In some SoCs (observed on the STM32MP15) the M_CAN IP core keeps the
CAN state and CAN error counters over an internal reset cycle. The
STM32MP15 SoC provides an external reset, which is shared between both
M_CAN cores.
Add support for an optional external reset. Take care of shared
resets, de-assert reset during the probe phase in
m_can_class_register() and while the interface is up, assert the reset
otherwise.
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
---
drivers/net/can/m_can/m_can.c | 26 +++++++++++++++++++++++---
drivers/net/can/m_can/m_can.h | 1 +
2 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
index 9528af8500af..93085bf1c267 100644
--- a/drivers/net/can/m_can/m_can.c
+++ b/drivers/net/can/m_can/m_can.c
@@ -23,6 +23,7 @@
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
+#include <linux/reset.h>
#include "m_can.h"
@@ -1834,6 +1835,7 @@ static int m_can_close(struct net_device *dev)
close_candev(dev);
+ reset_control_assert(cdev->rst);
m_can_clk_stop(cdev);
phy_power_off(cdev->transceiver);
@@ -2076,11 +2078,15 @@ static int m_can_open(struct net_device *dev)
if (err)
goto out_phy_power_off;
+ err = reset_control_deassert(cdev->rst);
+ if (err)
+ goto exit_disable_clks;
+
/* open the can device */
err = open_candev(dev);
if (err) {
netdev_err(dev, "failed to open can device\n");
- goto exit_disable_clks;
+ goto out_reset_control_assert;
}
if (cdev->is_peripheral)
@@ -2136,6 +2142,8 @@ static int m_can_open(struct net_device *dev)
else
napi_disable(&cdev->napi);
close_candev(dev);
+out_reset_control_assert:
+ reset_control_assert(cdev->rst);
exit_disable_clks:
m_can_clk_stop(cdev);
out_phy_power_off:
@@ -2426,15 +2434,23 @@ int m_can_class_register(struct m_can_classdev *cdev)
}
}
+ cdev->rst = devm_reset_control_get_optional_shared(cdev->dev, NULL);
+ if (IS_ERR(cdev->rst))
+ return PTR_ERR(cdev->rst);
+
ret = m_can_clk_start(cdev);
if (ret)
return ret;
+ ret = reset_control_deassert(cdev->rst);
+ if (ret)
+ goto clk_disable;
+
if (cdev->is_peripheral) {
ret = can_rx_offload_add_manual(cdev->net, &cdev->offload,
NAPI_POLL_WEIGHT);
if (ret)
- goto clk_disable;
+ goto out_reset_control_assert;
}
if (!cdev->net->irq) {
@@ -2463,8 +2479,10 @@ int m_can_class_register(struct m_can_classdev *cdev)
KBUILD_MODNAME, cdev->net->irq, cdev->version);
/* Probe finished
- * Stop clocks. They will be reactivated once the M_CAN device is opened
+ * Assert reset and stop clocks.
+ * They will be reactivated once the M_CAN device is opened
*/
+ reset_control_assert(cdev->rst);
m_can_clk_stop(cdev);
return 0;
@@ -2472,6 +2490,8 @@ int m_can_class_register(struct m_can_classdev *cdev)
rx_offload_del:
if (cdev->is_peripheral)
can_rx_offload_del(&cdev->offload);
+out_reset_control_assert:
+ reset_control_assert(cdev->rst);
clk_disable:
m_can_clk_stop(cdev);
diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
index bd4746c63af3..7b7600697c6b 100644
--- a/drivers/net/can/m_can/m_can.h
+++ b/drivers/net/can/m_can/m_can.h
@@ -86,6 +86,7 @@ struct m_can_classdev {
struct device *dev;
struct clk *hclk;
struct clk *cclk;
+ struct reset_control *rst;
struct workqueue_struct *tx_wq;
struct phy *transceiver;
--
2.51.0On Tue Sep 9, 2025 at 7:53 PM CEST, Marc Kleine-Budde wrote:
> In some SoCs (observed on the STM32MP15) the M_CAN IP core keeps the
> CAN state and CAN error counters over an internal reset cycle. The
> STM32MP15 SoC provides an external reset, which is shared between both
> M_CAN cores.
>
> Add support for an optional external reset. Take care of shared
> resets, de-assert reset during the probe phase in
> m_can_class_register() and while the interface is up, assert the reset
> otherwise.
