Commit c0ba5947 authored by Nicolas Ferre's avatar Nicolas Ferre Committed by Vinod Koul
Browse files

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: default avatarNicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: default avatarUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent d8cb04b0

drivers/dma/at_hdmac.c

+87 −1
Original line number Diff line number Diff line
@@ -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,

};

drivers/dma/at_hdmac_regs.h

+7 −0
Original line number Diff line number Diff line
@@ -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;

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