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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, &work.work);
  *  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
  *            CXL_READ_MIN_SIZE.
  */
 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 */

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