[1/6] i.MX: Allow GPT timer to rollover.

Commit Message

Jean-Christophe Dubois Jan. 26, 2016, 9:44 p.m. UTC

GPT timer need to rolloever when it reaches 0xffffffff.

It also need to reset to 0 when in "retart mode" and crossing the
compare 1 register.

Signed-off-by: Jean-Christophe Dubois <[e-mail]>
---
 hw/timer/imx_gpt.c | 27 +++++++++++++++------------
 1 file changed, 15 insertions(+), 12 deletions(-)

Comments

Eric Blake Jan. 26, 2016, 9:54 p.m. UTC | #1

On 01/26/2016 02:44 PM, Jean-Christophe Dubois wrote:

[meta-reply]
Make sure your git settings properly thread your messages. Your 1/6 came
through as a top-level thread, rather than in-reply-to the 0/6 cover
letter (likewise for the rest of the series).

> GPT timer need to rolloever when it reaches 0xffffffff.

s/rolloever/rollover/

> 
> It also need to reset to 0 when in "retart mode" and crossing the

s/retart/restart/

> compare 1 register.

Jean-Christophe Dubois Jan. 26, 2016, 10:21 p.m. UTC | #2

Le 26/01/2016 22:54, Eric Blake a écrit :
> On 01/26/2016 02:44 PM, Jean-Christophe Dubois wrote:
>
> [meta-reply]
> Make sure your git settings properly thread your messages. Your 1/6 came
> through as a top-level thread, rather than in-reply-to the 0/6 cover
> letter (likewise for the rest of the series).

Yes, sorry about that, I forgot to set the "threaded" option.

>
>> GPT timer need to rolloever when it reaches 0xffffffff.
> s/rolloever/rollover/
>
>> It also need to reset to 0 when in "retart mode" and crossing the
> s/retart/restart/
>
>> compare 1 register.
>

Patch

diff --git a/hw/timer/imx_gpt.c b/hw/timer/imx_gpt.c
index b1893b8..b227256 100644
--- a/hw/timer/imx_gpt.c
+++ b/hw/timer/imx_gpt.c
@@ -133,7 +133,7 @@  static inline uint32_t imx_gpt_find_limit(uint32_t count, uint32_t reg,
 static void imx_gpt_compute_next_timeout(IMXGPTState *s, bool event)
 {
     uint32_t timeout = GPT_TIMER_MAX;
-    uint32_t count = 0;
+    uint32_t count;
     long long limit;
 
     if (!(s->cr & GPT_CR_EN)) {
@@ -141,20 +141,23 @@  static void imx_gpt_compute_next_timeout(IMXGPTState *s, bool event)
         return;
     }
 
-    if (event) {
-        /* This is a timer event  */
+    /* update the count */
+    count = imx_gpt_update_count(s);
 
-        if ((s->cr & GPT_CR_FRR)  && (s->next_timeout != GPT_TIMER_MAX)) {
-            /*
-             * if we are in free running mode and we have not reached
-             * the GPT_TIMER_MAX limit, then update the count
+    if (event) {
+        /*
+         * This is an event (the ptimer reached 0 and stopped), and the
+         * timer counter is now equal to s->next_timeout.
+         */
+        if (!(s->cr & GPT_CR_FRR) && (count == s->ocr1)) {
+            /* We are in restart mode and we crossed the compare channel 1
+             * value. We need to reset the counter to 0.
              */
-            count = imx_gpt_update_count(s);
+            count = s->cnt = s->next_timeout = 0;
+        } else if (count == GPT_TIMER_MAX) {
+            /* We reached GPT_TIMER_MAX so we need to rollover */
+            count = s->cnt = s->next_timeout = 0;
         }
-    } else {
-        /* not a timer event, then just update the count */
-
-        count = imx_gpt_update_count(s);
     }
 
     /* now, find the next timeout related to count */