[PATCH] usbtty: fix possible alignment issues

[Seung-Woo Kim]

With gcc9, below warnings are shown:
  drivers/serial/usbtty.c: In function 'usbtty_init_strings':
  drivers/serial/usbtty.c:590:44: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    590 |  str2wide (CONFIG_USBD_MANUFACTURER, string->wData);
        |                                      ~~~~~~^~~~~~~
  drivers/serial/usbtty.c:596:44: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    597 |  str2wide (CONFIG_USBD_PRODUCT_NAME, string->wData);
        |                                      ~~~~~~^~~~~~~
  drivers/serial/usbtty.c:603:33: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    604 |  str2wide (serial_number, string->wData);
        |                           ~~~~~~^~~~~~~
  drivers/serial/usbtty.c:610:49: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    611 |  str2wide (CONFIG_USBD_CONFIGURATION_STR, string->wData);
        |                                           ~~~~~~^~~~~~~
  drivers/serial/usbtty.c:617:50: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    618 |  str2wide (CONFIG_USBD_DATA_INTERFACE_STR, string->wData);
        |                                            ~~~~~~^~~~~~~
  drivers/serial/usbtty.c:623:50: warning: taking address of packed member of 'struct usb_string_descriptor' may result in an unaligned pointer value [-Waddress-of-packed-member]
    624 |  str2wide (CONFIG_USBD_CTRL_INTERFACE_STR, string->wData);
        |                                            ~~~~~~^~~~~~~

Fix the issues by using packed structure.

Ref: commit 616ebd8b9cb4 ("usb: composite: fix possible alignment issues")
Signed-off-by: Seung-Woo Kim <sw0312.kim at samsung.com>
---
 drivers/serial/usbtty.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/serial/usbtty.c b/drivers/serial/usbtty.c
index f1c1a260da..54e67dd0d1 100644
--- a/drivers/serial/usbtty.c
+++ b/drivers/serial/usbtty.c
@@ -48,6 +48,8 @@
 #define CONFIG_USBD_DATA_INTERFACE_STR "Bulk Data Interface"
 #define CONFIG_USBD_CTRL_INTERFACE_STR "Control Interface"
 
+typedef struct { __le16 val; } __attribute__((aligned(16))) __le16_packed;
+
 /*
  * Buffers to hold input and output data
  */
@@ -372,14 +374,15 @@ static int fill_buffer (circbuf_t * buf);
 void usbtty_poll (void);
 
 /* utility function for converting char* to wide string used by USB */
-static void str2wide (char *str, u16 * wide)
+static void str2wide (char *str, void *wide)
 {
 	int i;
+	__le16_packed	*tmp = wide;
 	for (i = 0; i < strlen (str) && str[i]; i++){
 		#if defined(__LITTLE_ENDIAN)
-			wide[i] = (u16) str[i];
+			tmp[i].val = (u16) str[i];
 		#elif defined(__BIG_ENDIAN)
-			wide[i] = ((u16)(str[i])<<8);
+			tmp[i].val = ((u16)(str[i])<<8);
 		#else
 			#error "__LITTLE_ENDIAN or __BIG_ENDIAN undefined"
 		#endif
-- 
2.19.2