mmc: dw_mmc: handle unaligned buffers and sizes

Update functions for PIO pushing and pulling data to and from the FIFO
so that they can handle unaligned output buffers and unaligned buffer
lengths. This makes more of the tests in mmc_test pass.

Unaligned lengths in pulls are handled by reading the full FIFO item,
and storing the remaining bytes in a small internal buffer (part_buf).
The next data pull will copy data out of this buffer first before
accessing the FIFO again. Similarly, for pushes the final bytes that
don't fill a FIFO item are stored in the part_buf (or sent anyway if
it's the last transfer), and then the part_buf is included at the
beginning of the next buffer pushed.

Unaligned buffers in pulls are handled specially if the architecture
cannot do efficient unaligned accesses, by reading FIFO items into a
aligned local buffer, and memcpy'ing them into the output buffer, again
storing any remaining bytes in the internal buffer. Similarly for pushes
the buffer is memcpy'd into an aligned local buffer then written to the
FIFO.
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Acked-by: Will Newton <will.newton@imgtec.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/dw_mmc.c

@@ -495,6 +495,8 @@ static void dw_mci_submit_data(struct dw_mci *host, struct mmc_data *data)
 	if (dw_mci_submit_data_dma(host, data)) {
 		host->sg = data->sg;
 		host->pio_offset = 0;
+		host->part_buf_start = 0;
+		host->part_buf_count = 0;
 		if (data->flags & MMC_DATA_READ)
 			host->dir_status = DW_MCI_RECV_STATUS;
 		else
@@ -957,86 +959,280 @@ static void dw_mci_tasklet_func(unsigned long priv)
 
 }
 
-static void dw_mci_push_data16(struct dw_mci *host, void *buf, int cnt)
+/* push final bytes to part_buf, only use during push */
+static void dw_mci_set_part_bytes(struct dw_mci *host, void *buf, int cnt)
+{
+	memcpy((void *)&host->part_buf, buf, cnt);
+	host->part_buf_count = cnt;
+}
+
+/* append bytes to part_buf, only use during push */
+static int dw_mci_push_part_bytes(struct dw_mci *host, void *buf, int cnt)
 {
-	u16 *pdata = (u16 *)buf;
+	cnt = min(cnt, (1 << host->data_shift) - host->part_buf_count);
+	memcpy((void *)&host->part_buf + host->part_buf_count, buf, cnt);
+	host->part_buf_count += cnt;
+	return cnt;
+}
 
-	WARN_ON(cnt % 2 != 0);
+/* pull first bytes from part_buf, only use during pull */
+static int dw_mci_pull_part_bytes(struct dw_mci *host, void *buf, int cnt)
+{
+	cnt = min(cnt, (int)host->part_buf_count);
+	if (cnt) {
+		memcpy(buf, (void *)&host->part_buf + host->part_buf_start,
+		       cnt);
+		host->part_buf_count -= cnt;
+		host->part_buf_start += cnt;
+	}
+	return cnt;
+}
 
-	cnt = cnt >> 1;
-	while (cnt > 0) {
+/* pull final bytes from the part_buf, assuming it's just been filled */
+static void dw_mci_pull_final_bytes(struct dw_mci *host, void *buf, int cnt)
+{
+	memcpy(buf, &host->part_buf, cnt);
+	host->part_buf_start = cnt;
+	host->part_buf_count = (1 << host->data_shift) - cnt;
+}
+
+static void dw_mci_push_data16(struct dw_mci *host, void *buf, int cnt)
+{
+	/* try and push anything in the part_buf */
+	if (unlikely(host->part_buf_count)) {
+		int len = dw_mci_push_part_bytes(host, buf, cnt);
+		buf += len;
+		cnt -= len;
+		if (!sg_next(host->sg) || host->part_buf_count == 2) {
+			mci_writew(host, DATA, host->part_buf16);
+			host->part_buf_count = 0;
+		}
+	}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x1)) {
+		while (cnt >= 2) {
+			u16 aligned_buf[64];
+			int len = min(cnt & -2, (int)sizeof(aligned_buf));
+			int items = len >> 1;
+			int i;
+			/* memcpy from input buffer into aligned buffer */
+			memcpy(aligned_buf, buf, len);
+			buf += len;
+			cnt -= len;
+			/* push data from aligned buffer into fifo */
+			for (i = 0; i < items; ++i)
+				mci_writew(host, DATA, aligned_buf[i]);
+		}
+	} else
+#endif
+	{
+		u16 *pdata = buf;
+		for (; cnt >= 2; cnt -= 2)
 			mci_writew(host, DATA, *pdata++);
-		cnt--;
+		buf = pdata;
+	}
+	/* put anything remaining in the part_buf */
+	if (cnt) {
+		dw_mci_set_part_bytes(host, buf, cnt);
+		if (!sg_next(host->sg))
+			mci_writew(host, DATA, host->part_buf16);
 	}
 }
 
