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

Hi Sascha,

Thanks for the review.

On Mon, Feb 07, 2011 at 09:25:21AM +0100, Sascha Hauer wrote:

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

quoted

This patch adds dma support for Freescale MXS-based SoC i.MX23/28,
including apbh-dma and apbx-dma.

* apbh-dma and apbx-dma are supported in the driver as two instances,
  and have to be filtered by dma clients via device id.  It becomes
  the convention that apbh-dma always gets registered prior to
  apbx-dma.

* apbh-dma is different between mx23 and mx28, hardware version
  register is used to handle the differences.

* Every the mxs dma channel is statically assigned to client device
  by soc design with fixed irq.  The irq number is being passed by
  alloc_chan function with mxs_dma_data, and client driver has to
  filter the correct channel by its channel id.

* mxs-dma supports pio function besides data transfer.  The driver
  uses dma_data_direction DMA_NONE to identify the pio mode, and
  steals sgl and sg_len to get pio words and numbers from clients.

* mxs dmaengine has some very specific features, like sense function
  and the special NAND support (nand_lock, nand_wait4ready).  These
  are too specific to implemented in generic dmaengine driver.

* The parameter "flags" of prep functions is currently being used to
  pass wait4end flag from clients.

* The driver refers to imx-sdma and only a single descriptor is
  statically assigned to each channel.

Signed-off-by: Shawn Guo <redacted>
---
 arch/arm/mach-mxs/include/mach/dma.h |   16 +
 drivers/dma/Kconfig                  |    8 +
 drivers/dma/Makefile                 |    1 +
 drivers/dma/mxs-dma.c                |  702 ++++++++++++++++++++++++++++++++++
 4 files changed, 727 insertions(+), 0 deletions(-)
 create mode 100644 arch/arm/mach-mxs/include/mach/dma.h
 create mode 100644 drivers/dma/mxs-dma.c

diff --git a/arch/arm/mach-mxs/include/mach/dma.h b/arch/arm/mach-mxs/include/mach/dma.h
new file mode 100644
index 0000000..429f431
--- /dev/null
+++ b/arch/arm/mach-mxs/include/mach/dma.h
+
+static struct dma_async_tx_descriptor *mxs_dma_prep_slave_sg(
+             struct dma_chan *chan, struct scatterlist *sgl,
+             unsigned int sg_len, enum dma_data_direction direction,
+             unsigned long flags)
+{
+     struct mxs_dma_chan *mxs_chan = to_mxs_dma_chan(chan);
+     struct mxs_dma_engine *mxs_dma = mxs_chan->mxs_dma;
+     struct mxs_dma_ccw *ccw;
+     struct scatterlist *sg;
+     int ret, i, j;
+     u32 *pio;
+
+     dev_dbg(mxs_dma->dev, "%s: channel %d\n", __func__, chan->chan_id);
+
+     if (mxs_chan->status == DMA_IN_PROGRESS)
+             return NULL;
+
+     mxs_chan->status = DMA_IN_PROGRESS;
+     mxs_chan->flags = 0;
+
+     dev_dbg(mxs_dma->dev, "%s: setting up %d entries\n", __func__, sg_len);
+
+     if (sg_len > ((direction == DMA_NONE) ? MXS_PIO_WORDS : NUM_CCW)) {
+             dev_err(mxs_dma->dev, "maximum number of sg exceeded: %d > %d\n",
+                             sg_len, NUM_CCW);
+             ret = -EINVAL;
+             goto err_out;
+     }
+
+     if (direction == DMA_NONE) {
+             ccw = &mxs_chan->ccw[0];
+             pio = (u32 *) sgl;
+
+             for (j = 0; j < sg_len;)
+                     ccw->pio_words[j++] = *pio++;
+
+             ccw->next = 0;
+             ccw->bits.chain = 0;
+             ccw->bits.irq = 1;
+             ccw->bits.dec_sem = 1;
+             ccw->bits.wait4end = flags;
+             ccw->bits.halt_on_terminate = 1;
+             ccw->bits.terminate_flush = 1;
+             ccw->bits.pio_num = sg_len;
+             ccw->bits.command = MXS_DMA_NO_XFER;

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.

If you happen to have a look at mxs-mmc patch set, you could find it.

quoted

+     } 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.

I agree, if there is already a member like dev_name in dma_device.
There is dev_id but no dev_name.  Suggestion on how to use device
name for matching?

Regards,
Shawn

quoted

+
+     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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