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From:   minyard@acm.org
To:     Andrew Banman <abanman@hpe.com>
Cc:     openipmi-developer@lists.sourceforge.net,
        linux-kernel@vger.kernel.org, rja@hpe.com, frank.ramsay@hpe.com,
        justin.ernst@hpe.com, Corey Minyard <cminyard@mvista.com>
Subject: [PATCH 1/2] ipmi: Move BT capabilities detection to the detect call
Date:   Thu, 23 Aug 2018 15:37:02 -0500
Message-Id: <1535056623-26634-2-git-send-email-minyard@acm.org>
In-Reply-To: <1535056623-26634-1-git-send-email-minyard@acm.org>
References: <1535056623-26634-1-git-send-email-minyard@acm.org>
Sender: linux-kernel-owner@vger.kernel.org
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From: Corey Minyard <cminyard@mvista.com>

The capabilities detection was being done as part of the normal
state machine, but it was possible for it to be running while
the upper layers of the IPMI driver were initializing the
device, resulting in error and failure to initialize.

Move the capabilities detection to the the detect function,
so it's done before anything else runs on the device.  This also
simplifies the state machine and removes some code, as a bonus.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
Reported-by: Andrew Banman <abanman@hpe.com>
---
 drivers/char/ipmi/ipmi_bt_sm.c | 92 ++++++++++++++++++++++--------------------
 1 file changed, 48 insertions(+), 44 deletions(-)

diff --git a/drivers/char/ipmi/ipmi_bt_sm.c b/drivers/char/ipmi/ipmi_bt_sm.c
index cbc6126..b4133832e 100644
--- a/drivers/char/ipmi/ipmi_bt_sm.c
+++ b/drivers/char/ipmi/ipmi_bt_sm.c
@@ -59,8 +59,6 @@ enum bt_states {
 	BT_STATE_RESET3,
 	BT_STATE_RESTART,
 	BT_STATE_PRINTME,
-	BT_STATE_CAPABILITIES_BEGIN,
-	BT_STATE_CAPABILITIES_END,
 	BT_STATE_LONG_BUSY	/* BT doesn't get hosed :-) */
 };
 
@@ -86,7 +84,6 @@ struct si_sm_data {
 	int		error_retries;	/* end of "common" fields */
 	int		nonzero_status;	/* hung BMCs stay all 0 */
 	enum bt_states	complete;	/* to divert the state machine */
-	int		BT_CAP_outreqs;
 	long		BT_CAP_req2rsp;
 	int		BT_CAP_retries;	/* Recommended retries */
 };
@@ -137,8 +134,6 @@ static char *state2txt(unsigned char state)
 	case BT_STATE_RESET3:		return("RESET3");
 	case BT_STATE_RESTART:		return("RESTART");
 	case BT_STATE_LONG_BUSY:	return("LONG_BUSY");
-	case BT_STATE_CAPABILITIES_BEGIN: return("CAP_BEGIN");
-	case BT_STATE_CAPABILITIES_END:	return("CAP_END");
 	}
 	return("BAD STATE");
 }
@@ -185,7 +180,6 @@ static unsigned int bt_init_data(struct si_sm_data *bt, struct si_sm_io *io)
 	bt->complete = BT_STATE_IDLE;	/* end here */
 	bt->BT_CAP_req2rsp = BT_NORMAL_TIMEOUT * USEC_PER_SEC;
 	bt->BT_CAP_retries = BT_NORMAL_RETRY_LIMIT;
-	/* BT_CAP_outreqs == zero is a flag to read BT Capabilities */
 	return 3; /* We claim 3 bytes of space; ought to check SPMI table */
 }
 
@@ -447,7 +441,7 @@ static enum si_sm_result error_recovery(struct si_sm_data *bt,
 
 static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
 {
-	unsigned char status, BT_CAP[8];
+	unsigned char status;
 	static enum bt_states last_printed = BT_STATE_PRINTME;
 	int i;
 
@@ -500,12 +494,6 @@ static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
 		if (status & BT_H_BUSY)		/* clear a leftover H_BUSY */
 			BT_CONTROL(BT_H_BUSY);
 
-		bt->timeout = bt->BT_CAP_req2rsp;
-
-		/* Read BT capabilities if it hasn't been done yet */
-		if (!bt->BT_CAP_outreqs)
-			BT_STATE_CHANGE(BT_STATE_CAPABILITIES_BEGIN,
-					SI_SM_CALL_WITHOUT_DELAY);
 		BT_SI_SM_RETURN(SI_SM_IDLE);
 
 	case BT_STATE_XACTION_START:
@@ -610,37 +598,6 @@ static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
 		BT_STATE_CHANGE(BT_STATE_XACTION_START,
 				SI_SM_CALL_WITH_DELAY);
 
