[PATCH v6 2/7] i2c: mediatek: Reset the handshake signal between i2c and dma

[Kewei Xu]

Due to changes in the hardware design of the handshaking signal
between i2c and dma, it is necessary to reset the handshaking
signal before each transfer to ensure that the multi-msgs can
be transferred correctly.

Signed-off-by: Kewei Xu <kewei.xu at mediatek.com>
---
 drivers/i2c/busses/i2c-mt65xx.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 2661ed0..7a1c538 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -15,6 +15,7 @@
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/iopoll.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/module.h>
@@ -47,6 +48,9 @@
 #define I2C_RD_TRANAC_VALUE		0x0001
 #define I2C_SCL_MIS_COMP_VALUE		0x0000
 #define I2C_CHN_CLR_FLAG		0x0000
+#define I2C_CLR_DEBUGCTR		0x0000
+#define I2C_RELIABILITY			0x0010
+#define I2C_DMAACK_ENABLE		0x0008
 
 #define I2C_DMA_CON_TX			0x0000
 #define I2C_DMA_CON_RX			0x0001
@@ -842,6 +846,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 	u16 restart_flag = 0;
 	u16 dma_sync = 0;
 	u32 reg_4g_mode;
+	u32 reg_dma_reset;
 	u8 *dma_rd_buf = NULL;
 	u8 *dma_wr_buf = NULL;
 	dma_addr_t rpaddr = 0;
@@ -855,6 +860,27 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 
 	reinit_completion(&i2c->msg_complete);
 
+	if (i2c->dev_comp->apdma_sync && i2c->op != I2C_MASTER_WRRD && num > 1) {
+		mtk_i2c_writew(i2c, I2C_CLR_DEBUGCTR, OFFSET_DEBUGCTRL);
+		writel(I2C_DMA_HANDSHAKE_RST | I2C_DMA_WARM_RST,
+		       i2c->pdmabase + OFFSET_RST);
+
+		ret = readw_poll_timeout(i2c->pdmabase + OFFSET_RST,
+					 reg_dma_reset,
+					 !(reg_dma_reset & I2C_DMA_WARM_RST),
+					 0, 100);
+		if (ret) {
+			dev_err(i2c->dev, "DMA warm reset timeout\n");
+			return -ETIMEDOUT;
+		}
+
+		writel(I2C_DMA_CLR_FLAG, i2c->pdmabase + OFFSET_RST);
+		mtk_i2c_writew(i2c, I2C_HANDSHAKE_RST, OFFSET_SOFTRESET);
+		mtk_i2c_writew(i2c, I2C_CHN_CLR_FLAG, OFFSET_SOFTRESET);
+		mtk_i2c_writew(i2c, I2C_RELIABILITY | I2C_DMAACK_ENABLE,
+			       OFFSET_DEBUGCTRL);
+	}
+
 	control_reg = mtk_i2c_readw(i2c, OFFSET_CONTROL) &
 			~(I2C_CONTROL_DIR_CHANGE | I2C_CONTROL_RS);
 	if ((i2c->speed_hz > I2C_MAX_FAST_MODE_PLUS_FREQ) || (left_num >= 1))
-- 
1.9.1