* Russell King - ARM Linux <li...@arm.linux.org.uk> [120424 03:42]:
> Here's another patch - for the OMAP NAND driver.
>
> One thing this doesn't do is configure up the source/destination bursts,
> which the old code did:
>
> omap_set_dma_dest_burst_mode(info->dma_ch,
> OMAP_DMA_DATA_BURST_16);
> omap_set_dma_src_burst_mode(info->dma_ch,
> OMAP_DMA_DATA_BURST_16);
Grazvydas, care to give this patch a go?
> In dma-engine speak, I'm using "burst" for the number of elements to
> transfer for each frame, with frame sync in place (in other words, the
> number of transfers to occur for every assertion of the DMA request.)
> That's how burst is defined on other DMA hardware, so I'm not entirely
> sure at the moment how critical (or what) the above bursts are doing,
> whether they're configuring the memory side of the transfer or not.
> I'll take a deeper look into that this evening, but in the mean time,
> what's below should be a direct conversion.
For omaps it enables multiple access.
> MTD does have this weirdness that it uses vmalloc regions and passes
> addresses in vmalloc regions into drivers - I've left that hack in but
> it is _highly_ undefined whether the DMA activity would be visible via
> the vmalloc mapping as things currently stand. (You're probably going
> to be okay with non-aliasing VIPT caches, but VIVT and aliasing VIPT
> caches are potential random data corruption candidates.) That's a
> short-coming across many MTD drivers, one which needs sorting out across
> the board.
>
> drivers/mtd/nand/omap2.c | 93
> +++++++++++++++++++++++++++++++++++++++++++++-
> 1 files changed, 92 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index c2b0bba..bd4ed08 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -9,6 +9,7 @@
> */
>
> #include <linux/platform_device.h>
> +#include <linux/dmaengine.h>
> #include <linux/dma-mapping.h>
> #include <linux/delay.h>
> #include <linux/module.h>
> @@ -119,6 +120,7 @@ struct omap_nand_info {
> int gpmc_cs;
> unsigned long phys_base;
> struct completion comp;
> + struct dma_chan *dma;
> int dma_ch;
> int gpmc_irq;
> enum {
> @@ -336,6 +338,10 @@ static void omap_nand_dma_cb(int lch, u16 ch_status,
> void *data)
> {
> complete((struct completion *) data);
> }
> +static void omap_nand_dma_callback(void *data)
> +{
> + complete((struct completion *) data);
> +}
>
> /*
> * omap_nand_dma_transfer: configer and start dma transfer
> @@ -373,6 +379,56 @@ static inline int omap_nand_dma_transfer(struct mtd_info
> *mtd, void *addr,
> addr = page_address(p1) + ((size_t)addr & ~PAGE_MASK);
> }
>
> + if (info->dma) {
> + struct dma_async_tx_descriptor *tx;
> + struct scatterlist sg;
> + unsigned n;
> +
> + sg_init_one(&sg, addr, len);
> + n = dma_map_sg(info->dma->device->dev, &sg, 1, dir);
> + if (n == 0) {
> + dev_err(&info->pdev->dev,
> + "Couldn't DMA map a %d byte buffer\n", len);
> + goto out_copy;
> + }
> +
> + tx = dmaengine_prep_slave_sg(info->dma, &sg, n,
> + is_write ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM,
> + DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> + if (!tx) {
> + dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
> + goto out_copy;
> + }
> + tx->callback = omap_nand_dma_callback;
> + tx->callback_param = &info->comp;
> + dmaengine_submit(tx);
> +
> + /* configure and start prefetch transfer */
> + ret = gpmc_prefetch_enable(info->gpmc_cs,
> + PREFETCH_FIFOTHRESHOLD_MAX, 0x1, len, is_write);
> + if (ret) {
> + /* PFPW engine is busy, use cpu copy method */
> + dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
> + goto out_copy;
> + }
> +
> + init_completion(&info->comp);
> + dma_async_issue_pending(info->dma);
> +
> + /* setup and start DMA using dma_addr */
> + wait_for_completion(&info->comp);
> + tim = 0;
> + limit = (loops_per_jiffy *
> msecs_to_jiffies(OMAP_NAND_TIMEOUT_MS));
> + while (gpmc_read_status(GPMC_PREFETCH_COUNT) && (tim++ < limit))
> + cpu_relax();
> +
> + /* disable and stop the PFPW engine */
> + gpmc_prefetch_reset(info->gpmc_cs);
> +
> + dma_unmap_sg(info->dma->device->dev, &sg, 1, dir);
> + return 0;
> + }
> +
> dma_addr = dma_map_single(&info->pdev->dev, addr, len, dir);
> if (dma_mapping_error(&info->pdev->dev, dma_addr)) {
> dev_err(&info->pdev->dev,
> @@ -405,7 +461,6 @@ static inline int omap_nand_dma_transfer(struct mtd_info
> *mtd, void *addr,
> goto out_copy;
>
> init_completion(&info->comp);
> -
> omap_start_dma(info->dma_ch);
>
> /* setup and start DMA using dma_addr */
> @@ -925,12 +980,16 @@ static int omap_dev_ready(struct mtd_info *mtd)
> return 1;
> }
>
> +extern bool omap_dma_filter_fn(struct dma_chan *chan, void *param);
> +
> static int __devinit omap_nand_probe(struct platform_device *pdev)
> {
> struct omap_nand_info *info;
> struct omap_nand_platform_data *pdata;
> int err;
> int i, offset;
> + dma_cap_mask_t mask;
> + unsigned sig;
>
> pdata = pdev->dev.platform_data;
> if (pdata == NULL) {
> @@ -1011,6 +1070,33 @@ static int __devinit omap_nand_probe(struct
> platform_device *pdev)
> break;
>
> case NAND_OMAP_PREFETCH_DMA:
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> + sig = OMAP24XX_DMA_GPMC;
> + info->dma = dma_request_channel(mask, omap_dma_filter_fn, &sig);
> + if (!info->dma) {
> + dev_warn(&pdev->dev, "DMA engine request failed\n");
> + } else {
> + struct dma_slave_config cfg;
> + int rc;
> +
> + memset(&cfg, 0, sizeof(cfg));
> + cfg.src_addr = info->phys_base;
> + cfg.dst_addr = info->phys_base;
> + cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + cfg.src_maxburst = 16;
> + cfg.dst_maxburst = 16;
> + rc = dmaengine_slave_config(info->dma, &cfg);
> + if (rc) {
> + dev_err(&pdev->dev, "DMA engine slave config
> failed: %d\n",
> + rc);
> + goto out_release_mem_region;
> + }
> + info->nand.read_buf = omap_read_buf_dma_pref;
> + info->nand.write_buf = omap_write_buf_dma_pref;
> + break;
> + }
> err = omap_request_dma(OMAP24XX_DMA_GPMC, "NAND",
> omap_nand_dma_cb, &info->comp, &info->dma_ch);
> if (err < 0) {
> @@ -1110,6 +1196,8 @@ static int __devinit omap_nand_probe(struct
> platform_device *pdev)
> return 0;
>
> out_release_mem_region:
> + if (info->dma)
> + dma_release_channel(info->dma);
> release_mem_region(info->phys_base, NAND_IO_SIZE);
> out_free_info:
> kfree(info);
> @@ -1127,6 +1215,9 @@ static int omap_nand_remove(struct platform_device
> *pdev)
> if (info->dma_ch != -1)
> omap_free_dma(info->dma_ch);
>
> + if (info->dma)
> + dma_release_channel(info->dma);
> +
> if (info->gpmc_irq)
> free_irq(info->gpmc_irq, info);
>
>
> --
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