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authorLinus Walleij <linus.walleij@linaro.org>2011-04-19 00:31:32 (GMT)
committerVinod Koul <vinod.koul@intel.com>2011-05-13 14:10:15 (GMT)
commita7c57cf7d4327c41510f8cbf45b1b970e02c34f8 (patch)
tree2f1b7ae4940d9540d966f8a287a7337d14cb7c76 /drivers/dma/dw_dmac.c
parent69cea5a00d3135677939fce1fefe54ed522055a0 (diff)
downloadlinux-a7c57cf7d4327c41510f8cbf45b1b970e02c34f8.tar.xz
dmaengine/dw_dmac: implement pause and resume in dwc_control
Some peripherals like amba-pl011 needs pause to be implemented in DMA controller drivers. This also returns correct status from dwc_tx_status() in case chan is paused. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Viresh Kumar <viresh.kumar@st.com> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma/dw_dmac.c')
-rw-r--r--drivers/dma/dw_dmac.c59
1 files changed, 39 insertions, 20 deletions
diff --git a/drivers/dma/dw_dmac.c b/drivers/dma/dw_dmac.c
index 442b98b..eec675b 100644
--- a/drivers/dma/dw_dmac.c
+++ b/drivers/dma/dw_dmac.c
@@ -862,34 +862,50 @@ static int dwc_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
struct dw_dma *dw = to_dw_dma(chan->device);
struct dw_desc *desc, *_desc;
unsigned long flags;
+ u32 cfglo;
LIST_HEAD(list);
- /* Only supports DMA_TERMINATE_ALL */
- if (cmd != DMA_TERMINATE_ALL)
- return -ENXIO;
+ if (cmd == DMA_PAUSE) {
+ spin_lock_irqsave(&dwc->lock, flags);
- /*
- * This is only called when something went wrong elsewhere, so
- * we don't really care about the data. Just disable the
- * channel. We still have to poll the channel enable bit due
- * to AHB/HSB limitations.
- */
- spin_lock_irqsave(&dwc->lock, flags);
+ cfglo = channel_readl(dwc, CFG_LO);
+ channel_writel(dwc, CFG_LO, cfglo | DWC_CFGL_CH_SUSP);
+ while (!(channel_readl(dwc, CFG_LO) & DWC_CFGL_FIFO_EMPTY))
+ cpu_relax();
- channel_clear_bit(dw, CH_EN, dwc->mask);
+ dwc->paused = true;
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ } else if (cmd == DMA_RESUME) {
+ if (!dwc->paused)
+ return 0;
- while (dma_readl(dw, CH_EN) & dwc->mask)
- cpu_relax();
+ spin_lock_irqsave(&dwc->lock, flags);
- /* active_list entries will end up before queued entries */
- list_splice_init(&dwc->queue, &list);
- list_splice_init(&dwc->active_list, &list);
+ cfglo = channel_readl(dwc, CFG_LO);
+ channel_writel(dwc, CFG_LO, cfglo & ~DWC_CFGL_CH_SUSP);
+ dwc->paused = false;
- spin_unlock_irqrestore(&dwc->lock, flags);
+ spin_unlock_irqrestore(&dwc->lock, flags);
+ } else if (cmd == DMA_TERMINATE_ALL) {
+ spin_lock_irqsave(&dwc->lock, flags);
- /* Flush all pending and queued descriptors */
- list_for_each_entry_safe(desc, _desc, &list, desc_node)
- dwc_descriptor_complete(dwc, desc, false);
+ channel_clear_bit(dw, CH_EN, dwc->mask);
+ while (dma_readl(dw, CH_EN) & dwc->mask)
+ cpu_relax();
+
+ dwc->paused = false;
+
+ /* active_list entries will end up before queued entries */
+ list_splice_init(&dwc->queue, &list);
+ list_splice_init(&dwc->active_list, &list);
+
+ spin_unlock_irqrestore(&dwc->lock, flags);
+
+ /* Flush all pending and queued descriptors */
+ list_for_each_entry_safe(desc, _desc, &list, desc_node)
+ dwc_descriptor_complete(dwc, desc, false);
+ } else
+ return -ENXIO;
return 0;
}
@@ -923,6 +939,9 @@ dwc_tx_status(struct dma_chan *chan,
else
dma_set_tx_state(txstate, last_complete, last_used, 0);
+ if (dwc->paused)
+ return DMA_PAUSED;
+
return ret;
}