[10/16] c_can: add 16bit align 32bit access functions

The FlexCard only allows 32bit access to DCAN registers, otherwise the
register value can be wraped up. Add a new helper function to access
registers 16bit aligned but 32bit access.

Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
---
 drivers/net/can/c_can/c_can.c          |  1 +
 drivers/net/can/c_can/c_can.h          |  1 +
 drivers/net/can/c_can/c_can_platform.c | 38 ++++++++++++++++++++++++++++++++--
 3 files changed, 38 insertions(+), 2 deletions(-)

On 09/09/2013 09:25 AM, Benedikt Spranger wrote:
> The FlexCard only allows 32bit access to DCAN registers, otherwise the
> register value can be wraped up. Add a new helper function to access
> registers 16bit aligned but 32bit access.

You are modifying code you have previously added. You should shuffle
your patches that this is not necessary.

> Signed-off-by: Benedikt Spranger <b.spranger@linutronix.de>
> ---
>  drivers/net/can/c_can/c_can.c          |  1 +
>  drivers/net/can/c_can/c_can.h          |  1 +
>  drivers/net/can/c_can/c_can_platform.c | 38 ++++++++++++++++++++++++++++++++--
>  3 files changed, 38 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> index c573399..46d741d 100644
> --- a/drivers/net/can/c_can/c_can.c
> +++ b/drivers/net/can/c_can/c_can.c
> @@ -1305,6 +1305,7 @@ struct net_device *alloc_c_can_dev(void)
>  	priv->can.ctrlmode_supported = CAN_CTRLMODE_LOOPBACK |
>  					CAN_CTRLMODE_LISTENONLY |
>  					CAN_CTRLMODE_BERR_REPORTING;
> +	spin_lock_init(&priv->lock);
>  
>  	return dev;
>  }
> diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> index 9f0eda8..beea437 100644
> --- a/drivers/net/can/c_can/c_can.h
> +++ b/drivers/net/can/c_can/c_can.h
> @@ -175,6 +175,7 @@ struct c_can_priv {
>  	u32 __iomem *raminit_ctrlreg;
>  	unsigned int instance;
>  	void (*raminit) (const struct c_can_priv *priv, bool enable);
> +	spinlock_t lock;
>  };
>  
>  struct net_device *alloc_c_can_dev(void);
> diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> index 43a3e3f..c6c1eb4 100644
> --- a/drivers/net/can/c_can/c_can_platform.c
> +++ b/drivers/net/can/c_can/c_can_platform.c
> @@ -58,6 +58,40 @@ static void c_can_plat_write_reg_aligned_to_16bit(struct c_can_priv *priv,
>  	writew(val, priv->base + priv->regs[index]);
>  }
>  
> +#define ALIGN_DOWN(p, a)	((typeof(p))round_down((unsigned long)(p), (a)))
> +
> +static u16 c_can_plat_read_16bit_align_32bit_access(struct c_can_priv *priv,
> +						    enum reg index)
> +{
> +	void *addr = priv->base + priv->regs[index];

Please compile with C=2. Should be void __iomem *.

> +	u32 reg;
> +	reg = readl(ALIGN_DOWN(addr, 4));
> +
> +	return IS_ALIGNED((unsigned long)addr, 4) ?
> +			reg & 0xffff :
> +			reg >> 16;
> +}
> +
> +static void c_can_plat_write_16bit_align_32bit_access(struct c_can_priv *priv,
> +						      enum reg index, u16 val)
> +{
> +	unsigned long flags;
> +	void *addr = priv->base + priv->regs[index];

dito

> +	u32 reg;
> +
> +	spin_lock_irqsave(&priv->lock, flags);
> +	reg = readl(ALIGN_DOWN(addr, 4));
> +	if (IS_ALIGNED((unsigned long)addr, 4)) {
> +		reg &= 0xffff0000;
> +		reg |= val;
> +	} else {
> +		reg &= 0xffff;
> +		reg |= val << 16;
> +	}
> +	writel(reg, ALIGN_DOWN(addr, 4));
> +	spin_unlock_irqrestore(&priv->lock, flags);
> +}
> +
>  static u16 c_can_plat_read_reg_aligned_to_32bit(struct c_can_priv *priv,
>  						enum reg index)
>  {
> @@ -317,8 +351,8 @@ static int c_can_plat_probe(struct platform_device *pdev)
>  	case BOSCH_D_CAN_FLEXCARD:
>  		priv->regs = reg_map_d_can;
>  		priv->can.ctrlmode_supported |= CAN_CTRLMODE_3_SAMPLES;
> -		priv->read_reg = c_can_plat_read_reg_aligned_to_16bit;
> -		priv->write_reg = c_can_plat_write_reg_aligned_to_16bit;
> +		priv->read_reg = c_can_plat_read_16bit_align_32bit_access;
> +		priv->write_reg = c_can_plat_write_16bit_align_32bit_access;
>  		priv->instance = pdev->id;
>  
>  		res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> 

Marc