zd1211rw: fix beacon interval setup

Vendor driver uses CR_BNC_INTERVAL at various places, one is HW_EnableBeacon()
that combinies beacon interval with BSS-type flag and DTIM value in upper 16bit
of u32. The other one is HW_UpdateBcnInterval() that set_aw_pt_bi()
appears to be based on. HW_UpdateBcnInterval() takes interval argument as u16
and uses that for calculations, set_aw_pt_bi() uses u32 value that has flags
and dtim in upper part. This clearly seems wrong. Also HW_UpdateBcnInterval()
updates only lower 16bit part of CR_BNC_INTERVAL. So make set_aw_pt_bi() do
calculations on only lower u16 part of s->beacon_interval.

Also set 32bit beacon interval register before reading values from device,
as HW_EnableBeacon() on vendor driver does. This is required to make beacon
work on AP-mode, simply reading and then writing updated values is not enough
at least with zd1211b.
Signed-off-by: Jussi Kivilinna <jussi.kivilinna@mbnet.fi>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/zd1211rw/zd_chip.c

@@ -849,11 +849,12 @@ static int get_aw_pt_bi(struct zd_chip *chip, struct aw_pt_bi *s)
 static int set_aw_pt_bi(struct zd_chip *chip, struct aw_pt_bi *s)
 {
 	struct zd_ioreq32 reqs[3];
+	u16 b_interval = s->beacon_interval & 0xffff;
 
-	if (s->beacon_interval <= 5)
-		s->beacon_interval = 5;
-	if (s->pre_tbtt < 4 || s->pre_tbtt >= s->beacon_interval)
-		s->pre_tbtt = s->beacon_interval - 1;
+	if (b_interval <= 5)
+		b_interval = 5;
+	if (s->pre_tbtt < 4 || s->pre_tbtt >= b_interval)
+		s->pre_tbtt = b_interval - 1;
 	if (s->atim_wnd_period >= s->pre_tbtt)
 		s->atim_wnd_period = s->pre_tbtt - 1;
 
@@ -862,7 +863,7 @@ static int set_aw_pt_bi(struct zd_chip *chip, struct aw_pt_bi *s)
 	reqs[1].addr = CR_PRE_TBTT;
 	reqs[1].value = s->pre_tbtt;
 	reqs[2].addr = CR_BCN_INTERVAL;
-	reqs[2].value = s->beacon_interval;
+	reqs[2].value = (s->beacon_interval & ~0xffff) | b_interval;
 
 	return zd_iowrite32a_locked(chip, reqs, ARRAY_SIZE(reqs));
 }
@@ -874,10 +875,13 @@ static int set_beacon_interval(struct zd_chip *chip, u32 interval)
 	struct aw_pt_bi s;
 
 	ZD_ASSERT(mutex_is_locked(&chip->mutex));
+
+	r = zd_iowrite32_locked(chip, interval, CR_BCN_INTERVAL);
+	if (r)
+		return r;
 	r = get_aw_pt_bi(chip, &s);
 	if (r)
 		return r;
-	s.beacon_interval = interval;
 	return set_aw_pt_bi(chip, &s);
 }