diff --git a/sim/bfin/ChangeLog b/sim/bfin/ChangeLog
index d3445bc313..36c8665f28 100644
--- a/sim/bfin/ChangeLog
+++ b/sim/bfin/ChangeLog
@@ -1,3 +1,20 @@
+2011-03-23  Mike Frysinger  <vapier@gentoo.org>
+
+	* devices.h (dv_w1c): Fix typos in documentation of "bits" arg.
+	* dv-bfin_cec.c (bfin_cec_io_write_buffer): Pass 0xffee to dv_w1c_4.
+	* dv-bfin_emac.c (bfin_emac_io_write_buffer): Pass 0xe1 to dv_w1c_4
+	for systat MMR and -1 to dv_w1c_4 for [rt]x_stky/mmc_[rt]irqs MMRs.
+	* dv-bfin_eppi.c (bfin_eppi_io_write_buffer): Pass 0x1ff to dv_w1c_2.
+	* dv-bfin_gpio.c (bfin_gpio_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_jtag.c (bfin_jtag_io_write_buffer): Invert bits to dv_w1c_4.
+	* dv-bfin_nfc.c (bfin_nfc_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_otp.c (bfin_otp_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_ppi.c (bfin_ppi_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_rtc.c (bfin_rtc_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_spi.c (bfin_spi_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_twi.c (bfin_twi_io_write_buffer): Invert bits to dv_w1c_2.
+	* dv-bfin_uart2.c (bfin_uart_io_write_buffer): Invert bits to dv_w1c_2.
+
 2011-03-23  Mike Frysinger  <vapier@gentoo.org>
 
 	* dv-bfin_uart.h (TFI, BI, FE, PE, OE): Define.
diff --git a/sim/bfin/devices.h b/sim/bfin/devices.h
index 76854ed33a..3dc5481a11 100644
--- a/sim/bfin/devices.h
+++ b/sim/bfin/devices.h
@@ -81,8 +81,8 @@ static inline void dv_store_4 (void *ptr, bu32 val)
   dv_store_2 (ptr, val);
 }
 
-/* Helpers for MMRs where all bits are W1C except for the specified
-   bits -- those ones are RO.  */
+/* Helpers for MMRs where only the specified bits are W1C.  The
+   rest are left unmodified.  */
 #define dv_w1c(ptr, val, bits) (*(ptr) &= ~((val) & (bits)))
 static inline void dv_w1c_2 (bu16 *ptr, bu16 val, bu16 bits)
 {
diff --git a/sim/bfin/dv-bfin_cec.c b/sim/bfin/dv-bfin_cec.c
index 85fe6fcd1a..0c6a8235a6 100644
--- a/sim/bfin/dv-bfin_cec.c
+++ b/sim/bfin/dv-bfin_cec.c
@@ -100,7 +100,7 @@ bfin_cec_io_write_buffer (struct hw *me, const void *source,
       /* Read-only register.  */
       break;
     case mmr_offset(ilat):
-      dv_w1c_4 (&cec->ilat, value, 0);
+      dv_w1c_4 (&cec->ilat, value, 0xffee);
       break;
     case mmr_offset(iprio):
       cec->iprio = (value & IVG_UNMASKABLE_B);
diff --git a/sim/bfin/dv-bfin_emac.c b/sim/bfin/dv-bfin_emac.c
index a64198d45b..af14103ea4 100644
--- a/sim/bfin/dv-bfin_emac.c
+++ b/sim/bfin/dv-bfin_emac.c
@@ -224,7 +224,7 @@ bfin_emac_io_write_buffer (struct hw *me, const void *source,
       dv_w1c_4_partial (valuep, value, 0xf20);
       break;
     case mmr_offset(systat):
-      dv_w1c_4 (valuep, value, 0x1e);
+      dv_w1c_4 (valuep, value, 0xe1);
       break;
