Add slave transfer capability to BCM2835 dmaengine driver. This patch is pulled from the bcm2708-dmaengine driver in the Raspberry Pi repo. The work was done by Gellert Weisz.
Tested with the bcm2835-mmc driver from the same repo. Signed-off-by: Noralf Trønnes <nor...@tronnes.org> --- Gellert Weisz has ended his internship with Raspberry Pi Trading and was not available to sign off this patch. Changes from original code: Remove slave_id use. SDHCI_BCM_DMA_WAITS changed to BCM2835_DMA_WAIT_CYCLES. Use SZ_* macros instead of decimal values. Change MAX_LITE_TRANSFER from 32k to 64K - 1. Fix several whitespace issues. Lee Jones' comments in previous email to Piotr Król: Remove __func__ from dev_err message. Cleanup comments. Quick testing: Enable CONFIG_DMA_BCM2835 Apply patch: https://gist.github.com/notro/0c9184df1b43a793f006 drivers/dma/bcm2835-dma.c | 200 ++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 186 insertions(+), 14 deletions(-) diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c index c92d6a7..4230aac 100644 --- a/drivers/dma/bcm2835-dma.c +++ b/drivers/dma/bcm2835-dma.c @@ -1,11 +1,10 @@ /* * BCM2835 DMA engine support * - * This driver only supports cyclic DMA transfers - * as needed for the I2S module. - * * Author: Florian Meier <florian.me...@koalo.de> * Copyright 2013 + * Gellert Weisz <gell...@raspberrypi.org> + * Copyright 2013-2014 * * Based on * OMAP DMAengine support by Russell King @@ -89,6 +88,8 @@ struct bcm2835_desc { size_t size; }; +#define BCM2835_DMA_WAIT_CYCLES 0 /* Slow down DMA transfers: 0-31 */ + #define BCM2835_DMA_CS 0x00 #define BCM2835_DMA_ADDR 0x04 #define BCM2835_DMA_SOURCE_AD 0x0c @@ -105,12 +106,16 @@ struct bcm2835_desc { #define BCM2835_DMA_RESET BIT(31) /* WO, self clearing */ #define BCM2835_DMA_INT_EN BIT(0) +#define BCM2835_DMA_WAIT_RESP BIT(3) #define BCM2835_DMA_D_INC BIT(4) +#define BCM2835_DMA_D_WIDTH BIT(5) #define BCM2835_DMA_D_DREQ BIT(6) #define BCM2835_DMA_S_INC BIT(8) +#define BCM2835_DMA_S_WIDTH BIT(9) #define BCM2835_DMA_S_DREQ BIT(10) #define BCM2835_DMA_PER_MAP(x) ((x) << 16) +#define BCM2835_DMA_WAITS(x) (((x) & 0x1f) << 21) #define BCM2835_DMA_DATA_TYPE_S8 1 #define BCM2835_DMA_DATA_TYPE_S16 2 @@ -124,6 +129,9 @@ struct bcm2835_desc { #define BCM2835_DMA_CHAN(n) ((n) << 8) /* Base address */ #define BCM2835_DMA_CHANIO(base, n) ((base) + BCM2835_DMA_CHAN(n)) +#define MAX_LITE_TRANSFER (SZ_64K - 1) +#define MAX_NORMAL_TRANSFER SZ_1G + static inline struct bcm2835_dmadev *to_bcm2835_dma_dev(struct dma_device *d) { return container_of(d, struct bcm2835_dmadev, ddev); @@ -217,12 +225,18 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data) d = c->desc; if (d) { - /* TODO Only works for cyclic DMA */ - vchan_cyclic_callback(&d->vd); - } + if (c->cyclic) { + vchan_cyclic_callback(&d->vd); - /* Keep the DMA engine running */ - writel(BCM2835_DMA_ACTIVE, c->chan_base + BCM2835_DMA_CS); + /* Keep the DMA engine running */ + writel(BCM2835_DMA_ACTIVE, + c->chan_base + BCM2835_DMA_CS); + + } else { + vchan_cookie_complete(&c->desc->vd); + bcm2835_dma_start_desc(c); + } + } spin_unlock_irqrestore(&c->vc.lock, flags); @@ -323,8 +337,6 @@ static void bcm2835_dma_issue_pending(struct dma_chan *chan) struct bcm2835_chan *c = to_bcm2835_dma_chan(chan); unsigned long flags; - c->cyclic = true; /* Nothing else is implemented */ - spin_lock_irqsave(&c->vc.lock, flags); if (vchan_issue_pending(&c->vc) && !c->desc) bcm2835_dma_start_desc(c); @@ -342,7 +354,7 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( struct bcm2835_desc *d; dma_addr_t dev_addr; unsigned int es, sync_type; - unsigned int frame; + unsigned int frame, max_size; /* Grab configuration */ if (!is_slave_direction(direction)) { @@ -375,7 +387,12 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( return NULL; d->dir = direction; - d->frames = buf_len / period_len; + if (c->ch >= 8) /* LITE channel */ + max_size = MAX_LITE_TRANSFER; + else + max_size = MAX_NORMAL_TRANSFER; + period_len = min(period_len, max_size); + d->frames = (buf_len - 1) / (period_len + 1); /* Allocate memory for control blocks */ d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb); @@ -420,12 +437,16 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( BCM2835_DMA_PER_MAP(c->dreq); /* Length of a frame */ - control_block->length = period_len; + if (frame != d->frames - 1) + control_block->length = period_len; + else + control_block->length = buf_len - (d->frames - 1) * + period_len; d->size += control_block->length; /* * Next block is the next frame. - * This DMA engine driver currently only supports cyclic DMA. + * This function is called on cyclic DMA transfers. * Therefore, wrap around at number of frames. */ control_block->next = d->control_block_base_phys + @@ -433,6 +454,155 @@ static struct dma_async_tx_descriptor *bcm2835_dma_prep_dma_cyclic( * ((frame + 1) % d->frames); } + c->cyclic = true; + + return vchan_tx_prep(&c->vc, &d->vd, flags); +} + +static struct dma_async_tx_descriptor * +bcm2835_dma_prep_slave_sg(struct dma_chan *chan, + struct scatterlist *sgl, + unsigned int sg_len, + enum dma_transfer_direction direction, + unsigned long flags, void *context) +{ + struct bcm2835_chan *c = to_bcm2835_dma_chan(chan); + enum dma_slave_buswidth dev_width; + struct bcm2835_desc *d; + dma_addr_t dev_addr; + struct scatterlist *sgent; + unsigned int es, sync_type; + unsigned int i, j, splitct, max_size; + + if (!is_slave_direction(direction)) { + dev_err(chan->device->dev, "direction not supported\n"); + return NULL; + } + + if (direction == DMA_DEV_TO_MEM) { + dev_addr = c->cfg.src_addr; + dev_width = c->cfg.src_addr_width; + sync_type = BCM2835_DMA_S_DREQ; + } else { + dev_addr = c->cfg.dst_addr; + dev_width = c->cfg.dst_addr_width; + sync_type = BCM2835_DMA_D_DREQ; + } + + /* Bus width translates to the element size (ES) */ + switch (dev_width) { + case DMA_SLAVE_BUSWIDTH_4_BYTES: + es = BCM2835_DMA_DATA_TYPE_S32; + break; + default: + return NULL; + } + + /* Allocate and setup the descriptor. */ + d = kzalloc(sizeof(*d), GFP_NOWAIT); + if (!d) + return NULL; + + d->dir = direction; + + if (c->ch >= 8) /* LITE channel */ + max_size = MAX_LITE_TRANSFER; + else + max_size = MAX_NORMAL_TRANSFER; + + /* + * Store the length of the SG list in d->frames + * taking care to account for splitting