Currently, there is core support for tuning during
initialization. There can also be a need to re-tune
periodically (e.g. sdhci) or to re-tune after the
host controller is powered off (e.g. after PM
runtime suspend / resume) or to re-tune in response
to CRC errors.
The main requirements for re-tuning are:
- ability to enable / disable re-tuning
- ability to flag that re-tuning is needed
- ability to re-tune before any request
- ability to hold off re-tuning if the card is busy
- ability to hold off re-tuning if re-tuning is in
progress
- ability to run a re-tuning timer
To support those requirements 6 members are added to struct
mmc_host:
unsigned int can_retune:1; /* re-tuning can be used */
unsigned int doing_retune:1; /* re-tuning in progress */
unsigned int retune_now:1; /* do re-tuning at next req */
int need_retune; /* re-tuning is needed */
int hold_retune; /* hold off re-tuning */
struct timer_list retune_timer; /* for periodic re-tuning */
need_retune is an integer so it can be set without needing
synchronization. hold_retune is a integer to allow nesting.
Various simple functions are provided to set / clear those
variables. Also host operations are added to let the host
know when re-tuning is held, for example, to enable
synchronization with runtime suspend / resume.
Subsequent patches take those functions into use.
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
---
drivers/mmc/core/host.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/mmc/host.h | 34 +++++++++++++++++++++
2 files changed, 112 insertions(+)
diff --git a/drivers/mmc/core/host.c b/drivers/mmc/core/host.c
index 8be0df7..fe6aa57 100644
--- a/drivers/mmc/core/host.c
+++ b/drivers/mmc/core/host.c
@@ -301,6 +301,83 @@ static inline void mmc_host_clk_sysfs_init(struct mmc_host *host)
#endif
+void mmc_retune_enable(struct mmc_host *host, unsigned int period)
+{
+ host->can_retune = 1;
+ if (period)
+ mod_timer(&host->retune_timer, jiffies + period * HZ);
+}
+EXPORT_SYMBOL(mmc_retune_enable);
+
+void mmc_retune_disable(struct mmc_host *host)
+{
+ host->can_retune = 0;
+ del_timer_sync(&host->retune_timer);
+ host->retune_now = 0;
+ host->need_retune = 0;
+}
+EXPORT_SYMBOL(mmc_retune_disable);
+
+void mmc_retune_timer_stop(struct mmc_host *host)
+{
+ del_timer_sync(&host->retune_timer);
+}
+EXPORT_SYMBOL(mmc_retune_timer_stop);
+
+void mmc_retune_hold(struct mmc_host *host)
+{
+ if (!host->hold_retune) {
+ if (host->ops->hold_tuning)
+ host->ops->hold_tuning(host);
+ host->retune_now = 1;
+ }
+ host->hold_retune += 1;
+}
+EXPORT_SYMBOL(mmc_retune_hold);
+
+void mmc_retune_release(struct mmc_host *host)
+{
+ if (host->hold_retune) {
+ host->hold_retune -= 1;
+ if (!host->hold_retune && host->ops->release_tuning)
+ host->ops->release_tuning(host);
+ } else {
+ WARN_ON(1);
+ }
+}
+EXPORT_SYMBOL(mmc_retune_release);
+
+int mmc_retune(struct mmc_host *host)
+{
+ int err;
+
+ if (host->retune_now)
+ host->retune_now = 0;
+ else
+ return 0;
+
+ if (!host->need_retune || host->doing_retune || !host->card)
+ return 0;
+
+ host->need_retune = 0;
+
+ host->doing_retune = 1;
+
+ err = mmc_execute_tuning(host->card);
+
+ host->doing_retune = 0;
+
+ return err;
+}
+EXPORT_SYMBOL(mmc_retune);
+
+static void mmc_retune_timer(unsigned long data)
+{
+ struct mmc_host *host = (struct mmc_host *)data;
+
+ mmc_retune_needed(host);
+}
+
/**
* mmc_of_parse() - parse host's device-tree node
* @host: host whose node should be parsed.
@@ -504,6 +581,7 @@ struct mmc_host *mmc_alloc_host(int extra, struct device *dev)
#ifdef CONFIG_PM
host->pm_notify.notifier_call = mmc_pm_notify;
#endif
+ setup_timer(&host->retune_timer, mmc_retune_timer, (unsigned long)host);
/*
* By default, hosts do not support SGIO or large requests.
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 0c8cbe5..bf08e3e 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -12,6 +12,7 @@
#include <linux/leds.h>
#include <linux/mutex.h>
+#include <linux/timer.h>
#include <linux/sched.h>
#include <linux/device.h>
#include <linux/fault-inject.h>
@@ -134,6 +135,8 @@ struct mmc_host_ops {
/* The tuning command opcode value is different for SD and eMMC cards */
int (*execute_tuning)(struct mmc_host *host, u32 opcode);
+ void (*hold_tuning)(struct mmc_host *host);
+ void (*release_tuning)(struct mmc_host *host);
/* Prepare HS400 target operating frequency depending host driver */
int (*prepare_hs400_tuning)(struct mmc_host *host, struct mmc_ios *ios);
@@ -327,10 +330,17 @@ struct mmc_host {
#ifdef CONFIG_MMC_DEBUG
unsigned int removed:1; /* host is being removed */
#endif
+ unsigned int can_retune:1; /* re-tuning can be used */
+ unsigned int doing_retune:1; /* re-tuning in progress */
+ unsigned int retune_now:1; /* do re-tuning at next req */
int rescan_disable; /* disable card detection */
int rescan_entered; /* used with nonremovable devices */
+ int need_retune; /* re-tuning is needed */
+ int hold_retune; /* hold off re-tuning */
+ struct timer_list retune_timer; /* for periodic re-tuning */
+
bool trigger_card_event; /* card_event necessary */
struct mmc_card *card; /* device attached to this host */
@@ -519,4 +529,28 @@ static inline bool mmc_card_hs400(struct mmc_card *card)
return card->host->ios.timing == MMC_TIMING_MMC_HS400;
}
+void mmc_retune_enable(struct mmc_host *host, unsigned int period);
+void mmc_retune_disable(struct mmc_host *host);
+void mmc_retune_timer_stop(struct mmc_host *host);
+void mmc_retune_hold(struct mmc_host *host);
+void mmc_retune_release(struct mmc_host *host);
+int mmc_retune(struct mmc_host *host);
+
+static inline void mmc_retune_needed(struct mmc_host *host)
+{
+ if (host->can_retune)
+ host->need_retune = 1;
+}
+
+static inline void mmc_retune_not_needed(struct mmc_host *host)
+{
+ host->need_retune = 0;
+}
+
+static inline void mmc_retune_recheck(struct mmc_host *host)
+{
+ if (host->hold_retune <= 1)
+ host->retune_now = 1;
+}
+
#endif /* LINUX_MMC_HOST_H */
--
1.9.1
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