[PATCH 3/3] i2c: mediatek: Use DMA safe buffers for i2c transactions

[Jun Gao <jun.gao-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>]

From: Jun Gao <jun.gao-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>

DMA mode will always be used in i2c transactions, try to allocate
a DMA safe buffer if the buf of struct i2c_msg used is not DMA safe.

Signed-off-by: Jun Gao <jun.gao-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org>
---
 drivers/i2c/busses/i2c-mt65xx.c | 62 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 55 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 806e8b90..dd014ee 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -441,6 +441,8 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	u16 control_reg;
 	u16 restart_flag = 0;
 	u32 reg_4g_mode;
+	u8 *dma_rd_buf;
+	u8 *dma_wr_buf;
 	dma_addr_t rpaddr = 0;
 	dma_addr_t wpaddr = 0;
 	int ret;
@@ -500,10 +502,18 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	if (i2c->op == I2C_MASTER_RD) {
 		writel(I2C_DMA_INT_FLAG_NONE, i2c->pdmabase + OFFSET_INT_FLAG);
 		writel(I2C_DMA_CON_RX, i2c->pdmabase + OFFSET_CON);
-		rpaddr = dma_map_single(i2c->dev, msgs->buf,
+
+		dma_rd_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+		if (!dma_rd_buf)
+			return -ENOMEM;
+
+		rpaddr = dma_map_single(i2c->dev, dma_rd_buf,
 					msgs->len, DMA_FROM_DEVICE);
-		if (dma_mapping_error(i2c->dev, rpaddr))
+		if (dma_mapping_error(i2c->dev, rpaddr)) {
+			i2c_free_dma_safe_msg_buf(msgs, dma_rd_buf);
+
 			return -ENOMEM;
+		}
 
 		if (i2c->dev_comp->support_33bits) {
 			reg_4g_mode = mtk_i2c_set_4g_mode(rpaddr);
@@ -515,10 +525,18 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	} else if (i2c->op == I2C_MASTER_WR) {
 		writel(I2C_DMA_INT_FLAG_NONE, i2c->pdmabase + OFFSET_INT_FLAG);
 		writel(I2C_DMA_CON_TX, i2c->pdmabase + OFFSET_CON);
-		wpaddr = dma_map_single(i2c->dev, msgs->buf,
+
+		dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+		if (!dma_wr_buf)
+			return -ENOMEM;
+
+		wpaddr = dma_map_single(i2c->dev, dma_wr_buf,
 					msgs->len, DMA_TO_DEVICE);
-		if (dma_mapping_error(i2c->dev, wpaddr))
+		if (dma_mapping_error(i2c->dev, wpaddr)) {
+			i2c_free_dma_safe_msg_buf(msgs, dma_wr_buf);
+
 			return -ENOMEM;
+		}
 
 		if (i2c->dev_comp->support_33bits) {
 			reg_4g_mode = mtk_i2c_set_4g_mode(wpaddr);
@@ -530,16 +548,39 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	} else {
 		writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_INT_FLAG);
 		writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_CON);
-		wpaddr = dma_map_single(i2c->dev, msgs->buf,
+
+		dma_wr_buf = i2c_get_dma_safe_msg_buf(msgs, 0);
+		if (!dma_wr_buf)
+			return -ENOMEM;
+
+		wpaddr = dma_map_single(i2c->dev, dma_wr_buf,
 					msgs->len, DMA_TO_DEVICE);
-		if (dma_mapping_error(i2c->dev, wpaddr))
+		if (dma_mapping_error(i2c->dev, wpaddr)) {
+			i2c_free_dma_safe_msg_buf(msgs, dma_wr_buf);
+
 			return -ENOMEM;
-		rpaddr = dma_map_single(i2c->dev, (msgs + 1)->buf,
+		}
+
+		dma_rd_buf = i2c_get_dma_safe_msg_buf((msgs + 1), 0);
+		if (!dma_rd_buf) {
+			dma_unmap_single(i2c->dev, wpaddr,
+					 msgs->len, DMA_TO_DEVICE);
+
+			i2c_free_dma_safe_msg_buf(msgs, dma_wr_buf);
+
+			return -ENOMEM;
+		}
+
+		rpaddr = dma_map_single(i2c->dev, dma_rd_buf,
 					(msgs + 1)->len,
 					DMA_FROM_DEVICE);
 		if (dma_mapping_error(i2c->dev, rpaddr)) {
 			dma_unmap_single(i2c->dev, wpaddr,
 					 msgs->len, DMA_TO_DEVICE);
+
+			i2c_free_dma_safe_msg_buf(msgs, dma_wr_buf);
+			i2c_free_dma_safe_msg_buf((msgs + 1), dma_rd_buf);
+
 			return -ENOMEM;
 		}
 
@@ -578,14 +619,21 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	if (i2c->op == I2C_MASTER_WR) {
 		dma_unmap_single(i2c->dev, wpaddr,
 				 msgs->len, DMA_TO_DEVICE);
+
+		i2c_release_dma_safe_msg_buf(msgs, dma_wr_buf);
 	} else if (i2c->op == I2C_MASTER_RD) {
 		dma_unmap_single(i2c->dev, rpaddr,
 				 msgs->len, DMA_FROM_DEVICE);
+
+		i2c_release_dma_safe_msg_buf(msgs, dma_rd_buf);
 	} else {
 		dma_unmap_single(i2c->dev, wpaddr, msgs->len,
 				 DMA_TO_DEVICE);
 		dma_unmap_single(i2c->dev, rpaddr, (msgs + 1)->len,
 				 DMA_FROM_DEVICE);
+
+		i2c_release_dma_safe_msg_buf(msgs, dma_wr_buf);
+		i2c_release_dma_safe_msg_buf((msgs + 1), dma_rd_buf);
 	}
 
 	if (ret == 0) {
-- 
1.8.1.1