* [PATCH v5 1/4] can: dev: Add support for limiting configured bitrate
2017-08-18 20:21 [PATCH v5 0/4] can: Support transceiver based bit rate limit Franklin S Cooper Jr
@ 2017-08-18 20:21 ` Franklin S Cooper Jr
[not found] ` <20170818202137.29816-1-fcooper-l0cyMroinI0@public.gmane.org>
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Franklin S Cooper Jr @ 2017-08-18 20:21 UTC (permalink / raw)
To: linux-kernel, devicetree, netdev, linux-can, wg, mkl, robh+dt,
quentin.schulz, dev.kurt, andrew, sergei.shtylyov, socketcan
Cc: Franklin S Cooper Jr
Various CAN or CAN-FD IP may be able to run at a faster rate than
what the transceiver the CAN node is connected to. This can lead to
unexpected errors. However, CAN transceivers typically have fixed
limitations and provide no means to discover these limitations at
runtime. Therefore, add support for a can-transceiver node that
can be reused by other CAN peripheral drivers to determine for both
CAN and CAN-FD what the max bitrate that can be used. If the user
tries to configure CAN to pass these maximum bitrates it will throw
an error.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
---
Version 5 changes:
Set values for some variables at the very top.
Remove usage of is_bitrate_limited
drivers/net/can/dev.c | 39 +++++++++++++++++++++++++++++++++++++++
include/linux/can/dev.h | 4 ++++
2 files changed, 43 insertions(+)
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 365a8cc..d0e5b46 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -27,6 +27,7 @@
#include <linux/can/skb.h>
#include <linux/can/netlink.h>
#include <linux/can/led.h>
+#include <linux/of.h>
#include <net/rtnetlink.h>
#define MOD_DESC "CAN device driver interface"
@@ -814,6 +815,30 @@ int open_candev(struct net_device *dev)
}
EXPORT_SYMBOL_GPL(open_candev);
+#ifdef CONFIG_OF
+/*
+ * Common function that can be used to understand the limitation of
+ * a transceiver when it provides no means to determine these limitations
+ * at runtime.
+ */
+void of_can_transceiver(struct net_device *dev)
+{
+ struct device_node *dn;
+ struct can_priv *priv = netdev_priv(dev);
+ struct device_node *np = dev->dev.parent->of_node;
+ int ret;
+
+ dn = of_get_child_by_name(np, "can-transceiver");
+ if (!dn)
+ return;
+
+ ret = of_property_read_u32(dn, "max-bitrate", &priv->max_bitrate);
+ if ((ret && ret != -EINVAL) || (!ret && !priv->max_bitrate))
+ netdev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit.\n");
+}
+EXPORT_SYMBOL(of_can_transceiver);
+#endif
+
/*
* Common close function for cleanup before the device gets closed.
*
@@ -913,6 +938,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
priv->bitrate_const_cnt);
if (err)
return err;
+
+ if (priv->max_bitrate && bt.bitrate > priv->max_bitrate) {
+ netdev_err(dev, "arbitration bitrate surpasses transceiver capabilities of %d bps\n",
+ priv->max_bitrate);
+ return -EINVAL;
+ }
+
memcpy(&priv->bittiming, &bt, sizeof(bt));
if (priv->do_set_bittiming) {
@@ -997,6 +1029,13 @@ static int can_changelink(struct net_device *dev, struct nlattr *tb[],
priv->data_bitrate_const_cnt);
if (err)
return err;
+
+ if (priv->max_bitrate && dbt.bitrate > priv->max_bitrate) {
+ netdev_err(dev, "canfd data bitrate surpasses transceiver capabilities of %d bps\n",
+ priv->max_bitrate);
+ return -EINVAL;
+ }
+
memcpy(&priv->data_bittiming, &dbt, sizeof(dbt));
if (priv->do_set_data_bittiming) {
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 141b05a..0063c51 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -47,6 +47,8 @@ struct can_priv {
unsigned int data_bitrate_const_cnt;
struct can_clock clock;
+ unsigned int max_bitrate;
+
enum can_state state;
/* CAN controller features - see include/uapi/linux/can/netlink.h */
@@ -165,6 +167,8 @@ void can_put_echo_skb(struct sk_buff *skb, struct net_device *dev,
