Author: tychon
Date: Fri Apr 18 16:05:12 2014
New Revision: 264651
URL: http://svnweb.freebsd.org/changeset/base/264651
Log:
Add support for the PIT 'readback' command -- based on a patch by grehan@.
Approved by: grehan (co-mentor)
Modified:
head/sys/amd64/vmm/io/vatpit.c
Modified: head/sys/amd64/vmm/io/vatpit.c
==============================================================================
--- head/sys/amd64/vmm/io/vatpit.c Fri Apr 18 16:01:19 2014
(r264650)
+++ head/sys/amd64/vmm/io/vatpit.c Fri Apr 18 16:05:12 2014
(r264651)
@@ -56,6 +56,15 @@ static MALLOC_DEFINE(M_VATPIT, "atpit",
#define TIMER_MODE_MASK 0x0f
#define TIMER_SEL_READBACK 0xc0
+#define TIMER_STS_OUT 0x80
+#define TIMER_STS_NULLCNT 0x40
+
+#define TIMER_RB_LCTR 0x20
+#define TIMER_RB_LSTATUS 0x10
+#define TIMER_RB_CTR_2 0x08
+#define TIMER_RB_CTR_1 0x04
+#define TIMER_RB_CTR_0 0x02
+
#define TMR2_OUT_STS 0x20
#define PIT_8254_FREQ 1193182
@@ -73,6 +82,8 @@ struct channel {
sbintime_t now_sbt; /* uptime when counter was loaded */
uint8_t cr[2];
uint8_t ol[2];
+ bool slatched; /* status latched */
+ uint8_t status;
int crbyte;
int olbyte;
int frbyte;
@@ -198,6 +209,7 @@ pit_update_counter(struct vatpit *vatpit
*/
c->initial = TIMER_DIV(PIT_8254_FREQ, 100);
c->now_sbt = sbinuptime();
+ c->status &= ~TIMER_STS_NULLCNT;
}
delta_ticks = (sbinuptime() - c->now_sbt) / vatpit->freq_sbt;
@@ -214,6 +226,57 @@ pit_update_counter(struct vatpit *vatpit
}
static int
+pit_readback1(struct vatpit *vatpit, int channel, uint8_t cmd)
+{
+ struct channel *c;
+
+ c = &vatpit->channel[channel];
+
+ /*
+ * Latch the count/status of the timer if not already latched.
+ * N.B. that the count/status latch-select bits are active-low.
+ */
+ if (!(cmd & TIMER_RB_LCTR) && !c->olbyte) {
+ (void) pit_update_counter(vatpit, c, true);
+ }
+
+ if (!(cmd & TIMER_RB_LSTATUS) && !c->slatched) {
+ c->slatched = true;
+ /*
+ * For mode 0, see if the elapsed time is greater
+ * than the initial value - this results in the
+ * output pin being set to 1 in the status byte.
+ */
+ if (c->mode == TIMER_INTTC && vatpit_get_out(vatpit, channel))
+ c->status |= TIMER_STS_OUT;
+ else
+ c->status &= ~TIMER_STS_OUT;
+ }
+
+ return (0);
+}
+
+static int
+pit_readback(struct vatpit *vatpit, uint8_t cmd)
+{
+ int error;
+
+ /*
+ * The readback command can apply to all timers.
+ */
+ error = 0;
+ if (cmd & TIMER_RB_CTR_0)
+ error = pit_readback1(vatpit, 0, cmd);
+ if (!error && cmd & TIMER_RB_CTR_1)
+ error = pit_readback1(vatpit, 1, cmd);
+ if (!error && cmd & TIMER_RB_CTR_2)
+ error = pit_readback1(vatpit, 2, cmd);
+
+ return (error);
+}
+
+
+static int
vatpit_update_mode(struct vatpit *vatpit, uint8_t val)
{
struct channel *c;
@@ -224,7 +287,7 @@ vatpit_update_mode(struct vatpit *vatpit
mode = val & TIMER_MODE_MASK;
if (sel == TIMER_SEL_READBACK)
- return (-1);
+ return (pit_readback(vatpit, val));
if (rw != TIMER_LATCH && rw != TIMER_16BIT)
return (-1);
@@ -247,6 +310,7 @@ vatpit_update_mode(struct vatpit *vatpit
else {
c->mode = mode;
c->olbyte = 0; /* reset latch after reprogramming */
+ c->status |= TIMER_STS_NULLCNT;
}
return (0);
@@ -287,7 +351,14 @@ vatpit_handler(void *vm, int vcpuid, boo
c = &vatpit->channel[port - TIMER_CNTR0];
VATPIT_LOCK(vatpit);
- if (in) {
+ if (in && c->slatched) {
+ /*
+ * Return the status byte if latched
+ */
+ *eax = c->status;
+ c->slatched = false;
+ c->status = 0;
+ } else if (in) {
/*
* The spec says that once the output latch is completely
* read it should revert to "following" the counter. Use
@@ -309,6 +380,7 @@ vatpit_handler(void *vm, int vcpuid, boo
} else {
c->cr[c->crbyte++] = *eax;
if (c->crbyte == 2) {
+ c->status &= ~TIMER_STS_NULLCNT;
c->frbyte = 0;
c->crbyte = 0;
c->initial = c->cr[0] | (uint16_t)c->cr[1] << 8;
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
