[PATCH v2 01/15] dmaengine: dw: fix byte order of hw descriptor fields

Andy Shevchenko
2016-02-22T16:08:57Z

From: Mans Rullgard <mans@mansr.com>

If the DMA controller uses a different byte order than the host CPU,
the hardware linked list descriptor fields need to be byte-swapped.

This patch makes the driver write these fields using the same byte
order it uses for mmio accesses to the DMA engine. I do not know
if this is guaranteed to always be correct.

Signed-off-by: Mans Rullgard <mans@mansr.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
drivers/dma/dw/core.c | 109 ++++++++++++++++++++++++--------------------------
drivers/dma/dw/regs.h | 32 +++++++++++----
2 files changed, 78 insertions(+), 63 deletions(-)

diff --git a/drivers/dma/dw/core.c b/drivers/dma/dw/core.c
index 5ad0ec1..cd7616e 100644
--- a/drivers/dma/dw/core.c
+++ b/drivers/dma/dw/core.c
@@ -209,12 +209,12 @@ static inline void dwc_do_single_block(struct dw_dma_chan *dwc,
* Software emulation of LLP mode relies on interrupts to continue
* multi block transfer.
*/
- ctllo = desc->lli.ctllo | DWC_CTLL_INT_EN;
+ ctllo = lli_read(desc, ctllo) | DWC_CTLL_INT_EN;

- channel_writel(dwc, SAR, desc->lli.sar);
- channel_writel(dwc, DAR, desc->lli.dar);
+ channel_writel(dwc, SAR, lli_read(desc, sar));
+ channel_writel(dwc, DAR, lli_read(desc, dar));
channel_writel(dwc, CTL_LO, ctllo);
- channel_writel(dwc, CTL_HI, desc->lli.ctlhi);
+ channel_writel(dwc, CTL_HI, lli_read(desc, ctlhi));
channel_set_bit(dw, CH_EN, dwc->mask);

/* Move pointer to next descriptor */
@@ -432,7 +432,7 @@ static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)
}

/* Check first descriptors llp */
- if (desc->lli.llp == llp) {
+ if (lli_read(desc, llp) == llp) {
/* This one is currently in progress */
dwc->residue -= dwc_get_sent(dwc);
spin_unlock_irqrestore(&dwc->lock, flags);
@@ -441,7 +441,7 @@ static void dwc_scan_descriptors(struct dw_dma *dw, struct dw_dma_chan *dwc)

dwc->residue -= desc->len;
list_for_each_entry(child, &desc->tx_list, desc_node) {
- if (child->lli.llp == llp) {
+ if (lli_read(child, llp) == llp) {
/* Currently in progress */
dwc->residue -= dwc_get_sent(dwc);
spin_unlock_irqrestore(&dwc->lock, flags);
@@ -743,25 +743,24 @@ dwc_prep_dma_memcpy(struct dma_chan *chan, dma_addr_t dest, dma_addr_t src,
if (!desc)
goto err_desc_get;

- desc->lli.sar = src + offset;
- desc->lli.dar = dest + offset;
- desc->lli.ctllo = ctllo;
- desc->lli.ctlhi = xfer_count;
+ lli_write(desc, sar, src + offset);
+ lli_write(desc, dar, dest + offset);
+ lli_write(desc, ctllo, ctllo);
+ lli_write(desc, ctlhi, xfer_count);
desc->len = xfer_count << src_width;

if (!first) {
first = desc;
} else {
- prev->lli.llp = desc->txd.phys;
- list_add_tail(&desc->desc_node,
- &first->tx_list);
+ lli_write(prev, llp, desc->txd.phys);
+ list_add_tail(&desc->desc_node, &first->tx_list);
}
prev = desc;
}

if (flags & DMA_PREP_INTERRUPT)
/* Trigger interrupt after last block */
- prev->lli.ctllo |= DWC_CTLL_INT_EN;
+ lli_set(prev, ctllo, DWC_CTLL_INT_EN);

prev->lli.llp = 0;
first->txd.flags = flags;
@@ -831,9 +830,9 @@ slave_sg_todev_fill_desc:
if (!desc)
goto err_desc_get;

