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

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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.

[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.

> +
>  /* 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)?

> +
> +	/* 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);

> +
> +	/* 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?

> +#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.

> +
> +	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 ^^
> +	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

> +		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 "=".

>  };
>  
>  module_platform_driver(c_can_plat_driver);
> 

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
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