[PATCH v2] flexcan: disable bus error interrupts for the i.MX28

[PATCH v2] flexcan: disable bus error interrupts for the i.MX28

[Wolfgang Grandegger]

Due to a bug in most Flexcan cores, the bus error interrupt needs
to be enabled. Otherwise we don't get any error warning or passive
interrupts. This is _not_ necessary for the i.MX28 and this patch
disables bus error interrupts if "berr-reporting" is not requested.
This avoids bus error flooding, which might harm, especially on
low-end systems.

To handle such quirks of the Flexcan cores, a hardware feature flag
has been introduced, also replacing the "hw_ver" variable. We got
some version info about what Flexcan core version is available on
what Freescale SOC which have been summarized as comment.

Changes since v1:

- add known version info and hw bugs as comment
- remove FLEXCAN_HAS_BROKEN_ERR_STATE for i.MX6Q

CC: Hui Wang <jason77.wang@gmail.com>
CC: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 drivers/net/can/flexcan.c |   42 ++++++++++++++++++++++++++++++++----------
 1 files changed, 32 insertions(+), 10 deletions(-)

diff --git a/drivers/net/can/flexcan.c b/drivers/net/can/flexcan.c
index c5f1431..f07128b 100644
--- a/drivers/net/can/flexcan.c
+++ b/drivers/net/can/flexcan.c
@@ -144,6 +144,23 @@
 
 #define FLEXCAN_MB_CODE_MASK		(0xf0ffffff)
 
+/*
+ * FLEXCAN hardware feature flags
+ *
+ * Below is some version info we got:
+ *    SOC   Version   IP-Version  Glitch-  [TR]WRN_INT
+ *                                Filter?   connected?
+ *   MX25  FlexCAN2  03.00.00.00     no         no
+ *   MX28  FlexCAN2  03.00.04.00    yes        yes
+ *   MX35  FlexCAN2  03.00.00.00     no         no
+ *   MX53  FlexCAN2  03.00.00.00    yes         no
+ *   MX6s  FlexCAN3  10.00.12.00     ?         yes
+ *
+ * Some SOCs do not have the RX_WARN & TX_WARN interrupt line connected.
+ */
+#define FLEXCAN_HAS_V10_FEATURES	BIT(1) /* For core version >= 10 */
+#define FLEXCAN_HAS_BROKEN_ERR_STATE	BIT(2) /* [TR]WRN_INT not connected */
+
 /* Structure of the message buffer */
 struct flexcan_mb {
 	u32 can_ctrl;
@@ -178,7 +195,7 @@ struct flexcan_regs {
 };
 
 struct flexcan_devtype_data {
-	u32 hw_ver;	/* hardware controller version */
+	u32 features;	/* hardware controller features */
 };
 
 struct flexcan_priv {
@@ -197,11 +214,11 @@ struct flexcan_priv {
 };
 
 static struct flexcan_devtype_data fsl_p1010_devtype_data = {
-	.hw_ver = 3,
+	.features = FLEXCAN_HAS_BROKEN_ERR_STATE,
 };
-
+static struct flexcan_devtype_data fsl_imx28_devtype_data;
 static struct flexcan_devtype_data fsl_imx6q_devtype_data = {
-	.hw_ver = 10,
+	.features = FLEXCAN_HAS_V10_FEATURES,
 };
 
 static const struct can_bittiming_const flexcan_bittiming_const = {
@@ -741,15 +758,19 @@ static int flexcan_chip_start(struct net_device *dev)
 	 * enable tx and rx warning interrupt
 	 * enable bus off interrupt
 	 * (== FLEXCAN_CTRL_ERR_STATE)
-	 *
-	 * _note_: we enable the "error interrupt"
-	 * (FLEXCAN_CTRL_ERR_MSK), too. Otherwise we don't get any
-	 * warning or bus passive interrupts.
 	 */
 	reg_ctrl = flexcan_read(&regs->ctrl);
 	reg_ctrl &= ~FLEXCAN_CTRL_TSYN;
 	reg_ctrl |= FLEXCAN_CTRL_BOFF_REC | FLEXCAN_CTRL_LBUF |
-		FLEXCAN_CTRL_ERR_STATE | FLEXCAN_CTRL_ERR_MSK;
+		FLEXCAN_CTRL_ERR_STATE;
+	/*
+	 * enable the "error interrupt" (FLEXCAN_CTRL_ERR_MSK),
+	 * on most Flexcan cores, too. Otherwise we don't get
+	 * any error warning or passive interrupts.
+	 */
+	if (priv->devtype_data->features & FLEXCAN_HAS_BROKEN_ERR_STATE ||
+	    priv->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)
+		reg_ctrl |= FLEXCAN_CTRL_ERR_MSK;
 