up transfers + * too large for a LITE channel + */ + d->frames = 0; + for_each_sg(sgl, sgent, sg_len, i) { + unsigned int len = sg_dma_len(sgent); + + d->frames += 1 + len / max_size; + } + + /* Allocate memory for control blocks */ + d->control_block_size = d->frames * sizeof(struct bcm2835_dma_cb); + d->control_block_base = dma_zalloc_coherent(chan->device->dev, + d->control_block_size, &d->control_block_base_phys, + GFP_NOWAIT); + if (!d->control_block_base) { + kfree(d); + return NULL; + } + + /* + * Iterate over all SG entries, create a control block + * for each frame and link them together. + * Count the number of times an SG entry had to be split + * as a result of using a LITE channel + */ + splitct = 0; + + for_each_sg(sgl, sgent, sg_len, i) { + dma_addr_t addr = sg_dma_address(sgent); + unsigned int len = sg_dma_len(sgent); + + for (j = 0; j < len; j += max_size) { + struct bcm2835_dma_cb *control_block = + &d->control_block_base[i + splitct]; + + /* Setup addresses */ + if (d->dir == DMA_DEV_TO_MEM) { + control_block->info = BCM2835_DMA_D_INC | + BCM2835_DMA_D_WIDTH | + BCM2835_DMA_S_DREQ; + control_block->src = dev_addr; + control_block->dst = addr + (dma_addr_t)j; + } else { + control_block->info = BCM2835_DMA_S_INC | + BCM2835_DMA_S_WIDTH | + BCM2835_DMA_D_DREQ; + control_block->src = addr + (dma_addr_t)j; + control_block->dst = dev_addr; + } + + /* Common part */ + control_block->info |= + BCM2835_DMA_WAITS(BCM2835_DMA_WAIT_CYCLES); + control_block->info |= BCM2835_DMA_WAIT_RESP; + + /* Enable */ + if (i == sg_len - 1 && len - j <= max_size) + control_block->info |= BCM2835_DMA_INT_EN; + + /* Setup synchronization */ + if (sync_type != 0) + control_block->info |= sync_type; + + /* Setup DREQ channel */ + if (c->dreq) + control_block->info |= + BCM2835_DMA_PER_MAP(c->dreq); + + /* Length of a frame */ + control_block->length = min(len - j, max_size); + d->size += control_block->length; + + if (i < sg_len - 1 || len - j > max_size) { + /* Next block is the next frame. */ + control_block->next = + d->control_block_base_phys + + sizeof(struct bcm2835_dma_cb) * + (i + splitct + 1); + } else { + /* Next block is empty. */ + control_block->next = 0; + } + + if (len - j > max_size) + splitct++; + } + } + + c->cyclic = false; + return vchan_tx_prep(&c->vc, &d->vd, flags); } @@ -590,6 +760,7 @@ static int bcm2835_dma_probe(struct platform_device *pdev) od->ddev.device_tx_status = bcm2835_dma_tx_status; od->ddev.device_issue_pending = bcm2835_dma_issue_pending; od->ddev.device_prep_dma_cyclic = bcm2835_dma_prep_dma_cyclic; + od->ddev.device_prep_slave_sg = bcm2835_dma_prep_slave_sg; od->ddev.device_config = bcm2835_dma_slave_config; od->ddev.device_terminate_all = bcm2835_dma_terminate_all; od->ddev.src_addr_widths = BIT(DMA_SLAVE_BUSWIDTH_4_BYTES); @@ -678,4 +849,5 @@ module_platform_driver(bcm2835_dma_driver); MODULE_ALIAS("platform:bcm2835-dma"); MODULE_DESCRIPTION("BCM2835 DMA engine driver"); MODULE_AUTHOR("Florian Meier <florian.me...@koalo.de>"); +MODULE_AUTHOR("Gellert Weisz <gell...@raspberrypi.org>"); MODULE_LICENSE("GPL v2"); -- 2.2.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
