Introduce iwm_nic_assert_locked() to verify that the driver has correctly

requested MAC access before accessing certain registers, as required
by the hardware.

Use it to assert that hardware is still in an accessible state before
reading or writing such a register. For now, panic if that check fails.
The long term goal is to make this a non-fatal error and handle it properly
in all code paths that end up reading or writing such a register.

Fix a missing NIC lock on 8000 hardware, found by this new assertion.

Also, grab the NIC lock early during hardware init and keep it until init
is done. The previous code relinquished and reacquired the NIC lock several
times during the init sequence. It seems this is what was causing some random
errors when the interface was brought up, such as "could not enable Tx queue",
"could not add aux station", and "could not add phy context".
For some reason, bsd.rd kernels were suffering particularly hard from such
problems, to the point where some machines could not be upgraded over iwm(4).
This change does not eliminate such problems entirely but is a step forward.

Prodded by deraadt@
This change has already been in snaps for a while.

1 files changed, 42 insertions, 34 deletions

diff --git a/sys/dev/pci/if_iwm.c b/sys/dev/pci/if_iwm.c
index 0ef52180b5d..062919b59cc 100644
--- a/sys/dev/pci/if_iwm.c
+++ b/sys/dev/pci/if_iwm.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: if_iwm.c,v 1.191 2017/06/09 13:46:15 stsp Exp $	*/
+/*	$OpenBSD: if_iwm.c,v 1.192 2017/06/09 13:47:26 stsp Exp $	*/
 
 /*
  * Copyright (c) 2014, 2016 genua gmbh <info@genua.de>
@@ -256,6 +256,7 @@ int	iwm_write_mem(struct iwm_softc *, uint32_t, const void *, int);
 int	iwm_write_mem32(struct iwm_softc *, uint32_t, uint32_t);
 int	iwm_poll_bit(struct iwm_softc *, int, uint32_t, uint32_t, int);
 int	iwm_nic_lock(struct iwm_softc *);
+void	iwm_nic_assert_locked(struct iwm_softc *);
 void	iwm_nic_unlock(struct iwm_softc *);
 void	iwm_set_bits_mask_prph(struct iwm_softc *, uint32_t, uint32_t,
 	    uint32_t);
@@ -832,6 +833,7 @@ iwm_read_firmware(struct iwm_softc *sc, enum iwm_ucode_type ucode_type)
 uint32_t
 iwm_read_prph(struct iwm_softc *sc, uint32_t addr)
 {
+	iwm_nic_assert_locked(sc);
 	IWM_WRITE(sc,
 	    IWM_HBUS_TARG_PRPH_RADDR, ((addr & 0x000fffff) | (3 << 24)));
 	IWM_BARRIER_READ_WRITE(sc);
@@ -841,6 +843,7 @@ iwm_read_prph(struct iwm_softc *sc, uint32_t addr)
 void
 iwm_write_prph(struct iwm_softc *sc, uint32_t addr, uint32_t val)
 {
+	iwm_nic_assert_locked(sc);
 	IWM_WRITE(sc,
 	    IWM_HBUS_TARG_PRPH_WADDR, ((addr & 0x000fffff) | (3 << 24)));
 	IWM_BARRIER_WRITE(sc);
@@ -909,9 +912,8 @@ iwm_poll_bit(struct iwm_softc *sc, int reg, uint32_t bits, uint32_t mask,
 int
 iwm_nic_lock(struct iwm_softc *sc)
 {
-	int rv = 0;
-
 	if (sc->sc_nic_locks > 0) {
+		iwm_nic_assert_locked(sc);
 		sc->sc_nic_locks++;
 		return 1; /* already locked */
 	}
@@ -925,15 +927,25 @@ iwm_nic_lock(struct iwm_softc *sc)
 	if (iwm_poll_bit(sc, IWM_CSR_GP_CNTRL,
 	    IWM_CSR_GP_CNTRL_REG_VAL_MAC_ACCESS_EN,
 	    IWM_CSR_GP_CNTRL_REG_FLAG_MAC_CLOCK_READY
-	     | IWM_CSR_GP_CNTRL_REG_FLAG_GOING_TO_SLEEP, 15000)) {
-	    	rv = 1;
+	     | IWM_CSR_GP_CNTRL_REG_FLAG_GOING_TO_SLEEP, 150000)) {
 		sc->sc_nic_locks++;
-	} else {
-		printf("%s: acquiring device failed\n", DEVNAME(sc));
-		IWM_WRITE(sc, IWM_CSR_RESET, IWM_CSR_RESET_REG_FLAG_FORCE_NMI);
+		return 1;
 	}
 
-	return rv;
+	printf("%s: acquiring device failed\n", DEVNAME(sc));
+	return 0;
+}
+
+void
+iwm_nic_assert_locked(struct iwm_softc *sc)
+{
+	uint32_t reg = IWM_READ(sc, IWM_CSR_GP_CNTRL);
+	if ((reg & IWM_CSR_GP_CNTRL_REG_FLAG_MAC_CLOCK_READY) == 0)
+		panic("%s: mac clock not ready", DEVNAME(sc));
+	if (reg & IWM_CSR_GP_CNTRL_REG_FLAG_GOING_TO_SLEEP)
+		panic("%s: mac gone to sleep", DEVNAME(sc));
+	if (sc->sc_nic_locks <= 0)
+		panic("%s: nic locks counter %d", DEVNAME(sc), sc->sc_nic_locks);
 }
 
 void
@@ -1781,8 +1793,7 @@ const uint8_t iwm_ac_to_tx_fifo[] = {
 int
 iwm_enable_txq(struct iwm_softc *sc, int sta_id, int qid, int fifo)
 {
-	if (!iwm_nic_lock(sc))
-		return EBUSY;
+	iwm_nic_assert_locked(sc);
 
