[3.11.y.z extended stable] Patch "can: flexcan: fix transition from and to freeze mode in" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    can: flexcan: fix transition from and to freeze mode in

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 426471b713c453657dcb7831febc55c632dab680 Mon Sep 17 00:00:00 2001
From: Marc Kleine-Budde <mkl at pengutronix.de>
Date: Fri, 28 Feb 2014 17:08:21 +0100
Subject: can: flexcan: fix transition from and to freeze mode in
 chip_{,un}freeze

commit b1aa1c7a2165b44ecce66286a3095cc6c7667d1c upstream.

This patch factors out freeze and unfreeze of the CAN core into seperate
functions. Experiments have shown that the transition from and to freeze mode
may take several microseconds, especially the time entering the freeze mode
depends on the current bitrate.

This patch adds a while loop which polls the Freeze Mode ACK bit (FRZ_ACK) that
indicates a successfull mode change. If the function runs into a timeout a
error value is returned.

Signed-off-by: Marc Kleine-Budde <mkl at pengutronix.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/net/can/flexcan.c | 60 ++++++++++++++++++++++++++++++++++++++---------
 1 file changed, 49 insertions(+), 11 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index d065715..bc30fd1 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -322,6 +322,44 @@ static int flexcan_chip_disable(struct flexcan_priv *priv)
 	return 0;
 }

+static int flexcan_chip_freeze(struct flexcan_priv *priv)
+{
+	struct flexcan_regs __iomem *regs = priv->base;
+	unsigned int timeout = 1000 * 1000 * 10 / priv->can.bittiming.bitrate;
+	u32 reg;
+
+	reg = flexcan_read(&regs->mcr);
+	reg |= FLEXCAN_MCR_HALT;
+	flexcan_write(reg, &regs->mcr);
+
+	while (timeout-- && !(flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
+		usleep_range(100, 200);
+
+	if (!(flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
+static int flexcan_chip_unfreeze(struct flexcan_priv *priv)
+{
+	struct flexcan_regs __iomem *regs = priv->base;
+	unsigned int timeout = FLEXCAN_TIMEOUT_US / 10;
+	u32 reg;
+
+	reg = flexcan_read(&regs->mcr);
+	reg &= ~FLEXCAN_MCR_HALT;
+	flexcan_write(reg, &regs->mcr);
+
+	while (timeout-- && (flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK))
+		usleep_range(10, 20);
+
+	if (flexcan_read(&regs->mcr) & FLEXCAN_MCR_FRZ_ACK)
+		return -ETIMEDOUT;
+
+	return 0;
+}
+
 static int flexcan_get_berr_counter(const struct net_device *dev,
 				    struct can_berr_counter *bec)
 {
@@ -753,7 +791,7 @@ static int flexcan_chip_start(struct net_device *dev)
 		netdev_err(dev, "Failed to softreset can module (mcr=0x%08x)\n",
 			   reg_mcr);
 		err = -ENODEV;
-		goto out;
+		goto out_chip_disable;
 	}

 	flexcan_set_bittiming(dev);
@@ -823,12 +861,12 @@ static int flexcan_chip_start(struct net_device *dev)

 	err = flexcan_transceiver_enable(priv);
 	if (err)
-		goto out;
+		goto out_chip_disable;

 	/* synchronize with the can bus */
-	reg_mcr = flexcan_read(&regs->mcr);
-	reg_mcr &= ~FLEXCAN_MCR_HALT;
-	flexcan_write(reg_mcr, &regs->mcr);
+	err = flexcan_chip_unfreeze(priv);
+	if (err)
+		goto out_transceiver_disable;

 	priv->can.state = CAN_STATE_ERROR_ACTIVE;

@@ -841,7 +879,9 @@ static int flexcan_chip_start(struct net_device *dev)

 	return 0;

- out:
+ out_transceiver_disable:
+	flexcan_transceiver_disable(priv);
+ out_chip_disable:
 	flexcan_chip_disable(priv);
 	return err;
 }
@@ -856,12 +896,10 @@ static void flexcan_chip_stop(struct net_device *dev)
 {
 	struct flexcan_priv *priv = netdev_priv(dev);
 	struct flexcan_regs __iomem *regs = priv->base;
-	u32 reg;

-	/* Disable + halt module */
-	reg = flexcan_read(&regs->mcr);
-	reg |= FLEXCAN_MCR_MDIS | FLEXCAN_MCR_HALT;
-	flexcan_write(reg, &regs->mcr);
+	/* freeze + disable module */
+	flexcan_chip_freeze(priv);
+	flexcan_chip_disable(priv);

 	/* Disable all interrupts */
 	flexcan_write(0, &regs->imask1);
--
1.9.0