iwlwifi: mvm: reset the HW before dumping if HW error is detected

If the hardware is stuck, we can't read any of the memory we need to
dump it, so we end up printing only 0xa5a5a5a5, which is useless.

To solve this, poke the hardware by triggering a reset and re-enabling
the clocks if we detect a HW error.
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/utils.c

@@ -69,6 +69,7 @@
 #include "iwl-debug.h"
 #include "iwl-io.h"
 #include "iwl-prph.h"
+#include "iwl-csr.h"
 #include "fw-dbg.h"
 #include "mvm.h"
 #include "fw-api-rs.h"
@@ -497,6 +498,7 @@ static void iwl_mvm_dump_lmac_error_log(struct iwl_mvm *mvm, u32 base)
 {
 	struct iwl_trans *trans = mvm->trans;
 	struct iwl_error_event_table table;
+	u32 val;
 
 	if (mvm->cur_ucode == IWL_UCODE_INIT) {
 		if (!base)
@@ -515,6 +517,36 @@ static void iwl_mvm_dump_lmac_error_log(struct iwl_mvm *mvm, u32 base)
 		return;
 	}
 
+	/* check if there is a HW error */
+	val = iwl_trans_read_mem32(trans, base);
+	if (((val & ~0xf) == 0xa5a5a5a0) || ((val & ~0xf) == 0x5a5a5a50)) {
+		int err;
+
+		IWL_ERR(trans, "HW error, resetting before reading\n");
+
+		/* reset the device */
+		iwl_set_bit(trans, CSR_RESET, CSR_RESET_REG_FLAG_SW_RESET);
+		usleep_range(1000, 2000);
+
+		/* set INIT_DONE flag */
+		iwl_set_bit(trans, CSR_GP_CNTRL,
+			    CSR_GP_CNTRL_REG_FLAG_INIT_DONE);
+
+		/* and wait for clock stabilization */
+		if (trans->cfg->device_family == IWL_DEVICE_FAMILY_8000)
+			udelay(2);
+
+		err = iwl_poll_bit(trans, CSR_GP_CNTRL,
+				   CSR_GP_CNTRL_REG_FLAG_MAC_CLOCK_READY,
+				   CSR_GP_CNTRL_REG_FLAG_MAC_CLOCK_READY,
+				   25000);
+		if (err < 0) {
+			IWL_DEBUG_INFO(trans,
+				       "Failed to reset the card for the dump\n");
+			return;
+		}
+	}
+
 	iwl_trans_read_mem_bytes(trans, base, &table, sizeof(table));
 
 	if (ERROR_START_OFFSET <= table.valid * ERROR_ELEM_SIZE) {