystem -> ../../../../bus/cxl
├── target_id
└── uevent

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/acpi.c |   99 +++++++++++++++++++++++++++++++++++++++++++++++++++
 drivers/cxl/core.c |  100 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 drivers/cxl/cxl.h  |    5 +++
 3 files changed, 203 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index d54c2d5de730..bc2a35ae880b 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -5,18 +5,117 @@
 #include <linux/device.h>
 #include <linux/kernel.h>
 #include <linux/acpi.h>
+#include <linux/pci.h>
 #include "cxl.h"
 
+static int match_ACPI0016(struct device *dev, const void *host)
+{
+	struct acpi_device *adev = to_acpi_device(dev);
+	const char *hid = acpi_device_hid(adev);
+
+	return strcmp(hid, "ACPI0016") == 0;
+}
+
+struct cxl_walk_context {
+	struct device *dev;
+	struct pci_bus *root;
+	struct cxl_port *port;
+	int error;
+	int count;
+};
+
+static int match_add_root_ports(struct pci_dev *pdev, void *data)
+{
+	struct cxl_walk_context *ctx = data;
+	struct pci_bus *root_bus = ctx->root;
+	struct cxl_port *port = ctx->port;
+	int type = pci_pcie_type(pdev);
+	struct device *dev = ctx->dev;
+	resource_size_t cxl_regs_phys;
+	int target_id = ctx->count;
+
+	if (pdev->bus != root_bus)
+		return 0;
+	if (!pci_is_pcie(pdev))
+		return 0;
+	if (type != PCI_EXP_TYPE_ROOT_PORT)
+		return 0;
+
+	ctx->count++;
+
+	/* TODO walk DVSEC to find component register base */
+	cxl_regs_phys = -1;
+
+	port = devm_cxl_add_port(dev, port, &pdev->dev, target_id,
+				 cxl_regs_phys);
+	if (IS_ERR(port)) {
+		ctx->error = PTR_ERR(port);
+		return ctx->error;
+	}
+
+	dev_dbg(dev, "%s: register: %s\n", dev_name(&pdev->dev),
+		dev_name(&port->dev));
+
+	return 0;
+}
+
+/*
+ * A host bridge may contain one or more root ports.  Register each port
+ * as a child of the cxl_root.
+ */
+static int cxl_acpi_register_ports(struct device *dev, struct acpi_device *root,
+				   struct cxl_port *port, int idx)
+{
+	struct acpi_pci_root *pci_root = acpi_pci_find_root(root->handle);
+	struct cxl_walk_context ctx;
+
+	if (!pci_root)
+		return -ENXIO;
+
+	/* TODO: fold in CEDT.CHBS retrieval */
+	port = devm_cxl_add_port(dev, port, &root->dev, idx, ~0ULL);
+	if (IS_ERR(port))
+		return PTR_ERR(port);
+	dev_dbg(dev, "%s: register: %s\n", dev_name(&root->dev),
+		dev_name(&port->dev));
+
+	ctx = (struct cxl_walk_context) {
+		.dev = dev,
+		.root = pci_root->bus,
+		.port = port,
+	};
+	pci_walk_bus(pci_root->bus, match_add_root_ports, &ctx);
+
+	if (ctx.count == 0)
+		return -ENODEV;
+	return ctx.error;
+}
+
 static int cxl_acpi_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct acpi_device *adev = ACPI_COMPANION(dev);
+	struct device *bridge = NULL;
 	struct cxl_root *cxl_root;
+	int rc, i = 0;
 
 	cxl_root = devm_cxl_add_root(dev, NULL, 0);
 	if (IS_ERR(cxl_root))
 		return PTR_ERR(cxl_root);
 	dev_dbg(dev, "register: %s\n", dev_name(&cxl_root->port.dev));
 
+	while (true) {
+		bridge = bus_find_device(adev->dev.bus, bridge, dev,
+					 match_ACPI0016);
+		if (!bridge)
+			break;
+
+		rc = cxl_acpi_register_ports(dev, to_acpi_device(bridge),
+					     &cxl_root->port, i++);
+		if (rc)
+			return rc;
+	}
+
 	return 0;
 }
 
diff --git a/drivers/cxl/core.c b/drivers/cxl/core.c
index 07b58cfda392..9beb6855e7f6 100644
--- a/drivers/cxl/core.c
+++ b/drivers/cxl/core.c
@@ -148,6 +148,15 @@ static void cxl_root_release(struct device *dev)
 	kfree(cxl_root);
 }
 
+static void cxl_port_release(struct device *dev)
+{
+	struct cxl_port *port = to_cxl_port(dev);
+
+	ida_free(&cxl_port_ida, port->id);
+	put_device(port->port_dev);
+	kfree(port);
+}
+
 static ssize_t target_id_show(struct device *dev, struct device_attribute *attr,
 			      char *buf)
 {
@@ -178,6 +187,12 @@ static const struct device_type cxl_root_type = {
 	.groups = cxl_port_attribute_groups,
 };
 
