[PATCH v2] mtd: rawnand: cadence: support 64-bit slave dma interface

[PATCH v2] mtd: rawnand: cadence: support 64-bit slave dma interface

[Valentin Korenblit]

32-bit accesses on 64-bit sdma trigger sdma_err in intr_status register.

Check dma capabilities before reading/writing from/to sdma interface.

Link to discussion:
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/3NMACGIM5NDUBPXRT5RTBZON6LQE5A3B/

Signed-off-by: Valentin Korenblit <vkorenblit@sequans.com>

---

Changes v1 -> v2:
	- Replaced ioread64_rep by cadence_nand_readsq (suggested by Arnd)
	- Replaced iowrite64_rep by cadence_nand_writesq (suggested by Arnd)
	- Do not try to access 64-bit sdma if __raw_readq/__raw_writeq are not defined
---
 .../mtd/nand/raw/cadence-nand-controller.c    | 96 ++++++++++++++++---
 1 file changed, 84 insertions(+), 12 deletions(-)

diff --git a/drivers/mtd/nand/raw/cadence-nand-controller.c b/drivers/mtd/nand/raw/cadence-nand-controller.c
index 9dac3ca69d57..0309a6b0d3d3 100644
--- a/drivers/mtd/nand/raw/cadence-nand-controller.c
+++ b/drivers/mtd/nand/raw/cadence-nand-controller.c
@@ -1869,6 +1869,46 @@ static int cadence_nand_slave_dma_transfer(struct cdns_nand_ctrl *cdns_ctrl,
 	return -EIO;
 }
 
+static inline void cadence_nand_readsq(struct cdns_nand_ctrl *cdns_ctrl,
+				       void *buffer, unsigned int count)
+{
+#ifdef __raw_readq
+	const volatile void __iomem *addr = cdns_ctrl->io.virt;
+
+        if (count) {
+                u64 *buf = buffer;
+
+                do {
+                        u64 x = __raw_readq(addr);
+                        *buf++ = x;
+                } while (--count);
+        }
+#else
+	dev_err(cdns_ctrl->dev,
+		"cannot read 64-bit sdma on !64-bit architectures");
+#endif
+}
+
+static inline void cadence_nand_writesq(struct cdns_nand_ctrl *cdns_ctrl,
+					const void *buffer,
+					unsigned int count)
+{
+#ifdef __raw_writeq
+	volatile void __iomem *addr = cdns_ctrl->io.virt;
+
+        if (count) {
+                const u64 *buf = buffer;
+
+                do {
+                        __raw_writeq(*buf++, addr);
+                } while (--count);
+        }
+#else
+	dev_err(cdns_ctrl->dev,
+		"cannot write 64-bit sdma on !64-bit architectures");
+#endif
+}
+
 static int cadence_nand_read_buf(struct cdns_nand_ctrl *cdns_ctrl,
 				 u8 *buf, int len)
 {
@@ -1882,17 +1922,33 @@ static int cadence_nand_read_buf(struct cdns_nand_ctrl *cdns_ctrl,
 		return status;
 
 	if (!cdns_ctrl->caps1->has_dma) {
-		int len_in_words = len >> 2;
+		u8 data_dma_width = cdns_ctrl->caps2.data_dma_width;
+
+		int len_in_words = (data_dma_width == 4) ? len >> 2 : len >> 3;
 
 		/* read alingment data */
-		ioread32_rep(cdns_ctrl->io.virt, buf, len_in_words);
+		if (data_dma_width == 4)
+			ioread32_rep(cdns_ctrl->io.virt, buf, len_in_words);
+		else
+			cadence_nand_readsq(cdns_ctrl, buf, len_in_words);
+
 		if (sdma_size > len) {
+			int read_bytes = (data_dma_width == 4) ?
+				len_in_words << 2 : len_in_words << 3;
+
 			/* read rest data from slave DMA interface if any */
-			ioread32_rep(cdns_ctrl->io.virt, cdns_ctrl->buf,
-				     sdma_size / 4 - len_in_words);
+			if (data_dma_width == 4)
+				ioread32_rep(cdns_ctrl->io.virt,
+					     cdns_ctrl->buf,
+					     sdma_size / 4 - len_in_words);
+			else
+				cadence_nand_readsq(cdns_ctrl,
+					     cdns_ctrl->buf,
+					     sdma_size / 8 - len_in_words);
+
 			/* copy rest of data */
-			memcpy(buf + (len_in_words << 2), cdns_ctrl->buf,
-			       len - (len_in_words << 2));
+			memcpy(buf + read_bytes, cdns_ctrl->buf,
+			       len - read_bytes);
 		}
 		return 0;
 	}
@@ -1936,16 +1992,32 @@ static int cadence_nand_write_buf(struct cdns_nand_ctrl *cdns_ctrl,
 		return status;
 
