[PATCH v5 3/5] i2c: mediatek: Add arb clock in i2c driver

[Qii Wang]

When two i2c controllers are internally connected to the same
GPIO pins, the arb clock is needed to ensure that the waveforms
do not interfere with each other.

Signed-off-by: Qii Wang <qii.wang@xxxxxxxxxxxx>
---
 drivers/i2c/busses/i2c-mt65xx.c |   25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
index 428ac99..14d6b38 100644
--- a/drivers/i2c/busses/i2c-mt65xx.c
+++ b/drivers/i2c/busses/i2c-mt65xx.c
@@ -35,6 +35,7 @@
 #include <linux/slab.h>
 
 #define I2C_RS_TRANSFER			(1 << 4)
+#define I2C_ARB_LOST			(1 << 3)
 #define I2C_HS_NACKERR			(1 << 2)
 #define I2C_ACKERR			(1 << 1)
 #define I2C_TRANSAC_COMP		(1 << 0)
@@ -181,6 +182,7 @@ struct mtk_i2c {
 	struct clk *clk_main;		/* main clock for i2c bus */
 	struct clk *clk_dma;		/* DMA clock for i2c via DMA */
 	struct clk *clk_pmic;		/* PMIC clock for i2c from PMIC */
+	struct clk *clk_arb;		/* Arbitrator clock for i2c */
 	bool have_pmic;			/* can use i2c pins from PMIC */
 	bool use_push_pull;		/* IO config push-pull mode */
 
@@ -299,8 +301,18 @@ static int mtk_i2c_clock_enable(struct mtk_i2c *i2c)
 		if (ret)
 			goto err_pmic;
 	}
+
+	if (i2c->clk_arb) {
+		ret = clk_prepare_enable(i2c->clk_arb);
+		if (ret)
+			goto err_arb;
+	}
+
 	return 0;
 
+err_arb:
+	if (i2c->have_pmic)
+		clk_disable_unprepare(i2c->clk_pmic);
 err_pmic:
 	clk_disable_unprepare(i2c->clk_main);
 err_main:
@@ -311,6 +323,9 @@ static int mtk_i2c_clock_enable(struct mtk_i2c *i2c)
 
 static void mtk_i2c_clock_disable(struct mtk_i2c *i2c)
 {
+	if (i2c->clk_arb)
+		clk_disable_unprepare(i2c->clk_arb);
+
 	if (i2c->have_pmic)
 		clk_disable_unprepare(i2c->clk_pmic);
 
@@ -519,13 +534,13 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 
 	/* Clear interrupt status */
 	mtk_i2c_writew(i2c, restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
-	       I2C_TRANSAC_COMP, OFFSET_INTR_STAT);
+			    I2C_ARB_LOST | I2C_TRANSAC_COMP, OFFSET_INTR_STAT);
 
 	mtk_i2c_writew(i2c, I2C_FIFO_ADDR_CLR, OFFSET_FIFO_ADDR_CLR);
 
 	/* Enable interrupt */
 	mtk_i2c_writew(i2c, restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
-	       I2C_TRANSAC_COMP, OFFSET_INTR_MASK);
+			    I2C_ARB_LOST | I2C_TRANSAC_COMP, OFFSET_INTR_MASK);
 
 	/* Set transfer and transaction len */
 	if (i2c->op == I2C_MASTER_WRRD) {
@@ -659,7 +674,7 @@ static int mtk_i2c_do_transfer(struct mtk_i2c *i2c, struct i2c_msg *msgs,
 
 	/* Clear interrupt mask */
 	mtk_i2c_writew(i2c, ~(restart_flag | I2C_HS_NACKERR | I2C_ACKERR |
-	       I2C_TRANSAC_COMP), OFFSET_INTR_MASK);
+			    I2C_ARB_LOST | I2C_TRANSAC_COMP), OFFSET_INTR_MASK);
 
 	if (i2c->op == I2C_MASTER_WR) {
 		dma_unmap_single(i2c->dev, wpaddr,
@@ -884,6 +899,10 @@ static int mtk_i2c_probe(struct platform_device *pdev)
 		return PTR_ERR(i2c->clk_dma);
 	}
 
+	i2c->clk_arb = devm_clk_get(&pdev->dev, "arb");
+	if (IS_ERR(i2c->clk_arb))
+		i2c->clk_arb = NULL;
+
 	clk = i2c->clk_main;
 	if (i2c->have_pmic) {
 		i2c->clk_pmic = devm_clk_get(&pdev->dev, "pmic");
-- 
1.7.9.5