[PATCH v2 2/5] spi: spi-mtk-nor: fix mishandled logics in checking SPI memory operation

[Ikjoon Jang]

Fix a simple bug which can limits its transfer size,
and add a simple helper function for code cleanups.

Fixes: a59b2c7c56bf ("spi: spi-mtk-nor: support standard spi properties")
Signed-off-by: Ikjoon Jang <ikjn at chromium.org>

---

(no changes since v1)

 drivers/spi/spi-mtk-nor.c | 62 ++++++++++++++++++++++++---------------
 1 file changed, 38 insertions(+), 24 deletions(-)

diff --git a/drivers/spi/spi-mtk-nor.c b/drivers/spi/spi-mtk-nor.c
index 6e6ca2b8e6c8..54b2c0fde95b 100644
--- a/drivers/spi/spi-mtk-nor.c
+++ b/drivers/spi/spi-mtk-nor.c
@@ -167,52 +167,63 @@ static bool mtk_nor_match_read(const struct spi_mem_op *op)
 	return false;
 }
 
-static int mtk_nor_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+static bool need_bounce(void *cpu_addr, unsigned long len)
 {
-	size_t len;
+	return !!(((uintptr_t)cpu_addr) & MTK_NOR_DMA_ALIGN_MASK);
+}
 
+static int mtk_nor_adjust_op_size(struct spi_mem *mem, struct spi_mem_op *op)
+{
 	if (!op->data.nbytes)
 		return 0;
 
 	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
-		if ((op->data.dir == SPI_MEM_DATA_IN) &&
-		    mtk_nor_match_read(op)) {
+		switch (op->data.dir) {
+		case SPI_MEM_DATA_IN:
+			if (!mtk_nor_match_read(op))
+				return -EINVAL;
+			/* check if it's DMAable */
 			if ((op->addr.val & MTK_NOR_DMA_ALIGN_MASK) ||
-			    (op->data.nbytes < MTK_NOR_DMA_ALIGN))
+			    (op->data.nbytes < MTK_NOR_DMA_ALIGN)) {
 				op->data.nbytes = 1;
-			else if (!((ulong)(op->data.buf.in) &
-				   MTK_NOR_DMA_ALIGN_MASK))
+			} else {
+				if (need_bounce(op->data.buf.in, op->data.nbytes) &&
+				    (op->data.nbytes > MTK_NOR_BOUNCE_BUF_SIZE))
+					op->data.nbytes = MTK_NOR_BOUNCE_BUF_SIZE;
 				op->data.nbytes &= ~MTK_NOR_DMA_ALIGN_MASK;
-			else if (op->data.nbytes > MTK_NOR_BOUNCE_BUF_SIZE)
-				op->data.nbytes = MTK_NOR_BOUNCE_BUF_SIZE;
-			return 0;
-		} else if (op->data.dir == SPI_MEM_DATA_OUT) {
+			}
+			break;
+		case SPI_MEM_DATA_OUT:
 			if (op->data.nbytes >= MTK_NOR_PP_SIZE)
 				op->data.nbytes = MTK_NOR_PP_SIZE;
 			else
 				op->data.nbytes = 1;
-			return 0;
+			break;
+		default:
+			break;
 		}
+	} else {
+		u8 len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
+
+		if (len > MTK_NOR_PRG_MAX_SIZE)
+			return -EINVAL;
+		if (op->data.nbytes && !(MTK_NOR_PRG_MAX_SIZE - len))
+			return -EINVAL;
+		if (op->data.nbytes > (MTK_NOR_PRG_MAX_SIZE - len))
+			op->data.nbytes = MTK_NOR_PRG_MAX_SIZE - len;
 	}
 
-	len = MTK_NOR_PRG_MAX_SIZE - op->cmd.nbytes - op->addr.nbytes -
-	      op->dummy.nbytes;
-	if (op->data.nbytes > len)
-		op->data.nbytes = len;
-
 	return 0;
 }
 
 static bool mtk_nor_supports_op(struct spi_mem *mem,
 				const struct spi_mem_op *op)
 {
-	size_t len;
-
 	if (op->cmd.buswidth != 1)
 		return false;
 
 	if ((op->addr.nbytes == 3) || (op->addr.nbytes == 4)) {
-		switch(op->data.dir) {
+		switch (op->data.dir) {
 		case SPI_MEM_DATA_IN:
 			if (!mtk_nor_match_read(op))
 				return false;
@@ -226,11 +237,14 @@ static bool mtk_nor_supports_op(struct spi_mem *mem,
 		default:
 			break;
 		}
+	} else {
+		u8 len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
+
+		if (len > MTK_NOR_PRG_MAX_SIZE)
+			return false;
+		if (op->data.nbytes && !(MTK_NOR_PRG_MAX_SIZE - len))
+			return false;
 	}
-	len = op->cmd.nbytes + op->addr.nbytes + op->dummy.nbytes;
-	if ((len > MTK_NOR_PRG_MAX_SIZE) ||
-	    ((op->data.nbytes) && (len == MTK_NOR_PRG_MAX_SIZE)))
-		return false;
 
 	return spi_mem_default_supports_op(mem, op);
 }
-- 
2.28.0.681.g6f77f65b4e-goog