via_dmablit.c

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/* via_dmablit.c -- PCI DMA BitBlt support for the VIA Unichrome/Pro
 * 
 * Copyright (C) 2005 Thomas Hellstrom, All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sub license,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the
 * next paragraph) shall be included in all copies or substantial portions
 * of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
 * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, 
 * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR 
 * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 
 * USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: 
 *    Thomas Hellstrom.
 *    Partially based on code obtained from Digeo Inc.
 */


/*
 * Unmaps the DMA mappings. 
 * FIXME: Is this a NoOp on x86? Also 
 * FIXME: What happens if this one is called and a pending blit has previously done 
 * the same DMA mappings? 
 */

#include "drmP.h"
#include "via_drm.h"
#include "via_drv.h"
#include "via_dmablit.h"

#include <linux/pagemap.h>

#define VIA_PGDN(x)             (((unsigned long)(x)) & PAGE_MASK)
#define VIA_PGOFF(x)            (((unsigned long)(x)) & ~PAGE_MASK)
#define VIA_PFN(x)              ((unsigned long)(x) >> PAGE_SHIFT)

typedef struct _drm_via_descriptor {
	uint32_t mem_addr;
	uint32_t dev_addr;
	uint32_t size;
	uint32_t next;
} drm_via_descriptor_t;


/*
 * Unmap a DMA mapping.
 */



static void
via_unmap_blit_from_device(struct pci_dev *pdev, drm_via_sg_info_t *vsg)
{
	int num_desc = vsg->num_desc;
	unsigned cur_descriptor_page = num_desc / vsg->descriptors_per_page;
	unsigned descriptor_this_page = num_desc % vsg->descriptors_per_page;
	drm_via_descriptor_t *desc_ptr = vsg->desc_pages[cur_descriptor_page] + 
		descriptor_this_page;
	dma_addr_t next = vsg->chain_start;

	while(num_desc--) {
		if (descriptor_this_page-- == 0) {
			cur_descriptor_page--;
			descriptor_this_page = vsg->descriptors_per_page - 1;
			desc_ptr = vsg->desc_pages[cur_descriptor_page] + 
				descriptor_this_page;
		}
		dma_unmap_single(&pdev->dev, next, sizeof(*desc_ptr), DMA_TO_DEVICE);
		dma_unmap_page(&pdev->dev, desc_ptr->mem_addr, desc_ptr->size, vsg->direction);
		next = (dma_addr_t) desc_ptr->next;
		desc_ptr--;
	}
}

/*
 * If mode = 0, count how many descriptors are needed.
 * If mode = 1, Map the DMA pages for the device, put together and map also the descriptors.
 * Descriptors are run in reverse order by the hardware because we are not allowed to update the
 * 'next' field without syncing calls when the descriptor is already mapped.
 */

static void
via_map_blit_for_device(struct pci_dev *pdev,
		   const drm_via_dmablit_t *xfer,
		   drm_via_sg_info_t *vsg, 
		   int mode)
{
	unsigned cur_descriptor_page = 0;
	unsigned num_descriptors_this_page = 0;
	unsigned char *mem_addr = xfer->mem_addr;
	unsigned char *cur_mem;
	unsigned char *first_addr = (unsigned char *)VIA_PGDN(mem_addr);
	uint32_t fb_addr = xfer->fb_addr;
	uint32_t cur_fb;
	unsigned long line_len;
	unsigned remaining_len;
	int num_desc = 0;
	int cur_line;
	dma_addr_t next = 0 | VIA_DMA_DPR_EC;
	drm_via_descriptor_t *desc_ptr = NULL;

	if (mode == 1) 
		desc_ptr = vsg->desc_pages[cur_descriptor_page];

	for (cur_line = 0; cur_line < xfer->num_lines; ++cur_line) {

		line_len = xfer->line_length;
		cur_fb = fb_addr;
		cur_mem = mem_addr;
		
		while (line_len > 0) {

                        remaining_len = min(PAGE_SIZE-VIA_PGOFF(cur_mem), line_len);
			line_len -= remaining_len;

			if (mode == 1) {
                                desc_ptr->mem_addr = 
					dma_map_page(&pdev->dev, 
						     vsg->pages[VIA_PFN(cur_mem) - 
								VIA_PFN(first_addr)],
						     VIA_PGOFF(cur_mem), remaining_len, 
						     vsg->direction);
                                desc_ptr->dev_addr = cur_fb;
				
