RE: [PATCH 4/4] can: c_can: Add d_can suspend resume support

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Marc,

Thanks for the comments,

On Tue, Sep 04, 2012 at 01:31:35, Marc Kleine-Budde wrote:
> On 09/03/2012 01:52 PM, AnilKumar Ch wrote:
> > Adds suspend resume support to DCAN driver which enables
> > DCAN power down mode bit (PDR). Then DCAN will ack the local
> > power-down mode by setting PDA bit in STATUS register.
> > 
> > Also adds a status flag to know the status of DCAN module,
> > whether it is opened or not.
> 
> Use "ndev->flags & IFF_UP" for that. Have a look at the at91_can driver
> [1]. I'm not sure if you need locking here.
> 

Then I can use this to check the status, lock is not
required.

> [1] http://lxr.free-electrons.com/source/drivers/net/can/at91_can.c#L1198
> 
> > Signed-off-by: AnilKumar Ch <anilkumar@xxxxxx>
> > ---
> >  drivers/net/can/c_can/c_can.c          |   78 ++++++++++++++++++++++++++++++++
> >  drivers/net/can/c_can/c_can.h          |    5 ++
> >  drivers/net/can/c_can/c_can_platform.c |   70 ++++++++++++++++++++++++++--
> >  3 files changed, 150 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
> > index c175410..36d5db4 100644
> > --- a/drivers/net/can/c_can/c_can.c
> > +++ b/drivers/net/can/c_can/c_can.c
> > @@ -46,6 +46,9 @@
> >  #define IF_ENUM_REG_LEN		11
> >  #define C_CAN_IFACE(reg, iface)	(C_CAN_IF1_##reg + (iface) * IF_ENUM_REG_LEN)
> >  
> > +/* control extension register D_CAN specific */
> > +#define CONTROL_EX_PDR		BIT(8)
> > +
> >  /* control register */
> >  #define CONTROL_TEST		BIT(7)
> >  #define CONTROL_CCE		BIT(6)
> > @@ -65,6 +68,7 @@
> >  #define TEST_BASIC		BIT(2)
> >  
> >  /* status register */
> > +#define STATUS_PDA		BIT(10)
> >  #define STATUS_BOFF		BIT(7)
> >  #define STATUS_EWARN		BIT(6)
> >  #define STATUS_EPASS		BIT(5)
> > @@ -164,6 +168,9 @@
> >  /* minimum timeout for checking BUSY status */
> >  #define MIN_TIMEOUT_VALUE	6
> >  
> > +/* Wait for ~1 sec for INIT bit */
> > +#define INIT_WAIT_COUNT		1000
> 
> What unit? INIT_WAIT_MS would be a better name.
> 

Sure, will change

> > +
> >  /* napi related */
> >  #define C_CAN_NAPI_WEIGHT	C_CAN_MSG_OBJ_RX_NUM
> >  
> > @@ -1102,6 +1109,7 @@ static int c_can_open(struct net_device *dev)
> >  
> >  	netif_start_queue(dev);
> >  
> > +	priv->is_opened = true;
> >  	return 0;
> >  
> >  exit_irq_fail:
> > @@ -1126,6 +1134,7 @@ static int c_can_close(struct net_device *dev)
> >  	/* De-Initialize DCAN RAM */
> >  	c_can_reset_ram(priv, false);
> >  	c_can_pm_runtime_put_sync(priv);
> > +	priv->is_opened = false;
> >  
> >  	return 0;
> >  }
> > @@ -1154,6 +1163,75 @@ struct net_device *alloc_c_can_dev(void)
> >  }
> >  EXPORT_SYMBOL_GPL(alloc_c_can_dev);
> >  
> > +#ifdef CONFIG_PM
> > +int c_can_power_down(struct net_device *dev)
> > +{
> > +	unsigned long time_out;
> > +	struct c_can_priv *priv = netdev_priv(dev);
> > +
> > +	if (!priv->is_opened)
> > +		return 0;
> 
> Should we add a BUG_ON(id->driver_data != BOSCH_D_CAN)?

These APIs are called from platform driver where device type
device type is verified. I think we have to add BUG_ON() in
platform driver.

