include/misc/cxl.h

   1 /* SPDX-License-Identifier: GPL-2.0-or-later */
   2 /*
   3  * Copyright 2015 IBM Corp.
   4  */
   5
   6 #ifndef _MISC_CXL_H
   7 #define _MISC_CXL_H
   8
   9 #include <linux/pci.h>
  10 #include <linux/poll.h>
  11 #include <linux/interrupt.h>
  12 #include <uapi/misc/cxl.h>
  13
  14 /*
  15  * This documents the in kernel API for driver to use CXL. It allows kernel
  16  * drivers to bind to AFUs using an AFU configuration record exposed as a PCI
  17  * configuration record.
  18  *
  19  * This API enables control over AFU and contexts which can't be part of the
  20  * generic PCI API. This API is agnostic to the actual AFU.
  21  */
  22
  23 /* Get the AFU associated with a pci_dev */
  24 struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);
  25
  26 /* Get the AFU conf record number associated with a pci_dev */
  27 unsigned int cxl_pci_to_cfg_record(struct pci_dev *dev);
  28
  29
  30 /*
  31  * Context lifetime overview:
  32  *
  33  * An AFU context may be inited and then started and stoppped multiple times
  34  * before it's released. ie.
  35  *    - cxl_dev_context_init()
  36  *      - cxl_start_context()
  37  *      - cxl_stop_context()
  38  *      - cxl_start_context()
  39  *      - cxl_stop_context()
  40  *     ...repeat...
  41  *    - cxl_release_context()
  42  * Once released, a context can't be started again.
  43  *
  44  * One context is inited by the cxl driver for every pci_dev. This is to be
  45  * used as a default kernel context. cxl_get_context() will get this
  46  * context. This context will be released by PCI hot unplug, so doesn't need to
  47  * be released explicitly by drivers.
  48  *
  49  * Additional kernel contexts may be inited using cxl_dev_context_init().
  50  * These must be released using cxl_context_detach().
  51  *
  52  * Once a context has been inited, IRQs may be configured. Firstly these IRQs
  53  * must be allocated (cxl_allocate_afu_irqs()), then individually mapped to
  54  * specific handlers (cxl_map_afu_irq()).
  55  *
  56  * These IRQs can be unmapped (cxl_unmap_afu_irq()) and finally released
  57  * (cxl_free_afu_irqs()).
  58  *
  59  * The AFU can be reset (cxl_afu_reset()). This will cause the PSL/AFU
  60  * hardware to lose track of all contexts. It's upto the caller of
  61  * cxl_afu_reset() to restart these contexts.
  62  */
  63
  64 /*
  65  * On pci_enabled_device(), the cxl driver will init a single cxl context for
  66  * use by the driver. It doesn't start this context (as that will likely
  67  * generate DMA traffic for most AFUs).
  68  *
  69  * This gets the default context associated with this pci_dev.  This context
  70  * doesn't need to be released as this will be done by the PCI subsystem on hot
  71  * unplug.
  72  */
  73 struct cxl_context *cxl_get_context(struct pci_dev *dev);
  74 /*
  75  * Allocate and initalise a context associated with a AFU PCI device. This
  76  * doesn't start the context in the AFU.
  77  */
  78 struct cxl_context *cxl_dev_context_init(struct pci_dev *dev);
  79 /*
  80  * Release and free a context. Context should be stopped before calling.
  81  */
  82 int cxl_release_context(struct cxl_context *ctx);
  83
  84 /*
  85  * Set and get private data associated with a context. Allows drivers to have a
  86  * back pointer to some useful structure.
  87  */
  88 int cxl_set_priv(struct cxl_context *ctx, void *priv);
  89 void *cxl_get_priv(struct cxl_context *ctx);
  90
  91 /*
  92  * Allocate AFU interrupts for this context. num=0 will allocate the default
  93  * for this AFU as given in the AFU descriptor. This number doesn't include the
  94  * interrupt 0 (CAIA defines AFU IRQ 0 for page faults). Each interrupt to be
  95  * used must map a handler with cxl_map_afu_irq.
  96  */
  97 int cxl_allocate_afu_irqs(struct cxl_context *cxl, int num);
  98 /* Free allocated interrupts */
  99 void cxl_free_afu_irqs(struct cxl_context *cxl);
 100
 101 /*
 102  * Map a handler for an AFU interrupt associated with a particular context. AFU
 103  * IRQS numbers start from 1 (CAIA defines AFU IRQ 0 for page faults). cookie
 104  * is private data is that will be provided to the interrupt handler.
 105  */
 106 int cxl_map_afu_irq(struct cxl_context *cxl, int num,
 107                     irq_handler_t handler, void *cookie, char *name);
 108 /* unmap mapped IRQ handlers */
 109 void cxl_unmap_afu_irq(struct cxl_context *cxl, int num, void *cookie);
 110
 111 /*
 112  * Start work on the AFU. This starts an cxl context and associates it with a
 113  * task. task == NULL will make it a kernel context.
 114  */
 115 int cxl_start_context(struct cxl_context *ctx, u64 wed,
 116                       struct task_struct *task);
 117 /*
 118  * Stop a context and remove it from the PSL
 119  */
 120 int cxl_stop_context(struct cxl_context *ctx);
 121
 122 /* Reset the AFU */
 123 int cxl_afu_reset(struct cxl_context *ctx);
 124
 125 /*
 126  * Set a context as a master context.
 127  * This sets the default problem space area mapped as the full space, rather
 128  * than just the per context area (for slaves).
 129  */
 130 void cxl_set_master(struct cxl_context *ctx);
 131
 132 /*
 133  * Map and unmap the AFU Problem Space area. The amount and location mapped
 134  * depends on if this context is a master or slave.
