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/* SPDX-License-Identifier: GPL-2.0-or-later */
* Copyright 2015 IBM Corp.
#ifndef _MISC_CXL_H
#define _MISC_CXL_H
#include <linux/pci.h>
#include <linux/poll.h>
#include <linux/interrupt.h>
#include <uapi/misc/cxl.h>
* This documents the in kernel API for driver to use CXL. It allows kernel
* drivers to bind to AFUs using an AFU configuration record exposed as a PCI
* configuration record.
* This API enables control over AFU and contexts which can't be part of the
* generic PCI API. This API is agnostic to the actual AFU.
/* Get the AFU associated with a pci_dev */
struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);
/* Get the AFU conf record number associated with a pci_dev */
unsigned int cxl_pci_to_cfg_record(struct pci_dev *dev);
* Context lifetime overview:
* An AFU context may be inited and then started and stoppped multiple times
* before it's released. ie.
* - cxl_dev_context_init()
* - cxl_start_context()
* - cxl_stop_context()
* - cxl_start_context()
* - cxl_stop_context()
* ...repeat...
* - cxl_release_context()
* Once released, a context can't be started again.
* One context is inited by the cxl driver for every pci_dev. This is to be
* used as a default kernel context. cxl_get_context() will get this
* context. This context will be released by PCI hot unplug, so doesn't need to
* be released explicitly by drivers.
* Additional kernel contexts may be inited using cxl_dev_context_init().
* These must be released using cxl_context_detach().
* Once a context has been inited, IRQs may be configured. Firstly these IRQs
* must be allocated (cxl_allocate_afu_irqs()), then individually mapped to
* specific handlers (cxl_map_afu_irq()).
* These IRQs can be unmapped (cxl_unmap_afu_irq()) and finally released
* (cxl_free_afu_irqs()).
* The AFU can be reset (cxl_afu_reset()). This will cause the PSL/AFU
* hardware to lose track of all contexts. It's upto the caller of
* cxl_afu_reset() to restart these contexts.
* On pci_enabled_device(), the cxl driver will init a single cxl context for
* use by the driver. It doesn't start this context (as that will likely
* generate DMA traffic for most AFUs).
* This gets the default context associated with this pci_dev. This context
* doesn't need to be released as this will be done by the PCI subsystem on hot
* unplug.
struct cxl_context *cxl_get_context(struct pci_dev *dev);
* Allocate and initalise a context associated with a AFU PCI device. This
* doesn't start the context in the AFU.
struct cxl_context *cxl_dev_context_init(struct pci_dev *dev);
* Release and free a context. Context should be stopped before calling.
int cxl_release_context(struct cxl_context *ctx);
* Set and get private data associated with a context. Allows drivers to have a
* back pointer to some useful structure.
int cxl_set_priv(struct cxl_context *ctx, void *priv);
void *cxl_get_priv(struct cxl_context *ctx);
* Allocate AFU interrupts for this context. num=0 will allocate the default
* for this AFU as given in the AFU descriptor. This number doesn't include the
* interrupt 0 (CAIA defines AFU IRQ 0 for page faults). Each interrupt to be
* used must map a handler with cxl_map_afu_irq.
int cxl_allocate_afu_irqs(struct cxl_context *cxl, int num);
/* Free allocated interrupts */
void cxl_free_afu_irqs(struct cxl_context *cxl);
* Map a handler for an AFU interrupt associated with a particular context. AFU
* IRQS numbers start from 1 (CAIA defines AFU IRQ 0 for page faults). cookie
* is private data is that will be provided to the interrupt handler.
int cxl_map_afu_irq(struct cxl_context *cxl, int num,
irq_handler_t handler, void *cookie, char *name);
/* unmap mapped IRQ handlers */
void cxl_unmap_afu_irq(struct cxl_context *cxl, int num, void *cookie);
* Start work on the AFU. This starts an cxl context and associates it with a
* task. task == NULL will make it a kernel context.
int cxl_start_context(struct cxl_context *ctx, u64 wed,
struct task_struct *task);
* Stop a context and remove it from the PSL
int cxl_stop_context(struct cxl_context *ctx);
/* Reset the AFU */
int cxl_afu_reset(struct cxl_context *ctx);
* Set a context as a master context.