+static const struct device_type cxl_port_type = {
+	.name = "cxl_port",
+	.release = cxl_port_release,
+	.groups = cxl_port_attribute_groups,
+};
+
 struct cxl_root *to_cxl_root(struct device *dev)
 {
 	if (dev_WARN_ONCE(dev, dev->type != &cxl_root_type,
@@ -188,7 +203,9 @@ struct cxl_root *to_cxl_root(struct device *dev)
 
 struct cxl_port *to_cxl_port(struct device *dev)
 {
-	if (dev_WARN_ONCE(dev, dev->type != &cxl_root_type,
+	if (dev_WARN_ONCE(dev,
+			  dev->type != &cxl_root_type &&
+			  dev->type != &cxl_port_type,
 			  "not a cxl_port device\n"))
 		return NULL;
 	return container_of(dev, struct cxl_port, dev);
@@ -296,6 +313,87 @@ struct cxl_root *devm_cxl_add_root(struct device *parent,
 }
 EXPORT_SYMBOL_GPL(devm_cxl_add_root);
 
+static void cxl_unlink_port(void *_port)
+{
+	struct cxl_port *port = _port;
+
+	sysfs_remove_link(&port->dev.kobj, "host");
+}
+
+static int devm_cxl_link_port(struct device *dev, struct cxl_port *port)
+{
+	int rc;
+
+	rc = sysfs_create_link(&port->dev.kobj, &port->port_dev->kobj, "host");
+	if (rc)
+		return rc;
+	return devm_add_action_or_reset(dev, cxl_unlink_port, port);
+}
+
+/**
+ * devm_cxl_add_port() - add a cxl_port to the topology
+ * @parent: devm context / discovery agent
+ * @upstream_port: port parent
+ * @port_dev: device hosting this port
+ * @target_id: if there are port siblings, local id
+ * @cxl_regs_phys: CXL component register base address
+ */
+struct cxl_port *devm_cxl_add_port(struct device *parent,
+				   struct cxl_port *upstream_port,
+				   struct device *port_dev, int target_id,
+				   resource_size_t cxl_regs_phys)
+{
+	struct cxl_port *port;
+	struct device *dev;
+	int rc;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return ERR_PTR(-ENOMEM);
+
+	rc = ida_alloc(&cxl_port_ida, GFP_KERNEL);
+	if (rc < 0)
+		goto err_id;
+	port->id = rc;
+
+	port->port_dev = get_device(port_dev);
+	if (!port->port_dev)
+		goto err_port_dev;
+
+	dev = &port->dev;
+	device_initialize(dev);
+	device_set_pm_not_required(dev);
+	dev->parent = &upstream_port->dev;
+	dev->bus = &cxl_bus_type;
+	dev->type = &cxl_port_type;
+
+	rc = dev_set_name(dev, "port%d", port->id);
+	if (rc == 0)
+		rc = device_add(dev);
+
+	if (rc) {
+		put_device(dev);
+		return ERR_PTR(rc);
+	}
+
+	rc = devm_add_action_or_reset(parent, unregister_dev, dev);
+	if (rc)
+		return ERR_PTR(rc);
+
+	rc = devm_cxl_link_port(parent, port);
+	if (rc)
+		return ERR_PTR(rc);
+
+	return port;
+
+err_port_dev:
+	ida_free(&cxl_port_ida, port->id);
+err_id:
+	kfree(port);
+	return ERR_PTR(rc);
+}
+EXPORT_SYMBOL_GPL(devm_cxl_add_port);
+
 /*
  * cxl_setup_device_regs() - Detect CXL Device register blocks
  * @dev: Host device of the @base mapping
diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f1a2271cfbb5..14e64b87baba 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -134,5 +134,10 @@ struct cxl_address_space_dev *to_cxl_address_space(struct device *dev);
 struct cxl_root *devm_cxl_add_root(struct device *parent,
 				   struct cxl_address_space *cxl_space,
 				   int nr_spaces);
+struct cxl_port *devm_cxl_add_port(struct device *parent,
+				   struct cxl_port *upstream_port,
+				   struct device *port_dev, int target_id,
+				   resource_size_t cxl_regs_phys);
+
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */

[PATCH 8/8] cxl/acpi: Add module parameters to stand in for ACPI tables

[Dan Williams]

[debug / to-be-replaced / not-for-upstream]

Given ACPICA support is needed before drivers can integrate ACPI
functionality add some module parameters as proxies.
---
 drivers/cxl/acpi.c |   81 +++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 2 deletions(-)

diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
index bc2a35ae880b..2a48a728f3e0 100644
--- a/drivers/cxl/acpi.c
+++ b/drivers/cxl/acpi.c
@@ -4,10 +4,84 @@
 #include <linux/module.h>
 #include <linux/device.h>
 #include <linux/kernel.h>
+#include <linux/range.h>
 #include <linux/acpi.h>
 #include <linux/pci.h>
 #include "cxl.h"
 
