Re: [i2c] [PATCH 3/8] i2c-omap: Add high-speed support to omap-i2c

[Ben Dooks <ben-linux@fluff.org>]

On Thu, Sep 25, 2008 at 10:53:49AM +0300, Tony Lindgren wrote:
> From: Syed Mohammed Khasim <x0khasim@ti.com>
> 
> Omap2430 has additional support for high-speed I2C.
> 
> This patch moves I2C speed parameter (from module) to platform data.
> Also added basic High Speed support based on I2C bus speed.
> 
> This patch is tested for high speed I2C (with TWL4030 Keypad) and works as
> expected.
> 
> Signed-off-by: Syed Mohammed Khasim  <x0khasim@ti.com>
> Signed-off-by: Tony Lindgren <tony@atomide.com>
> ---
>  drivers/i2c/busses/i2c-omap.c |  111 +++++++++++++++++++++++++++++-----------
>  1 files changed, 80 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-omap.c b/drivers/i2c/busses/i2c-omap.c
> index a06ad42..0d30790 100644
> --- a/drivers/i2c/busses/i2c-omap.c
> +++ b/drivers/i2c/busses/i2c-omap.c
> @@ -83,6 +83,7 @@
>  /* I2C Configuration Register (OMAP_I2C_CON): */
>  #define OMAP_I2C_CON_EN		(1 << 15)	/* I2C module enable */
>  #define OMAP_I2C_CON_BE		(1 << 14)	/* Big endian mode */
> +#define OMAP_I2C_CON_OPMODE	(1 << 12)	/* High Speed support */
>  #define OMAP_I2C_CON_STB	(1 << 11)	/* Start byte mode (master) */
>  #define OMAP_I2C_CON_MST	(1 << 10)	/* Master/slave mode */
>  #define OMAP_I2C_CON_TRX	(1 << 9)	/* TX/RX mode (master only) */
> @@ -91,6 +92,10 @@
>  #define OMAP_I2C_CON_STP	(1 << 1)	/* Stop cond (master only) */
>  #define OMAP_I2C_CON_STT	(1 << 0)	/* Start condition (master) */
>  
> +/* I2C SCL time value when Master */
> +#define OMAP_I2C_SCLL_HSSCLL	8
> +#define OMAP_I2C_SCLH_HSSCLH	8
> +
>  /* I2C System Test Register (OMAP_I2C_SYSTEST): */
>  #ifdef DEBUG
>  #define OMAP_I2C_SYSTEST_ST_EN		(1 << 15)	/* System test enable */
> @@ -109,12 +114,6 @@
>  /* I2C System Configuration Register (OMAP_I2C_SYSC): */
>  #define OMAP_I2C_SYSC_SRST		(1 << 1)	/* Soft Reset */
>  
> -/* REVISIT: Use platform_data instead of module parameters */
> -/* Fast Mode = 400 kHz, Standard = 100 kHz */
> -static int clock = 100; /* Default: 100 kHz */
> -module_param(clock, int, 0);
> -MODULE_PARM_DESC(clock, "Set I2C clock in kHz: 400=fast mode (default == 100)");
> -
>  struct omap_i2c_dev {
>  	struct device		*dev;
>  	void __iomem		*base;		/* virtual */
> @@ -123,6 +122,7 @@ struct omap_i2c_dev {
>  	struct clk		*fclk;		/* Functional clock */
>  	struct completion	cmd_complete;
>  	struct resource		*ioarea;
> +	u32			speed;		/* Speed of bus in Khz */
>  	u16			cmd_err;
>  	u8			*buf;
>  	size_t			buf_len;
> @@ -152,17 +152,28 @@ static int omap_i2c_get_clocks(struct omap_i2c_dev *dev)
>  			return -ENODEV;
>  		}
>  	}
> -
> -	dev->fclk = clk_get(dev->dev, "i2c_fck");
> -	if (IS_ERR(dev->fclk)) {
> -		if (dev->iclk != NULL) {
> -			clk_put(dev->iclk);
> -			dev->iclk = NULL;
> +	/* For I2C operations on 2430 we need 96Mhz clock */
> +	if (cpu_is_omap2430()) {
> +		dev->fclk = clk_get(dev->dev, "i2chs_fck");
> +		if (IS_ERR(dev->fclk)) {
> +			if (dev->iclk != NULL) {
> +				clk_put(dev->iclk);
> +				dev->iclk = NULL;
> +			}

I'm sorry, but I think this is mis-use of the clock system. The
actual name of the clock should be provided for the driver, not
the driver having to search for different clocks.