                                desc_ptr->size = remaining_len;
				desc_ptr->next = (uint32_t) next;
				next = dma_map_single(&pdev->dev, desc_ptr, sizeof(*desc_ptr), 
						      DMA_TO_DEVICE);
				desc_ptr++;
				if (++num_descriptors_this_page >= vsg->descriptors_per_page) {
					num_descriptors_this_page = 0;
					desc_ptr = vsg->desc_pages[++cur_descriptor_page];
				}
			}
			
			num_desc++;
			cur_mem += remaining_len;
			cur_fb += remaining_len;
		}
		
		mem_addr += xfer->mem_stride;
		fb_addr += xfer->fb_stride;
	}

	if (mode == 1) {
		vsg->chain_start = next;
		vsg->state = dr_via_device_mapped;
	}
	vsg->num_desc = num_desc;
}

/*
 * Function that frees up all resources for a blit. It is usable even if the 
 * blit info has only be partially built as long as the status enum is consistent
 * with the actual status of the used resources.
 */


static void
via_free_sg_info(struct pci_dev *pdev, drm_via_sg_info_t *vsg) 
{
	struct page *page;
	int i;

	switch(vsg->state) {
	case dr_via_device_mapped:
		via_unmap_blit_from_device(pdev, vsg);
	case dr_via_desc_pages_alloc:
		for (i=0; i<vsg->num_desc_pages; ++i) {
			if (vsg->desc_pages[i] != NULL)
			  free_page((unsigned long)vsg->desc_pages[i]);
		}
		kfree(vsg->desc_pages);
	case dr_via_pages_locked:
		for (i=0; i<vsg->num_pages; ++i) {
			if ( NULL != (page = vsg->pages[i])) {
				if (! PageReserved(page) && (DMA_FROM_DEVICE == vsg->direction)) 
					SetPageDirty(page);
				page_cache_release(page);
			}
		}
	case dr_via_pages_alloc:
		vfree(vsg->pages);
	default:
		vsg->state = dr_via_sg_init;
	}
	if (vsg->bounce_buffer) {
		vfree(vsg->bounce_buffer);
		vsg->bounce_buffer = NULL;
	}
	vsg->free_on_sequence = 0;
}		

/*
 * Fire a blit engine.
 */

static void
via_fire_dmablit(drm_device_t *dev, drm_via_sg_info_t *vsg, int engine)
{
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;

	VIA_WRITE(VIA_PCI_DMA_MAR0 + engine*0x10, 0);
	VIA_WRITE(VIA_PCI_DMA_DAR0 + engine*0x10, 0);
	VIA_WRITE(VIA_PCI_DMA_CSR0 + engine*0x04, VIA_DMA_CSR_DD | VIA_DMA_CSR_TD | 
		  VIA_DMA_CSR_DE);
	VIA_WRITE(VIA_PCI_DMA_MR0  + engine*0x04, VIA_DMA_MR_CM | VIA_DMA_MR_TDIE);
	VIA_WRITE(VIA_PCI_DMA_BCR0 + engine*0x10, 0);
	VIA_WRITE(VIA_PCI_DMA_DPR0 + engine*0x10, vsg->chain_start);
	VIA_WRITE(VIA_PCI_DMA_CSR0 + engine*0x04, VIA_DMA_CSR_DE | VIA_DMA_CSR_TS);
}

/*
 * Obtain a page pointer array and lock all pages into system memory. A segmentation violation will
 * occur here if the calling user does not have access to the submitted address.
 */

static int
via_lock_all_dma_pages(drm_via_sg_info_t *vsg,  drm_via_dmablit_t *xfer)
{
	int ret;
	unsigned long first_pfn = VIA_PFN(xfer->mem_addr);
	vsg->num_pages = VIA_PFN(xfer->mem_addr + (xfer->num_lines * xfer->mem_stride -1)) - 
		first_pfn + 1;
	
	if (NULL == (vsg->pages = vmalloc(sizeof(struct page *) * vsg->num_pages)))
		return DRM_ERR(ENOMEM);
	memset(vsg->pages, 0, sizeof(struct page *) * vsg->num_pages);
	down_read(&current->mm->mmap_sem);
	ret = get_user_pages(current, current->mm, (unsigned long) xfer->mem_addr,
			     vsg->num_pages, vsg->direction, 0, vsg->pages, NULL);

	up_read(&current->mm->mmap_sem);
	if (ret != vsg->num_pages) {
		if (ret < 0) 
			return ret;
		vsg->state = dr_via_pages_locked;
		return DRM_ERR(EINVAL);
	}
	vsg->state = dr_via_pages_locked;
	DRM_DEBUG("DMA pages locked\n");
	return 0;
}

