include/misc/cxl.h

   1 /*
   2  * Copyright 2015 IBM Corp.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #ifndef _MISC_CXL_H
  11 #define _MISC_CXL_H
  12
  13 #include <linux/pci.h>
  14 #include <linux/poll.h>
  15 #include <linux/interrupt.h>
  16 #include <uapi/misc/cxl.h>
  17
  18 /*
  19  * This documents the in kernel API for driver to use CXL. It allows kernel
  20  * drivers to bind to AFUs using an AFU configuration record exposed as a PCI
  21  * configuration record.
  22  *
  23  * This API enables control over AFU and contexts which can't be part of the
  24  * generic PCI API. This API is agnostic to the actual AFU.
  25  */
  26
  27 /* Get the AFU associated with a pci_dev */
  28 struct cxl_afu *cxl_pci_to_afu(struct pci_dev *dev);
  29
  30 /* Get the AFU conf record number associated with a pci_dev */
  31 unsigned int cxl_pci_to_cfg_record(struct pci_dev *dev);
  32
  33
  34 /*
  35  * Context lifetime overview:
  36  *
  37  * An AFU context may be inited and then started and stoppped multiple times
  38  * before it's released. ie.
  39  *    - cxl_dev_context_init()
  40  *      - cxl_start_context()
  41  *      - cxl_stop_context()
  42  *      - cxl_start_context()
  43  *      - cxl_stop_context()
  44  *     ...repeat...
  45  *    - cxl_release_context()
  46  * Once released, a context can't be started again.
  47  *
  48  * One context is inited by the cxl driver for every pci_dev. This is to be
  49  * used as a default kernel context. cxl_get_context() will get this
  50  * context. This context will be released by PCI hot unplug, so doesn't need to
  51  * be released explicitly by drivers.
  52  *
  53  * Additional kernel contexts may be inited using cxl_dev_context_init().
  54  * These must be released using cxl_context_detach().
  55  *
  56  * Once a context has been inited, IRQs may be configured. Firstly these IRQs
  57  * must be allocated (cxl_allocate_afu_irqs()), then individually mapped to
  58  * specific handlers (cxl_map_afu_irq()).
  59  *
  60  * These IRQs can be unmapped (cxl_unmap_afu_irq()) and finally released
  61  * (cxl_free_afu_irqs()).
  62  *
  63  * The AFU can be reset (cxl_afu_reset()). This will cause the PSL/AFU
  64  * hardware to lose track of all contexts. It's upto the caller of
  65  * cxl_afu_reset() to restart these contexts.
  66  */
  67
  68 /*
  69  * On pci_enabled_device(), the cxl driver will init a single cxl context for
  70  * use by the driver. It doesn't start this context (as that will likely
  71  * generate DMA traffic for most AFUs).
  72  *
  73  * This gets the default context associated with this pci_dev.  This context
  74  * doesn't need to be released as this will be done by the PCI subsystem on hot
  75  * unplug.
  76  */
  77 struct cxl_context *cxl_get_context(struct pci_dev *dev);
  78 /*
  79  * Allocate and initalise a context associated with a AFU PCI device. This
  80  * doesn't start the context in the AFU.
  81  */
  82 struct cxl_context *cxl_dev_context_init(struct pci_dev *dev);
  83 /*
  84  * Release and free a context. Context should be stopped before calling.
  85  */
  86 int cxl_release_context(struct cxl_context *ctx);
  87
  88 /*
  89  * Set and get private data associated with a context. Allows drivers to have a
  90  * back pointer to some useful structure.
  91  */
  92 int cxl_set_priv(struct cxl_context *ctx, void *priv);
  93 void *cxl_get_priv(struct cxl_context *ctx);
  94
  95 /*
  96  * Allocate AFU interrupts for this context. num=0 will allocate the default
  97  * for this AFU as given in the AFU descriptor. This number doesn't include the
  98  * interrupt 0 (CAIA defines AFU IRQ 0 for page faults). Each interrupt to be
  99  * used must map a handler with cxl_map_afu_irq.