unsigned int can_get_echo_skb(struct net_device *dev, unsigned int idx);
void can_free_echo_skb(struct net_device *dev, unsigned int idx);
+void of_can_transceiver(struct net_device *dev);
+
struct sk_buff *alloc_can_skb(struct net_device *dev, struct can_frame **cf);
struct sk_buff *alloc_canfd_skb(struct net_device *dev,
struct canfd_frame **cfd);
--
2.9.4.dirty
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v5 3/4] dt-bindings: can: m_can: Document new can transceiver binding
2017-08-18 20:21 [PATCH v5 0/4] can: Support transceiver based bit rate limit Franklin S Cooper Jr
2017-08-18 20:21 ` [PATCH v5 1/4] can: dev: Add support for limiting configured bitrate Franklin S Cooper Jr
[not found] ` <20170818202137.29816-1-fcooper-l0cyMroinI0@public.gmane.org>
@ 2017-08-18 20:21 ` Franklin S Cooper Jr
2017-08-18 20:21 ` [PATCH v5 4/4] can: m_can: Add call to of_can_transceiver Franklin S Cooper Jr
3 siblings, 0 replies; 5+ messages in thread
From: Franklin S Cooper Jr @ 2017-08-18 20:21 UTC (permalink / raw)
To: linux-kernel, devicetree, netdev, linux-can, wg, mkl, robh+dt,
quentin.schulz, dev.kurt, andrew, sergei.shtylyov, socketcan
Cc: Franklin S Cooper Jr
Add information regarding can-transceiver binding. This is especially
important for MCAN since the IP allows CAN FD mode to run significantly
faster than what most transceivers are capable of.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
---
Remove @ symbol from can-transceiver example
Documentation/devicetree/bindings/net/can/m_can.txt | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/Documentation/devicetree/bindings/net/can/m_can.txt b/Documentation/devicetree/bindings/net/can/m_can.txt
index 9e33177..0bdae2a 100644
--- a/Documentation/devicetree/bindings/net/can/m_can.txt
+++ b/Documentation/devicetree/bindings/net/can/m_can.txt
@@ -43,6 +43,11 @@ Required properties:
Please refer to 2.4.1 Message RAM Configuration in
Bosch M_CAN user manual for details.
+Optional Subnode:
+- can-transceiver : Can-transceiver subnode describing maximum speed
+ that can be used for CAN/CAN-FD modes. See
+ Documentation/devicetree/bindings/net/can/can-transceiver.txt
+ for details.
Example:
SoC dtsi:
m_can1: can@020e8000 {
@@ -64,4 +69,8 @@ Board dts:
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_m_can1>;
status = "enabled";
+
+ can-transceiver {
+ max-bitrate = <5000000>;
+ };
};
--
2.9.4.dirty
^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v5 4/4] can: m_can: Add call to of_can_transceiver
2017-08-18 20:21 [PATCH v5 0/4] can: Support transceiver based bit rate limit Franklin S Cooper Jr
` (2 preceding siblings ...)
2017-08-18 20:21 ` [PATCH v5 3/4] dt-bindings: can: m_can: Document new can transceiver binding Franklin S Cooper Jr
@ 2017-08-18 20:21 ` Franklin S Cooper Jr
3 siblings, 0 replies; 5+ messages in thread
From: Franklin S Cooper Jr @ 2017-08-18 20:21 UTC (permalink / raw)
To: linux-kernel, devicetree, netdev, linux-can, wg, mkl, robh+dt,
quentin.schulz, dev.kurt, andrew, sergei.shtylyov, socketcan
Cc: Franklin S Cooper Jr
Add call to new generic functions that provides support via a binding
to limit the arbitration rate and/or data rate imposed by the physical
transceiver connected to the MCAN peripheral.
Signed-off-by: Franklin S Cooper Jr <fcooper@ti.com>
---
drivers/net/can/m_can/m_can.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index f4947a7..f72116e 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -1649,6 +1649,8 @@ static int m_can_plat_probe(struct platform_device *pdev)
devm_can_led_init(dev);
+ of_can_transceiver(dev);
+
dev_info(&pdev->dev, "%s device registered (irq=%d, version=%d)\n",
KBUILD_MODNAME, dev->irq, priv->version);
--
2.9.4.dirty
^ permalink raw reply related [flat|nested] 5+ messages in thread