can: at91_can: make can_id of mailbox 0 configurable
Due to a chip bug (errata 50.2.6.3 & 50.3.5.3 in
"AT91SAM9263 Preliminary 6249H-ATARM-27-Jul-09") the contents of mailbox
0 may be send under certain conditions (even if disabled or in rx mode).
The workaround in the errata suggests not to use the mailbox and load it
with an unused identifier.
This patch implements the second part of the workaround. A sysfs entry
"mb0_id" is introduced. While the interface is down it can be used to
configure the can_id of mailbox 0. The default value id 0x7ff.
In order to use an extended can_id add the CAN_EFF_FLAG (0x80000000U)
to the can_id. Example:
- standard id 0x7ff:
echo 0x7ff > /sys/class/net/can0/mb0_id
- extended id 0x1fffffff:
echo 0x9fffffff > /sys/class/net/can0/mb0_id
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Acked-by: Kurt Van Dijck <kurt.van.dijck@eia.be>
For the Documentation-part:
Acked-by: Wolfram Sang <w.sang@pengutronix.de>
diff --git a/drivers/net/can/at91_can.c b/drivers/net/can/at91_can.c
index 16e45a5..2532b96 100644
--- a/drivers/net/can/at91_can.c
+++ b/drivers/net/can/at91_can.c
@@ -30,6 +30,7 @@
#include <linux/module.h>
#include <linux/netdevice.h>
#include <linux/platform_device.h>
+#include <linux/rtnetlink.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/string.h>
@@ -169,6 +170,8 @@
struct clk *clk;
struct at91_can_data *pdata;
+
+ canid_t mb0_id;
};
static struct can_bittiming_const at91_bittiming_const = {
@@ -221,6 +224,18 @@
set_mb_mode_prio(priv, mb, mode, 0);
}
+static inline u32 at91_can_id_to_reg_mid(canid_t can_id)
+{
+ u32 reg_mid;
+
+ if (can_id & CAN_EFF_FLAG)
+ reg_mid = (can_id & CAN_EFF_MASK) | AT91_MID_MIDE;
+ else
+ reg_mid = (can_id & CAN_SFF_MASK) << 18;
+
+ return reg_mid;
+}
+
/*
* Swtich transceiver on or off
*/
@@ -234,6 +249,7 @@
{
struct at91_priv *priv = netdev_priv(dev);
unsigned int i;
+ u32 reg_mid;
/*
* Due to a chip bug (errata 50.2.6.3 & 50.3.5.3) the first
@@ -242,8 +258,13 @@
* overwrite option. The overwrite flag indicates a FIFO
* overflow.
*/
- for (i = 0; i < AT91_MB_RX_FIRST; i++)
+ reg_mid = at91_can_id_to_reg_mid(priv->mb0_id);
+ for (i = 0; i < AT91_MB_RX_FIRST; i++) {
set_mb_mode(priv, i, AT91_MB_MODE_DISABLED);
+ at91_write(priv, AT91_MID(i), reg_mid);
+ at91_write(priv, AT91_MCR(i), 0x0); /* clear dlc */
+ }
+
for (i = AT91_MB_RX_FIRST; i < AT91_MB_RX_LAST; i++)
set_mb_mode(priv, i, AT91_MB_MODE_RX);
set_mb_mode(priv, AT91_MB_RX_LAST, AT91_MB_MODE_RX_OVRWR);
@@ -378,12 +399,7 @@
netdev_err(dev, "BUG! TX buffer full when queue awake!\n");
return NETDEV_TX_BUSY;
}
-
- if (cf->can_id & CAN_EFF_FLAG)
- reg_mid = (cf->can_id & CAN_EFF_MASK) | AT91_MID_MIDE;
- else
- reg_mid = (cf->can_id & CAN_SFF_MASK) << 18;
-
+ reg_mid = at91_can_id_to_reg_mid(cf->can_id);
reg_mcr = ((cf->can_id & CAN_RTR_FLAG) ? AT91_MCR_MRTR : 0) |
(cf->can_dlc << 16) | AT91_MCR_MTCR;
@@ -1047,6 +1063,64 @@
.ndo_start_xmit = at91_start_xmit,
};
+static ssize_t at91_sysfs_show_mb0_id(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct at91_priv *priv = netdev_priv(to_net_dev(dev));
+
+ if (priv->mb0_id & CAN_EFF_FLAG)
+ return snprintf(buf, PAGE_SIZE, "0x%08x\n", priv->mb0_id);
+ else
+ return snprintf(buf, PAGE_SIZE, "0x%03x\n", priv->mb0_id);
+}
+
+static ssize_t at91_sysfs_set_mb0_id(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct net_device *ndev = to_net_dev(dev);
+ struct at91_priv *priv = netdev_priv(ndev);
+ unsigned long can_id;
+ ssize_t ret;
+ int err;
+
+ rtnl_lock();
+
+ if (ndev->flags & IFF_UP) {
+ ret = -EBUSY;
+ goto out;
+ }
+
+ err = strict_strtoul(buf, 0, &can_id);
+ if (err) {
+ ret = err;
+ goto out;
+ }
+
+ if (can_id & CAN_EFF_FLAG)
+ can_id &= CAN_EFF_MASK | CAN_EFF_FLAG;
+ else
+ can_id &= CAN_SFF_MASK;
+
+ priv->mb0_id = can_id;
+ ret = count;
+
+ out:
+ rtnl_unlock();
+ return ret;
+}
+
+static DEVICE_ATTR(mb0_id, S_IWUGO | S_IRUGO,
+ at91_sysfs_show_mb0_id, at91_sysfs_set_mb0_id);
+
+static struct attribute *at91_sysfs_attrs[] = {
+ &dev_attr_mb0_id.attr,
+ NULL,
+};
+
+static struct attribute_group at91_sysfs_attr_group = {
+ .attrs = at91_sysfs_attrs,
+};
+
static int __devinit at91_can_probe(struct platform_device *pdev)
{
struct net_device *dev;
@@ -1092,6 +1166,7 @@
dev->netdev_ops = &at91_netdev_ops;
dev->irq = irq;
dev->flags |= IFF_ECHO;
+ dev->sysfs_groups[0] = &at91_sysfs_attr_group;
priv = netdev_priv(dev);
priv->can.clock.freq = clk_get_rate(clk);
@@ -1103,6 +1178,7 @@
priv->dev = dev;
priv->clk = clk;
priv->pdata = pdev->dev.platform_data;
+ priv->mb0_id = 0x7ff;
netif_napi_add(dev, &priv->napi, at91_poll, AT91_NAPI_WEIGHT);