 100  */
 101 int cxl_allocate_afu_irqs(struct cxl_context *cxl, int num);
 102 /* Free allocated interrupts */
 103 void cxl_free_afu_irqs(struct cxl_context *cxl);
 104
 105 /*
 106  * Map a handler for an AFU interrupt associated with a particular context. AFU
 107  * IRQS numbers start from 1 (CAIA defines AFU IRQ 0 for page faults). cookie
 108  * is private data is that will be provided to the interrupt handler.
 109  */
 110 int cxl_map_afu_irq(struct cxl_context *cxl, int num,
 111                     irq_handler_t handler, void *cookie, char *name);
 112 /* unmap mapped IRQ handlers */
 113 void cxl_unmap_afu_irq(struct cxl_context *cxl, int num, void *cookie);
 114
 115 /*
 116  * Start work on the AFU. This starts an cxl context and associates it with a
 117  * task. task == NULL will make it a kernel context.
 118  */
 119 int cxl_start_context(struct cxl_context *ctx, u64 wed,
 120                       struct task_struct *task);
 121 /*
 122  * Stop a context and remove it from the PSL
 123  */
 124 int cxl_stop_context(struct cxl_context *ctx);
 125
 126 /* Reset the AFU */
 127 int cxl_afu_reset(struct cxl_context *ctx);
 128
 129 /*
 130  * Set a context as a master context.
 131  * This sets the default problem space area mapped as the full space, rather
 132  * than just the per context area (for slaves).
 133  */
 134 void cxl_set_master(struct cxl_context *ctx);
 135
 136 /*
 137  * Map and unmap the AFU Problem Space area. The amount and location mapped
 138  * depends on if this context is a master or slave.
 139  */
 140 void __iomem *cxl_psa_map(struct cxl_context *ctx);
 141 void cxl_psa_unmap(void __iomem *addr);
 142
 143 /*  Get the process element for this context */
 144 int cxl_process_element(struct cxl_context *ctx);
 145
 146 /*
 147  * These calls allow drivers to create their own file descriptors and make them
 148  * identical to the cxl file descriptor user API. An example use case:
 149  *
 150  * struct file_operations cxl_my_fops = {};
 151  * ......
 152  *      // Init the context
 153  *      ctx = cxl_dev_context_init(dev);
 154  *      if (IS_ERR(ctx))
 155  *              return PTR_ERR(ctx);
 156  *      // Create and attach a new file descriptor to my file ops
 157  *      file = cxl_get_fd(ctx, &cxl_my_fops, &fd);
 158  *      // Start context
 159  *      rc = cxl_start_work(ctx, &work.work);
 160  *      if (rc) {
 161  *              fput(file);
 162  *              put_unused_fd(fd);
 163  *              return -ENODEV;
 164  *      }
 165  *      // No error paths after installing the fd
 166  *      fd_install(fd, file);
 167  *      return fd;
 168  *
 169  * This inits a context, and gets a file descriptor and associates some file
 170  * ops to that file descriptor. If the file ops are blank, the cxl driver will
 171  * fill them in with the default ones that mimic the standard user API.  Once
 172  * completed, the file descriptor can be installed. Once the file descriptor is
 173  * installed, it's visible to the user so no errors must occur past this point.
 174  *
 175  * If cxl_fd_release() file op call is installed, the context will be stopped
 176  * and released when the fd is released. Hence the driver won't need to manage
 177  * this itself.
 178  */
 179
 180 /*
 181  * Take a context and associate it with my file ops. Returns the associated
 182  * file and file descriptor. Any file ops which are blank are filled in by the
 183  * cxl driver with the default ops to mimic the standard API.