     case mmr_offset(staadd):
       *valuep = value | STABUSY;
@@ -242,7 +242,7 @@ bfin_emac_io_write_buffer (struct hw *me, const void *source,
     case mmr_offset(tx_stky):
     case mmr_offset(mmc_rirqs):
     case mmr_offset(mmc_tirqs):
-      dv_w1c_4 (valuep, value, 0);
+      dv_w1c_4 (valuep, value, -1);
       break;
     case mmr_offset(mmc_ctl):
       /* Writing to bit 0 clears all counters.  */
diff --git a/sim/bfin/dv-bfin_eppi.c b/sim/bfin/dv-bfin_eppi.c
index df76f97d15..c151f3cfc1 100644
--- a/sim/bfin/dv-bfin_eppi.c
+++ b/sim/bfin/dv-bfin_eppi.c
@@ -106,7 +106,7 @@ bfin_eppi_io_write_buffer (struct hw *me, const void *source,
     {
     case mmr_offset(status):
       dv_bfin_mmr_require_16 (me, addr, nr_bytes, true);
-      dv_w1c_2 (value16p, value, 0);
+      dv_w1c_2 (value16p, value, 0x1ff);
       break;
     case mmr_offset(hcount):
     case mmr_offset(hdelay):
diff --git a/sim/bfin/dv-bfin_gpio.c b/sim/bfin/dv-bfin_gpio.c
index c4a7481f6a..50baf03e71 100644
--- a/sim/bfin/dv-bfin_gpio.c
+++ b/sim/bfin/dv-bfin_gpio.c
@@ -92,7 +92,7 @@ bfin_gpio_io_write_buffer (struct hw *me, const void *source, int space,
     case mmr_offset(clear):
     case mmr_offset(maska_clear):
     case mmr_offset(maskb_clear):
-      dv_w1c_2 (valuep, value, 0);
+      dv_w1c_2 (valuep, value, -1);
       break;
     case mmr_offset(set):
     case mmr_offset(maska_set):
diff --git a/sim/bfin/dv-bfin_jtag.c b/sim/bfin/dv-bfin_jtag.c
index b4b4824385..e2d105d991 100644
--- a/sim/bfin/dv-bfin_jtag.c
+++ b/sim/bfin/dv-bfin_jtag.c
@@ -63,7 +63,7 @@ bfin_jtag_io_write_buffer (struct hw *me, const void *source, int space,
   switch (mmr_off)
     {
     case mmr_offset(dbgstat):
-      dv_w1c_4 (valuep, value, ~0xc);
+      dv_w1c_4 (valuep, value, 0xc);
       break;
     case mmr_offset(dspid):
       /* Discard writes to these.  */
diff --git a/sim/bfin/dv-bfin_nfc.c b/sim/bfin/dv-bfin_nfc.c
index 84246c85be..2bd8b9e764 100644
--- a/sim/bfin/dv-bfin_nfc.c
+++ b/sim/bfin/dv-bfin_nfc.c
@@ -108,7 +108,7 @@ bfin_nfc_io_write_buffer (struct hw *me, const void *source, int space,
       *valuep = value;
       break;
     case mmr_offset(irqstat):
-      dv_w1c_2 (valuep, value, 0);
+      dv_w1c_2 (valuep, value, -1);
       break;
     default:
       dv_bfin_mmr_invalid (me, addr, nr_bytes, true);
diff --git a/sim/bfin/dv-bfin_otp.c b/sim/bfin/dv-bfin_otp.c
index 34bfb8d6e5..5b15eeb118 100644
--- a/sim/bfin/dv-bfin_otp.c
+++ b/sim/bfin/dv-bfin_otp.c
@@ -149,7 +149,7 @@ bfin_otp_io_write_buffer (struct hw *me, const void *source, int space,
     case mmr_offset(status):
       dv_bfin_mmr_require_16 (me, addr, nr_bytes, true);
       /* XXX: All bits seem to be W1C.  */
-      dv_w1c_2 (value16p, value, 0);
+      dv_w1c_2 (value16p, value, -1);
       break;
