Sansa AMS: refactor DBOP button reading (e200v2/Fuze/c200v2)

This gets rid of LCD glitches on Sansa Fuze, and now LCD transfers can
get interrupted by button reading

Flyspray: FS #10603
Author: Bertrik Sikken

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@24192 a1c6a512-1295-4272-9138-f99709370657

1 files changed, 77 insertions, 0 deletions

diff --git a/firmware/target/arm/as3525/dbop-as3525.c b/firmware/target/arm/as3525/dbop-as3525.c
new file mode 100644
index 0000000000..938eee2fb1
--- /dev/null
+++ b/firmware/target/arm/as3525/dbop-as3525.c
@@ -0,0 +1,77 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * Copyright (C) 2009 by Bertrik Sikken
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include "config.h"
+#include "as3525.h"
+#include "dbop-as3525.h"
+
+#if defined(SANSA_FUZE)
+#define DBOP_PRECHARGE 0x80FF
+#elif defined(SANSA_E200V2) || defined(SANSA_C200V2)
+#define DBOP_PRECHARGE 0xF0FF
+#endif
+
+static short int dbop_input_value = 0;
+
+/* read the DBOP data pins */
+unsigned short dbop_read_input(void)
+{
+    unsigned int dbop_ctrl_old = DBOP_CTRL;
+    unsigned int dbop_timpol23_old = DBOP_TIMPOL_23;
+
+    /* make sure that the DBOP FIFO is empty */
+    while ((DBOP_STAT & (1<<10)) == 0);
+
+    /* write DBOP_DOUT to pre-charge DBOP data lines with a defined level */
+    DBOP_TIMPOL_23 = 0xe007e007;    /* no strobe towards lcd */
+    int delay = 10;
+    while (delay--) asm volatile ("nop\n");
+    DBOP_CTRL = (1 << 19) |         /* tri-state output */
+                (1 << 16) |         /* enw=1 (enable write) */
+                (1 << 12);          /* ow=1 (16-bit data width) */
+    DBOP_DOUT = DBOP_PRECHARGE;
+    while ((DBOP_STAT & (1<<10)) == 0);
+
+#if defined(SANSA_FUZE) || defined(SANSA_E200V2)
+    delay = 50;
+    while (delay--) asm volatile ("nop\n");
+#endif
+
+    /* perform a DBOP read */
+    DBOP_CTRL = (1 << 19) |         /* tri-state output */
+                (1 << 15) |         /* strd=1 (start read) */
+                (1 << 12) |         /* ow=1 (16-bit data width) */
+                (31 << 0);          /* rs_t=31 (read DBOP at end of cycle) */
+    while ((DBOP_STAT & (1<<16)) == 0);
+    dbop_input_value = DBOP_DIN;
+
+    /* restore previous values */
+    DBOP_TIMPOL_23 = dbop_timpol23_old;
+    DBOP_CTRL = dbop_ctrl_old;
+
+    return dbop_input_value;
+}
+
+/* for the debug menu */
+unsigned short dbop_debug(void)
+{
+    return dbop_input_value;
+}