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

Nicolas Boichat
2019-03-06T10:44:19Z

On Tue, Feb 26, 2019 at 9:11 PM Qii Wang <qii.wang@mediatek.com> wrote:
>
> 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>

Reviewed-by: Nicolas Boichat <drinkcat@chromium.org>

> ---
> 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
>