>
> Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
> Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
> ---
> drivers/net/can/m_can/m_can.c | 26 +++++++++++++++++++++++---
> drivers/net/can/m_can/m_can.h | 1 +
> 2 files changed, 24 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c
> index 9528af8500af..93085bf1c267 100644
> --- a/drivers/net/can/m_can/m_can.c
> +++ b/drivers/net/can/m_can/m_can.c
> @@ -23,6 +23,7 @@
> #include <linux/pinctrl/consumer.h>
> #include <linux/platform_device.h>
> #include <linux/pm_runtime.h>
> +#include <linux/reset.h>
>
> #include "m_can.h"
>
> @@ -1834,6 +1835,7 @@ static int m_can_close(struct net_device *dev)
>
> close_candev(dev);
>
> + reset_control_assert(cdev->rst);
> m_can_clk_stop(cdev);
> phy_power_off(cdev->transceiver);
>
> @@ -2076,11 +2078,15 @@ static int m_can_open(struct net_device *dev)
> if (err)
> goto out_phy_power_off;
>
> + err = reset_control_deassert(cdev->rst);
> + if (err)
> + goto exit_disable_clks;
> +
> /* open the can device */
> err = open_candev(dev);
> if (err) {
> netdev_err(dev, "failed to open can device\n");
> - goto exit_disable_clks;
> + goto out_reset_control_assert;
> }
>
> if (cdev->is_peripheral)
> @@ -2136,6 +2142,8 @@ static int m_can_open(struct net_device *dev)
> else
> napi_disable(&cdev->napi);
> close_candev(dev);
> +out_reset_control_assert:
> + reset_control_assert(cdev->rst);
> exit_disable_clks:
> m_can_clk_stop(cdev);
> out_phy_power_off:
> @@ -2426,15 +2434,23 @@ int m_can_class_register(struct m_can_classdev *cdev)
> }
> }
>
> + cdev->rst = devm_reset_control_get_optional_shared(cdev->dev, NULL);
> + if (IS_ERR(cdev->rst))
> + return PTR_ERR(cdev->rst);
Should this print an error message here?
Best
Markus
> +
> ret = m_can_clk_start(cdev);
> if (ret)
> return ret;
>
> + ret = reset_control_deassert(cdev->rst);
> + if (ret)
> + goto clk_disable;
> +
> if (cdev->is_peripheral) {
> ret = can_rx_offload_add_manual(cdev->net, &cdev->offload,
> NAPI_POLL_WEIGHT);
> if (ret)
> - goto clk_disable;
> + goto out_reset_control_assert;
> }
>
> if (!cdev->net->irq) {
> @@ -2463,8 +2479,10 @@ int m_can_class_register(struct m_can_classdev *cdev)
> KBUILD_MODNAME, cdev->net->irq, cdev->version);
>
> /* Probe finished
> - * Stop clocks. They will be reactivated once the M_CAN device is opened
> + * Assert reset and stop clocks.
> + * They will be reactivated once the M_CAN device is opened
> */
> + reset_control_assert(cdev->rst);
> m_can_clk_stop(cdev);
>
> return 0;
> @@ -2472,6 +2490,8 @@ int m_can_class_register(struct m_can_classdev *cdev)
> rx_offload_del:
> if (cdev->is_peripheral)
> can_rx_offload_del(&cdev->offload);
> +out_reset_control_assert:
> + reset_control_assert(cdev->rst);
> clk_disable:
> m_can_clk_stop(cdev);
>
> diff --git a/drivers/net/can/m_can/m_can.h b/drivers/net/can/m_can/m_can.h
> index bd4746c63af3..7b7600697c6b 100644
> --- a/drivers/net/can/m_can/m_can.h
> +++ b/drivers/net/can/m_can/m_can.h
> @@ -86,6 +86,7 @@ struct m_can_classdev {
> struct device *dev;
> struct clk *hclk;
> struct clk *cclk;
> + struct reset_control *rst;
>
> struct workqueue_struct *tx_wq;
> struct phy *transceiver;
On 10.09.2025 11:32:04, Markus Schneider-Pargmann wrote: > > diff --git a/drivers/net/can/m_can/m_can.c b/drivers/net/can/m_can/m_can.c > > index 9528af8500af..93085bf1c267 100644 > > --- a/drivers/net/can/m_can/m_can.c > > +++ b/drivers/net/can/m_can/m_can.c [...] > > + cdev->rst = devm_reset_control_get_optional_shared(cdev->dev, NULL); > > + if (IS_ERR(cdev->rst)) > > + return PTR_ERR(cdev->rst); > > Should this print an error message here? makes sense regards, Marc -- Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung Nürnberg | Phone: +49-5121-206917-129 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
© 2016 - 2025 Red Hat, Inc.