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

Qii Wang
2019-02-26T13:11:53Z

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@mediatek.com>
---
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