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Commit 68269660 authored by Ulf Hansson's avatar Ulf Hansson
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mmc: sdio: Add API to manage SDIO IRQs from a workqueue 



For hosts not supporting MMC_CAP2_SDIO_IRQ_NOTHREAD but MMC_CAP_SDIO_IRQ,
the SDIO IRQs are processed from a dedicated kernel thread. For these
cases, the host calls mmc_signal_sdio_irq() from its ISR to signal a new
SDIO IRQ.

Signaling an SDIO IRQ makes the host's ->enable_sdio_irq() callback to be
invoked to temporary disable the IRQs, before the kernel thread is woken up
to process it. When processing of the IRQs are completed, they are
re-enabled by the kernel thread, again via invoking the host's
->enable_sdio_irq().

The observation from this, is that the execution path is being unnecessary
complex, as the host driver already knows that it needs to temporary
disable the IRQs before signaling a new one. Moreover, replacing the kernel
thread with a work/workqueue would not only greatly simplify the code, but
also make it more robust.

To address the above problems, let's continue to build upon the support for
MMC_CAP2_SDIO_IRQ_NOTHREAD, as it already implements SDIO IRQs to be
processed without using the clumsy kernel thread and without the ping-pong
calls of the host's ->enable_sdio_irq() callback for each processed IRQ.

Therefore, let's add new API sdio_signal_irq(), which enables hosts to
signal/process SDIO IRQs by using a work/workqueue, rather than using the
kernel thread.

Add also a new host callback ->ack_sdio_irq(), which the work invokes when
the SDIO IRQs have been processed. This informs the host about when it
shall re-enable the SDIO IRQs. Potentially, we could re-use the existing
->enable_sdio_irq() callback instead of adding a new one, however it has
turned out that it's more convenient for hosts to get this information via
a separate callback.

Hosts that wants to use this new method to signal/process SDIO IRQs, must
enable MMC_CAP2_SDIO_IRQ_NOTHREAD and implement the ->ack_sdio_irq()
callback.

Signed-off-by: default avatarUlf Hansson <ulf.hansson@linaro.org>
Tested-by: default avatarDouglas Anderson <dianders@chromium.org>
Reviewed-by: default avatarDouglas Anderson <dianders@chromium.org>
parent e3a84267

drivers/mmc/core/host.c

+2 −0
Original line number Diff line number Diff line
@@ -30,6 +30,7 @@ 
#include "host.h"

#include "slot-gpio.h"

#include "pwrseq.h"

#include "sdio_ops.h"



#define cls_dev_to_mmc_host(d)	container_of(d, struct mmc_host, class_dev)
@@ -379,6 +380,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev) 
	spin_lock_init(&host->lock);

	init_waitqueue_head(&host->wq);

	INIT_DELAYED_WORK(&host->detect, mmc_rescan);

	INIT_DELAYED_WORK(&host->sdio_irq_work, sdio_irq_work);

	setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);



	/*

drivers/mmc/core/sdio_irq.c

+16 −0
Original line number Diff line number Diff line
@@ -98,11 +98,27 @@ void sdio_run_irqs(struct mmc_host *host) 
	if (host->sdio_irqs) {

		host->sdio_irq_pending = true;

		process_sdio_pending_irqs(host);

		if (host->ops->ack_sdio_irq)

			host->ops->ack_sdio_irq(host);

	}

	mmc_release_host(host);

}

EXPORT_SYMBOL_GPL(sdio_run_irqs);



void sdio_irq_work(struct work_struct *work)

{

	struct mmc_host *host =

		container_of(work, struct mmc_host, sdio_irq_work.work);



	sdio_run_irqs(host);

}



void sdio_signal_irq(struct mmc_host *host)

{

	queue_delayed_work(system_wq, &host->sdio_irq_work, 0);

}

EXPORT_SYMBOL_GPL(sdio_signal_irq);



static int sdio_irq_thread(void *_host)

{

	struct mmc_host *host = _host;

drivers/mmc/core/sdio_ops.h

+2 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 


struct mmc_host;

struct mmc_card;

struct work_struct;



int mmc_send_io_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr);

int mmc_io_rw_direct(struct mmc_card *card, int write, unsigned fn,
@@ -25,6 +26,7 @@ int mmc_io_rw_extended(struct mmc_card *card, int write, unsigned fn, 
	unsigned addr, int incr_addr, u8 *buf, unsigned blocks, unsigned blksz);

int sdio_reset(struct mmc_host *host);

unsigned int mmc_align_data_size(struct mmc_card *card, unsigned int sz);

void sdio_irq_work(struct work_struct *work);



static inline bool sdio_is_io_busy(u32 opcode, u32 arg)

{

include/linux/mmc/host.h

+3 −0
Original line number Diff line number Diff line
@@ -130,6 +130,7 @@ struct mmc_host_ops { 
	int	(*get_cd)(struct mmc_host *host);



	void	(*enable_sdio_irq)(struct mmc_host *host, int enable);

	void	(*ack_sdio_irq)(struct mmc_host *host);



	/* optional callback for HC quirks */

	void	(*init_card)(struct mmc_host *host, struct mmc_card *card);
@@ -358,6 +359,7 @@ struct mmc_host { 


	unsigned int		sdio_irqs;

	struct task_struct	*sdio_irq_thread;

	struct delayed_work	sdio_irq_work;

	bool			sdio_irq_pending;

	atomic_t		sdio_irq_thread_abort;
@@ -428,6 +430,7 @@ static inline void mmc_signal_sdio_irq(struct mmc_host *host) 
}



void sdio_run_irqs(struct mmc_host *host);

void sdio_signal_irq(struct mmc_host *host);



#ifdef CONFIG_REGULATOR

int mmc_regulator_get_ocrmask(struct regulator *supply);