 static void dw_mci_pull_data16(struct dw_mci *host, void *buf, int cnt)
 {
-	u16 *pdata = (u16 *)buf;
-
-	WARN_ON(cnt % 2 != 0);
-
-	cnt = cnt >> 1;
-	while (cnt > 0) {
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x1)) {
+		while (cnt >= 2) {
+			/* pull data from fifo into aligned buffer */
+			u16 aligned_buf[64];
+			int len = min(cnt & -2, (int)sizeof(aligned_buf));
+			int items = len >> 1;
+			int i;
+			for (i = 0; i < items; ++i)
+				aligned_buf[i] = mci_readw(host, DATA);
+			/* memcpy from aligned buffer into output buffer */
+			memcpy(buf, aligned_buf, len);
+			buf += len;
+			cnt -= len;
+		}
+	} else
+#endif
+	{
+		u16 *pdata = buf;
+		for (; cnt >= 2; cnt -= 2)
 			*pdata++ = mci_readw(host, DATA);
-		cnt--;
+		buf = pdata;
+	}
+	if (cnt) {
+		host->part_buf16 = mci_readw(host, DATA);
+		dw_mci_pull_final_bytes(host, buf, cnt);
 	}
 }
 
 static void dw_mci_push_data32(struct dw_mci *host, void *buf, int cnt)
 {
-	u32 *pdata = (u32 *)buf;
-
-	WARN_ON(cnt % 4 != 0);
-	WARN_ON((unsigned long)pdata & 0x3);
-
-	cnt = cnt >> 2;
-	while (cnt > 0) {
+	/* try and push anything in the part_buf */
+	if (unlikely(host->part_buf_count)) {
+		int len = dw_mci_push_part_bytes(host, buf, cnt);
+		buf += len;
+		cnt -= len;
+		if (!sg_next(host->sg) || host->part_buf_count == 4) {
+			mci_writel(host, DATA, host->part_buf32);
+			host->part_buf_count = 0;
+		}
+	}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x3)) {
+		while (cnt >= 4) {
+			u32 aligned_buf[32];
+			int len = min(cnt & -4, (int)sizeof(aligned_buf));
+			int items = len >> 2;
+			int i;
+			/* memcpy from input buffer into aligned buffer */
+			memcpy(aligned_buf, buf, len);
+			buf += len;
+			cnt -= len;
+			/* push data from aligned buffer into fifo */
+			for (i = 0; i < items; ++i)
+				mci_writel(host, DATA, aligned_buf[i]);
+		}
+	} else
+#endif
+	{
+		u32 *pdata = buf;
+		for (; cnt >= 4; cnt -= 4)
 			mci_writel(host, DATA, *pdata++);
-		cnt--;
+		buf = pdata;
+	}
+	/* put anything remaining in the part_buf */
+	if (cnt) {
+		dw_mci_set_part_bytes(host, buf, cnt);
+		if (!sg_next(host->sg))
+			mci_writel(host, DATA, host->part_buf32);
 	}
 }
 
