cxl/mbox: Move mailbox and other non-PCI specific infrastructure to the core

Now that the internals of mailbox operations are abstracted from the PCI
specifics a bulk of infrastructure can move to the core.

The CXL_PMEM driver intends to proxy LIBNVDIMM UAPI and driver requests
to the equivalent functionality provided by the CXL hardware mailbox
interface. In support of that intent move the mailbox implementation to
a shared location for the CXL_PCI driver native IOCTL path and CXL_PMEM
nvdimm command proxy path to share.

A unit test framework seeks to implement a unit test backend transport
for mailbox commands to communicate mocked up payloads. It can reuse all
of the mailbox infrastructure minus the PCI specifics, so that also gets
moved to the core.

Finally with the mailbox infrastructure and ioctl handling being
transport generic there is no longer any need to pass file
file_operations to devm_cxl_add_memdev(). That allows all the ioctl
boilerplate to move into the core for unit test reuse.

No functional change intended, just code movement.
Acked-by: Ben Widawsky <ben.widawsky@intel.com>
Reported-by: kernel test robot <lkp@intel.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Link: https://lore.kernel.org/r/163116435233.2460985.16197340449713287180.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

Documentation/driver-api/cxl/memory-devices.rst

@@ -45,6 +45,9 @@ CXL Core
 .. kernel-doc:: drivers/cxl/core/regs.c
    :doc: cxl registers
 
+.. kernel-doc:: drivers/cxl/core/mbox.c
+   :doc: cxl mbox
+
 External Interfaces
 ===================
 

drivers/cxl/core/Makefile

@@ -6,3 +6,4 @@ cxl_core-y := bus.o
 cxl_core-y += pmem.o
 cxl_core-y += regs.o
 cxl_core-y += memdev.o
+cxl_core-y += mbox.o

drivers/cxl/core/bus.c

@@ -635,6 +635,8 @@ static __init int cxl_core_init(void)
 {
 	int rc;
 
+	cxl_mbox_init();
+
 	rc = cxl_memdev_init();
 	if (rc)
 		return rc;
@@ -646,6 +648,7 @@ static __init int cxl_core_init(void)
 
 err:
 	cxl_memdev_exit();
+	cxl_mbox_exit();
 	return rc;
 }
 
@@ -653,6 +656,7 @@ static void cxl_core_exit(void)
 {
 	bus_unregister(&cxl_bus_type);
 	cxl_memdev_exit();
+	cxl_mbox_exit();
 }
 
 module_init(cxl_core_init);

drivers/cxl/core/core.h

@@ -14,7 +14,15 @@ static inline void unregister_cxl_dev(void *dev)
 	device_unregister(dev);
 }
 
+struct cxl_send_command;
+struct cxl_mem_query_commands;
+int cxl_query_cmd(struct cxl_memdev *cxlmd,
+		  struct cxl_mem_query_commands __user *q);
+int cxl_send_cmd(struct cxl_memdev *cxlmd, struct cxl_send_command __user *s);
+
 int cxl_memdev_init(void);
 void cxl_memdev_exit(void);
+void cxl_mbox_init(void);
+void cxl_mbox_exit(void);
 
 #endif /* __CXL_CORE_H__ */

drivers/cxl/core/memdev.c

@@ -8,6 +8,8 @@
 #include <cxlmem.h>
 #include "core.h"
 
+static DECLARE_RWSEM(cxl_memdev_rwsem);
+
 /*
  * An entire PCI topology full of devices should be enough for any
  * config
@@ -132,16 +134,21 @@ static const struct device_type cxl_memdev_type = {
 	.groups = cxl_memdev_attribute_groups,
 };
 
+static void cxl_memdev_shutdown(struct device *dev)
+{
+	struct cxl_memdev *cxlmd = to_cxl_memdev(dev);
+
+	down_write(&cxl_memdev_rwsem);
+	cxlmd->cxlm = NULL;
+	up_write(&cxl_memdev_rwsem);
+}
+
 static void cxl_memdev_unregister(void *_cxlmd)
 {
 	struct cxl_memdev *cxlmd = _cxlmd;
 	struct device *dev = &cxlmd->dev;
-	struct cdev *cdev = &cxlmd->cdev;
-	const struct cdevm_file_operations *cdevm_fops;
-
-	cdevm_fops = container_of(cdev->ops, typeof(*cdevm_fops), fops);
-	cdevm_fops->shutdown(dev);
 
