hw/input/tsc2005: Fix -Wchar-subscripts warning in tsc2005_txrx()

Check the function index is in range and use an unsigned
variable to avoid the following warning with GCC 13.2.0:

  [666/5358] Compiling C object libcommon.fa.p/hw_input_tsc2005.c.o
  hw/input/tsc2005.c: In function 'tsc2005_timer_tick':
  hw/input/tsc2005.c:416:26: warning: array subscript has type 'char' [-Wchar-subscripts]
    416 |     s->dav |= mode_regs[s->function];
        |                         ~^~~~~~~~~~

Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20240508143513.44996-1-philmd@linaro.org
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
[PMM: fixed missing ')']
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

1 files changed, 4 insertions, 1 deletions

diff --git a/hw/input/tsc2005.c b/hw/input/tsc2005.c
index 941f163d36..ac7f54eeaf 100644
--- a/hw/input/tsc2005.c
+++ b/hw/input/tsc2005.c
@@ -406,6 +406,9 @@ uint32_t tsc2005_txrx(void *opaque, uint32_t value, int len)
 static void tsc2005_timer_tick(void *opaque)
 {
     TSC2005State *s = opaque;
+    unsigned int function = s->function;
+
+    assert(function < ARRAY_SIZE(mode_regs));
 
     /* Timer ticked -- a set of conversions has been finished.  */
 
@@ -413,7 +416,7 @@ static void tsc2005_timer_tick(void *opaque)
         return;
 
     s->busy = false;
-    s->dav |= mode_regs[s->function];
+    s->dav |= mode_regs[function];
     s->function = -1;
     tsc2005_pin_update(s);
 }