+/*
+ * TODO: Replace all of the below module parameters with ACPI CXL
+ * resource descriptions once ACPICA makes them available.
+ */
+static unsigned long chbcr[4];
+module_param_named(chbcr0, chbcr[0], ulong, 0400);
+module_param_named(chbcr1, chbcr[1], ulong, 0400);
+module_param_named(chbcr2, chbcr[2], ulong, 0400);
+module_param_named(chbcr3, chbcr[3], ulong, 0400);
+
+/* TODO: cross-bridge interleave */
+static struct cxl_address_space cxl_space[] = {
+	[0] = { .range = { 0, -1 }, .targets = 0x1, },
+	[1] = { .range = { 0, -1 }, .targets = 0x1, },
+	[2] = { .range = { 0, -1 }, .targets = 0x1, },
+	[3] = { .range = { 0, -1 }, .targets = 0x1, },
+};
+
+static int set_range(const char *val, const struct kernel_param *kp)
+{
+	unsigned long long size, base;
+	struct cxl_address_space *space;
+	unsigned long flags;
+	char *p;
+	int rc;
+
+	size = memparse(val, &p);
+	if (*p != '@')
+		return -EINVAL;
+
+	base = memparse(p + 1, &p);
+	if (*p != ':')
+		return -EINVAL;
+
+	rc = kstrtoul(p + 1, 0, &flags);
+	if (rc)
+		return rc;
+	if (!flags || flags > CXL_ADDRSPACE_MASK)
+		return rc;
+
+	space = kp->arg;
+	*space = (struct cxl_address_space) {
+		.range = {
+			.start = base,
+			.end = base + size - 1,
+		},
+		.flags = flags,
+	};
+
+	return 0;
+}
+
+static int get_range(char *buf, const struct kernel_param *kp)
+{
+	struct cxl_address_space *space = kp->arg;
+
+	if (!range_len(&space->range))
+		return -EINVAL;
+
+	return sysfs_emit(buf, "%#llx@%#llx :%s%s%s%s\n",
+			  (unsigned long long)range_len(&space->range),
+			  (unsigned long long)space->range.start,
+			  space->flags & CXL_ADDRSPACE_RAM ? " ram" : "",
+			  space->flags & CXL_ADDRSPACE_PMEM ? " pmem" : "",
+			  space->flags & CXL_ADDRSPACE_TYPE2 ? " type2" : "",
+			  space->flags & CXL_ADDRSPACE_TYPE3 ? " type3" : "");
+}
+
+module_param_call(range0, set_range, get_range, &cxl_space[0], 0400);
+module_param_call(range1, set_range, get_range, &cxl_space[1], 0400);
+module_param_call(range2, set_range, get_range, &cxl_space[2], 0400);
+module_param_call(range3, set_range, get_range, &cxl_space[3], 0400);
+
 static int match_ACPI0016(struct device *dev, const void *host)
 {
 	struct acpi_device *adev = to_acpi_device(dev);
@@ -67,13 +141,16 @@ static int cxl_acpi_register_ports(struct device *dev, struct acpi_device *root,
 				   struct cxl_port *port, int idx)
 {
 	struct acpi_pci_root *pci_root = acpi_pci_find_root(root->handle);
+	resource_size_t chbcr_base = ~0ULL;
 	struct cxl_walk_context ctx;
 
 	if (!pci_root)
 		return -ENXIO;
 
 	/* TODO: fold in CEDT.CHBS retrieval */
-	port = devm_cxl_add_port(dev, port, &root->dev, idx, ~0ULL);
+	if (idx < ARRAY_SIZE(chbcr))
+		chbcr_base = chbcr[idx];
+	port = devm_cxl_add_port(dev, port, &root->dev, idx, chbcr_base);
 	if (IS_ERR(port))
 		return PTR_ERR(port);
 	dev_dbg(dev, "%s: register: %s\n", dev_name(&root->dev),
@@ -99,7 +176,7 @@ static int cxl_acpi_probe(struct platform_device *pdev)
 	struct cxl_root *cxl_root;
 	int rc, i = 0;
 
-	cxl_root = devm_cxl_add_root(dev, NULL, 0);
+	cxl_root = devm_cxl_add_root(dev, cxl_space, ARRAY_SIZE(cxl_space));
 	if (IS_ERR(cxl_root))
 		return PTR_ERR(cxl_root);
 	dev_dbg(dev, "register: %s\n", dev_name(&cxl_root->port.dev));

[PATCH v3 0/8] CXL Port Enumeration and Plans for v5.14

[Dan Williams]

Changes since v2 [1]:
- Add some rationale for moving definitions out of mem.c into mem.h
  (Jonathan)

- Fixup CXL_DEVICE_REGS kernel doc and declare the fixup for the
  struct cxl_mem kernel-doc in the changelog (Jonathan)

- Fixup cxl_setup_device_regs() kernel-doc (Jonathan)

- Cleanup comment in cxl_root_alloc() (Jonathan)

- [not changed] refactor device creation into alloc_and_add()
  anti-pattern.

