Subject: [PATCH 2/3] at91_udc: Add vbus polarity and polling mode

From: [email-masked] (Ryan Mallon)
Date: Thu, 01 Jul 2010 09:02:05 +1200

On 06/28/2010 04:39 PM, Ryan Mallon wrote:
> Allow the vbus signal to optionally use polling. This is required if
> the vbus signal is connected to an non-interrupting io expander for
> example. If vbus is in polling mode, then it is assumed that the vbus
> gpio may sleep. Also add an option to have vbus be an active low
> signal. Both options are set in the platform data for the device.
> 
> Signed-off-by: Ryan Mallon <[email-masked]>

Is anybody able to review this patch please? I have an ack for a patch
which depends on this one. This patch should have no impact (other than
slight code/data size increase) on existing users of the at91 udc driver
since it only adds an alternative code path for the case where vbus is
on a gpio which may sleep. The addition of the vbus polarity should also
not affect existing users since the default is active high.

Thanks,
~Ryan

> ---
>  arch/arm/mach-at91/include/mach/board.h |    2 +
>  drivers/usb/gadget/at91_udc.c           |   66 +++++++++++++++++++++++++------
>  drivers/usb/gadget/at91_udc.h           |    2 +
>  3 files changed, 57 insertions(+), 13 deletions(-)
> 
> diff --git a/arch/arm/mach-at91/include/mach/board.h b/arch/arm/mach-at91/include/mach/board.h
> index df2ed84..58528aa 100644
> --- a/arch/arm/mach-at91/include/mach/board.h
> +++ b/arch/arm/mach-at91/include/mach/board.h
> @@ -44,6 +44,8 @@
>   /* USB Device */
>  struct at91_udc_data {
>  	u8	vbus_pin;		/* high == host powering us */
> +	u8	vbus_active_low;	/* vbus polarity */
> +	u8	vbus_polled;		/* Use polling, not interrupt */
>  	u8	pullup_pin;		/* active == D+ pulled up */
>  	u8	pullup_active_low;	/* true == pullup_pin is active low */
>  };
> diff --git a/drivers/usb/gadget/at91_udc.c b/drivers/usb/gadget/at91_udc.c
> index eaa79c8..469a64c 100644
> --- a/drivers/usb/gadget/at91_udc.c
> +++ b/drivers/usb/gadget/at91_udc.c
> @@ -76,6 +76,7 @@
>  static const char driver_name [] = "at91_udc";
>  static const char ep0name[] = "ep0";
>  
> +#define VBUS_POLL_TIMEOUT	msecs_to_jiffies(1000)
>  
>  #define at91_udp_read(dev, reg) \
>  	__raw_readl((dev)->udp_baseaddr + (reg))
> @@ -1556,20 +1557,49 @@ static struct at91_udc controller = {
>  	/* ep6 and ep7 are also reserved (custom silicon might use them) */
>  };
>  
> +static void at91_vbus_update(struct at91_udc *udc, unsigned value)
> +{
> +	if (udc->board.vbus_active_low)
> +		value ^= 1;
> +	if (value != udc->vbus)
> +		at91_vbus_session(&udc->gadget, value);
> +}
> +
>  static irqreturn_t at91_vbus_irq(int irq, void *_udc)
>  {
>  	struct at91_udc	*udc = _udc;
> -	unsigned	value;
>  
>  	/* vbus needs at least brief debouncing */
>  	udelay(10);
> -	value = gpio_get_value(udc->board.vbus_pin);
> -	if (value != udc->vbus)
> -		at91_vbus_session(&udc->gadget, value);
> +	at91_vbus_update(udc, gpio_get_value(udc->board.vbus_pin));
>  
>  	return IRQ_HANDLED;
>  }
>  
> +static void at91_vbus_timer_work(struct work_struct *work)
> +{
> +	struct at91_udc *udc = container_of(work, struct at91_udc, 