 	if (!cdns_ctrl->caps1->has_dma) {
-		int len_in_words = len >> 2;
+		u8 data_dma_width = cdns_ctrl->caps2.data_dma_width;
+
+		int len_in_words = (data_dma_width == 4) ? len >> 2 : len >> 3;
+
+		if (data_dma_width == 4)
+			iowrite32_rep(cdns_ctrl->io.virt, buf, len_in_words);
+		else
+			cadence_nand_writesq(cdns_ctrl, buf, len_in_words);
 
-		iowrite32_rep(cdns_ctrl->io.virt, buf, len_in_words);
 		if (sdma_size > len) {
+			int written_bytes = (data_dma_width == 4) ?
+				len_in_words << 2 : len_in_words << 3;
+
 			/* copy rest of data */
-			memcpy(cdns_ctrl->buf, buf + (len_in_words << 2),
-			       len - (len_in_words << 2));
+			memcpy(cdns_ctrl->buf, buf + written_bytes,
+			       len - written_bytes);
+
 			/* write all expected by nand controller data */
-			iowrite32_rep(cdns_ctrl->io.virt, cdns_ctrl->buf,
-				      sdma_size / 4 - len_in_words);
+			if (data_dma_width == 4)
+				iowrite32_rep(cdns_ctrl->io.virt,
+					      cdns_ctrl->buf,
+					      sdma_size / 4 - len_in_words);
+			else
+				cadence_nand_writesq(cdns_ctrl,
+					      cdns_ctrl->buf,
+					      sdma_size / 8 - len_in_words);
 		}
 
 		return 0;
-- 
2.20.1

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Re: [PATCH v2] mtd: rawnand: cadence: support 64-bit slave dma interface

[Arnd Bergmann]

On Mon, Oct 17, 2022, at 5:26 PM, Valentin Korenblit wrote:
> 32-bit accesses on 64-bit sdma trigger sdma_err in intr_status register.
>
> Check dma capabilities before reading/writing from/to sdma interface.
>
> Link to discussion:
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/3NMACGIM5NDUBPXRT5RTBZON6LQE5A3B/
>
> Signed-off-by: Valentin Korenblit <vkorenblit@sequans.com>

Seems reasonable overall based on the discussion so far.

Minor comments:

> Changes v1 -> v2:
> 	- Replaced ioread64_rep by cadence_nand_readsq (suggested by Arnd)
> 	- Replaced iowrite64_rep by cadence_nand_writesq (suggested by Arnd)
> 	- Do not try to access 64-bit sdma if __raw_readq/__raw_writeq are not defined


> +static inline void cadence_nand_readsq(struct cdns_nand_ctrl 
> *cdns_ctrl,
> +				       void *buffer, unsigned int count)
> +{
> +#ifdef __raw_readq
> +	const volatile void __iomem *addr = cdns_ctrl->io.virt;
> +
> +        if (count) {
> +                u64 *buf = buffer;
> +
> +                do {
> +                        u64 x = __raw_readq(addr);
> +                        *buf++ = x;
> +                } while (--count);
> +        }

While this is correct, I suppose you don't actually need that
loop any more, since architectures that have __raw_readq()
should also also have ioread64_rep() or readsq(). We actually
just had a few issues with that in another context, but I think
starting with 6.1-rc1 you should be able to rely on that ;-)

> +#else
> +	dev_err(cdns_ctrl->dev,
> +		"cannot read 64-bit sdma on !64-bit architectures");
> +#endif

It would be nice to print an error at probe time and fail attaching
the device rather than waiting for the first transfer to continue
with incorrect data.

      Arnd

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