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authorNicolas Ferre <nicolas.ferre@atmel.com>2011-07-27 16:21:29 +0400
committerVinod Koul <vinod.koul@intel.com>2011-08-19 17:09:54 +0400
commitc0ba5947370a0900b1823922fc4faf41515bc901 (patch)
treef3c32b76f48fc7f78ebd32a6d33f5e6b99e1328a /drivers/dma/at_hdmac.c
parentd8cb04b070c2a55f7201714d231cff4f8f9fbd16 (diff)
downloadlinux-c0ba5947370a0900b1823922fc4faf41515bc901.tar.xz
dmaengine: at_hdmac: improve power management routines
Save/restore dma controller state across a suspend-resume sequence. The prepare() function will wait for the non-cyclic channels to become idle. It also deals with cyclic operations with the start at next period while resuming. Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Diffstat (limited to 'drivers/dma/at_hdmac.c')
-rw-r--r--drivers/dma/at_hdmac.c88
1 files changed, 87 insertions, 1 deletions
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index fd87b9690e1b..0ead008e3bdf 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -1385,27 +1385,113 @@ static void at_dma_shutdown(struct platform_device *pdev)
clk_disable(atdma->clk);
}
+static int at_dma_prepare(struct device *dev)
+{
+ struct platform_device *pdev = to_platform_device(dev);
+ struct at_dma *atdma = platform_get_drvdata(pdev);
+ struct dma_chan *chan, *_chan;
+
+ list_for_each_entry_safe(chan, _chan, &atdma->dma_common.channels,
+ device_node) {
+ struct at_dma_chan *atchan = to_at_dma_chan(chan);
+ /* wait for transaction completion (except in cyclic case) */
+ if (atc_chan_is_enabled(atchan) &&
+ !test_bit(ATC_IS_CYCLIC, &atchan->status))
+ return -EAGAIN;
+ }
+ return 0;
+}
+
+static void atc_suspend_cyclic(struct at_dma_chan *atchan)
+{
+ struct dma_chan *chan = &atchan->chan_common;
+
+ /* Channel should be paused by user
+ * do it anyway even if it is not done already */
+ if (!test_bit(ATC_IS_PAUSED, &atchan->status)) {
+ dev_warn(chan2dev(chan),
+ "cyclic channel not paused, should be done by channel user\n");
+ atc_control(chan, DMA_PAUSE, 0);
+ }
+
+ /* now preserve additional data for cyclic operations */
+ /* next descriptor address in the cyclic list */
+ atchan->save_dscr = channel_readl(atchan, DSCR);
+
+ vdbg_dump_regs(atchan);
+}
+
static int at_dma_suspend_noirq(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct at_dma *atdma = platform_get_drvdata(pdev);
+ struct dma_chan *chan, *_chan;
- at_dma_off(platform_get_drvdata(pdev));
+ /* preserve data */
+ list_for_each_entry_safe(chan, _chan, &atdma->dma_common.channels,
+ device_node) {
+ struct at_dma_chan *atchan = to_at_dma_chan(chan);
+
+ if (test_bit(ATC_IS_CYCLIC, &atchan->status))
+ atc_suspend_cyclic(atchan);
+ atchan->save_cfg = channel_readl(atchan, CFG);
+ }
+ atdma->save_imr = dma_readl(atdma, EBCIMR);
+
+ /* disable DMA controller */
+ at_dma_off(atdma);
clk_disable(atdma->clk);
return 0;
}
+static void atc_resume_cyclic(struct at_dma_chan *atchan)
+{
+ struct at_dma *atdma = to_at_dma(atchan->chan_common.device);
+
+ /* restore channel status for cyclic descriptors list:
+ * next descriptor in the cyclic list at the time of suspend */
+ channel_writel(atchan, SADDR, 0);
+ channel_writel(atchan, DADDR, 0);
+ channel_writel(atchan, CTRLA, 0);
+ channel_writel(atchan, CTRLB, 0);
+ channel_writel(atchan, DSCR, atchan->save_dscr);
+ dma_writel(atdma, CHER, atchan->mask);
+
+ /* channel pause status should be removed by channel user
+ * We cannot take the initiative to do it here */
+
+ vdbg_dump_regs(atchan);
+}
+
static int at_dma_resume_noirq(struct device *dev)
{
struct platform_device *pdev = to_platform_device(dev);
struct at_dma *atdma = platform_get_drvdata(pdev);
+ struct dma_chan *chan, *_chan;
+ /* bring back DMA controller */
clk_enable(atdma->clk);
dma_writel(atdma, EN, AT_DMA_ENABLE);
+
+ /* clear any pending interrupt */
+ while (dma_readl(atdma, EBCISR))
+ cpu_relax();
+
+ /* restore saved data */
+ dma_writel(atdma, EBCIER, atdma->save_imr);
+ list_for_each_entry_safe(chan, _chan, &atdma->dma_common.channels,
+ device_node) {
+ struct at_dma_chan *atchan = to_at_dma_chan(chan);
+
+ channel_writel(atchan, CFG, atchan->save_cfg);
+ if (test_bit(ATC_IS_CYCLIC, &atchan->status))
+ atc_resume_cyclic(atchan);
+ }
return 0;
}
static const struct dev_pm_ops at_dma_dev_pm_ops = {
+ .prepare = at_dma_prepare,
.suspend_noirq = at_dma_suspend_noirq,
.resume_noirq = at_dma_resume_noirq,
};