RE: [PATCH 1/3] can: c_can: Add d_can raminit support

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On Tue, Nov 20, 2012 at 16:20:41, Marc Kleine-Budde wrote:
> On 11/14/2012 07:08 PM, AnilKumar Ch wrote:
> > Add D_CAN raminit support to C_CAN driver to enable D_CAN RAM,
> > which holds all the message objects during transmission or
> > receiving of data. This initialization/de-initialization should
> > be done in synchronous with D_CAN clock.
> > 
> > In case of AM335X-EVM (active user of D_CAN driver) message RAM is
> > controlled through control module register for both instances. So
> > control module register details is required to initialization or
> > de-initialization of message RAM according to instance number.
> > 
> > Control module memory resource is obtained from D_CAN dt node and
> > instance number obtained from device tree aliases node.
> > 
> > Signed-off-by: AnilKumar Ch <anilkumar@xxxxxx>
> 
> Some nitpicks inline.

Thanks for the review.
 
> 
> > ---
> >  drivers/net/can/c_can/c_can.c          |   12 +++++++++++
> >  drivers/net/can/c_can/c_can.h          |    3 +++
> >  drivers/net/can/c_can/c_can_platform.c |   34 +++++++++++++++++++++++++++++++-
> >  3 files changed, 48 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> > index e5180df..c15830c 100644
> > --- a/drivers/net/can/c_can/c_can.c
> > +++ b/drivers/net/can/c_can/c_can.c
> > @@ -233,6 +233,12 @@ static inline void c_can_pm_runtime_put_sync(const struct c_can_priv *priv)
> >  		pm_runtime_put_sync(priv->device);
> >  }
> >  
> > +static inline void c_can_reset_ram(const struct c_can_priv *priv, bool enable)
> > +{
> > +	if (priv->ram_init)
> > +		priv->ram_init(priv, enable);
> > +}
> > +
> >  static inline int get_tx_next_msg_obj(const struct c_can_priv *priv)
> >  {
> >  	return (priv->tx_next & C_CAN_NEXT_MSG_OBJ_MASK) +
> > @@ -1090,6 +1096,7 @@ static int c_can_open(struct net_device *dev)
> >  	struct c_can_priv *priv = netdev_priv(dev);
> >  
> >  	c_can_pm_runtime_get_sync(priv);
> > +	c_can_reset_ram(priv, true);
> >  
> >  	/* open the can device */
> >  	err = open_candev(dev);
> > @@ -1118,6 +1125,7 @@ static int c_can_open(struct net_device *dev)
> >  exit_irq_fail:
> >  	close_candev(dev);
> >  exit_open_fail:
> > +	c_can_reset_ram(priv, false);
> >  	c_can_pm_runtime_put_sync(priv);
> >  	return err;
> >  }
> > @@ -1131,6 +1139,8 @@ static int c_can_close(struct net_device *dev)
> >  	c_can_stop(dev);
> >  	free_irq(dev->irq, dev);
> >  	close_candev(dev);
> > +
> > +	c_can_reset_ram(priv, false);
> >  	c_can_pm_runtime_put_sync(priv);
> >  
> >  	return 0;
> > @@ -1188,6 +1198,7 @@ int c_can_power_down(struct net_device *dev)
> >  
> >  	c_can_stop(dev);
> >  
> > +	c_can_reset_ram(priv, false);
> >  	c_can_pm_runtime_put_sync(priv);
> >  
> >  	return 0;
> > @@ -1206,6 +1217,7 @@ int c_can_power_up(struct net_device *dev)
> >  	WARN_ON(priv->type != BOSCH_D_CAN);
> >  
> >  	c_can_pm_runtime_get_sync(priv);
> > +	c_can_reset_ram(priv, true);
> >  
> >  	/* Clear PDR and INIT bits */
> >  	val = priv->read_reg(priv, C_CAN_CTRL_EX_REG);
> > diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> > index e5ed41d..419de5c 100644
> > --- a/drivers/net/can/c_can/c_can.h
> > +++ b/drivers/net/can/c_can/c_can.h
> > @@ -169,6 +169,9 @@ struct c_can_priv {
> >  	void *priv;		/* for board-specific data */
> >  	u16 irqstatus;
> >  	enum c_can_dev_id type;
> > +	u32 __iomem *raminit_ctrlreg;
> > +	unsigned int instance;
> > +	void (*ram_init) (const struct c_can_priv *priv, bool enable);
> >  };
> >  
> >  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 ee141613..2e61d69 100644
> > --- a/drivers/net/can/c_can/c_can_platform.c
> > +++ b/drivers/net/can/c_can/c_can_platform.c
> > @@ -38,6 +38,8 @@
> >  
> >  #include "c_can.h"
> >  
> > +#define CAN_RAMINIT_START_MASK(i)	(1 << (i))
> > +
> >  /*
> >   * 16-bit c_can registers can be arranged differently in the memory
> >   * architecture of different implementations. For example: 16-bit
> > @@ -68,6 +70,24 @@ static void c_can_plat_write_reg_aligned_to_32bit(struct c_can_priv *priv,
> >  	writew(val, priv->base + 2 * priv->regs[index]);
> >  }
> >  
> > +static void c_can_hw_raminit(const struct c_can_priv *priv, bool enable)
> > +{
> > +	u32 val;
> > +
> > +	if (!priv->raminit_ctrlreg || (priv->instance < 0))
> > +		return;
> 
> Can you move this sanity check to the probe function and only assign
> priv->ram_init if the above is true?

