[PATCH RFC v7 2/6] dma: mpc512x: add support for peripheral transfers
Alexander Popov
a13xp0p0v88 at gmail.com
Thu Feb 13 00:25:04 EST 2014
Introduce support for slave s/g transfer preparation and the associated
device control callback in the MPC512x DMA controller driver, which adds
support for data transfers between memory and peripheral I/O to the
previously supported mem-to-mem transfers.
Signed-off-by: Alexander Popov <a13xp0p0v88 at gmail.com>
---
drivers/dma/mpc512x_dma.c | 230 +++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 225 insertions(+), 5 deletions(-)
diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c
index 2ce248b..b978ef1 100644
--- a/drivers/dma/mpc512x_dma.c
+++ b/drivers/dma/mpc512x_dma.c
@@ -2,6 +2,7 @@
* Copyright (C) Freescale Semicondutor, Inc. 2007, 2008.
* Copyright (C) Semihalf 2009
* Copyright (C) Ilya Yanok, Emcraft Systems 2010
+ * Copyright (C) Alexander Popov, Promcontroller 2013
*
* Written by Piotr Ziecik <kosmo at semihalf.com>. Hardware description
* (defines, structures and comments) was taken from MPC5121 DMA driver
@@ -29,8 +30,15 @@
*/
/*
- * This is initial version of MPC5121 DMA driver. Only memory to memory
- * transfers are supported (tested using dmatest module).
+ * MPC512x and MPC8308 DMA driver. It supports
+ * memory to memory data transfers (tested using dmatest module) and
+ * data transfers between memory and peripheral I/O memory
+ * by means of slave s/g with these limitations:
+ * - chunked transfers (transfers with more than one part) are refused
+ * as long as proper support for scatter/gather is missing;
+ * - transfers on MPC8308 always start from software as this SoC appears
+ * not to have external request lines for peripheral flow control;
+ * - minimal memory <-> I/O memory transfer size is 4 bytes.
*/
#include <linux/module.h>
@@ -189,6 +197,7 @@ struct mpc_dma_desc {
dma_addr_t tcd_paddr;
int error;
struct list_head node;
+ int will_access_peripheral;
};
struct mpc_dma_chan {
@@ -201,6 +210,10 @@ struct mpc_dma_chan {
struct mpc_dma_tcd *tcd;
dma_addr_t tcd_paddr;
+ /* Settings for access to peripheral FIFO */
+ dma_addr_t per_paddr; /* FIFO address */
+ u32 tcd_nunits;
+
/* Lock for this structure */
spinlock_t lock;
};
@@ -251,8 +264,21 @@ static void mpc_dma_execute(struct mpc_dma_chan *mchan)
struct mpc_dma_desc *mdesc;
int cid = mchan->chan.chan_id;
- /* Move all queued descriptors to active list */
- list_splice_tail_init(&mchan->queued, &mchan->active);
+ while (!list_empty(&mchan->queued)) {
+ mdesc = list_first_entry(&mchan->queued,
+ struct mpc_dma_desc, node);
+
+ /* Grab either several mem-to-mem transfer descriptors
+ * or one peripheral transfer descriptor,
+ * don't mix mem-to-mem and peripheral transfer descriptors
+ * within the same 'active' list. */
+ if (mdesc->will_access_peripheral) {
+ if (list_empty(&mchan->active))
+ list_move_tail(&mdesc->node, &mchan->active);
+ break;
+ } else
+ list_move_tail(&mdesc->node, &mchan->active);
+ }
/* Chain descriptors into one transaction */
list_for_each_entry(mdesc, &mchan->active, node) {
@@ -278,7 +304,17 @@ static void mpc_dma_execute(struct mpc_dma_chan *mchan)
if (first != prev)
mdma->tcd[cid].e_sg = 1;
- out_8(&mdma->regs->dmassrt, cid);
+
+ if (mdma->is_mpc8308) {
+ /* MPC8308, no request lines, software initiated start */
+ out_8(&mdma->regs->dmassrt, cid);
+ } else if (first->will_access_peripheral) {
+ /* peripherals involved, start by external request signal */
+ out_8(&mdma->regs->dmaserq, cid);
+ } else {
+ /* memory to memory transfer, software initiated start */
+ out_8(&mdma->regs->dmassrt, cid);
+ }
}
/* Handle interrupt on one half of DMA controller (32 channels) */
@@ -596,6 +632,7 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
}
mdesc->error = 0;
+ mdesc->will_access_peripheral = 0;
tcd = mdesc->tcd;
/* Prepare Transfer Control Descriptor for this transaction */
@@ -643,6 +680,186 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
return &mdesc->desc;
}
+static struct dma_async_tx_descriptor *
+mpc_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 mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
+ struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
+ struct mpc_dma_desc *mdesc = NULL;
+ dma_addr_t per_paddr;
+ u32 tcd_nunits;
+ struct mpc_dma_tcd *tcd;
+ unsigned long iflags;
+ struct scatterlist *sg;
+ size_t len;
+ int iter, i;
+
+ /* currently there is no proper support for scatter/gather */
+ if (sg_len != 1)
+ return NULL;
+
+ for_each_sg(sgl, sg, sg_len, i) {
+ spin_lock_irqsave(&mchan->lock, iflags);
