shared-core/mach64_dma.c


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/* mach64_dma.c -- DMA support for mach64 (Rage Pro) driver -*- linux-c -*- */
/**
 * \file mach64_dma.c
 * DMA support for mach64 (Rage Pro) driver
 *
 * \author Gareth Hughes <gareth@valinux.com>
 * \author Frank C. Earl <fearl@airmail.net>
 * \author Leif Delgass <ldelgass@retinalburn.net>
 * \author José Fonseca <j_r_fonseca@yahoo.co.uk>
 */

/*
 * Copyright 2000 Gareth Hughes
 * Copyright 2002 Frank C. Earl
 * Copyright 2002-2003 Leif Delgass
 * 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, sublicense,
 * 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 NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT OWNER(S) 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.
 */

#include "drmP.h"
#include "drm.h"
#include "mach64_drm.h"
#include "mach64_drv.h"

/*******************************************************************/
/** \name Engine, FIFO control */
/*@{*/

/**
 * Waits for free entries in the FIFO.
 *
 * \note Most writes to Mach64 registers are automatically routed through
 * command FIFO which is 16 entry deep. Prior to writing to any draw engine
 * register one has to ensure that enough FIFO entries are available by calling
 * this function.  Failure to do so may cause the engine to lock.
 *
 * \param dev_priv pointer to device private data structure.
 * \param entries number of free entries in the FIFO to wait for.
 *
 * \returns zero on success, or -EBUSY if the timeout (specificed by
 * drm_mach64_private::usec_timeout) occurs.
 */
int mach64_do_wait_for_fifo(drm_mach64_private_t *dev_priv, int entries)
{
	int slots = 0, i;

	for (i = 0; i < dev_priv->usec_timeout; i++) {
		slots = (MACH64_READ(MACH64_FIFO_STAT) & MACH64_FIFO_SLOT_MASK);
		if (slots <= (0x8000 >> entries))
			return 0;
		DRM_UDELAY(1);
	}

	DRM_INFO("failed! slots=%d entries=%d\n", slots, entries);
	return -EBUSY;
}

/**
 * Wait for the draw engine to be idle.
 */
int mach64_do_wait_for_idle(drm_mach64_private_t *dev_priv)
{
	int i, ret;

	ret = mach64_do_wait_for_fifo(dev_priv, 16);
	if (ret < 0)
		return ret;

	for (i = 0; i < dev_priv->usec_timeout; i++) {
		if (!(MACH64_READ(MACH64_GUI_STAT) & MACH64_GUI_ACTIVE))
			return 0;
		DRM_UDELAY(1);
	}

	DRM_INFO("failed! GUI_STAT=0x%08x\n", MACH64_READ(MACH64_GUI_STAT));
	mach64_dump_ring_info(dev_priv);
	return -EBUSY;
}

/**
 * Wait for free entries in the ring buffer.
 *
 * The Mach64 bus master can be configured to act as a virtual FIFO, using a
 * circular buffer (commonly referred as "ring buffer" in other drivers) with
 * pointers to engine commands. This allows the CPU to do other things while
 * the graphics engine is busy, i.e., DMA mode.
 *
 * This function should be called before writing new entries to the ring
 * buffer.
 *
 * \param dev_priv pointer to device private data structure.
 * \param n number of free entries in the ring buffer to wait for.
 *
 * \returns zero on success, or -EBUSY if the timeout (specificed by
 * drm_mach64_private_t::usec_timeout) occurs.
 *
 * \sa mach64_dump_ring_info()
 */
int mach64_wait_ring(drm_mach64_private_t *dev_priv, int n)
{
	drm_mach64_descriptor_ring_t *ring = &dev_priv->ring;
	int i;

	for (i = 0; i < dev_priv->usec_timeout; i++) {
		mach64_update_ring_snapshot(dev_priv);
		if (ring->space >= n) {
			if (i > 0)
				DRM_DEBUG("%d usecs\n", i);
			return 0;
		}
		DRM_UDELAY(1);
	}

	/* FIXME: This is being ignored... */
	DRM_ERROR("failed!\n");
	mach64_dump_ring_info(dev_priv);
	return -EBUSY;
}

/**
 * Wait until all DMA requests have been processed...
 *
 * \sa mach64_wait_ring()
 */
static int mach64_ring_idle(drm_mach64_private_t *dev_priv)
{
	drm_mach64_descriptor_ring_t *ring = &dev_priv->ring;
	u32 head;
	int i;

	head = ring->head;
	i = 0;
	while (i < dev_priv->usec_timeout) {
		mach64_update_ring_snapshot(dev_priv);
		if (ring->head == ring->tail &&
		    !(MACH64_READ(MACH64_GUI_STAT) & MACH64_GUI_ACTIVE)) {
			if (i > 0)
				DRM_DEBUG("%d usecs\n", i);
			return 0;
		}
		if (ring->head == head) {
			++i;
		} else {
			head = ring->head;
			i = 0;
		}
		DRM_UDELAY(1);
	}

	DRM_INFO("failed! GUI_STAT=0x%08x\n", MACH64_READ(MACH64_GUI_STAT));
	mach64_dump_ring_info(dev_priv);
	return -EBUSY;
}

/**
 * Reset the the ring buffer descriptors.
 *
 * \sa mach64_do_engine_reset()
 */
static void mach64_ring_reset(drm_mach64_private_t *dev_priv)
{
	drm_mach64_descriptor_ring_t *ring = &dev_priv->ring;

	mach64_do_release_used_buffers(dev_priv);
	ring->head_addr = ring->start_addr;
	ring->head = ring->tail = 0;
	ring->space = ring->size;

	MACH64_WRITE(MACH64_BM_GUI_TABLE_CMD,
		     ring->head_addr | MACH64_CIRCULAR_BUF_SIZE_16KB);

	dev_priv->ring_running = 0;
}

/**
 * Ensure the all the queued commands will be processed.
 */
int mach64_do_dma_flush(drm_mach64_private_t *dev_priv)
{
	/* FIXME: It's not necessary to wait for idle when flushing
	 * we just need to ensure the ring will be completely processed
	 * in finite time without another ioctl
	 */
	return mach64_ring_idle(dev_priv);
}

/**
 * Stop all DMA activity.
 */
int mach64_do_dma_idle(drm_mach64_private_t *dev_priv)
{
	int ret;

	/* wait for completion */
	if ((ret = mach64_ring_idle(dev_priv)) < 0) {
		DRM_ERROR("failed BM_GUI_TABLE=0x%08x tail: %u\n",
			  MACH64_READ(MACH64_BM_GUI_TABLE),
			  dev_priv->ring.tail);
		return ret;
	}

	mach64_ring_stop(dev_priv);

	/* clean up after pass */
	mach64_do_release_used_buffers(dev_priv);
	return 0;
}

/**