From c0ba5947370a0900b1823922fc4faf41515bc901 Mon Sep 17 00:00:00 2001 From: Nicolas Ferre Date: Wed, 27 Jul 2011 12:21:29 +0000 Subject: [PATCH] dmaengine: at_hdmac: improve power management routines MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Signed-off-by: Uwe Kleine-König Signed-off-by: Vinod Koul --- drivers/dma/at_hdmac.c | 88 ++++++++++++++++++++++++++++++++++++++++++++- drivers/dma/at_hdmac_regs.h | 7 ++++ 2 files changed, 94 insertions(+), 1 deletion(-) diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c index fd87b96..0ead008 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, }; diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h index 087dbf1..6f0c4a3 100644 --- a/drivers/dma/at_hdmac_regs.h +++ b/drivers/dma/at_hdmac_regs.h @@ -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; -- 2.7.4