> +					    vbus_timer_work);
> +
> +	at91_vbus_update(udc, gpio_get_value_cansleep(udc->board.vbus_pin));
> +
> +	if (!timer_pending(&udc->vbus_timer))
> +		mod_timer(&udc->vbus_timer, jiffies + VBUS_POLL_TIMEOUT);
> +}
> +
> +static void at91_vbus_timer(unsigned long data)
> +{
> +	struct at91_udc *udc = (struct at91_udc *)data;
> +
> +	/*
> +	 * If we are polling vbus it is likely that the gpio is on an
> +	 * bus such as i2c or spi which may sleep, so schedule some work
> +	 * to read the vbus gpio
> +	 */
> +	if (!work_pending(&udc->vbus_timer_work))
> +		schedule_work(&udc->vbus_timer_work);
> +}
> +
>  int usb_gadget_register_driver (struct usb_gadget_driver *driver)
>  {
>  	struct at91_udc	*udc = &controller;
> @@ -1763,13 +1793,22 @@ static int __init at91udc_probe(struct platform_device *pdev)
>  		 * Get the initial state of VBUS - we cannot expect
>  		 * a pending interrupt.
>  		 */
> -		udc->vbus = gpio_get_value(udc->board.vbus_pin);
> -		if (request_irq(udc->board.vbus_pin, at91_vbus_irq,
> -				IRQF_DISABLED, driver_name, udc)) {
> -			DBG("request vbus irq %d failed\n",
> -					udc->board.vbus_pin);
> -			retval = -EBUSY;
> -			goto fail3;
> +		if (udc->board.vbus_polled) {
> +			udc->vbus = gpio_get_value_cansleep(udc->board.vbus_pin);
> +			INIT_WORK(&udc->vbus_timer_work, at91_vbus_timer_work);
> +			setup_timer(&udc->vbus_timer, at91_vbus_timer,
> +				    (unsigned long)udc);		
> +			mod_timer(&udc->vbus_timer,
> +				  jiffies + VBUS_POLL_TIMEOUT);
> +		} else {
> +			udc->vbus = gpio_get_value(udc->board.vbus_pin);
> +			if (request_irq(udc->board.vbus_pin, at91_vbus_irq,
> +					IRQF_DISABLED, driver_name, udc)) {
> +				DBG("request vbus irq %d failed\n",
> +				    udc->board.vbus_pin);
> +				retval = -EBUSY;
> +				goto fail3;
> +			}
>  		}
>  	} else {
>  		DBG("no VBUS detection, assuming always-on\n");
> @@ -1855,7 +1894,7 @@ static int at91udc_suspend(struct platform_device *pdev, pm_message_t mesg)
>  		enable_irq_wake(udc->udp_irq);
>  
>  	udc->active_suspend = wake;
> -	if (udc->board.vbus_pin > 0 && wake)
> +	if (udc->board.vbus_pin > 0 && !udc->board.vbus_polled && wake)
>  		enable_irq_wake(udc->board.vbus_pin);
>  	return 0;
>  }
> @@ -1864,7 +1903,8 @@ static int at91udc_resume(struct platform_device *pdev)
>  {
>  	struct at91_udc *udc = platform_get_drvdata(pdev);
>  
> -	if (udc->board.vbus_pin > 0 && udc->active_suspend)
> +	if (udc->board.vbus_pin > 0 && !udc->board.vbus_polled && 
> +	    udc->active_suspend)
>  		disable_irq_wake(udc->board.vbus_pin);
>  
>  	/* maybe reconnect to host; if so, clocks on */
> diff --git a/drivers/usb/gadget/at91_udc.h b/drivers/usb/gadget/at91_udc.h
> index c65d622..a1f4f54 100644
> --- a/drivers/usb/gadget/at91_udc.h
> +++ b/drivers/usb/gadget/at91_udc.h
> @@ -144,6 +144,8 @@ struct at91_udc {
>  	struct proc_dir_entry		*pde;
>  	void __iomem			*udp_baseaddr;
>  	int				udp_irq;
> +	struct timer_list		vbus_timer;
> +	struct work_struct		vbus_timer_work;
>  };
>  
>  static inline struct at91_udc *to_udc(struct usb_gadget *g)

-- 
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