-	/*
-	 * Get BT Capabilities, using timing of upper level state machine.
-	 * Set outreqs to prevent infinite loop on timeout.
-	 */
-	case BT_STATE_CAPABILITIES_BEGIN:
-		bt->BT_CAP_outreqs = 1;
-		{
-			unsigned char GetBT_CAP[] = { 0x18, 0x36 };
-			bt->state = BT_STATE_IDLE;
-			bt_start_transaction(bt, GetBT_CAP, sizeof(GetBT_CAP));
-		}
-		bt->complete = BT_STATE_CAPABILITIES_END;
-		BT_STATE_CHANGE(BT_STATE_XACTION_START,
-				SI_SM_CALL_WITH_DELAY);
-
-	case BT_STATE_CAPABILITIES_END:
-		i = bt_get_result(bt, BT_CAP, sizeof(BT_CAP));
-		bt_init_data(bt, bt->io);
-		if ((i == 8) && !BT_CAP[2]) {
-			bt->BT_CAP_outreqs = BT_CAP[3];
-			bt->BT_CAP_req2rsp = BT_CAP[6] * USEC_PER_SEC;
-			bt->BT_CAP_retries = BT_CAP[7];
-		} else
-			pr_warn("IPMI BT: using default values\n");
-		if (!bt->BT_CAP_outreqs)
-			bt->BT_CAP_outreqs = 1;
-		pr_warn("IPMI BT: req2rsp=%ld secs retries=%d\n",
-			bt->BT_CAP_req2rsp / USEC_PER_SEC, bt->BT_CAP_retries);
-		bt->timeout = bt->BT_CAP_req2rsp;
-		return SI_SM_CALL_WITHOUT_DELAY;
-
 	default:	/* should never occur */
 		return error_recovery(bt,
 				      status,
@@ -651,6 +608,11 @@ static enum si_sm_result bt_event(struct si_sm_data *bt, long time)
 
 static int bt_detect(struct si_sm_data *bt)
 {
+	unsigned char GetBT_CAP[] = { 0x18, 0x36 };
+	unsigned char BT_CAP[8];
+	enum si_sm_result smi_result;
+	int rv;
+
 	/*
 	 * It's impossible for the BT status and interrupt registers to be
 	 * all 1's, (assuming a properly functioning, self-initialized BMC)
@@ -661,6 +623,48 @@ static int bt_detect(struct si_sm_data *bt)
 	if ((BT_STATUS == 0xFF) && (BT_INTMASK_R == 0xFF))
 		return 1;
 	reset_flags(bt);
+
+	/*
+	 * Try getting the BT capabilities here.
+	 */
+	rv = bt_start_transaction(bt, GetBT_CAP, sizeof(GetBT_CAP));
+	if (rv) {
+		dev_warn(bt->io->dev,
+			 "Can't start capabilities transaction: %d\n", rv);
+		goto out_no_bt_cap;
+	}
+
+	smi_result = SI_SM_CALL_WITHOUT_DELAY;
+	for (;;) {
+		if (smi_result == SI_SM_CALL_WITH_DELAY ||
+		    smi_result == SI_SM_CALL_WITH_TICK_DELAY) {
+			schedule_timeout_uninterruptible(1);
+			smi_result = bt_event(bt, jiffies_to_usecs(1));
+		} else if (smi_result == SI_SM_CALL_WITHOUT_DELAY) {
+			smi_result = bt_event(bt, 0);
+		} else
+			break;
+	}
+
+	rv = bt_get_result(bt, BT_CAP, sizeof(BT_CAP));
+	bt_init_data(bt, bt->io);
+	if (rv < 8) {
+		dev_warn(bt->io->dev, "bt cap response too short: %d\n", rv);
+		goto out_no_bt_cap;
+	}
+
+	if (BT_CAP[2]) {
+		dev_warn(bt->io->dev, "Error fetching bt cap: %x\n", BT_CAP[2]);
+out_no_bt_cap:
+		dev_warn(bt->io->dev, "using default values\n");
+	} else {
+		bt->BT_CAP_req2rsp = BT_CAP[6] * USEC_PER_SEC;
+		bt->BT_CAP_retries = BT_CAP[7];
+	}
+
+	dev_info(bt->io->dev, "req2rsp=%ld secs retries=%d\n",
+		 bt->BT_CAP_req2rsp / USEC_PER_SEC, bt->BT_CAP_retries);
+
 	return 0;
 }
 
-- 
2.7.4