spi/sirf: fix the misunderstanding about len of spi_transfer

the unit of len of spi_transfer is in bytes, not in spi words. the
old codes misunderstood that and thought the len is the amount of
spi words. but it is actually how many bytes existing in the spi
buffer.

this patch fixes that and also rename left_tx_cnt and left_rx_cnt
to left_tx_word and left_rx_word to highlight they are in words.
Signed-off-by: Qipan Li <Qipan.Li@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/spi/spi-sirf.c

@@ -130,8 +130,7 @@
 
 #define ALIGNED(x) (!((u32)x & 0x3))
 #define IS_DMA_VALID(x) (x && ALIGNED(x->tx_buf) && ALIGNED(x->rx_buf) && \
-	ALIGNED(x->len * sspi->word_width) && (x->len * sspi->word_width < \
-		2 * PAGE_SIZE))
+	ALIGNED(x->len) && (x->len < 2 * PAGE_SIZE))
 
 struct sirfsoc_spi {
 	struct spi_bitbang bitbang;
@@ -152,8 +151,8 @@ struct sirfsoc_spi {
 	void (*tx_word) (struct sirfsoc_spi *);
 
 	/* number of words left to be tranmitted/received */
-	unsigned int left_tx_cnt;
-	unsigned int left_rx_cnt;
+	unsigned int left_tx_word;
+	unsigned int left_rx_word;
 
 	/* rx & tx DMA channels */
 	struct dma_chan *rx_chan;
@@ -178,7 +177,7 @@ static void spi_sirfsoc_rx_word_u8(struct sirfsoc_spi *sspi)
 		sspi->rx = rx;
 	}
 
-	sspi->left_rx_cnt--;
+	sspi->left_rx_word--;
 }
 
 static void spi_sirfsoc_tx_word_u8(struct sirfsoc_spi *sspi)
@@ -192,7 +191,7 @@ static void spi_sirfsoc_tx_word_u8(struct sirfsoc_spi *sspi)
 	}
 
 	writel(data, sspi->base + SIRFSOC_SPI_TXFIFO_DATA);
-	sspi->left_tx_cnt--;
+	sspi->left_tx_word--;
 }
 
 static void spi_sirfsoc_rx_word_u16(struct sirfsoc_spi *sspi)
@@ -207,7 +206,7 @@ static void spi_sirfsoc_rx_word_u16(struct sirfsoc_spi *sspi)
 		sspi->rx = rx;
 	}
 
-	sspi->left_rx_cnt--;
+	sspi->left_rx_word--;
 }
 
 static void spi_sirfsoc_tx_word_u16(struct sirfsoc_spi *sspi)
@@ -221,7 +220,7 @@ static void spi_sirfsoc_tx_word_u16(struct sirfsoc_spi *sspi)
 	}
 
 	writel(data, sspi->base + SIRFSOC_SPI_TXFIFO_DATA);
-	sspi->left_tx_cnt--;
+	sspi->left_tx_word--;
 }
 
 static void spi_sirfsoc_rx_word_u32(struct sirfsoc_spi *sspi)
@@ -236,7 +235,7 @@ static void spi_sirfsoc_rx_word_u32(struct sirfsoc_spi *sspi)
 		sspi->rx = rx;
 	}
 
-	sspi->left_rx_cnt--;
+	sspi->left_rx_word--;
 
 }
 
@@ -251,7 +250,7 @@ static void spi_sirfsoc_tx_word_u32(struct sirfsoc_spi *sspi)
 	}
 
 	writel(data, sspi->base + SIRFSOC_SPI_TXFIFO_DATA);
-	sspi->left_tx_cnt--;
+	sspi->left_tx_word--;
 }
 
 static irqreturn_t spi_sirfsoc_irq(int irq, void *dev_id)
@@ -272,18 +271,18 @@ static irqreturn_t spi_sirfsoc_irq(int irq, void *dev_id)
 			| SIRFSOC_SPI_RXFIFO_THD_REACH))
 		while (!((readl(sspi->base + SIRFSOC_SPI_RXFIFO_STATUS)
 				& SIRFSOC_SPI_FIFO_EMPTY)) &&
-				sspi->left_rx_cnt)
+				sspi->left_rx_word)
 			sspi->rx_word(sspi);
 
 	if (spi_stat & (SIRFSOC_SPI_FIFO_EMPTY
 			| SIRFSOC_SPI_TXFIFO_THD_REACH))
 		while (!((readl(sspi->base + SIRFSOC_SPI_TXFIFO_STATUS)
 				& SIRFSOC_SPI_FIFO_FULL)) &&
-				sspi->left_tx_cnt)
+				sspi->left_tx_word)
 			sspi->tx_word(sspi);
 
