mmc: sdhci: add support for retuning mode 1

Host Controller v3.00 can support retuning modes 1,2 or 3 depending on
the bits 46-47 of the Capabilities register. Also, the timer count for
retuning is indicated by bits 40-43 of the same register. We initialize
timer_list for retuning the first time we execute tuning procedure. This
condition is indicated by SDHCI_NEEDS_RETUNING not being set. Since
retuning mode 1 sets a limit of 4MB on the maximum data length, we set
max_blk_count appropriately. Once the tuning timer expires, we set
SDHCI_NEEDS_RETUNING flag, and if the flag is set, we execute tuning
procedure before sending the next command. We need to restore mmc_request
structure after executing retuning procedure since host->mrq is used
inside the procedure to send CMD19. We also disable and re-enable this
flag during suspend and resume respectively, as per the spec v3.00.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.
Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Tested-by: Philip Rakity <prakity@marvell.com>
Acked-by: Zhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/sdhci.c

@@ -46,6 +46,8 @@ static void sdhci_finish_data(struct sdhci_host *);
 
 static void sdhci_send_command(struct sdhci_host *, struct mmc_command *);
 static void sdhci_finish_command(struct sdhci_host *);
+static int sdhci_execute_tuning(struct mmc_host *mmc);
+static void sdhci_tuning_timer(unsigned long data);
 
 static void sdhci_dumpregs(struct sdhci_host *host)
 {
@@ -1206,8 +1208,27 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
 	if (!present || host->flags & SDHCI_DEVICE_DEAD) {
 		host->mrq->cmd->error = -ENOMEDIUM;
 		tasklet_schedule(&host->finish_tasklet);
-	} else
+	} else {
+		u32 present_state;
+
+		present_state = sdhci_readl(host, SDHCI_PRESENT_STATE);
+		/*
+		 * Check if the re-tuning timer has already expired and there
+		 * is no on-going data transfer. If so, we need to execute
+		 * tuning procedure before sending command.
+		 */
+		if ((host->flags & SDHCI_NEEDS_RETUNING) &&
+		    !(present_state & (SDHCI_DOING_WRITE | SDHCI_DOING_READ))) {
+			spin_unlock_irqrestore(&host->lock, flags);
+			sdhci_execute_tuning(mmc);
+			spin_lock_irqsave(&host->lock, flags);
+
+			/* Restore original mmc_request structure */
+			host->mrq = mrq;
+		}
+
 		sdhci_send_command(host, mrq->cmd);
+	}
 
 	mmiowb();
 	spin_unlock_irqrestore(&host->lock, flags);
@@ -1673,6 +1694,37 @@ static int sdhci_execute_tuning(struct mmc_host *mmc)
 	}
 
 out:
+	/*
+	 * If this is the very first time we are here, we start the retuning
+	 * timer. Since only during the first time, SDHCI_NEEDS_RETUNING
+	 * flag won't be set, we check this condition before actually starting
+	 * the timer.
+	 */
+	if (!(host->flags & SDHCI_NEEDS_RETUNING) && host->tuning_count &&
+	    (host->tuning_mode == SDHCI_TUNING_MODE_1)) {
+		mod_timer(&host->tuning_timer, jiffies +
+			host->tuning_count * HZ);
+		/* Tuning mode 1 limits the maximum data length to 4MB */
+		mmc->max_blk_count = (4 * 1024 * 1024) / mmc->max_blk_size;
+	} else {
+		host->flags &= ~SDHCI_NEEDS_RETUNING;
+		/* Reload the new initial value for timer */
+		if (host->tuning_mode == SDHCI_TUNING_MODE_1)
+			mod_timer(&host->tuning_timer, jiffies +
+				host->tuning_count * HZ);
+	}
+
+	/*
+	 * In case tuning fails, host controllers which support re-tuning can
+	 * try tuning again at a later time, when the re-tuning timer expires.
+	 * So for these controllers, we return 0. Since there might be other
+	 * controllers who do not have this capability, we return error for
+	 * them.
+	 */
+	if (err && host->tuning_count &&
+	    host->tuning_mode == SDHCI_TUNING_MODE_1)
+		err = 0;
+
 	sdhci_clear_set_irqs(host, SDHCI_INT_DATA_AVAIL, ier);
 	spin_unlock(&host->lock);
 	enable_irq(host->irq);
@@ -1775,6 +1827,9 @@ static void sdhci_tasklet_finish(unsigned long param)
 
 	del_timer(&host->timer);
 
+	if (host->version >= SDHCI_SPEC_300)
+		del_timer(&host->tuning_timer);
+
 	mrq = host->mrq;
 
 	/*
@@ -1848,6 +1903,20 @@ static void sdhci_timeout_timer(unsigned long data)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
+static void sdhci_tuning_timer(unsigned long data)
+{
+	struct sdhci_host *host;
+	unsigned long flags;
+
+	host = (struct sdhci_host *)data;
+
+	spin_lock_irqsave(&host->lock, flags);
+
+	host->flags |= SDHCI_NEEDS_RETUNING;
+
+	spin_unlock_irqrestore(&host->lock, flags);
+}
+
 /*****************************************************************************\
  *                                                                           *
  * Interrupt handling                                                        *
@@ -2122,6 +2191,14 @@ int sdhci_suspend_host(struct sdhci_host *host, pm_message_t state)
 
 	sdhci_disable_card_detection(host);
 