> 
> > +
> > +	/* set `PDR` value so the device goes to power down mode */
> > +	priv->write_reg(priv, C_CAN_CTRL_EX_REG,
> > +		priv->read_reg(priv, C_CAN_CTRL_EX_REG) | CONTROL_EX_PDR);
> 
> Please use an intermediate variable:
> 
> u32 val;
> 
> val = priv->read_reg(priv, C_CAN_CTRL_EX_REG);
> val |= CONTROL_EX_PDR;
> priv->write_reg(priv, C_CAN_CTRL_EX_REG, val);

I will change

> 
> > +
> > +	/* Wait for the PDA bit to get set */
> > +	time_out = jiffies + msecs_to_jiffies(INIT_WAIT_COUNT);
> > +	while (!(priv->read_reg(priv, C_CAN_STS_REG) & STATUS_PDA) &&
> > +				time_after(time_out, jiffies))
> > +		cpu_relax();
> > +
> > +	if (time_after(jiffies, time_out))
> > +		return -ETIMEDOUT;
> > +
> > +	c_can_stop(dev);
> > +
> > +	/* De-initialize DCAN RAM */
> > +	c_can_reset_ram(priv, false);
> > +	c_can_pm_runtime_put_sync(priv);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(c_can_power_down);
> > +
> > +int c_can_power_up(struct net_device *dev)
> > +{
> > +	unsigned long time_out;
> > +	struct c_can_priv *priv = netdev_priv(dev);
> > +
> 
> BUG_ON?
> 
> > +	if (!priv->is_opened)
> > +		return 0;
> > +
> > +	c_can_pm_runtime_get_sync(priv);
> > +	/* Initialize DCAN RAM */
> > +	c_can_reset_ram(priv, true);
> > +
> > +	/* Clear PDR and INIT bits */
> > +	priv->write_reg(priv, C_CAN_CTRL_EX_REG,
> > +		priv->read_reg(priv, C_CAN_CTRL_EX_REG) & ~CONTROL_EX_PDR);
> > +	priv->write_reg(priv, C_CAN_CTRL_REG,
> > +		priv->read_reg(priv, C_CAN_CTRL_REG) & ~CONTROL_INIT);
> > +
> > +	/* Wait for the PDA bit to get clear */
> > +	time_out = jiffies + msecs_to_jiffies(INIT_WAIT_COUNT);
> > +	while ((priv->read_reg(priv, C_CAN_STS_REG) & STATUS_PDA) &&
> > +				time_after(time_out, jiffies))
> > +		cpu_relax();
> > +
> > +	if (time_after(jiffies, time_out))
> > +		return -ETIMEDOUT;
> > +
> > +	c_can_start(dev);
> > +
> > +	return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(c_can_power_up);
> > +#else
> > +#define c_can_power_down NULL
> > +#define c_can_power_up NULL
> 
> These are not used, are they?

Not used, I will remove this else part and adding
#ifdef CONFIG_PM in header file as well.

