[PATCH v8 2/6] usb: ljca: Add transport interfaces for sub-module drivers

[Ye Xiang <xiang.ye@xxxxxxxxx>]

Adds the transport interfaces for various LJCA sub-module drivers
to communicate with LJCA hardware. The sub-modules of LJCA can use
ljca_transfer() to issue a transfer between host and hardware. And
ljca_register_event_cb is exported to LJCA sub-module drivers for
hardware event subscription.

Signed-off-by: Ye Xiang <xiang.ye@xxxxxxxxx>
---
 drivers/usb/misc/usb-ljca.c | 91 +++++++++++++++++++++++++++++++++++++
 include/linux/usb/ljca.h    | 52 +++++++++++++++++++++
 2 files changed, 143 insertions(+)

diff --git a/drivers/usb/misc/usb-ljca.c b/drivers/usb/misc/usb-ljca.c
index 4f76f73fdcac..3b68c9e472fc 100644
--- a/drivers/usb/misc/usb-ljca.c
+++ b/drivers/usb/misc/usb-ljca.c
@@ -368,6 +368,97 @@ static int ljca_stub_write(struct ljca_stub *stub, u8 cmd, const void *obuf, uns
 	return ret;
 }
 
+static int ljca_transfer_internal(struct ljca *ljca, u8 cmd, const void *obuf,
+				  unsigned int obuf_len, void *ibuf, unsigned int *ibuf_len,
+				  bool wait_ack)
+{
+	struct ljca_stub *stub;
+
+	stub = ljca_stub_find(ljca->dev, ljca->type);
+	if (IS_ERR(stub))
+		return PTR_ERR(stub);
+
+	return ljca_stub_write(stub, cmd, obuf, obuf_len, ibuf, ibuf_len, wait_ack,
+			       LJCA_USB_WRITE_ACK_TIMEOUT_MS);
+}
+
+int ljca_transfer(struct ljca *ljca, u8 cmd, const void *obuf, unsigned int obuf_len, void *ibuf,
+		  unsigned int *ibuf_len)
+{
+	return ljca_transfer_internal(ljca, cmd, obuf, obuf_len, ibuf, ibuf_len, true);
+}
+EXPORT_SYMBOL_NS_GPL(ljca_transfer, LJCA);
+
+int ljca_transfer_noack(struct ljca *ljca, u8 cmd, const void *obuf, unsigned int obuf_len)
+{
+	return ljca_transfer_internal(ljca, cmd, obuf, obuf_len, NULL, NULL, false);
+}
+EXPORT_SYMBOL_NS_GPL(ljca_transfer_noack, LJCA);
+
+int ljca_register_event_cb(struct ljca *ljca, ljca_event_cb_t event_cb, void *context)
+{
+	struct ljca_event_cb_entry *entry, *iter;
+	struct ljca_stub *stub;
+	unsigned long flags;
+	int ret;
+
+	stub = ljca_stub_find(ljca->dev, ljca->type);
+	if (IS_ERR(stub))
+		return PTR_ERR(stub);
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->notify = event_cb;
+	entry->context = context;
+	entry->id = ljca->id;
+
+	spin_lock_irqsave(&stub->event_cb_lock, flags);
+
+	list_for_each_entry(iter, &stub->event_entrys, list) {
+		if (iter->id == ljca->id) {
+			ret = -EBUSY;
+			break;
+		}
+	}
+
+	if (!ret)
+		list_add_tail(&entry->list, &stub->event_entrys);
+
+	spin_unlock_irqrestore(&stub->event_cb_lock, flags);
+
+	if (ret)
+		kfree(entry);
+
+	return ret;
+}
+EXPORT_SYMBOL_NS_GPL(ljca_register_event_cb, LJCA);
+
+void ljca_unregister_event_cb(struct ljca *ljca)
+{
+	struct ljca_stub *stub;
+	struct ljca_event_cb_entry *iter;
+	unsigned long flags;
+
+	stub = ljca_stub_find(ljca->dev, ljca->type);
+	if (IS_ERR(stub))
+		return;
+
+	spin_lock_irqsave(&stub->event_cb_lock, flags);
+
+	list_for_each_entry(iter, &stub->event_entrys, list) {
+		if (iter->id == ljca->id) {
+			list_del_init(&iter->list);
+			kfree(iter);
+			break;
+		}
+	}
+
+	spin_unlock_irqrestore(&stub->event_cb_lock, flags);
+}
+EXPORT_SYMBOL_NS_GPL(ljca_unregister_event_cb, LJCA);
+
 static void ljca_read_complete(struct urb *urb)
 {
 	struct ljca_msg *header = urb->transfer_buffer;
diff --git a/include/linux/usb/ljca.h b/include/linux/usb/ljca.h
index f209fa3ba54a..74e9729d05ec 100644
--- a/include/linux/usb/ljca.h
+++ b/include/linux/usb/ljca.h
@@ -47,4 +47,56 @@ struct ljca_spi_info {
  */
 typedef void (*ljca_event_cb_t)(void *context, u8 cmd, const void *evt_data, int len);
 
+/**
+ * ljca_register_event_cb - register a callback function to receive events
+ *
+ * @ljca: ljca device handle
+ * @event_cb: callback function
+ * @context: execution context of event callback
+ *
+ * Return: 0 in case of success, negative value in case of error
+ */
+int ljca_register_event_cb(struct ljca *ljca, ljca_event_cb_t event_cb, void *context);
+
+/**
+ * ljca_unregister_event_cb - unregister the callback function for an event
+ *
+ * @ljca: ljca device handle
+ */
+void ljca_unregister_event_cb(struct ljca *ljca);
+
+/**
+ * ljca_transfer - issue a LJCA command and wait for a response and the
+ * associated data
+ *
+ * @ljca: ljca device handle
+ * @cmd: the command to be sent to the device
+ * @obuf: the buffer to be sent to the device; it can be NULL if the user
+ *	doesn't need to transmit data with this command
+ * @obuf_len: the size of the buffer to be sent to the device; it should
+ *	be 0 when obuf is NULL
+ * @ibuf: any data associated with the response will be copied here; it can be
+ *	NULL if the user doesn't need the response data
+ * @ibuf_len: must be initialized to the input buffer size; it will be modified
+ *	to indicate the actual data transferred; it shouldn't be NULL as well
+ *	when ibuf isn't NULL
+ *
+ * Return: 0 for success, negative value for errors
+ */
+int ljca_transfer(struct ljca *ljca, u8 cmd, const void *obuf, unsigned int obuf_len,
+		  void *ibuf, unsigned int *ibuf_len);
+
+/**
+ * ljca_transfer_noack - issue a LJCA command without a response
+ *
+ * @ljca: ljca device handle
+ * @cmd: the command to be sent to the device
+ * @obuf: the buffer to be sent to the device; it can be NULL if the user
+ *	doesn't need to transmit data with this command
+ * @obuf_len: the size of the buffer to be sent to the device
+ *
+ * Return: 0 for success, negative value for errors
+ */
+int ljca_transfer_noack(struct ljca *ljca, u8 cmd, const void *obuf, unsigned int obuf_len);
+
 #endif
-- 
2.34.1