/*
 * Allocate DMA capable memory for the blit descriptor chain, and an array that keeps track of the
 * pages we allocate. We don't want to use kmalloc for the descriptor chain because it may be
 * quite large for some blits, and pages don't need to be contingous.
 */

static int 
via_alloc_desc_pages(drm_via_sg_info_t *vsg)
{
	int i;
	
	vsg->descriptors_per_page = PAGE_SIZE / sizeof( drm_via_descriptor_t);
	vsg->num_desc_pages = (vsg->num_desc + vsg->descriptors_per_page - 1) / 
		vsg->descriptors_per_page;

	if (NULL ==  (vsg->desc_pages = kmalloc(sizeof(void *) * vsg->num_desc_pages, GFP_KERNEL))) 
		return DRM_ERR(ENOMEM);
	
	memset(vsg->desc_pages, 0, sizeof(void *) * vsg->num_desc_pages);
	vsg->state = dr_via_desc_pages_alloc;
	for (i=0; i<vsg->num_desc_pages; ++i) {
		if (NULL == (vsg->desc_pages[i] = 
			     (drm_via_descriptor_t *) __get_free_page(GFP_KERNEL)))
			return DRM_ERR(ENOMEM);
	}
	DRM_DEBUG("Allocated %d pages for %d descriptors.\n", vsg->num_desc_pages,
		  vsg->num_desc);
	return 0;
}
			
static void
via_abort_dmablit(drm_device_t *dev, int engine)
{
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;

	VIA_WRITE(VIA_PCI_DMA_CSR0 + engine*0x04, VIA_DMA_CSR_TA);
}

static void
via_dmablit_engine_off(drm_device_t *dev, int engine)
{
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;

	VIA_WRITE(VIA_PCI_DMA_CSR0 + engine*0x04, VIA_DMA_CSR_TD | VIA_DMA_CSR_DD); 
}



/*
 * The dmablit part of the IRQ handler. Trying to do only reasonably fast things here.
 * The rest, like unmapping and freeing memory for done blits is done in a separate workqueue
 * task. Basically the task of the interrupt handler is to submit a new blit to the engine, while
 * the workqueue task takes care of processing associated with the old blit.
 */
		
void
via_dmablit_handler(drm_device_t *dev, int engine, int from_irq)
{
	drm_via_private_t *dev_priv = (drm_via_private_t *)dev->dev_private;
	drm_via_blitq_t *blitq = dev_priv->blit_queues + engine;
	int cur;
	int done_transfer;
	unsigned long irqsave=0;
	uint32_t status = 0;

	DRM_DEBUG("DMA blit handler called. engine = %d, from_irq = %d, blitq = 0x%lx\n",
		  engine, from_irq, (unsigned long) blitq);

	if (from_irq) {
		spin_lock(&blitq->blit_lock);
	} else {
		spin_lock_irqsave(&blitq->blit_lock, irqsave);
	}

	done_transfer = blitq->is_active && 
	  (( status = VIA_READ(VIA_PCI_DMA_CSR0 + engine*0x04)) & VIA_DMA_CSR_TD);
	done_transfer = done_transfer || ( blitq->aborting && !(status & VIA_DMA_CSR_DE)); 

	cur = blitq->cur;
	if (done_transfer) {

		blitq->blits[cur]->aborted = blitq->aborting;
		blitq->done_blit_handle++;
		DRM_WAKEUP(blitq->blit_queue + cur);		

		cur++;
		if (cur >= VIA_NUM_BLIT_SLOTS) 
			cur = 0;
		blitq->cur = cur;

		/*
		 * Clear transfer done flag.
		 */

		VIA_WRITE(VIA_PCI_DMA_CSR0 + engine*0x04,  VIA_DMA_CSR_TD);

		blitq->is_active = 0;
		blitq->aborting = 0;
		schedule_work(&blitq->wq);	

	} else if (blitq->is_active && time_after_eq(jiffies, blitq->end)) {

		/*
		 * Abort transfer after one second.
		 */

		via_abort_dmablit(dev, engine);
		blitq->aborting = 1;
		blitq->end = jiffies + DRM_HZ;
	}
	  		
	if (!blitq->is_active) {
		if (blitq->num_outstanding) {
			via_fire_dmablit(dev, blitq->blits[cur], engine);
			blitq->is_active = 1;
			blitq->cur = cur;
			blitq->num_outstanding--;
			blitq->end = jiffies + DRM_HZ;
			if (!timer_pending(&blitq->poll_timer)) {
				blitq->poll_timer.expires = jiffies+1;
				add_timer(&blitq->poll_timer);
			}
		} else {
			if (timer_pending(&blitq->poll_timer)) {
				del_timer(&blitq->poll_timer);
			}
			via_dmablit_engine_off(dev, engine);
		}
	}		

	if (from_irq) {
		spin_unlock(&blitq->blit_lock);
	} else {
		spin_unlock_irqrestore(&blitq->blit_lock, irqsave);
	}
} 



/*
 * Check whether this blit is still active, performing necessary locking.
 */

static int
via_dmablit_active(drm_via_blitq_t *blitq, int engine, uint32_t handle, wait_queue_head_t **queue)
{
	unsigned long irqsave;
	uint32_t slot;