 	IWM_WRITE(sc, IWM_HBUS_TARG_WRPTR, qid << 8 | 0);
 
@@ -1817,8 +1828,6 @@ iwm_enable_txq(struct iwm_softc *sc, int sta_id, int qid, int fifo)
 		struct iwm_scd_txq_cfg_cmd cmd;
 		int err;
 
-		iwm_nic_unlock(sc);
-
 		memset(&cmd, 0, sizeof(cmd));
 		cmd.scd_queue = qid;
 		cmd.enable = 1;
@@ -1831,16 +1840,11 @@ iwm_enable_txq(struct iwm_softc *sc, int sta_id, int qid, int fifo)
 		    sizeof(cmd), &cmd);
 		if (err)
 			return err;
-
-		if (!iwm_nic_lock(sc))
-			return EBUSY;
 	}
 
 	iwm_write_prph(sc, IWM_SCD_EN_CTRL,
 	    iwm_read_prph(sc, IWM_SCD_EN_CTRL) | qid);
 
-	iwm_nic_unlock(sc);
-
 	return 0;
 }
 
@@ -1873,15 +1877,10 @@ iwm_post_alive(struct iwm_softc *sc)
 
 	iwm_write_prph(sc, IWM_SCD_CHAINEXT_EN, 0);
 
-	iwm_nic_unlock(sc);
-
 	/* enable command channel */
 	err = iwm_enable_txq(sc, 0 /* unused */, IWM_CMD_QUEUE, 7);
 	if (err)
-		return err;
-
-	if (!iwm_nic_lock(sc))
-		return EBUSY;
+		goto out;
 
 	/* Activate TX scheduler. */
 	iwm_write_prph(sc, IWM_SCD_TXFACT, 0xff);
@@ -2609,10 +2608,13 @@ iwm_set_hw_address_8000(struct iwm_softc *sc, struct iwm_nvm_data *data,
 
 	if (nvm_hw) {
 		/* Read the mac address from WFMP registers. */
-		uint32_t mac_addr0 =
-		    htole32(iwm_read_prph(sc, IWM_WFMP_MAC_ADDR_0));
-		uint32_t mac_addr1 =
-		    htole32(iwm_read_prph(sc, IWM_WFMP_MAC_ADDR_1));
+		uint32_t mac_addr0, mac_addr1;
+
+		if (!iwm_nic_lock(sc))
+			goto out;
+		mac_addr0 = htole32(iwm_read_prph(sc, IWM_WFMP_MAC_ADDR_0));
+		mac_addr1 = htole32(iwm_read_prph(sc, IWM_WFMP_MAC_ADDR_1));
+		iwm_nic_unlock(sc);
 
 		hw_addr = (const uint8_t *)&mac_addr0;
 		data->hw_addr[0] = hw_addr[3];
@@ -2626,7 +2628,7 @@ iwm_set_hw_address_8000(struct iwm_softc *sc, struct iwm_nvm_data *data,
 
 		return;
 	}
-
+out:
 	printf("%s: mac address not found\n", DEVNAME(sc));
 	memset(data->hw_addr, 0, sizeof(data->hw_addr));
 }
@@ -5560,6 +5562,7 @@ iwm_newstate_task(void *psc)
 {
 	struct iwm_softc *sc = (struct iwm_softc *)psc;
 	struct ieee80211com *ic = &sc->sc_ic;
+	struct ifnet *ifp = IC2IFP(ic);
 	enum ieee80211_state nstate = sc->ns_nstate;
 	enum ieee80211_state ostate = ic->ic_state;
 	struct iwm_node *in = (struct iwm_node *)ic->ic_bss;
@@ -5580,7 +5583,11 @@ iwm_newstate_task(void *psc)
 	/* XXX Is there a way to switch states without a full reset? */
 	if (ostate > IEEE80211_S_SCAN && nstate < ostate) {
 		iwm_stop_device(sc);
-		iwm_init_hw(sc);
+		err = iwm_init_hw(sc);
+		if (err) {
+			iwm_stop(ifp, 1);
+			return;
+		}
 
 		/* 
 		 * Upon receiving a deauth frame from AP the net80211 stack
@@ -5958,6 +5965,9 @@ iwm_init_hw(struct iwm_softc *sc)
 		goto err;
 	}
 
+	if (!iwm_nic_lock(sc))
+		return EBUSY;
+
 	err = iwm_send_bt_init_conf(sc);
 	if (err) {
 		printf("%s: could not init bt coex (error %d)\n",
@@ -6056,10 +6066,8 @@ iwm_init_hw(struct iwm_softc *sc)
 		goto err;
 	}
 
-	return 0;
-
- err:
-	iwm_stop_device(sc);
+err:
+	iwm_nic_unlock(sc);
 	return err;
 }