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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>
This commit is contained in:
Nicolas Ferre 2011-07-27 12:21:29 +00:00 committed by Vinod Koul
parent d8cb04b070
commit c0ba594737
2 changed files with 94 additions and 1 deletions
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88
drivers/dma/at_hdmac.c
View File

@ -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,
};

7
drivers/dma/at_hdmac_regs.h
View File

@ -204,6 +204,9 @@ enum atc_status {
* @status: transmit status information from irq/prep* functions
* to tasklet (use atomic operations)
* @tasklet: bottom half to finish transaction work
* @save_cfg: configuration register that is saved on suspend/resume cycle
* @save_dscr: for cyclic operations, preserve next descriptor address in
* the cyclic list on suspend/resume cycle
* @lock: serializes enqueue/dequeue operations to descriptors lists
* @completed_cookie: identifier for the most recently completed operation
* @active_list: list of descriptors dmaengine is being running on
@ -218,6 +221,8 @@ struct at_dma_chan {
u8 mask;
unsigned long status;
struct tasklet_struct tasklet;
u32 save_cfg;
u32 save_dscr;
spinlock_t lock;
@ -248,6 +253,7 @@ static inline struct at_dma_chan *to_at_dma_chan(struct dma_chan *dchan)
* @chan_common: common dmaengine dma_device object members
* @ch_regs: memory mapped register base
* @clk: dma controller clock
* @save_imr: interrupt mask register that is saved on suspend/resume cycle
* @all_chan_mask: all channels availlable in a mask
* @dma_desc_pool: base of DMA descriptor region (DMA address)
* @chan: channels table to store at_dma_chan structures
@ -256,6 +262,7 @@ struct at_dma {
struct dma_device dma_common;
void __iomem *regs;
struct clk *clk;
u32 save_imr;
u8 all_chan_mask;