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>

2 files changed, 112 insertions, 3 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 07cca557c4b5..fa3301644b15 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/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);
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 6b0a0ee9ac6e..8ea11b7cf89a 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/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_USE_SDR50_TUNING 0x00002000
+#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