* This sets the default problem space area mapped as the full space, rather
* than just the per context area (for slaves).
void cxl_set_master(struct cxl_context *ctx);
* Map and unmap the AFU Problem Space area. The amount and location mapped
* depends on if this context is a master or slave.
void __iomem *cxl_psa_map(struct cxl_context *ctx);
void cxl_psa_unmap(void __iomem *addr);
/* Get the process element for this context */
int cxl_process_element(struct cxl_context *ctx);
* These calls allow drivers to create their own file descriptors and make them
* identical to the cxl file descriptor user API. An example use case:
* struct file_operations cxl_my_fops = {};
* ......
* // Init the context
* ctx = cxl_dev_context_init(dev);
* if (IS_ERR(ctx))
* return PTR_ERR(ctx);
* // Create and attach a new file descriptor to my file ops
* file = cxl_get_fd(ctx, &cxl_my_fops, &fd);
* // Start context
* rc = cxl_start_work(ctx, &;
* if (rc) {
* fput(file);
* put_unused_fd(fd);
* return -ENODEV;
* }
* // No error paths after installing the fd
* fd_install(fd, file);
* return fd;
* This inits a context, and gets a file descriptor and associates some file
* ops to that file descriptor. If the file ops are blank, the cxl driver will
* fill them in with the default ones that mimic the standard user API. Once
* completed, the file descriptor can be installed. Once the file descriptor is
* installed, it's visible to the user so no errors must occur past this point.
* If cxl_fd_release() file op call is installed, the context will be stopped
* and released when the fd is released. Hence the driver won't need to manage
* this itself.
* Take a context and associate it with my file ops. Returns the associated
* file and file descriptor. Any file ops which are blank are filled in by the
* cxl driver with the default ops to mimic the standard API.
struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
int *fd);
/* Get the context associated with this file */
struct cxl_context *cxl_fops_get_context(struct file *file);
* Start a context associated a struct cxl_ioctl_start_work used by the
* standard cxl user API.
int cxl_start_work(struct cxl_context *ctx,
struct cxl_ioctl_start_work *work);
* Export all the existing fops so drivers can use them
int cxl_fd_open(struct inode *inode, struct file *file);
int cxl_fd_release(struct inode *inode, struct file *file);
long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm);
__poll_t cxl_fd_poll(struct file *file, struct poll_table_struct *poll);
ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
loff_t *off);
* For EEH, a driver may want to assert a PERST will reload the same image
* from flash into the FPGA.
* This is a property of the entire adapter, not a single AFU, so drivers
* should set this property with care!
void cxl_perst_reloads_same_image(struct cxl_afu *afu,
bool perst_reloads_same_image);
* Read the VPD for the card where the AFU resides
ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);
* AFU driver ops allow an AFU driver to create their own events to pass to
* userspace through the file descriptor as a simpler alternative to overriding
* the read() and poll() calls that works with the generic cxl events. These
* events are given priority over the generic cxl events, so they will be
* delivered first if multiple types of events are pending.
* The AFU driver must call cxl_context_events_pending() to notify the cxl
* driver that new events are ready to be delivered for a specific context.
* cxl_context_events_pending() will adjust the current count of AFU driver
* events for this context, and wake up anyone waiting on the context wait
* queue.
* The cxl driver will then call fetch_event() to get a structure defining
* the size and address of the driver specific event data. The cxl driver
* will build a cxl header with type and process_element fields filled in,
* and header.size set to sizeof(struct cxl_event_header) + data_size.
* The total size of the event is limited to CXL_READ_MIN_SIZE (4K).
* fetch_event() is called with a spin lock held, so it must not sleep.
* The cxl driver will then deliver the event to userspace, and finally
* call event_delivered() to return the status of the operation, identified
* by cxl context and AFU driver event data pointers.
* 0 Success
* -EFAULT copy_to_user() has failed
* -EINVAL Event data pointer is NULL, or event size is greater than
struct cxl_afu_driver_ops {
struct cxl_event_afu_driver_reserved *(*fetch_event) (
struct cxl_context *ctx);
void (*event_delivered) (struct cxl_context *ctx,
struct cxl_event_afu_driver_reserved *event,
int rc);
* Associate the above driver ops with a specific context.
* Reset the current count of AFU driver events.
void cxl_set_driver_ops(struct cxl_context *ctx,
struct cxl_afu_driver_ops *ops);
/* Notify cxl driver that new events are ready to be delivered for context */
void cxl_context_events_pending(struct cxl_context *ctx,
unsigned int new_events);
#endif /* _MISC_CXL_H */