+
+ mdesc = list_first_entry(&mchan->free, struct mpc_dma_desc,
+ node);
+ if (!mdesc) {
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+ /* try to free completed descriptors */
+ mpc_dma_process_completed(mdma);
+ return NULL;
+ }
+
+ list_del(&mdesc->node);
+
+ per_paddr = mchan->per_paddr;
+ tcd_nunits = mchan->tcd_nunits;
+
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+
+ if (per_paddr == 0 || tcd_nunits == 0)
+ goto err_prep;
+
+ mdesc->error = 0;
+ mdesc->will_access_peripheral = 1;
+ tcd = mdesc->tcd;
+
+ /* Prepare Transfer Control Descriptor for this transaction */
+
+ memset(tcd, 0, sizeof(struct mpc_dma_tcd));
+
+ if (!IS_ALIGNED(sg_dma_address(sg), 4))
+ goto err_prep;
+
+ if (direction == DMA_DEV_TO_MEM) {
+ tcd->saddr = per_paddr;
+ tcd->daddr = sg_dma_address(sg);
+ tcd->soff = 0;
+ tcd->doff = 4;
+ } else if (direction == DMA_MEM_TO_DEV) {
+ tcd->saddr = sg_dma_address(sg);
+ tcd->daddr = per_paddr;
+ tcd->soff = 4;
+ tcd->doff = 0;
+ } else
+ goto err_prep;
+
+ tcd->ssize = MPC_DMA_TSIZE_4;
+ tcd->dsize = MPC_DMA_TSIZE_4;
+
+ len = sg_dma_len(sg);
+ tcd->nbytes = tcd_nunits * 4;
+ if (!IS_ALIGNED(len, tcd->nbytes))
+ goto err_prep;
+
+ iter = len / tcd->nbytes;
+ if (iter >= 1 << 15) {
+ /* len is too big */
+ goto err_prep;
+ } else {
+ /* citer_linkch contains the high bits of iter */
+ tcd->biter = iter & 0x1ff;
+ tcd->biter_linkch = iter >> 9;
+ tcd->citer = tcd->biter;
+ tcd->citer_linkch = tcd->biter_linkch;
+ }
+
+ tcd->e_sg = 0;
+ tcd->d_req = 1;
+
+ /* Place descriptor in prepared list */
+ spin_lock_irqsave(&mchan->lock, iflags);
+ list_add_tail(&mdesc->node, &mchan->prepared);
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+ }
+
+ return &mdesc->desc;
+
+err_prep:
+ /* Put the descriptor back */
+ spin_lock_irqsave(&mchan->lock, iflags);
+ list_add_tail(&mdesc->node, &mchan->free);
+ spin_unlock_irqrestore(&mchan->lock, iflags);
+
+ return NULL;
+}
+
+static int mpc_dma_device_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
+ unsigned long arg)
+{
+ struct mpc_dma_chan *mchan;
+ struct mpc_dma *mdma;
+ struct dma_slave_config *cfg;
+ unsigned long flags;
+
+ mchan = dma_chan_to_mpc_dma_chan(chan);
+ switch (cmd) {
+ case DMA_TERMINATE_ALL:
+ /* disable channel requests */
+ mdma = dma_chan_to_mpc_dma(chan);
+
+ spin_lock_irqsave(&mchan->lock, flags);
+
+ out_8(&mdma->regs->dmacerq, chan->chan_id);
+ list_splice_tail_init(&mchan->prepared, &mchan->free);
+ list_splice_tail_init(&mchan->queued, &mchan->free);
+ list_splice_tail_init(&mchan->active, &mchan->free);
+
+ spin_unlock_irqrestore(&mchan->lock, flags);
+
+ return 0;
+ case DMA_SLAVE_CONFIG:
+ /* Constraints:
+ * - only transfers between a peripheral device and
+ * memory are supported;
+ * - minimal transfer size is 4 bytes and consequently
+ * source and destination addresses must be 4-byte aligned and
+ * transfer size must be aligned on (4 * maxburst) boundary;
+ * - RAM address is being incremented by minimal transfer size
+ * during the transfer;
+ * - peripheral port's address is constant during the transfer.
+ */
+
+ cfg = (void *)arg;
+
+ if (cfg->direction != DMA_DEV_TO_MEM &&
+ cfg->direction != DMA_MEM_TO_DEV)
+ return -EINVAL;
+
+ if (cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES &&
+ cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
+ return -EINVAL;
+
+ spin_lock_irqsave(&mchan->lock, flags);
+
+ if (cfg->direction == DMA_DEV_TO_MEM) {
+ mchan->per_paddr = cfg->src_addr;
+ mchan->tcd_nunits = cfg->src_maxburst;
+ } else {
+ mchan->per_paddr = cfg->dst_addr;
+ mchan->tcd_nunits = cfg->dst_maxburst;
+ }
+
+ if (!IS_ALIGNED(mchan->per_paddr, 4)) {
+ spin_unlock_irqrestore(&mchan->lock, flags);
+ return -EINVAL;
+ }
+
+ if (mchan->tcd_nunits == 0)
+ mchan->tcd_nunits = 1; /* apply default */
+
+ spin_unlock_irqrestore(&mchan->lock, flags);
+
+ return 0;
+ default:
+ return -ENOSYS;
+ }
+
+ return -EINVAL;
+}
+
static int mpc_dma_probe(struct platform_device *op)
{
struct device_node *dn = op->dev.of_node;
@@ -727,9 +944,12 @@ static int mpc_dma_probe(struct platform_device *op)
dma->device_issue_pending = mpc_dma_issue_pending;
dma->device_tx_status = mpc_dma_tx_status;
dma->device_prep_dma_memcpy = mpc_dma_prep_memcpy;
+ dma->device_prep_slave_sg = mpc_dma_prep_slave_sg;
+ dma->device_control = mpc_dma_device_control;
INIT_LIST_HEAD(&dma->channels);
dma_cap_set(DMA_MEMCPY, dma->cap_mask);
+ dma_cap_set(DMA_SLAVE, dma->cap_mask);
for (i = 0; i < dma->chancnt; i++) {
mchan = &mdma->channels[i];
--
1.8.4.2
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