[PATCH 1/5] dmaengine: mxs-dma: add dma support for i.MX23/28

On Sat, Feb 05, 2011 at 10:08:12AM +0800, Shawn Guo wrote:

Does this have a valid usecase? I would just return some error code
here. pio_num and pio_words are unused in the driver and I don't think
a dmaengine driver should have some kind of PIO fallback.

+	} else {
+		for_each_sg(sgl, sg, sg_len, i) {
+			if (sg->length > MAX_XFER_BYTES) {
+				dev_err(mxs_dma->dev, "maximum bytes for sg entry exceeded: %d > %d\n",
+						sg->length, MAX_XFER_BYTES);
+				ret = -EINVAL;
+				goto err_out;
+			}
+
+			ccw = &mxs_chan->ccw[i];
+
+			ccw->next = mxs_chan->ccw_phys + sizeof(*ccw) * (i + 1);
+			ccw->bufaddr = sg->dma_address;
+			ccw->bits.xfer_bytes = sg->length;
+			ccw->bits.chain = 1;
+			ccw->bits.irq = 0;
+			ccw->bits.dec_sem = 0;
+			ccw->bits.wait4end = 0;
+			ccw->bits.halt_on_terminate = 1;
+			ccw->bits.terminate_flush = 1;
+			ccw->bits.pio_num = 0;
+			ccw->bits.command = (direction == DMA_FROM_DEVICE) ?
+						MXS_DMA_WRITE : MXS_DMA_READ;
+
+			if (i + 1 == sg_len) {
+				ccw->next = 0;
+				ccw->bits.chain = 0;
+				ccw->bits.irq = 1;
+				ccw->bits.dec_sem = 1;
+				ccw->bits.wait4end = 1;
+			}
+		}
+	}
+
+	return &mxs_chan->desc;
+
+err_out:
+	mxs_chan->status = DMA_ERROR;
+	return NULL;
+}
+
+
+static int __init mxs_dma_probe(struct platform_device *pdev)
+{
+	const struct platform_device_id *id_entry =
+				platform_get_device_id(pdev);
+	struct mxs_dma_engine *mxs_dma;
+	struct resource *iores;
+	int ret, i;
+
+	mxs_dma = kzalloc(sizeof(*mxs_dma), GFP_KERNEL);
+	if (!mxs_dma)
+		return -ENOMEM;
+
+	mxs_dma->dev = &pdev->dev;
+	mxs_dma->dev_id = id_entry->driver_data;
+
+	iores = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	if (!request_mem_region(iores->start, resource_size(iores),
+				pdev->name)) {
+		ret = -EBUSY;
+		goto err_request_region;
+	}
+
+	mxs_dma->base = ioremap(iores->start, resource_size(iores));
+	if (!mxs_dma->base) {
+		ret = -ENOMEM;
+		goto err_ioremap;
+	}
+
+	mxs_dma->clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(mxs_dma->clk)) {
+		ret = PTR_ERR(mxs_dma->clk);
+		goto err_clk;
+	}
+
+	dma_cap_set(DMA_SLAVE, mxs_dma->dma_device.cap_mask);
+	dma_cap_set(DMA_CYCLIC, mxs_dma->dma_device.cap_mask);
+
+	INIT_LIST_HEAD(&mxs_dma->dma_device.channels);
+
+	/* Initialize channel parameters */
+	for (i = 0; i < MXS_DMA_CHANNELS; i++) {
+		struct mxs_dma_chan *mxs_chan = &mxs_dma->mxs_chans[i];
+
+		mxs_chan->mxs_dma = mxs_dma;
+		spin_lock_init(&mxs_chan->lock);
+
+		mxs_chan->chan.device = &mxs_dma->dma_device;
+
+		/* Add the channel to mxs_chan list */
+		list_add_tail(&mxs_chan->chan.device_node, &mxs_dma->dma_device.channels);
+	}
+
+	ret = mxs_dma_init(mxs_dma);
+	if (ret)
+		goto err_init;
+
+	mxs_dma->dma_device.dev = &pdev->dev;
+
+	/* mxs_dma gets 65535 bytes maximum sg size */
+	mxs_dma->dma_device.dev->dma_parms = &mxs_dma->dma_parms;
+	dma_set_max_seg_size(mxs_dma->dma_device.dev, MAX_XFER_BYTES);
+
+	mxs_dma->dma_device.device_alloc_chan_resources = mxs_dma_alloc_chan_resources;
+	mxs_dma->dma_device.device_free_chan_resources = mxs_dma_free_chan_resources;
+	mxs_dma->dma_device.device_tx_status = mxs_dma_tx_status;
+	mxs_dma->dma_device.device_prep_slave_sg = mxs_dma_prep_slave_sg;
+	mxs_dma->dma_device.device_prep_dma_cyclic = mxs_dma_prep_dma_cyclic;
+	mxs_dma->dma_device.device_control = mxs_dma_control;
+	mxs_dma->dma_device.device_issue_pending = mxs_dma_issue_pending;
+
+	ret = dma_async_device_register(&mxs_dma->dma_device);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to register\n");
+		goto err_dma_register;
+	}
+
+	/*
+	 * dmaengine clients have to use dma_device.dev_id to filter
+	 * dma device between apbh and apbx, so need to ensure it is
+	 * identical to mxs_dma_engine.dev_id.
+	 */
+	if (mxs_dma->dma_device.dev_id != mxs_dma->dev_id) {
+		dev_err(&pdev->dev, "dev_id of dma_device %d differs from mxs_dma_engine %d\n",
+				mxs_dma->dma_device.dev_id, mxs_dma->dev_id);
+		goto err_init;
+	}

I think it makes more sense to match against device names (apbh vs.
apbx) in the client's filter function than to rely on exact numbering.

+
+	dev_info(mxs_dma->dev, "initialized\n");
+
+	return 0;
+
+err_init:
+	dma_async_device_unregister(&mxs_dma->dma_device);
+err_dma_register:
+	clk_put(mxs_dma->clk);
+err_clk:
+	iounmap(mxs_dma->base);
+err_ioremap:
+	release_mem_region(iores->start, resource_size(iores));
+err_request_region:
+	kfree(mxs_dma);
+	return ret;
+}
+
+static int __exit mxs_dma_remove(struct platform_device *pdev)
+{
+	return -EBUSY;
+}
+
+static struct platform_device_id mxs_dma_type[] = {
+	{
+		.name = "mxs-dma-apbh",
+		.driver_data = MXS_DMA_APBH,
+	}, {
+		.name = "mxs-dma-apbx",
+		.driver_data = MXS_DMA_APBX,
+	}
+};
+
+static struct platform_driver mxs_dma_driver = {
+	.driver		= {
+		.name	= "mxs-dma",
+	},
+	.id_table	= mxs_dma_type,
+	.remove		= __exit_p(mxs_dma_remove),
+};
+
+static int __init mxs_dma_module_init(void)
+{
+	return platform_driver_probe(&mxs_dma_driver, mxs_dma_probe);
+}
+subsys_initcall(mxs_dma_module_init);
-- 
1.7.1

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