- Add kernel doc to cxl_address_space_dev_add() to clarify why @host is
  needed as an arg. (Jonathan)

- Describe what the port devices are representing in "cxl/port:
  Introduce cxl_port objects" (Jonathan)

- Explain the rationale for /sys/bus/cxl (Bjorn)

[1]: http://lore.kernel.org/r/161728744224.2474040.12854720917440712854.stgit@dwillia2-desk3.amr.corp.intel.com

---

Plans for v5.14:

This series is a starting point for the persistent memory and dynamic
HDM decoder manipulation support targeting the v5.14 kernel. Among the
tasks to complete in that timeframe are:

- Region creation including CXL label support
- LIBNVDIMM integration for surfacing /dev/pmemX and /dev/daxX.Y devices
  on CXL resources
- HDM decoder enumeration and programming for setting up PMEM mappings
  alongside any "System RAM" mappings established by platform firmware
- CDAT-DOE support in support of dynamically created NUMA nodes
- CXL PMEM Shutdown semantics (global persistence flush coordination)

Contributions to cxl.git targeting the next merge window require a
non-author Reviewed-by. A patch with a Reviewed-by, no outstanding
objections, and a 3-5 day quiet period on the list is subject to be
applied to a non-rebasing cxl.git branch and merged into cxl.git/next.
Contributions targeting a current -rc (fixes) may go in on an expedited
schedule with only an Acked-by.

---

CXL Port Topology:

The enumeration starts with the ACPI0017 driver registering a 'struct
cxl_root' object to establish the top of a cxl_port topology. It then
scans the ACPI bus looking for ACPI0016 instances. The cxl_root object
is a singleton* anchor to hang "address-space" objects and be a parent
device for the downstream 'struct cxl_port' instances. An address-space
has a 1:1 relationship with a platform defined memory resource range,
like _CRS for PCIE Host Bridges. Use module parameters to model a
root-level HDM decoder that all downstream ports further decode, to be
replaced with a Code First ECN to do the same.

Each address space is modeled as a sysfs object that also shows up in
/proc/iomem as "CXL Address Space". That iomem resource is functionally
equivalent to the root-level 'PCI Bus' resources for PCIE.mmio while
'CXL Address Space' indicates space for CXL.mem to be mapped. "System
RAM" and "Persistent Memory", when mapped by HDM decoders, will appear
as child CXL.mem resources.

Once a 'struct cxl_root' is established the host bridge is modeled as 1
upstream 'struct cxl_port' and N downstream 'struct cxl_port' instances
(one per Root Port), just like a PCIE switch. The host-bridge upstream
port optionally has the HDM decoder registers from the CHBCR if the
host-bridge has multiple PCIE/CXL root ports. Single-ported host bridges
will not have HDM decoders in the CHBCR space (see CHBCR note in
8.2.5.12 CXL HDM Decoder Capability Structure), but the 'struct
cxl_port' object is still needed to represent other CXL capabilities and
access port-specific component registers outside of HDM decoders.

Each 'struct cxl_port' has a 'target_id' attribute that answers the
question "what port am I in my upstream port's HDM decoder target
list?". For the host-bridge struct cxl_port, the first tier of ports
below cxl_root.port, the id is derived from the ordinal mapping of the
ACPI0016 id (instance id, _UID, or other handle TBD), for all other
ports the id is the PCIE Root Port ID from the Link Capabilities
register [1]. The mapping of ordinal port identifiers relative to their
parent may change once libcxl and cxl-cli prove out region creation, or
a better option is found to establish a static device path / persistent
naming scheme. System software must not assume that 'struct cxl_port'
device names will be static from one boot to the next.

See patch7 for a tree(1) topology picture of what QEMU is producing
today with this enabling.

* cxl_root is singleton only by convention. A given cxl_root could
  represent 1 to N address spaces, this patch set chooses to implement 1
  cxl_root for all address spaces.

[1]: CXL 2.0 8.2.5.12.8 CXL HDM Decoder 0 Target List Low Register
     (Offset 24h) ...The Target Port Identifier for a given Downstream Port
     is reported via Port Number field in Link Capabilities Register. (See
     PCI Express Base Specification).

---

Dan Williams (8):
      cxl/mem: Move some definitions to mem.h
      cxl/mem: Introduce 'struct cxl_regs' for "composable" CXL devices
      cxl/core: Rename bus.c to core.c
      cxl/core: Refactor CXL register lookup for bridge reuse
      cxl/acpi: Introduce ACPI0017 driver and cxl_root
      cxl/Kconfig: Default drivers to CONFIG_CXL_BUS
      cxl/port: Introduce cxl_port objects
      cxl/acpi: Add module parameters to stand in for ACPI tables


