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List: linux-sh
Subject: [PATCH 1/3 v2] sh: prepare the DMA driver for slave functionality
From: Guennadi Liakhovetski <g.liakhovetski () gmx ! de>
Date: 2010-01-19 7:24:55
Message-ID: Pine.LNX.4.64.1001190810530.4607 () axis700 ! grange
[Download RAW message or body]
Slave DMA functionality uses scatter-gather arrays for data transfers,
whereas memcpy just uses a single data buffer. This patch converts the
current memcpy implementation in shdma.c to use scatter-gather, making it
just a special case with one SG-element. This allows us to isolate
descriptor list manipulations and locking into one function, thus reducing
error chances.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
---
On Thu, 7 Jan 2010, Dan Williams wrote:
> Guennadi Liakhovetski wrote:
> > Slightly clean up and prepare for slave DMA the shdma driver.
>
> Please add some notes about the why/what of factoring out sh_dmae_prep_sg()
> and sh_dmae_add_desc() . Reading this changelog I was expecting primarily
> simple cleanups, with maybe a few function renames.
>
> Otherwise looks ok to me.
v1 -> v2: improve patch description. The patch content remains unchanged.
Dan, does it look acceptable now?
drivers/dma/shdma.c | 221 +++++++++++++++++++++++++++++++++++----------------
1 files changed, 153 insertions(+), 68 deletions(-)
diff --git a/drivers/dma/shdma.c b/drivers/dma/shdma.c
index d10cc89..427c3ef 100644
--- a/drivers/dma/shdma.c
+++ b/drivers/dma/shdma.c
@@ -53,12 +53,12 @@ static void sh_dmae_chan_ld_cleanup(struct sh_dmae_chan *sh_chan, bool all);
#define SH_DMAC_CHAN_BASE(id) (dma_base_addr[id])
static void sh_dmae_writel(struct sh_dmae_chan *sh_dc, u32 data, u32 reg)
{
- ctrl_outl(data, (SH_DMAC_CHAN_BASE(sh_dc->id) + reg));
+ ctrl_outl(data, SH_DMAC_CHAN_BASE(sh_dc->id) + reg);
}
static u32 sh_dmae_readl(struct sh_dmae_chan *sh_dc, u32 reg)
{
- return ctrl_inl((SH_DMAC_CHAN_BASE(sh_dc->id) + reg));
+ return ctrl_inl(SH_DMAC_CHAN_BASE(sh_dc->id) + reg);
}
static void dmae_init(struct sh_dmae_chan *sh_chan)
@@ -95,14 +95,14 @@ static int sh_dmae_rst(int id)
return 0;
}
-static int dmae_is_busy(struct sh_dmae_chan *sh_chan)
+static bool dmae_is_busy(struct sh_dmae_chan *sh_chan)
{
u32 chcr = sh_dmae_readl(sh_chan, CHCR);
- if (chcr & CHCR_DE) {
- if (!(chcr & CHCR_TE))
- return -EBUSY; /* working */
- }
- return 0; /* waiting */
+
+ if ((chcr & (CHCR_DE | CHCR_TE)) == CHCR_DE)
+ return true; /* working */
+
+ return false; /* waiting */
}
static inline unsigned int calc_xmit_shift(struct sh_dmae_chan *sh_chan)
@@ -136,10 +136,9 @@ static void dmae_halt(struct sh_dmae_chan *sh_chan)
static int dmae_set_chcr(struct sh_dmae_chan *sh_chan, u32 val)
{
- int ret = dmae_is_busy(sh_chan);
/* When DMA was working, can not set data to CHCR */
- if (ret)
- return ret;
+ if (dmae_is_busy(sh_chan))
+ return -EBUSY;
sh_dmae_writel(sh_chan, val, CHCR);
return 0;
@@ -153,9 +152,9 @@ static int dmae_set_dmars(struct sh_dmae_chan *sh_chan, u16 val)
{
u32 addr;
int shift = 0;
