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 greatly simplify the code.
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, but it also avoids the
ping-ponging 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 are processed. This informs the host about when it can
re-enable the SDIO IRQs. Potentially, we could re-use the existing
->enable_sdio_irq() callback for this matter, however it has turned out
that it's more convenient for hosts to get this information via a separate
callback.
Hosts needs to enable MMC_CAP2_SDIO_IRQ_NOTHREAD to use the work/workqueue
to process SDIO IRQs, however implementing the ->ack_sdio_irq() is optional.
Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
---
drivers/mmc/core/host.c | 2 ++
drivers/mmc/core/sdio_irq.c | 21 +++++++++++++++++++++
drivers/mmc/core/sdio_ops.h | 2 ++
include/linux/mmc/host.h | 3 +++
4 files changed, 28 insertions(+)
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 3f8c85d..77058cb 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -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_WORK(&host->sdio_irq_work, sdio_irq_work);
setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);
/*
diff --git a/drivers/mmc/core/sdio_irq.c b/drivers/mmc/core/sdio_irq.c
index 44d9c86..8e28759 100644
--- a/drivers/mmc/core/sdio_irq.c
+++ b/drivers/mmc/core/sdio_irq.c
@@ -98,11 +98,32 @@ 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);
+
+ sdio_run_irqs(host);
+}
+
+void sdio_signal_irq(struct mmc_host *host)
+{
+ /*
+ * The system_freezable_wq helps us to avoid processing IRQs while being
+ * system PM suspended. Instead these IRQs becomes deferred and managed
+ * when userspace is unfrozen.
+ */
+ queue_work(system_freezable_wq, &host->sdio_irq_work);
+}
+EXPORT_SYMBOL_GPL(sdio_signal_irq);
+
static int sdio_irq_thread(void *_host)
{
struct mmc_host *host = _host;
diff --git a/drivers/mmc/core/sdio_ops.h b/drivers/mmc/core/sdio_ops.h
index bed8a83..836e405 100644
--- a/drivers/mmc/core/sdio_ops.h
+++ b/drivers/mmc/core/sdio_ops.h
@@ -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 mmc_is_io_op(u32 opcode)
{
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 21385ac..f03df539 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -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 work_struct 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);
--
2.7.4
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