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

From: [email-masked] (Ryan Mallon)
Date: Fri, 02 Jul 2010 16:40:30 +1200

On 07/02/2010 01:45 AM, Nicolas Ferre wrote:
> Le 28/06/2010 06:39, Ryan Mallon :
>   
>> 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]>
>>     
> Looks good, but... one question:
>
>   
>> @@ -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);
>>     
> Shouldn't we need here something like:
> udc->vbus =  (udc->board.vbus_active_low) ^ gpio_get_value_cansleep(udc->board.vbus_pin);
>   

Yes, thanks. The updated patch below fixes it. Also simplify
at91_vbus_update (always do the xor) and move the initial setting of
udc->vbus outside of the udc->board.vbus_polled test, since we can use
gpio_get_value_cansleep in both cases.

Signed-off-by: Ryan Mallon <[email-masked]>
---

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..be36f2f 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 +1557,48 @@ 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)
+{
+	value ^= udc->board.vbus_active_low;
+	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 +1792,23 @@ 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;
+		udc->vbus = gpio_get_value_cansleep(udc->board.vbus_pin) ^
+			udc->board.vbus_active_low;
+
+		if (udc->board.vbus_polled) {
+			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 {
+			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)