- desc->lli.sar = mem;
- desc->lli.dar = reg;
- desc->lli.ctllo = ctllo | DWC_CTLL_SRC_WIDTH(mem_width);
+ lli_write(desc, sar, mem);
+ lli_write(desc, dar, reg);
+ lli_write(desc, ctllo, ctllo | DWC_CTLL_SRC_WIDTH(mem_width));
if ((len >> mem_width) > dwc->block_size) {
dlen = dwc->block_size << mem_width;
mem += dlen;
@@ -843,15 +842,14 @@ slave_sg_todev_fill_desc:
len = 0;
}

- desc->lli.ctlhi = dlen >> mem_width;
+ lli_write(desc, ctlhi, dlen >> mem_width);
desc->len = dlen;

if (!first) {
first = desc;
} else {
- prev->lli.llp = desc->txd.phys;
- list_add_tail(&desc->desc_node,
- &first->tx_list);
+ lli_write(prev, llp, desc->txd.phys);
+ list_add_tail(&desc->desc_node, &first->tx_list);
}
prev = desc;
total_len += dlen;
@@ -888,9 +886,9 @@ slave_sg_fromdev_fill_desc:
if (!desc)
goto err_desc_get;

- desc->lli.sar = reg;
- desc->lli.dar = mem;
- desc->lli.ctllo = ctllo | DWC_CTLL_DST_WIDTH(mem_width);
+ lli_write(desc, sar, reg);
+ lli_write(desc, dar, mem);
+ lli_write(desc, ctllo, ctllo | DWC_CTLL_DST_WIDTH(mem_width));
if ((len >> reg_width) > dwc->block_size) {
dlen = dwc->block_size << reg_width;
mem += dlen;
@@ -899,15 +897,14 @@ slave_sg_fromdev_fill_desc:
dlen = len;
len = 0;
}
- desc->lli.ctlhi = dlen >> reg_width;
+ lli_write(desc, ctlhi, dlen >> reg_width);
desc->len = dlen;

if (!first) {
first = desc;
} else {
- prev->lli.llp = desc->txd.phys;
- list_add_tail(&desc->desc_node,
- &first->tx_list);
+ lli_write(prev, llp, desc->txd.phys);
+ list_add_tail(&desc->desc_node, &first->tx_list);
}
prev = desc;
total_len += dlen;
@@ -922,7 +919,7 @@ slave_sg_fromdev_fill_desc:

if (flags & DMA_PREP_INTERRUPT)
/* Trigger interrupt after last block */
- prev->lli.ctllo |= DWC_CTLL_INT_EN;
+ lli_set(prev, ctllo, DWC_CTLL_INT_EN);

prev->lli.llp = 0;
first->total_len = total_len;
@@ -1393,50 +1390,50 @@ struct dw_cyclic_desc *dw_dma_cyclic_prep(struct dma_chan *chan,

switch (direction) {
case DMA_MEM_TO_DEV:
- desc->lli.dar = sconfig->dst_addr;
- desc->lli.sar = buf_addr + (period_len * i);
- desc->lli.ctllo = (DWC_DEFAULT_CTLLO(chan)
- | DWC_CTLL_DST_WIDTH(reg_width)
- | DWC_CTLL_SRC_WIDTH(reg_width)
- | DWC_CTLL_DST_FIX
- | DWC_CTLL_SRC_INC
- | DWC_CTLL_INT_EN);
-
- desc->lli.ctllo |= sconfig->device_fc ?
- DWC_CTLL_FC(DW_DMA_FC_P_M2P) :
- DWC_CTLL_FC(DW_DMA_FC_D_M2P);
+ lli_write(desc, dar, sconfig->dst_addr);
+ lli_write(desc, sar, buf_addr + period_len * i);
+ lli_write(desc, ctllo, (DWC_DEFAULT_CTLLO(chan)
+ | DWC_CTLL_DST_WIDTH(reg_width)
+ | DWC_CTLL_SRC_WIDTH(reg_width)
+ | DWC_CTLL_DST_FIX
+ | DWC_CTLL_SRC_INC
+ | DWC_CTLL_INT_EN));
+
+ lli_set(desc, ctllo, sconfig->device_fc ?
+ DWC_CTLL_FC(DW_DMA_FC_P_M2P) :
+ DWC_CTLL_FC(DW_DMA_FC_D_M2P));