> +			dev->fclk = NULL;
> +			return -ENODEV;
> +		}
> +	} else {
> +		dev->fclk = clk_get(dev->dev, "i2c_fck");
> +		if (IS_ERR(dev->fclk)) {
> +			if (dev->iclk != NULL) {
> +				clk_put(dev->iclk);
> +				dev->iclk = NULL;
> +			}
> +			dev->fclk = NULL;
> +			return -ENODEV;
>  		}
> -		dev->fclk = NULL;
> -		return -ENODEV;
>  	}
> -
>  	return 0;
>  }
>  
> @@ -210,9 +221,11 @@ static void omap_i2c_idle(struct omap_i2c_dev *dev)
>  
>  static int omap_i2c_init(struct omap_i2c_dev *dev)
>  {
> -	u16 psc = 0;
> +	u16 psc = 0, scll = 0, sclh = 0;
> +	u16 fsscll = 0, fssclh = 0, hsscll = 0, hssclh = 0;
>  	unsigned long fclk_rate = 12000000;
>  	unsigned long timeout;
> +	unsigned long internal_clk = 0;
>  
>  	if (!dev->rev1) {
>  		omap_i2c_write_reg(dev, OMAP_I2C_SYSC_REG, OMAP_I2C_SYSC_SRST);
> @@ -255,18 +268,47 @@ static int omap_i2c_init(struct omap_i2c_dev *dev)
>  			psc = fclk_rate / 12000000;
>  	}
>  
> +	if (cpu_is_omap2430()) {
> +
> +		/* HSI2C controller internal clk rate should be 19.2 Mhz */
> +		internal_clk = 19200;
> +		fclk_rate = clk_get_rate(dev->fclk) / 1000;
> +
> +		/* Compute prescaler divisor */
> +		psc = fclk_rate / internal_clk;
> +		psc = psc - 1;
> +
> +		/* If configured for High Speed */
> +		if (dev->speed > 400) {
> +			/* For first phase of HS mode */
> +			fsscll = internal_clk / (400 * 2) - 6;
> +			fssclh = internal_clk / (400 * 2) - 6;
> +
> +			/* For second phase of HS mode */
> +			hsscll = fclk_rate / (dev->speed * 2) - 6;
> +			hssclh = fclk_rate / (dev->speed * 2) - 6;
> +		} else {
> +			/* To handle F/S modes */
> +			fsscll = internal_clk / (dev->speed * 2) - 6;
> +			fssclh = internal_clk / (dev->speed * 2) - 6;
> +		}
> +		scll = (hsscll << OMAP_I2C_SCLL_HSSCLL) | fsscll;
> +		sclh = (hssclh << OMAP_I2C_SCLH_HSSCLH) | fssclh;
> +	} else {
> +		/* Program desired operating rate */
> +		fclk_rate /= (psc + 1) * 1000;
> +		if (psc > 2)
> +			psc = 2;
> +		scll = fclk_rate / (dev->speed * 2) - 7 + psc;
> +		sclh = fclk_rate / (dev->speed * 2) - 7 + psc;
> +	}
> +
>  	/* Setup clock prescaler to obtain approx 12MHz I2C module clock: */
>  	omap_i2c_write_reg(dev, OMAP_I2C_PSC_REG, psc);
>  
> -	/* Program desired operating rate */
> -	fclk_rate /= (psc + 1) * 1000;
> -	if (psc > 2)
> -		psc = 2;
> -
> -	omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG,
> -			   fclk_rate / (clock * 2) - 7 + psc);
> -	omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG,
> -			   fclk_rate / (clock * 2) - 7 + psc);
> +	/* SCL low and high time values */
> +	omap_i2c_write_reg(dev, OMAP_I2C_SCLL_REG, scll);
> +	omap_i2c_write_reg(dev, OMAP_I2C_SCLH_REG, sclh);
>  
>  	/* Take the I2C module out of reset: */
>  	omap_i2c_write_reg(dev, OMAP_I2C_CON_REG, OMAP_I2C_CON_EN);
> @@ -326,6 +368,11 @@ static int omap_i2c_xfer_msg(struct i2c_adapter *adap,
>  	dev->cmd_err = 0;
>  
>  	w = OMAP_I2C_CON_EN | OMAP_I2C_CON_MST | OMAP_I2C_CON_STT;
> +
> +	/* High speed configuration */
> +	if (dev->speed > 400)
> +		w |= OMAP_I2C_CON_OPMODE;
> +
>  	if (msg->flags & I2C_M_TEN)
>  		w |= OMAP_I2C_CON_XA;
>  	if (!(msg->flags & I2C_M_RD))
> @@ -562,6 +609,7 @@ omap_i2c_probe(struct platform_device *pdev)
>  	struct i2c_adapter	*adap;
>  	struct resource		*mem, *irq, *ioarea;
>  	int r;
> +	u32 *speed = NULL;
>  
>  	/* NOTE: driver uses the static register mapping */
>  	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> @@ -582,17 +630,18 @@ omap_i2c_probe(struct platform_device *pdev)
>  		return -EBUSY;
>  	}
>  
> -	if (clock > 200)
> -		clock = 400;	/* Fast mode */
> -	else
> -		clock = 100;	/* Standard mode */
> -
>  	dev = kzalloc(sizeof(struct omap_i2c_dev), GFP_KERNEL);
>  	if (!dev) {
>  		r = -ENOMEM;
>  		goto err_release_region;
>  	}
>  
> +	if (pdev->dev.platform_data != NULL)
> +		speed = (u32 *) pdev->dev.platform_data;
> +	else
> +		*speed = 100; /* Defualt speed */
> +
> +	dev->speed = *speed;
>  	dev->dev = &pdev->dev;
>  	dev->irq = irq->start;
>  	dev->base = (void __iomem *) IO_ADDRESS(mem->start);
> @@ -618,7 +667,7 @@ omap_i2c_probe(struct platform_device *pdev)
>  	}
>  	r = omap_i2c_read_reg(dev, OMAP_I2C_REV_REG) & 0xff;
>  	dev_info(dev->dev, "bus %d rev%d.%d at %d kHz\n",
> -		 pdev->id, r >> 4, r & 0xf, clock);
> +		 pdev->id, r >> 4, r & 0xf, dev->speed);
>  
>  	adap = &dev->adapter;
>  	i2c_set_adapdata(adap, dev);
> -- 
> 1.5.6.rc3.21.g8c6b5
> 
> 
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-- 
Ben (ben@fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'