wimax/i2400m: Implement pre/post reset support in the USB driver

The USB stack can callback a driver is about to be reset by an
external entity and right after it, so the driver can save state and
then restore it.

This commit implements said support; it is implemented actually in the
core, bus-generic driver [i2400m_{pre,post}_reset()] and used by the
bus-specific drivers. This way the SDIO driver can also use it once
said support is brought to the SDIO stack.

Signed-off-by: Inaky Perez-Gonzalez <inaky@linux.intel.com>

drivers/net/wimax/i2400m/driver.c

@@ -619,6 +619,87 @@ int i2400m_pm_notifier(struct notifier_block *notifier,
 }
 
 
+/*
+ * pre-reset is called before a device is going on reset
+ *
+ * This has to be followed by a call to i2400m_post_reset(), otherwise
+ * bad things might happen.
+ */
+int i2400m_pre_reset(struct i2400m *i2400m)
+{
+	int result;
+	struct device *dev = i2400m_dev(i2400m);
+
+	d_fnstart(3, dev, "(i2400m %p)\n", i2400m);
+	d_printf(1, dev, "pre-reset shut down\n");
+
+	result = 0;
+	mutex_lock(&i2400m->init_mutex);
+	if (i2400m->updown) {
+		netif_tx_disable(i2400m->wimax_dev.net_dev);
+		__i2400m_dev_stop(i2400m);
+		result = 0;
+		/* down't set updown to zero -- this way
+		 * post_reset can restore properly */
+	}
+	mutex_unlock(&i2400m->init_mutex);
+	if (i2400m->bus_release)
+		i2400m->bus_release(i2400m);
+	d_fnend(3, dev, "(i2400m %p) = %d\n", i2400m, result);
+	return result;
+}
+EXPORT_SYMBOL_GPL(i2400m_pre_reset);
+
+
+/*
+ * Restore device state after a reset
+ *
+ * Do the work needed after a device reset to bring it up to the same
+ * state as it was before the reset.
+ *
+ * NOTE: this requires i2400m->init_mutex taken
+ */
+int i2400m_post_reset(struct i2400m *i2400m)
+{
+	int result = 0;
+	struct device *dev = i2400m_dev(i2400m);
+
+	d_fnstart(3, dev, "(i2400m %p)\n", i2400m);
+	d_printf(1, dev, "post-reset start\n");
+	if (i2400m->bus_setup) {
+		result = i2400m->bus_setup(i2400m);
+		if (result < 0) {
+			dev_err(dev, "bus-specific setup failed: %d\n",
+				result);
+			goto error_bus_setup;
+		}
+	}
+	mutex_lock(&i2400m->init_mutex);
+	if (i2400m->updown) {
+		result = __i2400m_dev_start(
+			i2400m, I2400M_BRI_SOFT | I2400M_BRI_MAC_REINIT);
+		if (result < 0)
+			goto error_dev_start;
+	}
+	mutex_unlock(&i2400m->init_mutex);
+	d_fnend(3, dev, "(i2400m %p) = %d\n", i2400m, result);
+	return result;
+
+error_dev_start:
+	if (i2400m->bus_release)
+		i2400m->bus_release(i2400m);
+error_bus_setup:
+	/* even if the device was up, it could not be recovered, so we
+	 * mark it as down. */
+	i2400m->updown = 0;
+	wmb();		/* see i2400m->updown's documentation  */
+	mutex_unlock(&i2400m->init_mutex);
+	d_fnend(3, dev, "(i2400m %p) = %d\n", i2400m, result);
+	return result;
+}
+EXPORT_SYMBOL_GPL(i2400m_post_reset);
+
+
 /*
  * The device has rebooted; fix up the device and the driver
  *

drivers/net/wimax/i2400m/i2400m.h

@@ -817,6 +817,8 @@ void i2400m_put(struct i2400m *i2400m)
 }
 
 extern int i2400m_dev_reset_handle(struct i2400m *, const char *);
+extern int i2400m_pre_reset(struct i2400m *);
+extern int i2400m_post_reset(struct i2400m *);
 
 /*
  * _setup()/_release() are called by the probe/disconnect functions of

drivers/net/wimax/i2400m/usb.c

@@ -637,6 +637,37 @@ int i2400mu_reset_resume(struct usb_interface *iface)
 }
 
 
+/*
+ * Another driver or user space is triggering a reset on the device
+ * which contains the interface passed as an argument. Cease IO and
+ * save any device state you need to restore.
+ *
+ * If you need to allocate memory here, use GFP_NOIO or GFP_ATOMIC, if
+ * you are in atomic context.
+ */
+static
+int i2400mu_pre_reset(struct usb_interface *iface)
+{
+	struct i2400mu *i2400mu = usb_get_intfdata(iface);
+	return i2400m_pre_reset(&i2400mu->i2400m);
+}
+
+
+/*
+ * The reset has completed.  Restore any saved device state and begin
+ * using the device again.
+ *
+ * If you need to allocate memory here, use GFP_NOIO or GFP_ATOMIC, if
+ * you are in atomic context.
+ */
+static
+int i2400mu_post_reset(struct usb_interface *iface)
+{
+	struct i2400mu *i2400mu = usb_get_intfdata(iface);
+	return i2400m_post_reset(&i2400mu->i2400m);
+}
+
+
 static
 struct usb_device_id i2400mu_id_table[] = {
 	{ USB_DEVICE(0x8086, USB_DEVICE_ID_I6050) },
@@ -660,6 +691,8 @@ struct usb_driver i2400mu_driver = {
 	.reset_resume = i2400mu_reset_resume,
 	.probe = i2400mu_probe,
 	.disconnect = i2400mu_disconnect,
+	.pre_reset = i2400mu_pre_reset,
+	.post_reset = i2400mu_post_reset,
 	.id_table = i2400mu_id_table,
 	.supports_autosuspend = 1,
 };