text: /*
   * Copyright 2014 IBM Corp.
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version
   * 2 of the License, or (at your option) any later version.
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/bitmap.h>
  #include <linux/sched.h>
  #include <linux/pid.h>
  #include <linux/fs.h>
  #include <linux/mm.h>
  #include <linux/debugfs.h>
  #include <linux/slab.h>
  #include <linux/idr.h>
  #include <asm/cputable.h>
  #include <asm/current.h>
  #include <asm/copro.h>
  
  #include "cxl.h"
  
  /*
   * Allocates space for a CXL context.
   */
  struct cxl_context *cxl_context_alloc(void)
  {
  	return kzalloc(sizeof(struct cxl_context), GFP_KERNEL);
  }
  
  /*
   * Initialises a CXL context.
   */
  int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
  		     struct address_space *mapping)
  {
  	int i;
  
  	spin_lock_init(&ctx->sste_lock);
  	ctx->afu = afu;
  	ctx->master = master;
  	ctx->pid = NULL; /* Set in start work ioctl */
  	mutex_init(&ctx->mapping_lock);
  	ctx->mapping = mapping;
  
  	/*
  	 * Allocate the segment table before we put it in the IDR so that we
  	 * can always access it when dereferenced from IDR. For the same
  	 * reason, the segment table is only destroyed after the context is
  	 * removed from the IDR.  Access to this in the IOCTL is protected by
  	 * Linux filesytem symantics (can't IOCTL until open is complete).
  	 */
  	i = cxl_alloc_sst(ctx);
  	if (i)
  		return i;
  
  	INIT_WORK(&ctx->fault_work, cxl_handle_fault);
  
  	init_waitqueue_head(&ctx->wq);
  	spin_lock_init(&ctx->lock);
  
  	ctx->irq_bitmap = NULL;
  	ctx->pending_irq = false;
  	ctx->pending_fault = false;
  	ctx->pending_afu_err = false;
  
  	/*
  	 * When we have to destroy all contexts in cxl_context_detach_all() we
  	 * end up with afu_release_irqs() called from inside a
  	 * idr_for_each_entry(). Hence we need to make sure that anything
  	 * dereferenced from this IDR is ok before we allocate the IDR here.
  	 * This clears out the IRQ ranges to ensure this.
  	 */
  	for (i = 0; i < CXL_IRQ_RANGES; i++)
  		ctx->irqs.range[i] = 0;
  
  	mutex_init(&ctx->status_mutex);
  
  	ctx->status = OPENED;
  
  	/*
  	 * Allocating IDR! We better make sure everything's setup that
  	 * dereferences from it.
  	 */
  	mutex_lock(&afu->contexts_lock);
  	idr_preload(GFP_KERNEL);
  	i = idr_alloc(&ctx->afu->contexts_idr, ctx, 0,
  		      ctx->afu->num_procs, GFP_NOWAIT);
  	idr_preload_end();
  	mutex_unlock(&afu->contexts_lock);
  	if (i < 0)
  		return i;
  
  	ctx->pe = i;
  	ctx->elem = &ctx->afu->spa[i];
  	ctx->pe_inserted = false;
  	return 0;
  }
  
  static int cxl_mmap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
  {
  	struct cxl_context *ctx = vma->vm_file->private_data;
  	unsigned long address = (unsigned long)vmf->virtual_address;
  	u64 area, offset;
  
  	offset = vmf->pgoff << PAGE_SHIFT;
  
  	pr_devel("%s: pe: %i address: 0x%lx offset: 0x%llx\n",
  			__func__, ctx->pe, address, offset);
  
  	if (ctx->afu->current_mode == CXL_MODE_DEDICATED) {
  		area = ctx->afu->psn_phys;
  		if (offset > ctx->afu->adapter->ps_size)
  			return VM_FAULT_SIGBUS;
  	} else {
  		area = ctx->psn_phys;
  		if (offset > ctx->psn_size)
  			return VM_FAULT_SIGBUS;
  	}
  
  	mutex_lock(&ctx->status_mutex);
  
  	if (ctx->status != STARTED) {
  		mutex_unlock(&ctx->status_mutex);
  		pr_devel("%s: Context not started, failing problem state access\n", __func__);
  		return VM_FAULT_SIGBUS;
  	}
  
  	vm_insert_pfn(vma, address, (area + offset) >> PAGE_SHIFT);
  
  	mutex_unlock(&ctx->status_mutex);
  
  	return VM_FAULT_NOPAGE;
  }
  
  static const struct vm_operations_struct cxl_mmap_vmops = {
  	.fault = cxl_mmap_fault,
  };
  