 	/* Received all words */
-	if ((sspi->left_rx_cnt == 0) && (sspi->left_tx_cnt == 0)) {
+	if ((sspi->left_rx_word == 0) && (sspi->left_tx_word == 0)) {
 		complete(&sspi->rx_done);
 		writel(0x0, sspi->base + SIRFSOC_SPI_INT_EN);
 	}
@@ -305,25 +304,28 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
 
 	sspi->tx = t->tx_buf ? t->tx_buf : sspi->dummypage;
 	sspi->rx = t->rx_buf ? t->rx_buf : sspi->dummypage;
-	sspi->left_tx_cnt = sspi->left_rx_cnt = t->len;
+	sspi->left_tx_word = sspi->left_rx_word = t->len / sspi->word_width;
 	INIT_COMPLETION(sspi->rx_done);
 	INIT_COMPLETION(sspi->tx_done);
 
 	writel(SIRFSOC_SPI_INT_MASK_ALL, sspi->base + SIRFSOC_SPI_INT_STATUS);
 
-	if (t->len == 1) {
+	if (sspi->left_tx_word == 1) {
 		writel(readl(sspi->base + SIRFSOC_SPI_CTRL) |
 			SIRFSOC_SPI_ENA_AUTO_CLR,
 			sspi->base + SIRFSOC_SPI_CTRL);
 		writel(0, sspi->base + SIRFSOC_SPI_TX_DMA_IO_LEN);
 		writel(0, sspi->base + SIRFSOC_SPI_RX_DMA_IO_LEN);
-	} else if ((t->len > 1) && (t->len < SIRFSOC_SPI_DAT_FRM_LEN_MAX)) {
+	} else if ((sspi->left_tx_word > 1) && (sspi->left_tx_word <
+				SIRFSOC_SPI_DAT_FRM_LEN_MAX)) {
 		writel(readl(sspi->base + SIRFSOC_SPI_CTRL) |
 				SIRFSOC_SPI_MUL_DAT_MODE |
 				SIRFSOC_SPI_ENA_AUTO_CLR,
 			sspi->base + SIRFSOC_SPI_CTRL);
-		writel(t->len - 1, sspi->base + SIRFSOC_SPI_TX_DMA_IO_LEN);
-		writel(t->len - 1, sspi->base + SIRFSOC_SPI_RX_DMA_IO_LEN);
+		writel(sspi->left_tx_word - 1,
+				sspi->base + SIRFSOC_SPI_TX_DMA_IO_LEN);
+		writel(sspi->left_tx_word - 1,
+				sspi->base + SIRFSOC_SPI_RX_DMA_IO_LEN);
 	} else {
 		writel(readl(sspi->base + SIRFSOC_SPI_CTRL),
 			sspi->base + SIRFSOC_SPI_CTRL);
@@ -338,18 +340,17 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
 
 	if (IS_DMA_VALID(t)) {
 		struct dma_async_tx_descriptor *rx_desc, *tx_desc;
-		unsigned int size = t->len * sspi->word_width;
 
 		sspi->dst_start = dma_map_single(&spi->dev, sspi->rx, t->len, DMA_FROM_DEVICE);
 		rx_desc = dmaengine_prep_slave_single(sspi->rx_chan,
-			sspi->dst_start, size, DMA_DEV_TO_MEM,
+			sspi->dst_start, t->len, DMA_DEV_TO_MEM,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		rx_desc->callback = spi_sirfsoc_dma_fini_callback;
 		rx_desc->callback_param = &sspi->rx_done;
 
 		sspi->src_start = dma_map_single(&spi->dev, (void *)sspi->tx, t->len, DMA_TO_DEVICE);
 		tx_desc = dmaengine_prep_slave_single(sspi->tx_chan,
-			sspi->src_start, size, DMA_MEM_TO_DEV,
+			sspi->src_start, t->len, DMA_MEM_TO_DEV,
 			DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 		tx_desc->callback = spi_sirfsoc_dma_fini_callback;
 		tx_desc->callback_param = &sspi->tx_done;
@@ -377,7 +378,7 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
 		dev_err(&spi->dev, "transfer timeout\n");
 		dmaengine_terminate_all(sspi->rx_chan);
 	} else
-		sspi->left_rx_cnt = 0;
+		sspi->left_rx_word = 0;
 
 	/*
 	 * we only wait tx-done event if transferring by DMA. for PIO,
@@ -402,7 +403,7 @@ static int spi_sirfsoc_transfer(struct spi_device *spi, struct spi_transfer *t)
 	writel(0, sspi->base + SIRFSOC_SPI_TX_RX_EN);
 	writel(0, sspi->base + SIRFSOC_SPI_INT_EN);
 
-	return t->len - sspi->left_rx_cnt;
+	return t->len - sspi->left_rx_word * sspi->word_width;
 }
 
 static void spi_sirfsoc_chipselect(struct spi_device *spi, int value)