 Documentation/driver-api/cxl/memory-devices.rst |    6 
 drivers/cxl/Kconfig                             |   16 +
 drivers/cxl/Makefile                            |    6 
 drivers/cxl/acpi.c                              |  215 +++++++++
 drivers/cxl/bus.c                               |   29 -
 drivers/cxl/core.c                              |  561 +++++++++++++++++++++++
 drivers/cxl/cxl.h                               |  148 ++++--
 drivers/cxl/mem.c                               |   97 +---
 drivers/cxl/mem.h                               |   82 +++
 9 files changed, 999 insertions(+), 161 deletions(-)
 create mode 100644 drivers/cxl/acpi.c
 delete mode 100644 drivers/cxl/bus.c
 create mode 100644 drivers/cxl/core.c
 create mode 100644 drivers/cxl/mem.h

base-commit: a38fd8748464831584a19438cbb3082b5a2dab15

[PATCH 1/8] cxl/mem: Move some definitions to mem.h

[Dan Williams]

In preparation for sharing cxl.h with other generic CXL consumers,
move / consolidate some of the memory device specifics to mem.h.

The motivation for moving out of cxl.h is to maintain least privilege
access to memory-device details since cxl.h is used in multiple files.
The motivation for moving definitions into a new mem.h header is for
code readability and organization. I.e. minimize implementation details
when reading data structures and other definitions.

Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
 drivers/cxl/cxl.h |   57 ------------------------------------
 drivers/cxl/mem.c |   25 +---------------
 drivers/cxl/mem.h |   85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 86 insertions(+), 81 deletions(-)
 create mode 100644 drivers/cxl/mem.h

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index 6f14838c2d25..2e3bdacb32e7 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -34,62 +34,5 @@
 #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
 #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
 
-/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
-#define CXLMDEV_STATUS_OFFSET 0x0
-#define   CXLMDEV_DEV_FATAL BIT(0)
-#define   CXLMDEV_FW_HALT BIT(1)
-#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
-#define     CXLMDEV_MS_NOT_READY 0
-#define     CXLMDEV_MS_READY 1
-#define     CXLMDEV_MS_ERROR 2
-#define     CXLMDEV_MS_DISABLED 3
-#define CXLMDEV_READY(status)                                                  \
-	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
-	 CXLMDEV_MS_READY)
-#define   CXLMDEV_MBOX_IF_READY BIT(4)
-#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
-#define     CXLMDEV_RESET_NEEDED_NOT 0
-#define     CXLMDEV_RESET_NEEDED_COLD 1
-#define     CXLMDEV_RESET_NEEDED_WARM 2
-#define     CXLMDEV_RESET_NEEDED_HOT 3
-#define     CXLMDEV_RESET_NEEDED_CXL 4
-#define CXLMDEV_RESET_NEEDED(status)                                           \
-	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
-	 CXLMDEV_RESET_NEEDED_NOT)
-
-struct cxl_memdev;
-/**
- * struct cxl_mem - A CXL memory device
- * @pdev: The PCI device associated with this CXL device.
- * @regs: IO mappings to the device's MMIO
- * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
- * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
- * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
- * @payload_size: Size of space for payload
- *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
- * @mbox_mutex: Mutex to synchronize mailbox access.
- * @firmware_version: Firmware version for the memory device.
- * @enabled_commands: Hardware commands found enabled in CEL.
- * @pmem_range: Persistent memory capacity information.
- * @ram_range: Volatile memory capacity information.
- */
-struct cxl_mem {
-	struct pci_dev *pdev;
-	void __iomem *regs;
-	struct cxl_memdev *cxlmd;
-
-	void __iomem *status_regs;
-	void __iomem *mbox_regs;
-	void __iomem *memdev_regs;
-
-	size_t payload_size;
-	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
-	char firmware_version[0x10];
-	unsigned long *enabled_cmds;
-
-	struct range pmem_range;
-	struct range ram_range;
-};
-
 extern struct bus_type cxl_bus_type;
 #endif /* __CXL_H__ */
diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index 244cb7d89678..45871ef65152 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -12,6 +12,7 @@
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include "pci.h"
 #include "cxl.h"
+#include "mem.h"
 
 /**
  * DOC: cxl mem
@@ -29,12 +30,6 @@
  *  - Handle and manage error conditions.
  */
 
-/*
- * An entire PCI topology full of devices should be enough for any
- * config
- */
-#define CXL_MEM_MAX_DEVS 65536
-
 #define cxl_doorbell_busy(cxlm)                                                \
 	(readl((cxlm)->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET) &                  \
 	 CXLDEV_MBOX_CTRL_DOORBELL)
@@ -91,24 +86,6 @@ struct mbox_cmd {
 #define CXL_MBOX_SUCCESS 0
 };
 
