linux-kernel - Re: [PATCH RESEND v6 3/6] i2c: mediatek: Add arb clock in i2c driver

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Date:   Fri, 12 Apr 2019 20:41:51 +0200
From:   Matthias Brugger <matthias.bgg@...il.com>
To:     Qii Wang <qii.wang@...iatek.com>, wsa@...-dreams.de
Cc:     devicetree@...r.kernel.org, srv_heupstream@...iatek.com,
        robh@...nel.org, leilk.liu@...iatek.com, xinping.qian@...iatek.com,
        linux-kernel@...r.kernel.org, liguo.zhang@...iatek.com,
        linux-mediatek@...ts.infradead.org, linux-i2c@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH RESEND v6 3/6] i2c: mediatek: Add arb clock in i2c driver



On 02/04/2019 14:35, Qii Wang 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. And we also need to enable
> the interrupt to find arb lost, old i2c controllers also have
> the bit.
> 
> Signed-off-by: Qii Wang <qii.wang@...iatek.com>
> Reviewed-by: Nicolas Boichat <drinkcat@...omium.org>
> ---
>  drivers/i2c/busses/i2c-mt65xx.c |   25 ++++++++++++++++++++++---
>  1 file changed, 22 insertions(+), 3 deletions(-)

Looks good:
Reviewed-by: Matthias Brugger <matthias.bgg@...il.com>

> 
> diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c-mt65xx.c
> index be36018..1a7235e 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");
>