- int ret = dmae_is_busy(sh_chan);
- if (ret)
- return ret;
+
+ if (dmae_is_busy(sh_chan))
+ return -EBUSY;
if (sh_chan->id & DMARS_CHAN_MSK)
shift = DMARS_SHIFT;
@@ -301,23 +300,95 @@ static void sh_dmae_free_chan_resources(struct dma_chan *chan)
kfree(desc);
}
-static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
- struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src,
- size_t len, unsigned long flags)
+/*
+ * sh_dmae_add_desc - get, set up and return one transfer descriptor
+ * @sh_chan: DMA channel
+ * @flags: DMA transfer flags
+ * @dest: destination DMA address, incremented when direction equals
+ * DMA_FROM_DEVICE or DMA_BIDIRECTIONAL
+ * @src: source DMA address, incremented when direction equals
+ * DMA_TO_DEVICE or DMA_BIDIRECTIONAL
+ * @len: DMA transfer length
+ * @first: if NULL, set to the current descriptor and cookie set to -EBUSY
+ * @direction: needed for slave DMA to decide which address to keep constant,
+ * equals DMA_BIDIRECTIONAL for MEMCPY
+ * Returns 0 or an error
+ * Locks: called with desc_lock held
+ */
+static struct sh_desc *sh_dmae_add_desc(struct sh_dmae_chan *sh_chan,
+ unsigned long flags, dma_addr_t *dest, dma_addr_t *src, size_t *len,
+ struct sh_desc **first, enum dma_data_direction direction)
{
- struct sh_dmae_chan *sh_chan;
- struct sh_desc *first = NULL, *prev = NULL, *new;
+ struct sh_desc *new;
size_t copy_size;
- LIST_HEAD(tx_list);
- int chunks = (len + SH_DMA_TCR_MAX) / (SH_DMA_TCR_MAX + 1);
- if (!chan)
+ if (!*len)
return NULL;
- if (!len)
+ /* Allocate the link descriptor from the free list */
+ new = sh_dmae_get_desc(sh_chan);
+ if (!new) {
+ dev_err(sh_chan->dev, "No free link descriptor available\n");
return NULL;
+ }
- sh_chan = to_sh_chan(chan);
+ copy_size = min(*len, (size_t)SH_DMA_TCR_MAX + 1);
+
+ new->hw.sar = *src;
+ new->hw.dar = *dest;
+ new->hw.tcr = copy_size;
+
+ if (!*first) {
+ /* First desc */
+ new->async_tx.cookie = -EBUSY;
+ *first = new;
+ } else {
+ /* Other desc - invisible to the user */
+ new->async_tx.cookie = -EINVAL;
+ }
+
+ dev_dbg(sh_chan->dev, "chaining (%u/%u)@%x -> %x with %p, cookie %d\n",
+ copy_size, *len, *src, *dest, &new->async_tx,
+ new->async_tx.cookie);
+
+ new->mark = DESC_PREPARED;
+ new->async_tx.flags = flags;
+
+ *len -= copy_size;
+ if (direction == DMA_BIDIRECTIONAL || direction == DMA_TO_DEVICE)
+ *src += copy_size;
+ if (direction == DMA_BIDIRECTIONAL || direction == DMA_FROM_DEVICE)
+ *dest += copy_size;
+
+ return new;
+}
+
+/*
+ * sh_dmae_prep_sg - prepare transfer descriptors from an SG list
+ *
+ * Common routine for public (MEMCPY) and slave DMA. The MEMCPY case is also
+ * converted to scatter-gather to guarantee consistent locking and a correct
+ * list manipulation. For slave DMA direction carries the usual meaning, and,
+ * logically, the SG list is RAM and the addr variable contains slave address,
+ * e.g., the FIFO I/O register. For MEMCPY direction equals DMA_BIDIRECTIONAL
+ * and the SG list contains only one element and points at the source buffer.
