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can: m_can: add support for optional reset

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This patch has been split from the original series [1].

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.

[1] https://lore.kernel.org/all/20250923-m_can-fix-state-handling-v3-0-06d8baccadbf@pengutronix.de

Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: Markus Schneider-Pargmann <msp@baylibre.com>
Link: https://patch.msgid.link/20251008-m_can-add-reset-v1-1-49f0bbf820c4@pengutronix.de
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
This commit is contained in:
Marc Kleine-Budde 2025-08-06 11:38:07 +02:00
parent 7e0d4c1113
commit 9271d0ea07
2 changed files with 25 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

27
drivers/net/can/m_can/m_can.c
View File

@ -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"
@ -1827,6 +1828,7 @@ 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);
@ -2069,11 +2071,15 @@ 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)
@ -2129,6 +2135,8 @@ 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:
@ -2417,15 +2425,24 @@ 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 dev_err_probe(cdev->dev, PTR_ERR(cdev->rst),
"Failed to get reset line\n");
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) {
@ -2454,8 +2471,10 @@ 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;
@ -2463,6 +2482,8 @@ 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);

1
drivers/net/can/m_can/m_can.h
View File

@ -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;