 184  */
 185 struct file *cxl_get_fd(struct cxl_context *ctx, struct file_operations *fops,
 186                         int *fd);
 187 /* Get the context associated with this file */
 188 struct cxl_context *cxl_fops_get_context(struct file *file);
 189 /*
 190  * Start a context associated a struct cxl_ioctl_start_work used by the
 191  * standard cxl user API.
 192  */
 193 int cxl_start_work(struct cxl_context *ctx,
 194                    struct cxl_ioctl_start_work *work);
 195 /*
 196  * Export all the existing fops so drivers can use them
 197  */
 198 int cxl_fd_open(struct inode *inode, struct file *file);
 199 int cxl_fd_release(struct inode *inode, struct file *file);
 200 long cxl_fd_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
 201 int cxl_fd_mmap(struct file *file, struct vm_area_struct *vm);
 202 __poll_t cxl_fd_poll(struct file *file, struct poll_table_struct *poll);
 203 ssize_t cxl_fd_read(struct file *file, char __user *buf, size_t count,
 204                            loff_t *off);
 205
 206 /*
 207  * For EEH, a driver may want to assert a PERST will reload the same image
 208  * from flash into the FPGA.
 209  *
 210  * This is a property of the entire adapter, not a single AFU, so drivers
 211  * should set this property with care!
 212  */
 213 void cxl_perst_reloads_same_image(struct cxl_afu *afu,
 214                                   bool perst_reloads_same_image);
 215
 216 /*
 217  * Read the VPD for the card where the AFU resides
 218  */
 219 ssize_t cxl_read_adapter_vpd(struct pci_dev *dev, void *buf, size_t count);
 220
 221 /*
 222  * AFU driver ops allow an AFU driver to create their own events to pass to
 223  * userspace through the file descriptor as a simpler alternative to overriding
 224  * the read() and poll() calls that works with the generic cxl events. These
 225  * events are given priority over the generic cxl events, so they will be
 226  * delivered first if multiple types of events are pending.
 227  *
 228  * The AFU driver must call cxl_context_events_pending() to notify the cxl
 229  * driver that new events are ready to be delivered for a specific context.
 230  * cxl_context_events_pending() will adjust the current count of AFU driver
 231  * events for this context, and wake up anyone waiting on the context wait
 232  * queue.
 233  *
 234  * The cxl driver will then call fetch_event() to get a structure defining
 235  * the size and address of the driver specific event data. The cxl driver
 236  * will build a cxl header with type and process_element fields filled in,
 237  * and header.size set to sizeof(struct cxl_event_header) + data_size.
 238  * The total size of the event is limited to CXL_READ_MIN_SIZE (4K).
 239  *
 240  * fetch_event() is called with a spin lock held, so it must not sleep.
 241  *
 242  * The cxl driver will then deliver the event to userspace, and finally
 243  * call event_delivered() to return the status of the operation, identified
 244  * by cxl context and AFU driver event data pointers.
 245  *   0        Success
 246  *   -EFAULT  copy_to_user() has failed
 247  *   -EINVAL  Event data pointer is NULL, or event size is greater than
 248  *            CXL_READ_MIN_SIZE.
 249  */
 250 struct cxl_afu_driver_ops {
 251         struct cxl_event_afu_driver_reserved *(*fetch_event) (
 252                                                 struct cxl_context *ctx);
 253         void (*event_delivered) (struct cxl_context *ctx,
 254                                  struct cxl_event_afu_driver_reserved *event,
 255                                  int rc);
 256 };
 257
 258 /*
 259  * Associate the above driver ops with a specific context.
 260  * Reset the current count of AFU driver events.
 261  */
 262 void cxl_set_driver_ops(struct cxl_context *ctx,
 263                         struct cxl_afu_driver_ops *ops);
 264
 265 /* Notify cxl driver that new events are ready to be delivered for context */
 266 void cxl_context_events_pending(struct cxl_context *ctx,
 267                                 unsigned int new_events);
 268
 269 #endif /* _MISC_CXL_H */