usb: gadget: pch_udc: Detecting VBUS through GPIO

Problem:
 In USB Suspend, pch_udc handles 'disconnect'.

Root cause:
 The current pch_udc is not monitoring VBUS.
 When USB cable is disconnected, USB Device Controller generates
 an interrupt of USB Suspend.
 pch_udc cannot distinguish it is USB Suspend or disconnect.
 Therefore, pch_udc handles 'disconnect' after an interrupt of
 USB Suspend happend.

Solution:
 VBUS is detected through GPIO.
 After an interrupt produced USB Suspend, if VBUS is Low,
 pch_udc handles 'disconnect'.
 If VBUS is High, pch_udc handles 'suspend'.

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

1 files changed, 142 insertions, 3 deletions

diff --git a/drivers/usb/gadget/pch_udc.c b/drivers/usb/gadget/pch_udc.c
index 82416aae816f..9c5ae2c10147 100644
--- a/drivers/usb/gadget/pch_udc.c
+++ b/drivers/usb/gadget/pch_udc.c
@@ -15,6 +15,13 @@
 #include <linux/interrupt.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
+#include <linux/gpio.h>
+
+/* GPIO port for VBUS detecting */
+static int vbus_gpio_port = -1;         /* GPIO port number (-1:Not used) */
+
+#define PCH_VBUS_PERIOD         3000    /* VBUS polling period (msec) */
+#define PCH_VBUS_INTERVAL       10      /* VBUS polling interval (msec) */
 
 /* Address offset of Registers */
 #define UDC_EP_REG_SHIFT        0x20    /* Offset to next EP */
@@ -296,6 +303,17 @@ struct pch_udc_ep {
 };
 
 /**
+ * struct pch_vbus_gpio_data - Structure holding GPIO informaton
+ *                                      for detecting VBUS
+ * @port:               gpio port number
+ * @irq_work_fall       Structure for WorkQueue
+ */
+struct pch_vbus_gpio_data {
+        int                     port;
+        struct work_struct      irq_work_fall;
+};
+
+/**
  * struct pch_udc_dev - Structure holding complete information
  *                      of the PCH USB device
  * @gadget:             gadget driver data
@@ -323,6 +341,7 @@ struct pch_udc_ep {
  * @base_addr:          for mapped device memory
  * @irq:                IRQ line for the device
  * @cfg_data:           current cfg, intf, and alt in use
+ * @vbus_gpio:          GPIO informaton for detecting VBUS
  */
 struct pch_udc_dev {
         struct usb_gadget               gadget;
@@ -349,7 +368,8 @@ struct pch_udc_dev {
         unsigned long                   phys_addr;
         void __iomem                    *base_addr;
         unsigned                        irq;
-        struct pch_udc_cfg_data cfg_data;
+        struct pch_udc_cfg_data         cfg_data;
+        struct pch_vbus_gpio_data       vbus_gpio;
 };
 
 #define PCH_UDC_PCI_BAR                 1
@@ -1226,6 +1246,115 @@ static const struct usb_gadget_ops pch_udc_ops = {
 };
 
