usb: gadget: pch_udc: Detecting VBUS through GPIO with interrupt

Problem:
 pch_udc continues operation even if VBUS becomes Low.
 pch_udc performs D+ pulling up before VBUS becomes High.
 USB device should be controlled according to VBUS state.

Root cause:
 The current pch_udc is not always monitoring VBUS.

Solution:
 The change of VBUS is detected using an interrupt of GPIO.
 If VBUS became Low, pch_udc handles 'disconnect'.
 After VBUS became High, a pull improves D+, and pch_udc
 handles 'connect'.

[ balbi@ti.com : make it actually compile ]

Signed-off-by: Tomoya MORINAGA <tomoya.rohm@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

1 files changed, 83 insertions, 4 deletions

diff --git a/drivers/usb/gadget/pch_udc.c b/drivers/usb/gadget/pch_udc.c
index 9c5ae2c10147..a992084d3890 100644
--- a/drivers/usb/gadget/pch_udc.c
+++ b/drivers/usb/gadget/pch_udc.c
@@ -306,11 +306,15 @@ struct pch_udc_ep {
  * struct pch_vbus_gpio_data - Structure holding GPIO informaton
  *                                      for detecting VBUS
  * @port:               gpio port number
+ * @intr:               gpio interrupt number
  * @irq_work_fall       Structure for WorkQueue
+ * @irq_work_rise       Structure for WorkQueue
  */
 struct pch_vbus_gpio_data {
         int                     port;
+        int                     intr;
         struct work_struct      irq_work_fall;
+        struct work_struct      irq_work_rise;
 };
 
 /**
@@ -1296,8 +1300,10 @@ static void pch_vbus_gpio_work_fall(struct work_struct *irq_work)
                                 dev->driver->disconnect(
                                         &dev->gadget);
                         }
-                        pch_udc_reconnect(dev);
-                        dev_dbg(&dev->pdev->dev, "VBUS fell");
+                        if (dev->vbus_gpio.intr)
+                                pch_udc_init(dev);
+                        else
+                                pch_udc_reconnect(dev);
                         return;
                 }
                 vbus_saved = vbus;
@@ -1306,6 +1312,57 @@ static void pch_vbus_gpio_work_fall(struct work_struct *irq_work)
 }
 
 /**
+ * pch_vbus_gpio_work_rise() - This API checks VBUS is High.
+ *                             If VBUS is High, connect is processed
+ * @irq_work:   Structure for WorkQueue
+ *
+ */
+static void pch_vbus_gpio_work_rise(struct work_struct *irq_work)
+{
+        struct pch_vbus_gpio_data *vbus_gpio = container_of(irq_work,
+                struct pch_vbus_gpio_data, irq_work_rise);
+        struct pch_udc_dev *dev =
+                container_of(vbus_gpio, struct pch_udc_dev, vbus_gpio);
+        int vbus;
+
+        if (!dev->vbus_gpio.port)
+                return;
+
+        mdelay(PCH_VBUS_INTERVAL);
+        vbus = pch_vbus_gpio_get_value(dev);
+
+        if (vbus == 1) {
+                dev_dbg(&dev->pdev->dev, "VBUS rose");
+                pch_udc_reconnect(dev);
+                return;
+        }
+}
+
+/**
+ * pch_vbus_gpio_irq() - IRQ handler for GPIO intrerrupt for changing VBUS
+ * @irq:        Interrupt request number
+ * @dev:        Reference to the device structure
+ *
+ * Return codes:
+ *      0: Success
+ *      -EINVAL: GPIO port is invalid or can't be initialized.
+ */
+static irqreturn_t pch_vbus_gpio_irq(int irq, void *data)
+{
+        struct pch_udc_dev *dev = (struct pch_udc_dev *)data;
+
+        if (!dev->vbus_gpio.port || !dev->vbus_gpio.intr)
+                return IRQ_NONE;
+
+        if (pch_vbus_gpio_get_value(dev))
+                schedule_work(&dev->vbus_gpio.irq_work_rise);
+        else
+                schedule_work(&dev->vbus_gpio.irq_work_fall);
+
+        return IRQ_HANDLED;
+}
+
+/**
  * pch_vbus_gpio_init() - This API initializes GPIO port detecting VBUS.
  * @dev:        Reference to the driver structure
  * @vbus_gpio   Number of GPIO port to detect gpio
@@ -1317,8 +1374,10 @@ static void pch_vbus_gpio_work_fall(struct work_struct *irq_work)
 static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port)
 {
         int err;
+        int irq_num = 0;
 
         dev->vbus_gpio.port = 0;
+        dev->vbus_gpio.intr = 0;
 
         if (vbus_gpio_port <= -1)
                 return -EINVAL;
@@ -1341,6 +1400,21 @@ static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port)
         gpio_direction_input(vbus_gpio_port);
         INIT_WORK(&dev->vbus_gpio.irq_work_fall, pch_vbus_gpio_work_fall);
 
+        irq_num = gpio_to_irq(vbus_gpio_port);
+        if (irq_num > 0) {
+                irq_set_irq_type(irq_num, IRQ_TYPE_EDGE_BOTH);
+                err = request_irq(irq_num, pch_vbus_gpio_irq, 0,
+                        "vbus_detect", dev);
+                if (!err) {
+                        dev->vbus_gpio.intr = irq_num;
+                        INIT_WORK(&dev->vbus_gpio.irq_work_rise,
+                                pch_vbus_gpio_work_rise);
+                } else {
+                        pr_err("%s: can't request irq %d, err: %d\n",
+                                __func__, irq_num, err);
+                }
+        }
+
         return 0;
 }
 
@@ -1350,6 +1424,9 @@ static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port)
  */
 static void pch_vbus_gpio_free(struct pch_udc_dev *dev)
 {
+        if (dev->vbus_gpio.intr)
+                free_irq(dev->vbus_gpio.intr, dev);
+
         if (dev->vbus_gpio.port)
                 gpio_free(dev->vbus_gpio.port);
 }
@@ -2676,7 +2753,8 @@ static void pch_udc_dev_isr(struct pch_udc_dev *dev, u32 dev_intr)
                         }
                         pch_udc_reconnect(dev);
                 } else if ((dev->vbus_session == 0)
-                        && (vbus == 1))
+                        && (vbus == 1)
+                        && !dev->vbus_gpio.intr)
                         schedule_work(&dev->vbus_gpio.irq_work_fall);
 
                 dev_dbg(&dev->pdev->dev, "USB_SUSPEND\n");
@@ -2941,7 +3019,8 @@ static int pch_udc_start(struct usb_gadget_driver *driver,
         pch_udc_setup_ep0(dev);
 
         /* clear SD */
-        pch_udc_clear_disconnect(dev);
+        if ((pch_vbus_gpio_get_value(dev) != 0) || !dev->vbus_gpio.intr)
+                pch_udc_clear_disconnect(dev);
 
         dev->connected = 1;
         return 0;