-/**
- * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
- * @dev: driver core device object
- * @cdev: char dev core object for ioctl operations
- * @cxlm: pointer to the parent device driver data
- * @ops_active: active user of @cxlm in ops handlers
- * @ops_dead: completion when all @cxlm ops users have exited
- * @id: id number of this memdev instance.
- */
-struct cxl_memdev {
-	struct device dev;
-	struct cdev cdev;
-	struct cxl_mem *cxlm;
-	struct percpu_ref ops_active;
-	struct completion ops_dead;
-	int id;
-};
-
 static int cxl_mem_major;
 static DEFINE_IDA(cxl_memdev_ida);
 static struct dentry *cxl_debugfs;
diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
new file mode 100644
index 000000000000..616bb6fd721f
--- /dev/null
+++ b/drivers/cxl/mem.h
@@ -0,0 +1,85 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Copyright(c) 2020-2021 Intel Corporation. */
+#ifndef __CXL_MEM_H__
+#define __CXL_MEM_H__
+
+/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
+#define CXLMDEV_STATUS_OFFSET 0x0
+#define   CXLMDEV_DEV_FATAL BIT(0)
+#define   CXLMDEV_FW_HALT BIT(1)
+#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
+#define     CXLMDEV_MS_NOT_READY 0
+#define     CXLMDEV_MS_READY 1
+#define     CXLMDEV_MS_ERROR 2
+#define     CXLMDEV_MS_DISABLED 3
+#define CXLMDEV_READY(status)                                                  \
+	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
+	 CXLMDEV_MS_READY)
+#define   CXLMDEV_MBOX_IF_READY BIT(4)
+#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
+#define     CXLMDEV_RESET_NEEDED_NOT 0
+#define     CXLMDEV_RESET_NEEDED_COLD 1
+#define     CXLMDEV_RESET_NEEDED_WARM 2
+#define     CXLMDEV_RESET_NEEDED_HOT 3
+#define     CXLMDEV_RESET_NEEDED_CXL 4
+#define CXLMDEV_RESET_NEEDED(status)                                           \
+	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
+	 CXLMDEV_RESET_NEEDED_NOT)
+
+/*
+ * An entire PCI topology full of devices should be enough for any
+ * config
+ */
+#define CXL_MEM_MAX_DEVS 65536
+
+/**
+ * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
+ * @dev: driver core device object
+ * @cdev: char dev core object for ioctl operations
+ * @cxlm: pointer to the parent device driver data
+ * @ops_active: active user of @cxlm in ops handlers
+ * @ops_dead: completion when all @cxlm ops users have exited
+ * @id: id number of this memdev instance.
+ */
+struct cxl_memdev {
+	struct device dev;
+	struct cdev cdev;
+	struct cxl_mem *cxlm;
+	struct percpu_ref ops_active;
+	struct completion ops_dead;
+	int id;
+};
+
+/**
+ * struct cxl_mem - A CXL memory device
+ * @pdev: The PCI device associated with this CXL device.
+ * @regs: IO mappings to the device's MMIO
+ * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
+ * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
+ * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
+ * @payload_size: Size of space for payload
+ *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
+ * @mbox_mutex: Mutex to synchronize mailbox access.
+ * @firmware_version: Firmware version for the memory device.
+ * @enabled_cmds: Hardware commands found enabled in CEL.
+ * @pmem_range: Persistent memory capacity information.
+ * @ram_range: Volatile memory capacity information.
+ */
+struct cxl_mem {
+	struct pci_dev *pdev;
+	void __iomem *regs;
+	struct cxl_memdev *cxlmd;
+
+	void __iomem *status_regs;
+	void __iomem *mbox_regs;
+	void __iomem *memdev_regs;
+
+	size_t payload_size;
+	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
+	char firmware_version[0x10];
+	unsigned long *enabled_cmds;
+
+	struct range pmem_range;
+	struct range ram_range;
+};
+#endif /* __CXL_MEM_H__ */

Re: [PATCH 1/8] cxl/mem: Move some definitions to mem.h

[Jonathan Cameron]

On Fri, 7 May 2021 15:51:20 -0700
Dan Williams <dan.j.williams@intel.com> wrote:

> In preparation for sharing cxl.h with other generic CXL consumers,
> move / consolidate some of the memory device specifics to mem.h.
> 
> The motivation for moving out of cxl.h is to maintain least privilege
> access to memory-device details since cxl.h is used in multiple files.
> The motivation for moving definitions into a new mem.h header is for
> code readability and organization. I.e. minimize implementation details
> when reading data structures and other definitions.
> 
> Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
I'll do these one by one as not sure if you use automated scripts to pick up
(which get confused by any time people do "for patches 1-4 + 7")
Basically I'm fine with all but patch 5...

Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

> ---
>  drivers/cxl/cxl.h |   57 ------------------------------------
>  drivers/cxl/mem.c |   25 +---------------
>  drivers/cxl/mem.h |   85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 86 insertions(+), 81 deletions(-)
>  create mode 100644 drivers/cxl/mem.h
> 
> diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
> index 6f14838c2d25..2e3bdacb32e7 100644
> --- a/drivers/cxl/cxl.h
> +++ b/drivers/cxl/cxl.h
> @@ -34,62 +34,5 @@
>  #define CXLDEV_MBOX_BG_CMD_STATUS_OFFSET 0x18
>  #define CXLDEV_MBOX_PAYLOAD_OFFSET 0x20
>  
> -/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
> -#define CXLMDEV_STATUS_OFFSET 0x0
> -#define   CXLMDEV_DEV_FATAL BIT(0)
> -#define   CXLMDEV_FW_HALT BIT(1)
> -#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
> -#define     CXLMDEV_MS_NOT_READY 0
> -#define     CXLMDEV_MS_READY 1
> -#define     CXLMDEV_MS_ERROR 2
> -#define     CXLMDEV_MS_DISABLED 3
> -#define CXLMDEV_READY(status)                                                  \
> -	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
> -	 CXLMDEV_MS_READY)
> -#define   CXLMDEV_MBOX_IF_READY BIT(4)
> -#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
> -#define     CXLMDEV_RESET_NEEDED_NOT 0
> -#define     CXLMDEV_RESET_NEEDED_COLD 1
> -#define     CXLMDEV_RESET_NEEDED_WARM 2
> -#define     CXLMDEV_RESET_NEEDED_HOT 3
> -#define     CXLMDEV_RESET_NEEDED_CXL 4
> -#define CXLMDEV_RESET_NEEDED(status)                                           \
> -	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
> -	 CXLMDEV_RESET_NEEDED_NOT)
> -
> -struct cxl_memdev;
> -/**
> - * struct cxl_mem - A CXL memory device
> - * @pdev: The PCI device associated with this CXL device.
> - * @regs: IO mappings to the device's MMIO
> - * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
> - * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
> - * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
> - * @payload_size: Size of space for payload
> - *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
> - * @mbox_mutex: Mutex to synchronize mailbox access.
> - * @firmware_version: Firmware version for the memory device.
> - * @enabled_commands: Hardware commands found enabled in CEL.
> - * @pmem_range: Persistent memory capacity information.
> - * @ram_range: Volatile memory capacity information.
> - */
> -struct cxl_mem {
> -	struct pci_dev *pdev;
> -	void __iomem *regs;
> -	struct cxl_memdev *cxlmd;
> -
> -	void __iomem *status_regs;
> -	void __iomem *mbox_regs;
> -	void __iomem *memdev_regs;
> -
> -	size_t payload_size;
> -	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
> -	char firmware_version[0x10];
> -	unsigned long *enabled_cmds;
> -
> -	struct range pmem_range;
> -	struct range ram_range;
> -};
> -
>  extern struct bus_type cxl_bus_type;
>  #endif /* __CXL_H__ */
> diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
> index 244cb7d89678..45871ef65152 100644
> --- a/drivers/cxl/mem.c
> +++ b/drivers/cxl/mem.c
> @@ -12,6 +12,7 @@
>  #include <linux/io-64-nonatomic-lo-hi.h>
>  #include "pci.h"
>  #include "cxl.h"
> +#include "mem.h"
>  
>  /**
>   * DOC: cxl mem
> @@ -29,12 +30,6 @@
>   *  - Handle and manage error conditions.
>   */
>  
> -/*
> - * An entire PCI topology full of devices should be enough for any
> - * config
> - */
> -#define CXL_MEM_MAX_DEVS 65536
> -
>  #define cxl_doorbell_busy(cxlm)                                                \
>  	(readl((cxlm)->mbox_regs + CXLDEV_MBOX_CTRL_OFFSET) &                  \
>  	 CXLDEV_MBOX_CTRL_DOORBELL)
> @@ -91,24 +86,6 @@ struct mbox_cmd {
>  #define CXL_MBOX_SUCCESS 0
>  };
>  
> -/**
> - * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
> - * @dev: driver core device object
> - * @cdev: char dev core object for ioctl operations
> - * @cxlm: pointer to the parent device driver data
> - * @ops_active: active user of @cxlm in ops handlers
> - * @ops_dead: completion when all @cxlm ops users have exited
> - * @id: id number of this memdev instance.
> - */
> -struct cxl_memdev {
> -	struct device dev;
> -	struct cdev cdev;
> -	struct cxl_mem *cxlm;
> -	struct percpu_ref ops_active;
> -	struct completion ops_dead;
> -	int id;
> -};
> -
>  static int cxl_mem_major;
>  static DEFINE_IDA(cxl_memdev_ida);
>  static struct dentry *cxl_debugfs;
> diff --git a/drivers/cxl/mem.h b/drivers/cxl/mem.h
> new file mode 100644
> index 000000000000..616bb6fd721f
> --- /dev/null
> +++ b/drivers/cxl/mem.h
> @@ -0,0 +1,85 @@
> +/* SPDX-License-Identifier: GPL-2.0-only */
> +/* Copyright(c) 2020-2021 Intel Corporation. */
> +#ifndef __CXL_MEM_H__
> +#define __CXL_MEM_H__
> +
> +/* CXL 2.0 8.2.8.5.1.1 Memory Device Status Register */
> +#define CXLMDEV_STATUS_OFFSET 0x0
> +#define   CXLMDEV_DEV_FATAL BIT(0)
> +#define   CXLMDEV_FW_HALT BIT(1)
> +#define   CXLMDEV_STATUS_MEDIA_STATUS_MASK GENMASK(3, 2)
> +#define     CXLMDEV_MS_NOT_READY 0
> +#define     CXLMDEV_MS_READY 1
> +#define     CXLMDEV_MS_ERROR 2
> +#define     CXLMDEV_MS_DISABLED 3
> +#define CXLMDEV_READY(status)                                                  \
> +	(FIELD_GET(CXLMDEV_STATUS_MEDIA_STATUS_MASK, status) ==                \
> +	 CXLMDEV_MS_READY)
> +#define   CXLMDEV_MBOX_IF_READY BIT(4)
> +#define   CXLMDEV_RESET_NEEDED_MASK GENMASK(7, 5)
> +#define     CXLMDEV_RESET_NEEDED_NOT 0
> +#define     CXLMDEV_RESET_NEEDED_COLD 1
> +#define     CXLMDEV_RESET_NEEDED_WARM 2
> +#define     CXLMDEV_RESET_NEEDED_HOT 3
> +#define     CXLMDEV_RESET_NEEDED_CXL 4
> +#define CXLMDEV_RESET_NEEDED(status)                                           \
> +	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
> +	 CXLMDEV_RESET_NEEDED_NOT)
> +
> +/*
> + * An entire PCI topology full of devices should be enough for any
> + * config
> + */
> +#define CXL_MEM_MAX_DEVS 65536
> +
> +/**
> + * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
> + * @dev: driver core device object
> + * @cdev: char dev core object for ioctl operations
> + * @cxlm: pointer to the parent device driver data
> + * @ops_active: active user of @cxlm in ops handlers
> + * @ops_dead: completion when all @cxlm ops users have exited
> + * @id: id number of this memdev instance.
> + */
> +struct cxl_memdev {
> +	struct device dev;
> +	struct cdev cdev;
> +	struct cxl_mem *cxlm;
> +	struct percpu_ref ops_active;
> +	struct completion ops_dead;
> +	int id;
> +};
> +
> +/**
> + * struct cxl_mem - A CXL memory device
> + * @pdev: The PCI device associated with this CXL device.
> + * @regs: IO mappings to the device's MMIO
> + * @status_regs: CXL 2.0 8.2.8.3 Device Status Registers
> + * @mbox_regs: CXL 2.0 8.2.8.4 Mailbox Registers
> + * @memdev_regs: CXL 2.0 8.2.8.5 Memory Device Registers
> + * @payload_size: Size of space for payload
> + *                (CXL 2.0 8.2.8.4.3 Mailbox Capabilities Register)
> + * @mbox_mutex: Mutex to synchronize mailbox access.
> + * @firmware_version: Firmware version for the memory device.
> + * @enabled_cmds: Hardware commands found enabled in CEL.
> + * @pmem_range: Persistent memory capacity information.
> + * @ram_range: Volatile memory capacity information.
> + */
> +struct cxl_mem {
> +	struct pci_dev *pdev;
> +	void __iomem *regs;
> +	struct cxl_memdev *cxlmd;
> +
> +	void __iomem *status_regs;
> +	void __iomem *mbox_regs;
> +	void __iomem *memdev_regs;
> +
> +	size_t payload_size;
> +	struct mutex mbox_mutex; /* Protects device mailbox and firmware */
> +	char firmware_version[0x10];
> +	unsigned long *enabled_cmds;
> +
> +	struct range pmem_range;
> +	struct range ram_range;
> +};
> +#endif /* __CXL_MEM_H__ */
> 