+	/* Disable tuning since we are suspending */
+	if (host->version >= SDHCI_SPEC_300 && host->tuning_count &&
+	    host->tuning_mode == SDHCI_TUNING_MODE_1) {
+		host->flags &= ~SDHCI_NEEDS_RETUNING;
+		mod_timer(&host->tuning_timer, jiffies +
+			host->tuning_count * HZ);
+	}
+
 	ret = mmc_suspend_host(host->mmc);
 	if (ret)
 		return ret;
@@ -2163,6 +2240,11 @@ int sdhci_resume_host(struct sdhci_host *host)
 	ret = mmc_resume_host(host->mmc);
 	sdhci_enable_card_detection(host);
 
+	/* Set the re-tuning expiration flag */
+	if ((host->version >= SDHCI_SPEC_300) && host->tuning_count &&
+	    (host->tuning_mode == SDHCI_TUNING_MODE_1))
+		host->flags |= SDHCI_NEEDS_RETUNING;
+
 	return ret;
 }
 
@@ -2414,6 +2496,21 @@ int sdhci_add_host(struct sdhci_host *host)
 	if (caps[1] & SDHCI_DRIVER_TYPE_D)
 		mmc->caps |= MMC_CAP_DRIVER_TYPE_D;
 
+	/* Initial value for re-tuning timer count */
+	host->tuning_count = (caps[1] & SDHCI_RETUNING_TIMER_COUNT_MASK) >>
+			      SDHCI_RETUNING_TIMER_COUNT_SHIFT;
+
+	/*
+	 * In case Re-tuning Timer is not disabled, the actual value of
+	 * re-tuning timer will be 2 ^ (n - 1).
+	 */
+	if (host->tuning_count)
+		host->tuning_count = 1 << (host->tuning_count - 1);
+
+	/* Re-tuning mode supported by the Host Controller */
+	host->tuning_mode = (caps[1] & SDHCI_RETUNING_MODE_MASK) >>
+			     SDHCI_RETUNING_MODE_SHIFT;
+
 	ocr_avail = 0;
 	/*
 	 * According to SD Host Controller spec v3.00, if the Host System
@@ -2559,9 +2656,15 @@ int sdhci_add_host(struct sdhci_host *host)
 
 	setup_timer(&host->timer, sdhci_timeout_timer, (unsigned long)host);
 
-	if (host->version >= SDHCI_SPEC_300)
+	if (host->version >= SDHCI_SPEC_300) {
 		init_waitqueue_head(&host->buf_ready_int);
 
+		/* Initialize re-tuning timer */
+		init_timer(&host->tuning_timer);
+		host->tuning_timer.data = (unsigned long)host;
+		host->tuning_timer.function = sdhci_tuning_timer;
+	}
+
 	ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
 		mmc_hostname(mmc), host);
 	if (ret)
@@ -2655,6 +2758,8 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
 	free_irq(host->irq, host);
 
 	del_timer_sync(&host->timer);
+	if (host->version >= SDHCI_SPEC_300)
+		del_timer_sync(&host->tuning_timer);
 
 	tasklet_kill(&host->card_tasklet);
 	tasklet_kill(&host->finish_tasklet);

drivers/mmc/host/sdhci.h

@@ -191,7 +191,11 @@
 #define  SDHCI_DRIVER_TYPE_A	0x00000010
 #define  SDHCI_DRIVER_TYPE_C	0x00000020
 #define  SDHCI_DRIVER_TYPE_D	0x00000040
+#define  SDHCI_RETUNING_TIMER_COUNT_MASK	0x00000F00
+#define  SDHCI_RETUNING_TIMER_COUNT_SHIFT	8
 #define  SDHCI_USE_SDR50_TUNING			0x00002000
+#define  SDHCI_RETUNING_MODE_MASK		0x0000C000
+#define  SDHCI_RETUNING_MODE_SHIFT		14
 #define  SDHCI_CLOCK_MUL_MASK	0x00FF0000
 #define  SDHCI_CLOCK_MUL_SHIFT	16
 

include/linux/mmc/sdhci.h

@@ -112,6 +112,7 @@ struct sdhci_host {
 #define SDHCI_REQ_USE_DMA	(1<<2)	/* Use DMA for this req. */
 #define SDHCI_DEVICE_DEAD	(1<<3)	/* Device unresponsive */
 #define SDHCI_SDR50_NEEDS_TUNING (1<<4)	/* SDR50 needs tuning */
+#define SDHCI_NEEDS_RETUNING	(1<<5)	/* Host needs retuning */
 
 	unsigned int version;	/* SDHCI spec. version */
 
@@ -152,6 +153,11 @@ struct sdhci_host {
 	wait_queue_head_t	buf_ready_int;	/* Waitqueue for Buffer Read Ready interrupt */
 	unsigned int		tuning_done;	/* Condition flag set when CMD19 succeeds */
 
+	unsigned int		tuning_count;	/* Timer count for re-tuning */
+	unsigned int		tuning_mode;	/* Re-tuning mode supported by host */
+#define SDHCI_TUNING_MODE_1	0
+	struct timer_list	tuning_timer;	/* Timer for tuning */
+
 	unsigned long private[0] ____cacheline_aligned;
 };
 #endif /* __SDHCI_H */