  /*
   * Map a per-context mmio space into the given vma.
   */
  int cxl_context_iomap(struct cxl_context *ctx, struct vm_area_struct *vma)
  {
  	u64 len = vma->vm_end - vma->vm_start;
  	len = min(len, ctx->psn_size);
  
  	if (ctx->afu->current_mode != CXL_MODE_DEDICATED) {
  		/* make sure there is a valid per process space for this AFU */
  		if ((ctx->master && !ctx->afu->psa) || (!ctx->afu->pp_psa)) {
  			pr_devel("AFU doesn't support mmio space\n");
  			return -EINVAL;
  		}
  
  		/* Can't mmap until the AFU is enabled */
  		if (!ctx->afu->enabled)
  			return -EBUSY;
  	}
  
  	pr_devel("%s: mmio physical: %llx pe: %i master:%i\n", __func__,
  		 ctx->psn_phys, ctx->pe , ctx->master);
  
  	vma->vm_flags |= VM_IO | VM_PFNMAP;
  	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
  	vma->vm_ops = &cxl_mmap_vmops;
  	return 0;
  }
  
  /*
   * Detach a context from the hardware. This disables interrupts and doesn't
   * return until all outstanding interrupts for this context have completed. The
   * hardware should no longer access *ctx after this has returned.
   */
  static void __detach_context(struct cxl_context *ctx)
  {
  	enum cxl_context_status status;
  
  	mutex_lock(&ctx->status_mutex);
  	status = ctx->status;
  	ctx->status = CLOSED;
  	mutex_unlock(&ctx->status_mutex);
  	if (status != STARTED)
  		return;
  
  	WARN_ON(cxl_detach_process(ctx));
  	afu_release_irqs(ctx);
  	flush_work(&ctx->fault_work); /* Only needed for dedicated process */
  	wake_up_all(&ctx->wq);
  }
  
  /*
   * Detach the given context from the AFU. This doesn't actually
   * free the context but it should stop the context running in hardware
   * (ie. prevent this context from generating any further interrupts
   * so that it can be freed).
   */
  void cxl_context_detach(struct cxl_context *ctx)
  {
  	__detach_context(ctx);
  }
  
  /*
   * Detach all contexts on the given AFU.
   */
  void cxl_context_detach_all(struct cxl_afu *afu)
  {
  	struct cxl_context *ctx;
  	int tmp;
  
  	mutex_lock(&afu->contexts_lock);
  	idr_for_each_entry(&afu->contexts_idr, ctx, tmp) {
  		/*
  		 * Anything done in here needs to be setup before the IDR is
  		 * created and torn down after the IDR removed
  		 */
  		__detach_context(ctx);
  
  		/*
  		 * We are force detaching - remove any active PSA mappings so
  		 * userspace cannot interfere with the card if it comes back.
  		 * Easiest way to exercise this is to unbind and rebind the
  		 * driver via sysfs while it is in use.
  		 */
  		mutex_lock(&ctx->mapping_lock);
  		if (ctx->mapping)
  			unmap_mapping_range(ctx->mapping, 0, 0, 1);
  		mutex_unlock(&ctx->mapping_lock);
  	}
  	mutex_unlock(&afu->contexts_lock);
  }
  
  void cxl_context_free(struct cxl_context *ctx)
  {
  	mutex_lock(&ctx->afu->contexts_lock);
  	idr_remove(&ctx->afu->contexts_idr, ctx->pe);
  	mutex_unlock(&ctx->afu->contexts_lock);
  	synchronize_rcu();
  
  	free_page((u64)ctx->sstp);
  	ctx->sstp = NULL;
  
  	put_pid(ctx->pid);
  	kfree(ctx);
  }
  