[PATCH 1/5] dmaengine: mxs-dma: add dma support for i.MX23/28
Shawn Guo
shawn.guo at freescale.com
Tue Feb 8 18:28:34 EST 2011
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:
> > 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 <shawn.guo at freescale.com>
> > ---
> > 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.
> > + } 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
> > +
> > + 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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