 static void dw_mci_pull_data32(struct dw_mci *host, void *buf, int cnt)
 {
-	u32 *pdata = (u32 *)buf;
-
-	WARN_ON(cnt % 4 != 0);
-	WARN_ON((unsigned long)pdata & 0x3);
-
-	cnt = cnt >> 2;
-	while (cnt > 0) {
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x3)) {
+		while (cnt >= 4) {
+			/* pull data from fifo into aligned buffer */
+			u32 aligned_buf[32];
+			int len = min(cnt & -4, (int)sizeof(aligned_buf));
+			int items = len >> 2;
+			int i;
+			for (i = 0; i < items; ++i)
+				aligned_buf[i] = mci_readl(host, DATA);
+			/* memcpy from aligned buffer into output buffer */
+			memcpy(buf, aligned_buf, len);
+			buf += len;
+			cnt -= len;
+		}
+	} else
+#endif
+	{
+		u32 *pdata = buf;
+		for (; cnt >= 4; cnt -= 4)
 			*pdata++ = mci_readl(host, DATA);
-		cnt--;
+		buf = pdata;
+	}
+	if (cnt) {
+		host->part_buf32 = mci_readl(host, DATA);
+		dw_mci_pull_final_bytes(host, buf, cnt);
 	}
 }
 
 static void dw_mci_push_data64(struct dw_mci *host, void *buf, int cnt)
 {
-	u64 *pdata = (u64 *)buf;
-
-	WARN_ON(cnt % 8 != 0);
-
-	cnt = cnt >> 3;
-	while (cnt > 0) {
+	/* try and push anything in the part_buf */
+	if (unlikely(host->part_buf_count)) {
+		int len = dw_mci_push_part_bytes(host, buf, cnt);
+		buf += len;
+		cnt -= len;
+		if (!sg_next(host->sg) || host->part_buf_count == 8) {
+			mci_writew(host, DATA, host->part_buf);
+			host->part_buf_count = 0;
+		}
+	}
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x7)) {
+		while (cnt >= 8) {
+			u64 aligned_buf[16];
+			int len = min(cnt & -8, (int)sizeof(aligned_buf));
+			int items = len >> 3;
+			int i;
+			/* memcpy from input buffer into aligned buffer */
+			memcpy(aligned_buf, buf, len);
+			buf += len;
+			cnt -= len;
+			/* push data from aligned buffer into fifo */
+			for (i = 0; i < items; ++i)
+				mci_writeq(host, DATA, aligned_buf[i]);
+		}
+	} else
+#endif
+	{
+		u64 *pdata = buf;
+		for (; cnt >= 8; cnt -= 8)
 			mci_writeq(host, DATA, *pdata++);
-		cnt--;
+		buf = pdata;
+	}
+	/* put anything remaining in the part_buf */
+	if (cnt) {
+		dw_mci_set_part_bytes(host, buf, cnt);
+		if (!sg_next(host->sg))
+			mci_writeq(host, DATA, host->part_buf);
 	}
 }
 
 static void dw_mci_pull_data64(struct dw_mci *host, void *buf, int cnt)
 {
-	u64 *pdata = (u64 *)buf;
-
-	WARN_ON(cnt % 8 != 0);
-
-	cnt = cnt >> 3;
-	while (cnt > 0) {
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (unlikely((unsigned long)buf & 0x7)) {
+		while (cnt >= 8) {
+			/* pull data from fifo into aligned buffer */
+			u64 aligned_buf[16];
+			int len = min(cnt & -8, (int)sizeof(aligned_buf));
+			int items = len >> 3;
+			int i;
+			for (i = 0; i < items; ++i)
+				aligned_buf[i] = mci_readq(host, DATA);
+			/* memcpy from aligned buffer into output buffer */
+			memcpy(buf, aligned_buf, len);
+			buf += len;
+			cnt -= len;
+		}
+	} else
+#endif
+	{
+		u64 *pdata = buf;
+		for (; cnt >= 8; cnt -= 8)
 			*pdata++ = mci_readq(host, DATA);
-		cnt--;
+		buf = pdata;
+	}
+	if (cnt) {
+		host->part_buf = mci_readq(host, DATA);
+		dw_mci_pull_final_bytes(host, buf, cnt);
 	}
 }
 