Sure, I will change

> 
> > +
> > +	val = readl(priv->raminit_ctrlreg);
> > +	if (enable) {
> > +		val &= ~CAN_RAMINIT_START_MASK(priv->instance);
> > +		val |= CAN_RAMINIT_START_MASK(priv->instance);
> > +		writel(val, priv->raminit_ctrlreg);
> > +	} else {
> > +		val &= ~CAN_RAMINIT_START_MASK(priv->instance);
> > +		writel(val, priv->raminit_ctrlreg);
> > +	}
> > +}
> > +
> >  static struct platform_device_id c_can_id_table[] = {
> >  	[BOSCH_C_CAN_PLATFORM] = {
> >  		.name = KBUILD_MODNAME,
> > @@ -99,7 +119,7 @@ static int __devinit c_can_plat_probe(struct platform_device *pdev)
> >  	const struct of_device_id *match;
> >  	const struct platform_device_id *id;
> >  	struct pinctrl *pinctrl;
> > -	struct resource *mem;
> > +	struct resource *mem, *res;
> >  	int irq;
> >  	struct clk *clk;
> >  
> > @@ -178,6 +198,18 @@ static int __devinit c_can_plat_probe(struct platform_device *pdev)
> >  		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;
> > +
> > +		res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > +		priv->raminit_ctrlreg =
> > +				devm_request_and_ioremap(&pdev->dev, res);
> 
> What happens if there isn't a second IORESOURCE_MEM region? devm_request
> will print an error in this case and any other error, too [1]. Do we
> need streamlining here?
> 
> [1] http://lxr.free-electrons.com/source/drivers/base/platform.c#L59

I did not get what the point is.

In most of the cases above two API's returns NULL. Even res is NULL
nothing to worry, first condition in devm_request_and_ioremap() is
NULL pointer check of res. If "res" is NULL then devm_xx will return
NULL which result into printing of below warning.

> 
> > +		if (!priv->raminit_ctrlreg)
> > +			dev_warn(&pdev->dev, "failed to obtain control memory\n");

I will change this warning to info

if (!priv->raminit_ctrlreg)
	dev_info(&pdev->dev, "control memory is not used for raminit\n");

> > +
> > +		if (pdev->dev.of_node)
> > +			pdev->id = of_alias_get_id(pdev->dev.of_node, "d_can");
> > +
> > +		priv->instance = pdev->id;
> 
> Please do not modify the pdev, better you use something like this:
> 
>     pdev->id < 0 ? of_alias_get_id(pdev->dev.of_node, "d_can") :
>         pdev->id;

I will change accordingly.

Thanks
AnilKumar
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