+	cxl_memdev_shutdown(dev);
 	cdev_device_del(&cxlmd->cdev, dev);
 	put_device(dev);
 }
@@ -180,16 +187,72 @@ static struct cxl_memdev *cxl_memdev_alloc(struct cxl_mem *cxlm,
 	return ERR_PTR(rc);
 }
 
+static long __cxl_memdev_ioctl(struct cxl_memdev *cxlmd, unsigned int cmd,
+			       unsigned long arg)
+{
+	switch (cmd) {
+	case CXL_MEM_QUERY_COMMANDS:
+		return cxl_query_cmd(cxlmd, (void __user *)arg);
+	case CXL_MEM_SEND_COMMAND:
+		return cxl_send_cmd(cxlmd, (void __user *)arg);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static long cxl_memdev_ioctl(struct file *file, unsigned int cmd,
+			     unsigned long arg)
+{
+	struct cxl_memdev *cxlmd = file->private_data;
+	int rc = -ENXIO;
+
+	down_read(&cxl_memdev_rwsem);
+	if (cxlmd->cxlm)
+		rc = __cxl_memdev_ioctl(cxlmd, cmd, arg);
+	up_read(&cxl_memdev_rwsem);
+
+	return rc;
+}
+
+static int cxl_memdev_open(struct inode *inode, struct file *file)
+{
+	struct cxl_memdev *cxlmd =
+		container_of(inode->i_cdev, typeof(*cxlmd), cdev);
+
+	get_device(&cxlmd->dev);
+	file->private_data = cxlmd;
+
+	return 0;
+}
+
+static int cxl_memdev_release_file(struct inode *inode, struct file *file)
+{
+	struct cxl_memdev *cxlmd =
+		container_of(inode->i_cdev, typeof(*cxlmd), cdev);
+
+	put_device(&cxlmd->dev);
+
+	return 0;
+}
+
+static const struct file_operations cxl_memdev_fops = {
+	.owner = THIS_MODULE,
+	.unlocked_ioctl = cxl_memdev_ioctl,
+	.open = cxl_memdev_open,
+	.release = cxl_memdev_release_file,
+	.compat_ioctl = compat_ptr_ioctl,
+	.llseek = noop_llseek,
+};
+
 struct cxl_memdev *
-devm_cxl_add_memdev(struct cxl_mem *cxlm,
-		    const struct cdevm_file_operations *cdevm_fops)
+devm_cxl_add_memdev(struct cxl_mem *cxlm)
 {
 	struct cxl_memdev *cxlmd;
 	struct device *dev;
 	struct cdev *cdev;
 	int rc;
 
-	cxlmd = cxl_memdev_alloc(cxlm, &cdevm_fops->fops);
+	cxlmd = cxl_memdev_alloc(cxlm, &cxl_memdev_fops);
 	if (IS_ERR(cxlmd))
 		return cxlmd;
 
@@ -219,7 +282,7 @@ devm_cxl_add_memdev(struct cxl_mem *cxlm,
 	 * The cdev was briefly live, shutdown any ioctl operations that
 	 * saw that state.
 	 */
-	cdevm_fops->shutdown(dev);
+	cxl_memdev_shutdown(dev);
 	put_device(dev);
 	return ERR_PTR(rc);
 }

drivers/cxl/cxlmem.h

@@ -2,6 +2,7 @@
 /* Copyright(c) 2020-2021 Intel Corporation. */
 #ifndef __CXL_MEM_H__
 #define __CXL_MEM_H__
+#include <uapi/linux/cxl_mem.h>
 #include <linux/cdev.h>
 #include "cxl.h"
 
@@ -28,21 +29,6 @@
 	(FIELD_GET(CXLMDEV_RESET_NEEDED_MASK, status) !=                       \
 	 CXLMDEV_RESET_NEEDED_NOT)
 
-/**
- * struct cdevm_file_operations - devm coordinated cdev file operations
- * @fops: file operations that are synchronized against @shutdown
- * @shutdown: disconnect driver data
- *
- * @shutdown is invoked in the devres release path to disconnect any
- * driver instance data from @dev. It assumes synchronization with any
- * fops operation that requires driver data. After @shutdown an
- * operation may only reference @device data.
- */
-struct cdevm_file_operations {
-	struct file_operations fops;
-	void (*shutdown)(struct device *dev);
-};
-
 /**
  * struct cxl_memdev - CXL bus object representing a Type-3 Memory Device
  * @dev: driver core device object
@@ -62,9 +48,7 @@ static inline struct cxl_memdev *to_cxl_memdev(struct device *dev)
 	return container_of(dev, struct cxl_memdev, dev);
 }
 
