mmc: dw_mmc: add quirk for broken data transfer over scheme

This patch add a new quirk to add a s/w timer to notify the driver
to terminate current transfer and report a data timeout to the core,
if DTO interrupt does NOT come within the given time.

dw_mmc call mmc_request_done func to finish transfer depends on
DTO interrupt. If DTO interrupt does not come in sending data state,
the current transfer will be blocked.

We got the reply from synopsys:
There are two counters but both use the same value of [31:8] bits.
Data timeout counter doesn't wait for stop clock and you should get
DRTO even when the clock is not stopped.
Host Starvation timeout counter is triggered with stop clock condition.

This means that host should get DRTO and DTO interrupt.

But this case really exists, when driver reads tuning data from
card on RK3288-pink2 board. I measured waveforms by oscilloscope
and found that card clock was always on and data lines were always
holded high level in sending data state.

There are two possibility that data over interrupt doesn't come in
reading data state on RK3X SoCs:
- get command done interrupt, but doesn't get any data-related interrupt.
- get data error interrupt, but doesn't get data over interrupt.

Signed-off-by: Addy Ke <[e-mail]>
Signed-off-by: Heiko Stuebner <[e-mail]>
Signed-off-by: Jaehoon Chung <[e-mail]>

drivers/mmc/host/dw_mmc-rockchip.c

···
 	/* It is slot 8 on Rockchip SoCs */
 	host->sdio_id0 = 8;
 
+	/* It needs this quirk on all Rockchip SoCs */
+	host->pdata->quirks |= DW_MCI_QUIRK_BROKEN_DTO;
+
 	return 0;
 }
 

drivers/mmc/host/dw_mmc.c

···
 	return data->error;
 }
 
+static void dw_mci_set_drto(struct dw_mci *host)
+{
+	unsigned int drto_clks;
+	unsigned int drto_ms;
+
+	drto_clks = mci_readl(host, TMOUT) >> 8;
+	drto_ms = DIV_ROUND_UP(drto_clks, host->bus_hz / 1000);
+
+	/* add a bit spare time */
+	drto_ms += 10;
+
+	mod_timer(&host->dto_timer, jiffies + msecs_to_jiffies(drto_ms));
+}
+
 static void dw_mci_tasklet_func(unsigned long priv)
 {
 	struct dw_mci *host = (struct dw_mci *)priv;
···
 			}
 
 			if (!test_and_clear_bit(EVENT_XFER_COMPLETE,
-						&host->pending_events))
+						&host->pending_events)) {
+				/*
+				 * If all data-related interrupts don't come
+				 * within the given time in reading data state.
+				 */
+				if ((host->quirks & DW_MCI_QUIRK_BROKEN_DTO) &&
+				    (host->dir_status == DW_MCI_RECV_STATUS))
+					dw_mci_set_drto(host);
 				break;
+			}
 
 			set_bit(EVENT_XFER_COMPLETE, &host->completed_events);
 
···
 
 		case STATE_DATA_BUSY:
 			if (!test_and_clear_bit(EVENT_DATA_COMPLETE,
-						&host->pending_events))
+						&host->pending_events)) {
+				/*
+				 * If data error interrupt comes but data over
+				 * interrupt doesn't come within the given time.
+				 * in reading data state.
+				 */
+				if ((host->quirks & DW_MCI_QUIRK_BROKEN_DTO) &&
+				    (host->dir_status == DW_MCI_RECV_STATUS))
+					dw_mci_set_drto(host);
 				break;
+			}
 
 			host->data = NULL;
 			set_bit(EVENT_DATA_COMPLETE, &host->completed_events);
···
 		}
 
 		if (pending & SDMMC_INT_DATA_OVER) {
+			if (host->quirks & DW_MCI_QUIRK_BROKEN_DTO)
+				del_timer(&host->dto_timer);
+
 			mci_writel(host, RINTSTS, SDMMC_INT_DATA_OVER);
 			if (!host->data_status)
 				host->data_status = pending;
···
 	tasklet_schedule(&host->tasklet);
 }
 
+static void dw_mci_dto_timer(unsigned long arg)
+{
+	struct dw_mci *host = (struct dw_mci *)arg;
+
+	switch (host->state) {
+	case STATE_SENDING_DATA:
+	case STATE_DATA_BUSY:
+		/*
+		 * If DTO interrupt does NOT come in sending data state,
+		 * we should notify the driver to terminate current transfer
+		 * and report a data timeout to the core.
+		 */
+		host->data_status = SDMMC_INT_DRTO;
+		set_bit(EVENT_DATA_ERROR, &host->pending_events);
+		set_bit(EVENT_DATA_COMPLETE, &host->pending_events);
+		tasklet_schedule(&host->tasklet);
+		break;
+	default:
+		break;
+	}
+}
+
 #ifdef CONFIG_OF
 static struct dw_mci_of_quirks {
 	char *quirk;
···
 		    dw_mci_cmd11_timer, (unsigned long)host);
 
 	host->quirks = host->pdata->quirks;
+
+	if (host->quirks & DW_MCI_QUIRK_BROKEN_DTO)
+		setup_timer(&host->dto_timer,
+			    dw_mci_dto_timer, (unsigned long)host);
 
 	spin_lock_init(&host->lock);
 	spin_lock_init(&host->irq_lock);

include/linux/mmc/dw_mmc.h

···
  * @irq_flags: The flags to be passed to request_irq.
  * @irq: The irq value to be passed to request_irq.
  * @sdio_id0: Number of slot0 in the SDIO interrupt registers.
+ * @dto_timer: Timer for broken data transfer over scheme.
  *
  * Locking
  * =======
···
 	int			sdio_id0;
 
 	struct timer_list       cmd11_timer;
+	struct timer_list       dto_timer;
 };
 
 /* DMA ops for Internal/External DMAC interface */
···
 #define DW_MCI_QUIRK_HIGHSPEED			BIT(2)
 /* Unreliable card detection */
 #define DW_MCI_QUIRK_BROKEN_CARD_DETECTION	BIT(3)
+/* Timer for broken data transfer over scheme */
+#define DW_MCI_QUIRK_BROKEN_DTO			BIT(4)
 
 struct dma_pdata;