> 
> > +#endif
> > +
> >  void free_c_can_dev(struct net_device *dev)
> >  {
> >  	free_candev(dev);
> > diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
> > index 5f6339c..e5dd7ef 100644
> > --- a/drivers/net/can/c_can/c_can.h
> > +++ b/drivers/net/can/c_can/c_can.h
> > @@ -24,6 +24,7 @@
> >  
> >  enum reg {
> >  	C_CAN_CTRL_REG = 0,
> > +	C_CAN_CTRL_EX_REG,
> >  	C_CAN_STS_REG,
> >  	C_CAN_ERR_CNT_REG,
> >  	C_CAN_BTR_REG,
> > @@ -104,6 +105,7 @@ static const u16 reg_map_c_can[] = {
> >  
> >  static const u16 reg_map_d_can[] = {
> >  	[C_CAN_CTRL_REG]	= 0x00,
> > +	[C_CAN_CTRL_EX_REG]	= 0x02,
> >  	[C_CAN_STS_REG]		= 0x04,
> >  	[C_CAN_ERR_CNT_REG]	= 0x08,
> >  	[C_CAN_BTR_REG]		= 0x0C,
> > @@ -166,6 +168,7 @@ struct c_can_priv {
> >  	unsigned int tx_echo;
> >  	void *priv;		/* for board-specific data */
> >  	u16 irqstatus;
> > +	bool is_opened;
> >  	unsigned int instance;
> >  	void (*ram_init) (unsigned int instance, bool enable);
> >  };
> > @@ -174,5 +177,7 @@ struct net_device *alloc_c_can_dev(void);
> >  void free_c_can_dev(struct net_device *dev);
> >  int register_c_can_dev(struct net_device *dev);
> >  void unregister_c_can_dev(struct net_device *dev);
> > +int c_can_power_up(struct net_device *dev);
> > +int c_can_power_down(struct net_device *dev);
> >  
> >  #endif /* C_CAN_H */
> > diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
> > index c6963b2..65ec232 100644
> > --- a/drivers/net/can/c_can/c_can_platform.c
> > +++ b/drivers/net/can/c_can/c_can_platform.c
> > @@ -255,15 +255,79 @@ static int __devexit c_can_plat_remove(struct platform_device *pdev)
> >  	return 0;
> >  }
> >  
> > +#ifdef CONFIG_PM
> > +static int c_can_suspend(struct platform_device *pdev, pm_message_t state)
> > +{
> > +	int ret;
> > +	struct net_device *ndev = platform_get_drvdata(pdev);
> > +	struct c_can_priv *priv = netdev_priv(ndev);
> > +	const struct platform_device_id *id = platform_get_device_id(pdev);
> 
> Does that work on DT probed devices? You probably have to save the
> id->driver_data in struct c_can_priv.

I will add extra variable to c_can_priv to save the dev_id so
that it will work for dt case as well.

> 
> > +
> > +	if (id->driver_data != BOSCH_D_CAN) {
> > +		dev_warn(&pdev->dev, "Not supported\n");
> > +		return 0;
> > +	}
> > +
> > +	if (netif_running(ndev)) {
> > +		netif_stop_queue(ndev);
> > +		netif_device_detach(ndev);
> > +	}
> > +
> > +	ret = c_can_power_down(ndev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "failed to enter power down mode\n");
> netdev_err
> > +		return ret;
> > +	}
> > +
> > +	priv->can.state = CAN_STATE_SLEEPING;
> > +
> > +	return 0;
> > +}
> > +
> > +static int c_can_resume(struct platform_device *pdev)
> > +{
> > +	int ret;
> > +
> please remove the empty line ^^

Sure

> > +	struct net_device *ndev = platform_get_drvdata(pdev);
> > +	struct c_can_priv *priv = netdev_priv(ndev);
> > +	const struct platform_device_id *id = platform_get_device_id(pdev);
> > +
> > +	if (id->driver_data != BOSCH_D_CAN) {
> > +		dev_warn(&pdev->dev, "Not supported\n");
> > +		return 0;
> > +	}
> > +
> > +	ret = c_can_power_up(ndev);
> > +	if (ret) {
> > +		dev_err(&pdev->dev, "Still in power down mode\n");
> 
> netdev_err

I will change.

> 
> > +		return ret;
> > +	}
> > +
> > +	priv->can.state = CAN_STATE_ERROR_ACTIVE;
> > +
> > +	if (netif_running(ndev)) {
> > +		netif_device_attach(ndev);
> > +		netif_start_queue(ndev);
> > +	}
> > +
> > +	return 0;
> > +}
> > +#else
> > +#define c_can_suspend NULL
> > +#define c_can_resume NULL
> > +#endif
> > +
> >  static struct platform_driver c_can_plat_driver = {
> >  	.driver = {
> >  		.name = KBUILD_MODNAME,
> >  		.owner = THIS_MODULE,
> >  		.of_match_table = of_match_ptr(c_can_of_table),
> >  	},
> > -	.probe = c_can_plat_probe,
> > -	.remove = __devexit_p(c_can_plat_remove),
> > -	.id_table = c_can_id_table,
> > +	.probe		= c_can_plat_probe,
> > +	.remove		= __devexit_p(c_can_plat_remove),
> > +	.suspend	= c_can_suspend,
> > +	.resume		= c_can_resume,
> > +	.id_table	= c_can_id_table,
> 
> Please don't indent here with tab. Just stay with one space on both
> sides of the "=".
> 

Point taken

Thanks
AnilKumar
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