+ */
+static struct dma_async_tx_descriptor *sh_dmae_prep_sg(struct sh_dmae_chan *sh_chan,
+ struct scatterlist *sgl, unsigned int sg_len, dma_addr_t *addr,
+ enum dma_data_direction direction, unsigned long flags)
+{
+ struct scatterlist *sg;
+ struct sh_desc *first = NULL, *new = NULL /* compiler... */;
+ LIST_HEAD(tx_list);
+ int chunks = 0;
+ int i;
+
+ if (!sg_len)
+ return NULL;
+
+ for_each_sg(sgl, sg, sg_len, i)
+ chunks += (sg_dma_len(sg) + SH_DMA_TCR_MAX) /
+ (SH_DMA_TCR_MAX + 1);
/* Have to lock the whole loop to protect against concurrent release */
spin_lock_bh(&sh_chan->desc_lock);
@@ -333,49 +404,32 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
* only during this function, then they are immediately spliced
* back onto the free list in form of a chain
*/
- do {
- /* Allocate the link descriptor from the free list */
- new = sh_dmae_get_desc(sh_chan);
- if (!new) {
- dev_err(sh_chan->dev,
- "No free memory for link descriptor\n");
- list_for_each_entry(new, &tx_list, node)
- new->mark = DESC_IDLE;
- list_splice(&tx_list, &sh_chan->ld_free);
- spin_unlock_bh(&sh_chan->desc_lock);
- return NULL;
- }
-
- copy_size = min(len, (size_t)SH_DMA_TCR_MAX + 1);
-
- new->hw.sar = dma_src;
- new->hw.dar = dma_dest;
- new->hw.tcr = copy_size;
- if (!first) {
- /* First desc */
- new->async_tx.cookie = -EBUSY;
- first = new;
- } else {
- /* Other desc - invisible to the user */
- new->async_tx.cookie = -EINVAL;
- }
-
- dev_dbg(sh_chan->dev,
- "chaining %u of %u with %p, dst %x, cookie %d\n",
- copy_size, len, &new->async_tx, dma_dest,
- new->async_tx.cookie);
-
- new->mark = DESC_PREPARED;
- new->async_tx.flags = flags;
- new->chunks = chunks--;
-
- prev = new;
- len -= copy_size;
- dma_src += copy_size;
- dma_dest += copy_size;
- /* Insert the link descriptor to the LD ring */
- list_add_tail(&new->node, &tx_list);
- } while (len);
+ for_each_sg(sgl, sg, sg_len, i) {
+ dma_addr_t sg_addr = sg_dma_address(sg);
+ size_t len = sg_dma_len(sg);
+
+ if (!len)
+ goto err_get_desc;
+
+ do {
+ dev_dbg(sh_chan->dev, "Add SG #%d@%p[%d], dma %llx\n",
+ i, sg, len, (unsigned long long)sg_addr);
+
+ if (direction == DMA_FROM_DEVICE)
+ new = sh_dmae_add_desc(sh_chan, flags,
+ &sg_addr, addr, &len, &first,
+ direction);
+ else
+ new = sh_dmae_add_desc(sh_chan, flags,
+ addr, &sg_addr, &len, &first,
+ direction);
+ if (!new)
+ goto err_get_desc;
+
+ new->chunks = chunks--;
+ list_add_tail(&new->node, &tx_list);
+ } while (len);
+ }
if (new != first)
new->async_tx.cookie = -ENOSPC;
@@ -386,6 +440,37 @@ static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
spin_unlock_bh(&sh_chan->desc_lock);
return &first->async_tx;
+
+err_get_desc:
+ list_for_each_entry(new, &tx_list, node)
+ new->mark = DESC_IDLE;
+ list_splice(&tx_list, &sh_chan->ld_free);
+
+ spin_unlock_bh(&sh_chan->desc_lock);
+
+ return NULL;
+}
+
+static struct dma_async_tx_descriptor *sh_dmae_prep_memcpy(
+ struct dma_chan *chan, dma_addr_t dma_dest, dma_addr_t dma_src,
+ size_t len, unsigned long flags)
+{
+ struct sh_dmae_chan *sh_chan;
+ struct scatterlist sg;
+
+ if (!chan || !len)
+ return NULL;
+
+ sh_chan = to_sh_chan(chan);
+
+ sg_init_table(&sg, 1);
+ sg_set_page(&sg, pfn_to_page(PFN_DOWN(dma_src)), len,
+ offset_in_page(dma_src));
+ sg_dma_address(&sg) = dma_src;
+ sg_dma_len(&sg) = len;
+
+ return sh_dmae_prep_sg(sh_chan, &sg, 1, &dma_dest, DMA_BIDIRECTIONAL,
+ flags);
}
static dma_async_tx_callback __ld_cleanup(struct sh_dmae_chan *sh_chan, bool all)
@@ -559,7 +644,7 @@ static irqreturn_t sh_dmae_err(int irq, void *data)
/* IRQ Multi */
if (shdev->pdata.mode & SHDMA_MIX_IRQ) {
- int cnt = 0;
+ int __maybe_unused cnt = 0;
switch (irq) {
#if defined(DMTE6_IRQ) && defined(DMAE1_IRQ)
case DMTE6_IRQ:
--
1.6.2.4
--
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