+static void dw_mci_pull_data(struct dw_mci *host, void *buf, int cnt)
+{
+	int len;
+
+	/* get remaining partial bytes */
+	len = dw_mci_pull_part_bytes(host, buf, cnt);
+	if (unlikely(len == cnt))
+		return;
+	buf += len;
+	cnt -= len;
+
+	/* get the rest of the data */
+	host->pull_data(host, buf, cnt);
+}
+
 static void dw_mci_read_data_pio(struct dw_mci *host)
 {
 	struct scatterlist *sg = host->sg;
@@ -1048,9 +1244,10 @@ static void dw_mci_read_data_pio(struct dw_mci *host)
 	unsigned int nbytes = 0, len;
 
 	do {
-		len = SDMMC_GET_FCNT(mci_readl(host, STATUS)) << shift;
+		len = host->part_buf_count +
+			(SDMMC_GET_FCNT(mci_readl(host, STATUS)) << shift);
 		if (offset + len <= sg->length) {
-			host->pull_data(host, (void *)(buf + offset), len);
+			dw_mci_pull_data(host, (void *)(buf + offset), len);
 
 			offset += len;
 			nbytes += len;
@@ -1066,7 +1263,7 @@ static void dw_mci_read_data_pio(struct dw_mci *host)
 			}
 		} else {
 			unsigned int remaining = sg->length - offset;
-			host->pull_data(host, (void *)(buf + offset),
+			dw_mci_pull_data(host, (void *)(buf + offset),
 					 remaining);
 			nbytes += remaining;
 
@@ -1077,7 +1274,7 @@ static void dw_mci_read_data_pio(struct dw_mci *host)
 
 			offset = len - remaining;
 			buf = sg_virt(sg);
-			host->pull_data(host, buf, offset);
+			dw_mci_pull_data(host, buf, offset);
 			nbytes += offset;
 		}
 
@@ -1094,7 +1291,6 @@ static void dw_mci_read_data_pio(struct dw_mci *host)
 			return;
 		}
 	} while (status & SDMMC_INT_RXDR); /*if the RXDR is ready read again*/
-	len = SDMMC_GET_FCNT(mci_readl(host, STATUS));
 	host->pio_offset = offset;
 	data->bytes_xfered += nbytes;
 	return;
@@ -1116,8 +1312,9 @@ static void dw_mci_write_data_pio(struct dw_mci *host)
 	unsigned int nbytes = 0, len;
 
 	do {
-		len = (host->fifo_depth -
-			SDMMC_GET_FCNT(mci_readl(host, STATUS))) << shift;
+		len = ((host->fifo_depth -
+			SDMMC_GET_FCNT(mci_readl(host, STATUS))) << shift)
+			- host->part_buf_count;
 		if (offset + len <= sg->length) {
 			host->push_data(host, (void *)(buf + offset), len);
 
@@ -1162,10 +1359,8 @@ static void dw_mci_write_data_pio(struct dw_mci *host)
 			return;
 		}
 	} while (status & SDMMC_INT_TXDR); /* if TXDR write again */
-
 	host->pio_offset = offset;
 	data->bytes_xfered += nbytes;
-
 	return;
 
 done:

include/linux/mmc/dw_mmc.h

@@ -76,6 +76,9 @@ struct mmc_data;
  * @slot: Slots sharing this MMC controller.
  * @fifo_depth: depth of FIFO.
  * @data_shift: log2 of FIFO item size.
+ * @part_buf_start: Start index in part_buf.
+ * @part_buf_count: Bytes of partial data in part_buf.
+ * @part_buf: Simple buffer for partial fifo reads/writes.
  * @push_data: Pointer to FIFO push function.
  * @pull_data: Pointer to FIFO pull function.
  * @quirks: Set of quirks that apply to specific versions of the IP.
@@ -149,6 +152,13 @@ struct dw_mci {
 	/* FIFO push and pull */
 	int			fifo_depth;
 	int			data_shift;
+	u8			part_buf_start;
+	u8			part_buf_count;
+	union {
+		u16		part_buf16;
+		u32		part_buf32;
+		u64		part_buf;
+	};
 	void (*push_data)(struct dw_mci *host, void *buf, int cnt);
 	void (*pull_data)(struct dw_mci *host, void *buf, int cnt);