iwlwifi: support firmware reset handshake

There are some races in the hardware that can possibly lead to
a bus lockup later during a restart when we manage to kill the
firmware at a bad time (while it's accessing the bus).

To work around this, add support for a new handshake between
firmware and driver to ensure that the firmware is in a well-
known state before we kill it.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201209231352.7756fcc9865c.I13de65e0ffcb4186dd4c1a465f66df2e98c9a947@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

4 files changed, 40 insertions, 0 deletions

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/internal.h b/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
index 309dec9d5a08..a528d3d99c5a 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/internal.h
@@ -406,6 +406,10 @@ struct iwl_trans_pcie {
 
 	void *base_rb_stts;
 	dma_addr_t base_rb_stts_dma;
+
+	bool fw_reset_handshake;
+	bool fw_reset_done;
+	wait_queue_head_t fw_reset_waitq;
 };
 
 static inline struct iwl_trans_pcie *
diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
index e82356abd0c4..37bbd9a07f36 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/rx.c
@@ -2242,6 +2242,12 @@ irqreturn_t iwl_pcie_irq_msix_handler(int irq, void *dev_id)
 		iwl_pcie_irq_handle_error(trans);
 	}
 
+	if (inta_hw & MSIX_HW_INT_CAUSES_REG_RESET_DONE) {
+		IWL_DEBUG_ISR(trans, "Reset flow completed\n");
+		trans_pcie->fw_reset_done = true;
+		wake_up(&trans_pcie->fw_reset_waitq);
+	}
+
 	iwl_pcie_clear_irq(trans, entry);
 
 	lock_map_release(&trans->sync_cmd_lockdep_map);
diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c
index c25a2fba3b17..c602b815dcc2 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans-gen2.c
@@ -88,6 +88,28 @@ static void iwl_pcie_gen2_apm_stop(struct iwl_trans *trans, bool op_mode_leave)
 	iwl_clear_bit(trans, CSR_GP_CNTRL, CSR_GP_CNTRL_REG_FLAG_INIT_DONE);
 }
 
+static void iwl_trans_pcie_fw_reset_handshake(struct iwl_trans *trans)
+{
+	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
+	int ret;
+
+	trans_pcie->fw_reset_done = false;
+
+	if (trans->trans_cfg->device_family < IWL_DEVICE_FAMILY_AX210)
+		iwl_write_umac_prph(trans, UREG_NIC_SET_NMI_DRIVER,
+				    UREG_NIC_SET_NMI_DRIVER_RESET_HANDSHAKE);
+	else
+		iwl_write_umac_prph(trans, UREG_DOORBELL_TO_ISR6,
+				    UREG_DOORBELL_TO_ISR6_RESET_HANDSHAKE);
+
+	/* wait 200ms */
+	ret = wait_event_timeout(trans_pcie->fw_reset_waitq,
+				 trans_pcie->fw_reset_done, HZ / 5);
+	if (!ret)
+		IWL_ERR(trans,
+			"firmware didn't ACK the reset - continue anyway\n");
+}
+
 void _iwl_trans_pcie_gen2_stop_device(struct iwl_trans *trans)
 {
 	struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
@@ -97,6 +119,10 @@ void _iwl_trans_pcie_gen2_stop_device(struct iwl_trans *trans)
 	if (trans_pcie->is_down)
 		return;
 
+	if (trans_pcie->fw_reset_handshake &&
+	    trans->state >= IWL_TRANS_FW_STARTED)
+		iwl_trans_pcie_fw_reset_handshake(trans);
+
 	trans_pcie->is_down = true;
 
 	/* tell the device to stop sending interrupts */
diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
index 29286346da91..285e0d586021 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
@@ -1048,6 +1048,7 @@ static struct iwl_causes_list causes_list[] = {
 	{MSIX_FH_INT_CAUSES_FH_ERR,		CSR_MSIX_FH_INT_MASK_AD, 0x5},
 	{MSIX_HW_INT_CAUSES_REG_ALIVE,		CSR_MSIX_HW_INT_MASK_AD, 0x10},
 	{MSIX_HW_INT_CAUSES_REG_WAKEUP,		CSR_MSIX_HW_INT_MASK_AD, 0x11},
+	{MSIX_HW_INT_CAUSES_REG_RESET_DONE,	CSR_MSIX_HW_INT_MASK_AD, 0x12},
 	{MSIX_HW_INT_CAUSES_REG_CT_KILL,	CSR_MSIX_HW_INT_MASK_AD, 0x16},
 	{MSIX_HW_INT_CAUSES_REG_RF_KILL,	CSR_MSIX_HW_INT_MASK_AD, 0x17},
 	{MSIX_HW_INT_CAUSES_REG_PERIODIC,	CSR_MSIX_HW_INT_MASK_AD, 0x18},
@@ -1889,6 +1890,8 @@ static void iwl_trans_pcie_configure(struct iwl_trans *trans,
 	 */
 	if (trans_pcie->napi_dev.reg_state != NETREG_DUMMY)
 		init_dummy_netdev(&trans_pcie->napi_dev);
+
+	trans_pcie->fw_reset_handshake = trans_cfg->fw_reset_handshake;
 }
 
 void iwl_trans_pcie_free(struct iwl_trans *trans)
@@ -3403,6 +3406,7 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,
 	spin_lock_init(&trans_pcie->alloc_page_lock);
 	mutex_init(&trans_pcie->mutex);
 	init_waitqueue_head(&trans_pcie->ucode_write_waitq);
+	init_waitqueue_head(&trans_pcie->fw_reset_waitq);
 
 	trans_pcie->rba.alloc_wq = alloc_workqueue("rb_allocator",
 						   WQ_HIGHPRI | WQ_UNBOUND, 1);