mmc: host: Add facility to support re-tuning

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 7 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 */
  unsigned int		retune_period;  /* re-tuning period in secs */
  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.

Subsequent patches take those functions into use.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index b5bedaec6223..f471193ef6d6 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>
@@ -321,10 +322,18 @@ 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 */
+        unsigned int            retune_period;  /* re-tuning period in secs */
+        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 */
@@ -513,4 +522,18 @@ static inline bool mmc_card_hs400(struct mmc_card *card)
         return card->host->ios.timing == MMC_TIMING_MMC_HS400;
 }
 
+void mmc_retune_timer_stop(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_recheck(struct mmc_host *host)
+{
+        if (host->hold_retune <= 1)
+                host->retune_now = 1;
+}
+
 #endif /* LINUX_MMC_HOST_H */