Input: cleanup ps2_command() timeout handling in libps2.

Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 62 insertions, 28 deletions

diff --git a/drivers/input/serio/libps2.c b/drivers/input/serio/libps2.c
index 92b92ee03791..d4c990f7c85e 100644
--- a/drivers/input/serio/libps2.c
+++ b/drivers/input/serio/libps2.c
@@ -98,6 +98,66 @@ void ps2_drain(struct ps2dev *ps2dev, int maxbytes, int timeout)
 }
 
 /*
+ * ps2_is_keyboard_id() checks received ID byte against the list of
+ * known keyboard IDs.
+ */
+
+static inline int ps2_is_keyboard_id(char id_byte)
+{
+        static char keyboard_ids[] = {
+                0xab,   /* Regular keyboards            */
+                0xac,   /* NCD Sun keyboard             */
+                0x2b,   /* Trust keyboard, translated   */
+                0x5d,   /* Trust keyboard               */
+                0x60,   /* NMB SGI keyboard, translated */
+                0x47,   /* NMB SGI keyboard             */
+        };
+
+        return memchr(keyboard_ids, id_byte, sizeof(keyboard_ids)) != NULL;
+}
+
+/*
+ * ps2_adjust_timeout() is called after receiving 1st byte of command
+ * response and tries to reduce remaining timeout to speed up command
+ * completion.
+ */
+
+static int ps2_adjust_timeout(struct ps2dev *ps2dev, int command, int timeout)
+{
+        switch (command) {
+                case PS2_CMD_RESET_BAT:
+                        /*
+                         * Device has sent the first response byte after
+                         * reset command, reset is thus done, so we can
+                         * shorten the timeout.
+                         * The next byte will come soon (keyboard) or not
+                         * at all (mouse).
+                         */
+                        if (timeout > msecs_to_jiffies(100))
+                                timeout = msecs_to_jiffies(100);
+                        break;
+
+                case PS2_CMD_GETID:
+                        /*
+                         * If device behind the port is not a keyboard there
+                         * won't be 2nd byte of ID response.
+                         */
+                        if (!ps2_is_keyboard_id(ps2dev->cmdbuf[1])) {
+                                serio_pause_rx(ps2dev->serio);
+                                ps2dev->flags = ps2dev->cmdcnt = 0;
+                                serio_continue_rx(ps2dev->serio);
+                                timeout = 0;
+                        }
+                        break;
+
+                default:
+                        break;
+        }
+
+        return timeout;
+}
+
+/*
  * ps2_command() sends a command and its parameters to the mouse,
  * then waits for the response and puts it in the param array.
  *
@@ -150,33 +210,7 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 
         if (ps2dev->cmdcnt && timeout > 0) {
 
-                if (command == PS2_CMD_RESET_BAT && timeout > msecs_to_jiffies(100)) {
-                        /*
-                         * Device has sent the first response byte
-                         * after a reset command, reset is thus done,
-                         * shorten the timeout. The next byte will come
-                         * soon (keyboard) or not at all (mouse).
-                         */
-                        timeout = msecs_to_jiffies(100);
-                }
-
-                if (command == PS2_CMD_GETID &&
-                    ps2dev->cmdbuf[receive - 1] != 0xab && /* Regular keyboards */
-                    ps2dev->cmdbuf[receive - 1] != 0xac && /* NCD Sun keyboard */
-                    ps2dev->cmdbuf[receive - 1] != 0x2b && /* Trust keyboard, translated */
-                    ps2dev->cmdbuf[receive - 1] != 0x5d && /* Trust keyboard */
-                    ps2dev->cmdbuf[receive - 1] != 0x60 && /* NMB SGI keyboard, translated */
-                    ps2dev->cmdbuf[receive - 1] != 0x47) { /* NMB SGI keyboard */
-                        /*
-                         * Device behind the port is not a keyboard
-                         * so we don't need to wait for the 2nd byte
-                         * of ID response.
-                         */
-                        serio_pause_rx(ps2dev->serio);
-                        ps2dev->flags = ps2dev->cmdcnt = 0;
-                        serio_continue_rx(ps2dev->serio);
-                }
-
+                timeout = ps2_adjust_timeout(ps2dev, command, timeout);
                 wait_event_timeout(ps2dev->wait,
                                    !(ps2dev->flags & PS2_FLAG_CMD), timeout);
         }
@@ -190,7 +224,7 @@ int ps2_command(struct ps2dev *ps2dev, unsigned char *param, int command)
 
         rc = 0;
 
-out:
+ out:
         serio_pause_rx(ps2dev->serio);
         ps2dev->flags = 0;
         serio_continue_rx(ps2dev->serio);