break;
case DMA_DEV_TO_MEM:
- desc->lli.dar = buf_addr + (period_len * i);
- desc->lli.sar = sconfig->src_addr;
- desc->lli.ctllo = (DWC_DEFAULT_CTLLO(chan)
- | DWC_CTLL_SRC_WIDTH(reg_width)
- | DWC_CTLL_DST_WIDTH(reg_width)
- | DWC_CTLL_DST_INC
- | DWC_CTLL_SRC_FIX
- | DWC_CTLL_INT_EN);
-
- desc->lli.ctllo |= sconfig->device_fc ?
- DWC_CTLL_FC(DW_DMA_FC_P_P2M) :
- DWC_CTLL_FC(DW_DMA_FC_D_P2M);
+ lli_write(desc, dar, buf_addr + period_len * i);
+ lli_write(desc, sar, sconfig->src_addr);
+ lli_write(desc, ctllo, (DWC_DEFAULT_CTLLO(chan)
+ | DWC_CTLL_SRC_WIDTH(reg_width)
+ | DWC_CTLL_DST_WIDTH(reg_width)
+ | DWC_CTLL_DST_INC
+ | DWC_CTLL_SRC_FIX
+ | DWC_CTLL_INT_EN));
+
+ lli_set(desc, ctllo, sconfig->device_fc ?
+ DWC_CTLL_FC(DW_DMA_FC_P_P2M) :
+ DWC_CTLL_FC(DW_DMA_FC_D_P2M));

break;
default:
break;
}

- desc->lli.ctlhi = (period_len >> reg_width);
+ lli_write(desc, ctlhi, period_len >> reg_width);
cdesc->desc[i] = desc;

if (last)
- last->lli.llp = desc->txd.phys;
+ lli_write(last, llp, desc->txd.phys);

last = desc;
}

/* Let's make a cyclic list */
- last->lli.llp = cdesc->desc[0]->txd.phys;
+ lli_write(last, llp, cdesc->desc[0]->txd.phys);

dev_dbg(chan2dev(&dwc->chan),
"cyclic prepared buf %pad len %zu period %zu periods %d\n",
diff --git a/drivers/dma/dw/regs.h b/drivers/dma/dw/regs.h
index 0a50c18..c5e566d 100644
--- a/drivers/dma/dw/regs.h
+++ b/drivers/dma/dw/regs.h
@@ -308,26 +308,44 @@ static inline struct dw_dma *to_dw_dma(struct dma_device *ddev)
return container_of(ddev, struct dw_dma, dma);
}

+#ifdef CONFIG_DW_DMAC_BIG_ENDIAN_IO
+typedef __be32 __dw32;
+#else
+typedef __le32 __dw32;
+#endif
+
/* LLI == Linked List Item; a.k.a. DMA block descriptor */
struct dw_lli {
/* values that are not changed by hardware */
- u32 sar;
- u32 dar;
- u32 llp; /* chain to next lli */
- u32 ctllo;
+ __dw32 sar;
+ __dw32 dar;
+ __dw32 llp; /* chain to next lli */
+ __dw32 ctllo;
/* values that may get written back: */
- u32 ctlhi;
+ __dw32 ctlhi;
/* sstat and dstat can snapshot peripheral register state.
* silicon config may discard either or both...
*/
- u32 sstat;
- u32 dstat;
+ __dw32 sstat;
+ __dw32 dstat;
};

struct dw_desc {
/* FIRST values the hardware uses */
struct dw_lli lli;

+#ifdef CONFIG_DW_DMAC_BIG_ENDIAN_IO
+#define lli_set(d, reg, v) ((d)->lli.reg |= cpu_to_be32(v))
+#define lli_clear(d, reg, v) ((d)->lli.reg &= ~cpu_to_be32(v))
+#define lli_read(d, reg) be32_to_cpu((d)->lli.reg)
+#define lli_write(d, reg, v) ((d)->lli.reg = cpu_to_be32(v))
+#else
+#define lli_set(d, reg, v) ((d)->lli.reg |= cpu_to_le32(v))
+#define lli_clear(d, reg, v) ((d)->lli.reg &= ~cpu_to_le32(v))
+#define lli_read(d, reg) le32_to_cpu((d)->lli.reg)
+#define lli_write(d, reg, v) ((d)->lli.reg = cpu_to_le32(v))
+#endif
+
/* THEN values for driver housekeeping */
struct list_head desc_node;
struct list_head tx_list;
--
2.7.0