 	/* save for later use */
 	priv->reg_ctrl_default = reg_ctrl;
@@ -772,7 +793,7 @@ static int flexcan_chip_start(struct net_device *dev)
 	flexcan_write(0x0, &regs->rx14mask);
 	flexcan_write(0x0, &regs->rx15mask);
 
-	if (priv->devtype_data->hw_ver >= 10)
+	if (priv->devtype_data->features & FLEXCAN_HAS_V10_FEATURES)
 		flexcan_write(0x0, &regs->rxfgmask);
 
 	flexcan_transceiver_switch(priv, 1);
@@ -954,6 +975,7 @@ static void __devexit unregister_flexcandev(struct net_device *dev)
 
 static const struct of_device_id flexcan_of_match[] = {
 	{ .compatible = "fsl,p1010-flexcan", .data = &fsl_p1010_devtype_data, },
+	{ .compatible = "fsl,imx28-flexcan", .data = &fsl_imx28_devtype_data, },
 	{ .compatible = "fsl,imx6q-flexcan", .data = &fsl_imx6q_devtype_data, },
 	{ /* sentinel */ },
 };
-- 
1.7.7.6

Re: [PATCH v2] flexcan: disable bus error interrupts for the i.MX28

[Marc Kleine-Budde]

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On 10/10/2012 09:10 PM, Wolfgang Grandegger wrote:
> Due to a bug in most Flexcan cores, the bus error interrupt needs
> to be enabled. Otherwise we don't get any error warning or passive
> interrupts. This is _not_ necessary for the i.MX28 and this patch
                                                   ^^^ and i.MX6q

No need to resend the patch, I'll change this while applying the patch.

> disables bus error interrupts if "berr-reporting" is not requested.
> This avoids bus error flooding, which might harm, especially on
> low-end systems.
> 
> To handle such quirks of the Flexcan cores, a hardware feature flag
> has been introduced, also replacing the "hw_ver" variable. We got
> some version info about what Flexcan core version is available on
> what Freescale SOC which have been summarized as comment.
> 
> Changes since v1:
> 
> - add known version info and hw bugs as comment
> - remove FLEXCAN_HAS_BROKEN_ERR_STATE for i.MX6Q

From my point of view, this should go into linux-can.

Marc
-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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Re: [PATCH v2] flexcan: disable bus error interrupts for the i.MX28

[Marc Kleine-Budde]

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On 10/10/2012 09:10 PM, Wolfgang Grandegger wrote:
> Due to a bug in most Flexcan cores, the bus error interrupt needs
> to be enabled. Otherwise we don't get any error warning or passive
> interrupts. This is _not_ necessary for the i.MX28 and this patch
> disables bus error interrupts if "berr-reporting" is not requested.
> This avoids bus error flooding, which might harm, especially on
> low-end systems.
> 
> To handle such quirks of the Flexcan cores, a hardware feature flag
> has been introduced, also replacing the "hw_ver" variable. We got
> some version info about what Flexcan core version is available on
> what Freescale SOC which have been summarized as comment.
> 
> Changes since v1:
> 
> - add known version info and hw bugs as comment
> - remove FLEXCAN_HAS_BROKEN_ERR_STATE for i.MX6Q

David was quick in applying the v1 version of this patch into his tree
directly. Wolfgang can you send an incremental patch? Please change the
list of can cores, according to Dong Aisheng, the mx6 has a glitch
filter, too.

regards, Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |


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