     case mmr_offset(timing):
     case mmr_offset(data0):
diff --git a/sim/bfin/dv-bfin_ppi.c b/sim/bfin/dv-bfin_ppi.c
index e7b404bcd4..e2f829246c 100644
--- a/sim/bfin/dv-bfin_ppi.c
+++ b/sim/bfin/dv-bfin_ppi.c
@@ -105,7 +105,7 @@ bfin_ppi_io_write_buffer (struct hw *me, const void *source, int space,
       *valuep = value;
       break;
     case mmr_offset(status):
-      dv_w1c_2 (valuep, value, (1 << 10));
+      dv_w1c_2 (valuep, value, ~(1 << 10));
       break;
     default:
       dv_bfin_mmr_invalid (me, addr, nr_bytes, true);
diff --git a/sim/bfin/dv-bfin_rtc.c b/sim/bfin/dv-bfin_rtc.c
index 870d6b1095..1b201484a7 100644
--- a/sim/bfin/dv-bfin_rtc.c
+++ b/sim/bfin/dv-bfin_rtc.c
@@ -80,7 +80,7 @@ bfin_rtc_io_write_buffer (struct hw *me, const void *source,
       /* XXX: Ignore these since we are wired to host.  */
       break;
     case mmr_offset(istat):
-      dv_w1c_2 (value16p, value, 1 << 14);
+      dv_w1c_2 (value16p, value, ~(1 << 14));
       break;
     case mmr_offset(alarm):
       break;
diff --git a/sim/bfin/dv-bfin_spi.c b/sim/bfin/dv-bfin_spi.c
index f3e5cf62e5..63204ecd18 100644
--- a/sim/bfin/dv-bfin_spi.c
+++ b/sim/bfin/dv-bfin_spi.c
@@ -88,7 +88,7 @@ bfin_spi_io_write_buffer (struct hw *me, const void *source, int space,
   switch (mmr_off)
     {
     case mmr_offset(stat):
-      dv_w1c_2 (valuep, value, SPIF | TXS | RXS);
+      dv_w1c_2 (valuep, value, ~(SPIF | TXS | RXS));
       break;
     case mmr_offset(tdbr):
       *valuep = value;
diff --git a/sim/bfin/dv-bfin_twi.c b/sim/bfin/dv-bfin_twi.c
index 8c775e6509..5d04f23368 100644
--- a/sim/bfin/dv-bfin_twi.c
+++ b/sim/bfin/dv-bfin_twi.c
@@ -102,10 +102,10 @@ bfin_twi_io_write_buffer (struct hw *me, const void *source, int space,
       *valuep = value;
       break;
     case mmr_offset(int_stat):
-      dv_w1c_2 (valuep, value, 0);
+      dv_w1c_2 (valuep, value, -1);
       break;
     case mmr_offset(master_stat):
-      dv_w1c_2 (valuep, value, MPROG | SDASEN | SCLSEN | BUSBUSY);
+      dv_w1c_2 (valuep, value, BUFWRERR | BUFRDERR | DNAK | ANAK | LOSTARB);
       break;
     case mmr_offset(slave_stat):
     case mmr_offset(fifo_stat):
diff --git a/sim/bfin/dv-bfin_uart2.c b/sim/bfin/dv-bfin_uart2.c
index 5b379bb3e5..facde1c6cd 100644
--- a/sim/bfin/dv-bfin_uart2.c
+++ b/sim/bfin/dv-bfin_uart2.c
@@ -97,10 +97,10 @@ bfin_uart_io_write_buffer (struct hw *me, const void *source,
       uart->ier |= value;
       break;
     case mmr_offset(ier_clear):
-      dv_w1c_2 (&uart->ier, value, 0);
+      dv_w1c_2 (&uart->ier, value, -1);
       break;
     case mmr_offset(lsr):
-      dv_w1c_2 (valuep, value, TEMT | THRE | DR);
+      dv_w1c_2 (valuep, value, TFI | BI | FE | PE | OE);
       break;
     case mmr_offset(rbr):
       /* XXX: Writes are ignored ?  */