 /**
+ * pch_vbus_gpio_get_value() - This API gets value of GPIO port as VBUS status.
+ * @dev:        Reference to the driver structure
+ *
+ * Return value:
+ *      1: VBUS is high
+ *      0: VBUS is low
+ *     -1: It is not enable to detect VBUS using GPIO
+ */
+static int pch_vbus_gpio_get_value(struct pch_udc_dev *dev)
+{
+        int vbus = 0;
+
+        if (dev->vbus_gpio.port)
+                vbus = gpio_get_value(dev->vbus_gpio.port) ? 1 : 0;
+        else
+                vbus = -1;
+
+        return vbus;
+}
+
+/**
+ * pch_vbus_gpio_work_fall() - This API keeps watch on VBUS becoming Low.
+ *                             If VBUS is Low, disconnect is processed
+ * @irq_work:   Structure for WorkQueue
+ *
+ */
+static void pch_vbus_gpio_work_fall(struct work_struct *irq_work)
+{
+        struct pch_vbus_gpio_data *vbus_gpio = container_of(irq_work,
+                struct pch_vbus_gpio_data, irq_work_fall);
+        struct pch_udc_dev *dev =
+                container_of(vbus_gpio, struct pch_udc_dev, vbus_gpio);
+        int vbus_saved = -1;
+        int vbus;
+        int count;
+
+        if (!dev->vbus_gpio.port)
+                return;
+
+        for (count = 0; count < (PCH_VBUS_PERIOD / PCH_VBUS_INTERVAL);
+                count++) {
+                vbus = pch_vbus_gpio_get_value(dev);
+
+                if ((vbus_saved == vbus) && (vbus == 0)) {
+                        dev_dbg(&dev->pdev->dev, "VBUS fell");
+                        if (dev->driver
+                                && dev->driver->disconnect) {
+                                dev->driver->disconnect(
+                                        &dev->gadget);
+                        }
+                        pch_udc_reconnect(dev);
+                        dev_dbg(&dev->pdev->dev, "VBUS fell");
+                        return;
+                }
+                vbus_saved = vbus;
+                mdelay(PCH_VBUS_INTERVAL);
+        }
+}
+
+/**
+ * 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
+ *
+ * Return codes:
+ *      0: Success
+ *      -EINVAL: GPIO port is invalid or can't be initialized.
+ */
+static int pch_vbus_gpio_init(struct pch_udc_dev *dev, int vbus_gpio_port)
+{
+        int err;
+
+        dev->vbus_gpio.port = 0;
+
+        if (vbus_gpio_port <= -1)
+                return -EINVAL;
+
+        err = gpio_is_valid(vbus_gpio_port);
+        if (!err) {
+                pr_err("%s: gpio port %d is invalid\n",
+                        __func__, vbus_gpio_port);
+                return -EINVAL;
+        }
+
+        err = gpio_request(vbus_gpio_port, "pch_vbus");
+        if (err) {
+                pr_err("%s: can't request gpio port %d, err: %d\n",
+                        __func__, vbus_gpio_port, err);
+                return -EINVAL;
+        }
+
+        dev->vbus_gpio.port = vbus_gpio_port;
+        gpio_direction_input(vbus_gpio_port);
+        INIT_WORK(&dev->vbus_gpio.irq_work_fall, pch_vbus_gpio_work_fall);
+
+        return 0;
+}
+
+/**
+ * pch_vbus_gpio_free() - This API frees resources of GPIO port
+ * @dev:        Reference to the driver structure
+ */
+static void pch_vbus_gpio_free(struct pch_udc_dev *dev)
+{
+        if (dev->vbus_gpio.port)
+                gpio_free(dev->vbus_gpio.port);
+}
+
+/**
  * complete_req() - This API is invoked from the driver when processing
  *                      of a request is complete
  * @ep:         Reference to the endpoint structure
@@ -2510,6 +2639,8 @@ static void pch_udc_svc_cfg_interrupt(struct pch_udc_dev *dev)
  */
 static void pch_udc_dev_isr(struct pch_udc_dev *dev, u32 dev_intr)
 {
+        int vbus;
+
         /* USB Reset Interrupt */
         if (dev_intr & UDC_DEVINT_UR) {
                 pch_udc_svc_ur_interrupt(dev);
@@ -2535,14 +2666,19 @@ static void pch_udc_dev_isr(struct pch_udc_dev *dev, u32 dev_intr)
                         spin_lock(&dev->lock);
                 }
 
-                if (dev->vbus_session == 0) {
+                vbus = pch_vbus_gpio_get_value(dev);
+                if ((dev->vbus_session == 0)
+                        && (vbus != 1)) {
                         if (dev->driver && dev->driver->disconnect) {
                                 spin_unlock(&dev->lock);
                                 dev->driver->disconnect(&dev->gadget);
                                 spin_lock(&dev->lock);
                         }
                         pch_udc_reconnect(dev);
-                }
+                } else if ((dev->vbus_session == 0)
+                        && (vbus == 1))
+                        schedule_work(&dev->vbus_gpio.irq_work_fall);
+
                 dev_dbg(&dev->pdev->dev, "USB_SUSPEND\n");
         }
         /* Clear the SOF interrupt, if enabled */
@@ -2704,6 +2840,7 @@ static int pch_udc_pcd_init(struct pch_udc_dev *dev)
 {
         pch_udc_init(dev);
         pch_udc_pcd_reinit(dev);
+        pch_vbus_gpio_init(dev, vbus_gpio_port);
         return 0;
 }
 
@@ -2882,6 +3019,8 @@ static void pch_udc_remove(struct pci_dev *pdev)
                                  UDC_EP0OUT_BUFF_SIZE * 4, DMA_FROM_DEVICE);
         kfree(dev->ep0out_buf);
 
+        pch_vbus_gpio_free(dev);
+
         pch_udc_exit(dev);
 
         if (dev->irq_registered)