-struct cxl_memdev *
-devm_cxl_add_memdev(struct cxl_mem *cxlm,
-		    const struct cdevm_file_operations *cdevm_fops);
+struct cxl_memdev *devm_cxl_add_memdev(struct cxl_mem *cxlm);
 
 /**
  * struct cxl_mbox_cmd - A command to be submitted to hardware.
@@ -158,4 +142,62 @@ struct cxl_mem {
 
 	int (*mbox_send)(struct cxl_mem *cxlm, struct cxl_mbox_cmd *cmd);
 };
+
+enum cxl_opcode {
+	CXL_MBOX_OP_INVALID		= 0x0000,
+	CXL_MBOX_OP_RAW			= CXL_MBOX_OP_INVALID,
+	CXL_MBOX_OP_GET_FW_INFO		= 0x0200,
+	CXL_MBOX_OP_ACTIVATE_FW		= 0x0202,
+	CXL_MBOX_OP_GET_SUPPORTED_LOGS	= 0x0400,
+	CXL_MBOX_OP_GET_LOG		= 0x0401,
+	CXL_MBOX_OP_IDENTIFY		= 0x4000,
+	CXL_MBOX_OP_GET_PARTITION_INFO	= 0x4100,
+	CXL_MBOX_OP_SET_PARTITION_INFO	= 0x4101,
+	CXL_MBOX_OP_GET_LSA		= 0x4102,
+	CXL_MBOX_OP_SET_LSA		= 0x4103,
+	CXL_MBOX_OP_GET_HEALTH_INFO	= 0x4200,
+	CXL_MBOX_OP_GET_ALERT_CONFIG	= 0x4201,
+	CXL_MBOX_OP_SET_ALERT_CONFIG	= 0x4202,
+	CXL_MBOX_OP_GET_SHUTDOWN_STATE	= 0x4203,
+	CXL_MBOX_OP_SET_SHUTDOWN_STATE	= 0x4204,
+	CXL_MBOX_OP_GET_POISON		= 0x4300,
+	CXL_MBOX_OP_INJECT_POISON	= 0x4301,
+	CXL_MBOX_OP_CLEAR_POISON	= 0x4302,
+	CXL_MBOX_OP_GET_SCAN_MEDIA_CAPS	= 0x4303,
+	CXL_MBOX_OP_SCAN_MEDIA		= 0x4304,
+	CXL_MBOX_OP_GET_SCAN_MEDIA	= 0x4305,
+	CXL_MBOX_OP_MAX			= 0x10000
+};
+
+/**
+ * struct cxl_mem_command - Driver representation of a memory device command
+ * @info: Command information as it exists for the UAPI
+ * @opcode: The actual bits used for the mailbox protocol
+ * @flags: Set of flags effecting driver behavior.
+ *
+ *  * %CXL_CMD_FLAG_FORCE_ENABLE: In cases of error, commands with this flag
+ *    will be enabled by the driver regardless of what hardware may have
+ *    advertised.
+ *
+ * The cxl_mem_command is the driver's internal representation of commands that
+ * are supported by the driver. Some of these commands may not be supported by
+ * the hardware. The driver will use @info to validate the fields passed in by
+ * the user then submit the @opcode to the hardware.
+ *
+ * See struct cxl_command_info.
+ */
+struct cxl_mem_command {
+	struct cxl_command_info info;
+	enum cxl_opcode opcode;
+	u32 flags;
+#define CXL_CMD_FLAG_NONE 0
+#define CXL_CMD_FLAG_FORCE_ENABLE BIT(0)
+};
+
+int cxl_mem_mbox_send_cmd(struct cxl_mem *cxlm, u16 opcode, void *in,
+			  size_t in_size, void *out, size_t out_size);
+int cxl_mem_identify(struct cxl_mem *cxlm);
+int cxl_mem_enumerate_cmds(struct cxl_mem *cxlm);
+int cxl_mem_create_range_info(struct cxl_mem *cxlm);
+struct cxl_mem *cxl_mem_create(struct device *dev);
 #endif /* __CXL_MEM_H__ */