Re: [PATCH 1/8] cxl/mem: Move some definitions to mem.h

[Dan Williams]

On Mon, May 10, 2021 at 8:17 AM Jonathan Cameron
<Jonathan.Cameron@huawei.com> wrote:
>
> On Fri, 7 May 2021 15:51:20 -0700
> Dan Williams <dan.j.williams@intel.com> wrote:
>
> > In preparation for sharing cxl.h with other generic CXL consumers,
> > move / consolidate some of the memory device specifics to mem.h.
> >
> > The motivation for moving out of cxl.h is to maintain least privilege
> > access to memory-device details since cxl.h is used in multiple files.
> > The motivation for moving definitions into a new mem.h header is for
> > code readability and organization. I.e. minimize implementation details
> > when reading data structures and other definitions.
> >
> > Reviewed-by: Ben Widawsky <ben.widawsky@intel.com>
> > Signed-off-by: Dan Williams <dan.j.williams@intel.com>
> I'll do these one by one as not sure if you use automated scripts to pick up
> (which get confused by any time people do "for patches 1-4 + 7")
> Basically I'm fine with all but patch 5...

Sounds good. I do use b4 which has the "--apply-cover-trailers"
option. So in the future if you do want to apply reviewed-by to the
whole series it's sufficient to just reply to the cover letter.

> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Thanks, Jonathan.