[U-Boot] [PATCH 2/6] i2c: designware_i2c: Add dw_i2c_enable() helper function

[Bin Meng]

Hi Stefan,

On Fri, Mar 18, 2016 at 3:54 PM, Stefan Roese <sr at denx.de> wrote:
> dw_i2c_enable() is used to dis-/en-able the I2C controller. It makes
> sense to add such a function, as the controller is dis-/en-abled
> multiple times in the code. Additionally, this function now checks,
> if the controller is really dis-/en-abled. This code is copied
> from the Linux I2C driver version.
>
> Signed-off-by: Stefan Roese <sr at denx.de>
> Cc: Simon Glass <sjg at chromium.org>
> Cc: Bin Meng <bmeng.cn at gmail.com>
> Cc: Marek Vasut <marex at denx.de>
> Cc: Heiko Schocher <hs at denx.de>
> ---
>  drivers/i2c/designware_i2c.c | 46 +++++++++++++++++++++++++-------------------
>  1 file changed, 26 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/i2c/designware_i2c.c b/drivers/i2c/designware_i2c.c
> index e768cde..c8ea520 100644
> --- a/drivers/i2c/designware_i2c.c
> +++ b/drivers/i2c/designware_i2c.c
> @@ -34,6 +34,26 @@ static struct i2c_regs *i2c_get_base(struct i2c_adapter *adap)
>         return NULL;
>  }
>
> +static void dw_i2c_enable(struct i2c_regs *i2c_base, bool enable)
> +{
> +       int timeout = 100;
> +
> +       do {
> +               writel(enable, &i2c_base->ic_enable);
> +               if ((readl(&i2c_base->ic_enable_status) & 1) == enable)
> +                       return;
> +
> +               /*
> +                * Wait 10 times the signaling period of the highest I2C
> +                * transfer supported by the driver (for 400KHz this is
> +                * 25us) as described in the DesignWare I2C databook.
> +                */
> +               udelay(25);
> +       } while (timeout--);
> +
> +       printf("timeout in %sabling I2C adapter\n", enable ? "en" : "dis");
> +}
> +
>  /*
>   * set_speed - Set the i2c speed mode (standard, high, fast)
>   * @i2c_spd:   required i2c speed mode
> @@ -45,12 +65,9 @@ static void set_speed(struct i2c_adapter *adap, int i2c_spd)
>         struct i2c_regs *i2c_base = i2c_get_base(adap);
>         unsigned int cntl;
>         unsigned int hcnt, lcnt;
> -       unsigned int enbl;
>
>         /* to set speed cltr must be disabled */
> -       enbl = readl(&i2c_base->ic_enable);
> -       enbl &= ~IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 0);

nits: change 0 to false since the parameter type is bool?

>
>         cntl = (readl(&i2c_base->ic_con) & (~IC_CON_SPD_MSK));
>
> @@ -84,8 +101,7 @@ static void set_speed(struct i2c_adapter *adap, int i2c_spd)
>         writel(cntl, &i2c_base->ic_con);
>
>         /* Enable back i2c now speed set */
> -       enbl |= IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 1);

ditto, 1-> true?

>  }
>
>  /*
> @@ -123,12 +139,9 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
>                         int slaveaddr)
>  {
>         struct i2c_regs *i2c_base = i2c_get_base(adap);
> -       unsigned int enbl;
>
>         /* Disable i2c */
> -       enbl = readl(&i2c_base->ic_enable);
> -       enbl &= ~IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 0);

ditto

>
>         writel((IC_CON_SD | IC_CON_SPD_FS | IC_CON_MM), &i2c_base->ic_con);
>         writel(IC_RX_TL, &i2c_base->ic_rx_tl);
> @@ -138,9 +151,7 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
>         writel(slaveaddr, &i2c_base->ic_sar);
>
>         /* Enable i2c */
> -       enbl = readl(&i2c_base->ic_enable);
> -       enbl |= IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 1);

ditto

>  }
>
>  /*
> @@ -152,19 +163,14 @@ static void dw_i2c_init(struct i2c_adapter *adap, int speed,
>  static void i2c_setaddress(struct i2c_adapter *adap, unsigned int i2c_addr)
>  {
>         struct i2c_regs *i2c_base = i2c_get_base(adap);
> -       unsigned int enbl;
>
>         /* Disable i2c */
> -       enbl = readl(&i2c_base->ic_enable);
> -       enbl &= ~IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 0);
>
>         writel(i2c_addr, &i2c_base->ic_tar);
>
>         /* Enable i2c */
> -       enbl = readl(&i2c_base->ic_enable);
> -       enbl |= IC_ENABLE_0B;
> -       writel(enbl, &i2c_base->ic_enable);
> +       dw_i2c_enable(i2c_base, 1);
>  }
>

Regards,
Bin