 135  */
 136 void __iomem *cxl_psa_map(struct cxl_context *ctx);
 137 void cxl_psa_unmap(void __iomem *addr);
 138
 139 /*  Get the process element for this context */
 140 int cxl_process_element(struct cxl_context *ctx);
 141
 142 /*
 143  * These calls allow drivers to create their own file descriptors and make them
 144  * identical to the cxl file descriptor user API. An example use case:
 145  *
 146  * struct file_operations cxl_my_fops = {};
 147  * ......
 148  *      // Init the context
 149  *      ctx = cxl_dev_context_init(dev);
 150  *      if (IS_ERR(ctx))
 151  *              return PTR_ERR(ctx);
 152  *      // Create and attach a new file descriptor to my file ops
 153  *      file = cxl_get_fd(ctx, &cxl_my_fops, &fd);
 154  *      // Start context
 155  *      rc = cxl_start_work(ctx, &work.work);
 156  *      if (rc) {
 157  *              fput(file);
 158  *              put_unused_fd(fd);
 159  *              return -ENODEV;
 160  *      }
 161  *      // No error paths after installing the fd
 162  *      fd_install(fd, file);
 163  *      return fd;
 164  *
 165  * This inits a context, and gets a file descriptor and associates some file
 166  * ops to that file descriptor. If the file ops are blank, the cxl driver will
 167  * fill them in with the default ones that mimic the standard user API.  Once
 168  * completed, the file descriptor can be installed. Once the file descriptor is
 169  * installed, it's visible to the user so no errors must occur past this point.
 170  *
 171  * If cxl_fd_release() file op call is installed, the context will be stopped
 172  * and released when the fd is released. Hence the driver won't need to manage
 173  * this itself.
 174  */
 175
 176 /*
 177  * Take a context and associate it with my file ops. Returns the associated
 178  * file and file descriptor. Any file ops which are blank are filled in by the
 179  * cxl driver with the default ops to mimic the standard API.
 180  */
 181 struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
 182                         int *fd);
 183 /* Get the context associated with this file */
 184 struct cxl_context *cxl_fops_get_context(struct file *file);
 185 /*
 186  * Start a context associated a struct cxl_ioctl_start_work used by the
 187  * standard cxl user API.
 188  */
 189 int cxl_start_work(struct cxl_context *ctx,
 190                    struct cxl_ioctl_start_work *work);
 191 /*
 192  * Export all the existing fops so drivers can use them
 193  */
 194 int cxl_fd_open(struct inode *inode, struct file *file);
 195 int cxl_fd_release(struct inode *inode, struct file *file);
 196 long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 197 int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm);
 198 __poll_t cxl_fd_poll(struct file *file, struct poll_table_struct *poll);
 199 ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
 200                            loff_t *off);
 201
 202 /*
 203  * For EEH, a driver may want to assert a PERST will reload the same image
 204  * from flash into the FPGA.
 205  *
 206  * This is a property of the entire adapter, not a single AFU, so drivers
 207  * should set this property with care!
 208  */
 209 void cxl_perst_reloads_same_image(struct cxl_afu *afu,
 210                                   bool perst_reloads_same_image);
 211
 212 /*
 213  * Read the VPD for the card where the AFU resides
 214  */
 215 ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);
 216
 217 /*
 218  * AFU driver ops allow an AFU driver to create their own events to pass to
 219  * userspace through the file descriptor as a simpler alternative to overriding
 220  * the read() and poll() calls that works with the generic cxl events. These
 221  * events are given priority over the generic cxl events, so they will be
 222  * delivered first if multiple types of events are pending.
 223  *
 224  * The AFU driver must call cxl_context_events_pending() to notify the cxl
 225  * driver that new events are ready to be delivered for a specific context.
 226  * cxl_context_events_pending() will adjust the current count of AFU driver
 227  * events for this context, and wake up anyone waiting on the context wait
 228  * queue.
 229  *
 230  * The cxl driver will then call fetch_event() to get a structure defining
 231  * the size and address of the driver specific event data. The cxl driver
 232  * will build a cxl header with type and process_element fields filled in,
 233  * and header.size set to sizeof(struct cxl_event_header) + data_size.
 234  * The total size of the event is limited to CXL_READ_MIN_SIZE (4K).
 235  *
 236  * fetch_event() is called with a spin lock held, so it must not sleep.
 237  *
 238  * The cxl driver will then deliver the event to userspace, and finally
 239  * call event_delivered() to return the status of the operation, identified
 240  * by cxl context and AFU driver event data pointers.
 241  *   0        Success
 242  *   -EFAULT  copy_to_user() has failed
 243  *   -EINVAL  Event data pointer is NULL, or event size is greater than
 244  *            CXL_READ_MIN_SIZE.
 245  */
 246 struct cxl_afu_driver_ops {
 247         struct cxl_event_afu_driver_reserved *(*fetch_event) (
 248                                                 struct cxl_context *ctx);
 249         void (*event_delivered) (struct cxl_context *ctx,
 250                                  struct cxl_event_afu_driver_reserved *event,
 251                                  int rc);
 252 };
 253
 254 /*
 255  * Associate the above driver ops with a specific context.
 256  * Reset the current count of AFU driver events.
 257  */
 258 void cxl_set_driver_ops(struct cxl_context *ctx,
 259                         struct cxl_afu_driver_ops *ops);
 260
 261 /* Notify cxl driver that new events are ready to be delivered for context */
 262 void cxl_context_events_pending(struct cxl_context *ctx,
 263                                 unsigned int new_events);
 264
 265 #endif /* _MISC_CXL_H */