[PATCH 4/4] can: flexcan: add wakeup support for imx95

Frank Li
2024-07-11T18:20:37Z

From: Haibo Chen <haibo.chen@nxp.com>

iMX95 define a bit in GPR that assert/desert IPG_STOP signal to Flex CAN
module. It control flexcan enter STOP mode. Wakeup should work even FlexCAN
is in STOP mode.

Due to iMX95 architecture design, A-Core can't access GPR. Only the system
manager (SM) can config GPR. To support the wakeup feature, follow below
steps:

For suspend:

1) linux suspend, when CAN suspend, do nothing for GPR, and keep CAN
related clock on.
2) In ATF, check whether the CAN need to support wakeup, if yes, send a
request to SM through SCMI protocol.
3) In SM, config the GPR and assert IPG_STOP.
4) A-Core suspend.

For wakeup and resume:

1) A-core wakeup event arrive.
2) In SM, deassert IPG_STOP.
3) Linux resume.

Add a new fsl_imx95_devtype_data and FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI to
reflect this.

Reviewed-by: Han Xu <han.xu@nxp.com>
Signed-off-by: Haibo Chen <haibo.chen@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp.com>
---
drivers/net/can/flexcan/flexcan-core.c | 49 ++++++++++++++++++++++++++++++----
drivers/net/can/flexcan/flexcan.h | 2 ++
2 files changed, 46 insertions(+), 5 deletions(-)

diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c
index f6e609c388d55..ad3240e7e6ab4 100644
--- a/drivers/net/can/flexcan/flexcan-core.c
+++ b/drivers/net/can/flexcan/flexcan-core.c
@@ -354,6 +354,14 @@ static struct flexcan_devtype_data fsl_imx93_devtype_data = {
FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR,
};

+static struct flexcan_devtype_data fsl_imx95_devtype_data = {
+ .quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
+ FLEXCAN_QUIRK_DISABLE_MECR | FLEXCAN_QUIRK_USE_RX_MAILBOX |
+ FLEXCAN_QUIRK_BROKEN_PERR_STATE | FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI |
+ FLEXCAN_QUIRK_SUPPORT_FD | FLEXCAN_QUIRK_SUPPORT_ECC |
+ FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX |
+ FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR,
+};
static const struct flexcan_devtype_data fsl_vf610_devtype_data = {
.quirks = FLEXCAN_QUIRK_DISABLE_RXFG | FLEXCAN_QUIRK_ENABLE_EACEN_RRS |
FLEXCAN_QUIRK_DISABLE_MECR | FLEXCAN_QUIRK_USE_RX_MAILBOX |
@@ -548,6 +556,13 @@ static inline int flexcan_enter_stop_mode(struct flexcan_priv *priv)
} else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR) {
regmap_update_bits(priv->stm.gpr, priv->stm.req_gpr,
1 << priv->stm.req_bit, 1 << priv->stm.req_bit);
+ } else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI) {
+ /* For the SCMI mode, driver do nothing, ATF will send request to
+ * SM(system manager, M33 core) through SCMI protocol after linux
+ * suspend. Once SM get this request, it will send IPG_STOP signal
+ * to Flex_CAN, let CAN in STOP mode.
+ */
+ return 0;
}

return flexcan_low_power_enter_ack(priv);
@@ -559,7 +574,11 @@ static inline int flexcan_exit_stop_mode(struct flexcan_priv *priv)
u32 reg_mcr;
int ret;

- /* remove stop request */
+ /* Remove stop request, for FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI,
+ * do nothing here, because ATF already send request to SM before
+ * linux resume. Once SM get this request, it will deassert the
+ * IPG_STOP signal to Flex_CAN.
+ */
if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCFW) {
ret = flexcan_stop_mode_enable_scfw(priv, false);
if (ret < 0)
@@ -1987,6 +2006,9 @@ static int flexcan_setup_stop_mode(struct platform_device *pdev)
ret = flexcan_setup_stop_mode_scfw(pdev);
else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_GPR)
ret = flexcan_setup_stop_mode_gpr(pdev);
+ else if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)
+ /* ATF will handle all STOP_IPG related work */
+ ret = 0;
else
/* return 0 directly if doesn't support stop mode feature */
return 0;
@@ -2013,6 +2035,7 @@ static const struct of_device_id flexcan_of_match[] = {
{ .compatible = "fsl,imx8qm-flexcan", .data = &fsl_imx8qm_devtype_data, },
{ .compatible = "fsl,imx8mp-flexcan", .data = &fsl_imx8mp_devtype_data, },
{ .compatible = "fsl,imx93-flexcan", .data = &fsl_imx93_devtype_data, },
+ { .compatible = "fsl,imx95-flexcan", .data = &fsl_imx95_devtype_data, },
{ .compatible = "fsl,imx6q-flexcan", .data = &fsl_imx6q_devtype_data, },
{ .compatible = "fsl,imx28-flexcan", .data = &fsl_imx28_devtype_data, },
{ .compatible = "fsl,imx53-flexcan", .data = &fsl_imx25_devtype_data, },
@@ -2311,9 +2334,22 @@ static int __maybe_unused flexcan_noirq_suspend(struct device *device)
if (netif_running(dev)) {
int err;

- if (device_may_wakeup(device))
+ if (device_may_wakeup(device)) {
flexcan_enable_wakeup_irq(priv, true);

+ /* For FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI, it need
+ * ATF to send request to SM through SCMI protocol,
+ * SM will assert the IPG_STOP signal. But all this
+ * works need the CAN clocks keep on.
+ * After the CAN module get the IPG_STOP mode, and
+ * switch to STOP mode, whether still keep the CAN
+ * clocks on or gate them off depend on the Hardware
+ * design.
+ */
+ if (priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)
+ return 0;
+ }
+
err = pm_runtime_force_suspend(device);
if (err)
return err;
@@ -2330,9 +2366,12 @@ static int __maybe_unused flexcan_noirq_resume(struct device *device)
if (netif_running(dev)) {
int err;

- err = pm_runtime_force_resume(device);
- if (err)
- return err;
+ if (!(device_may_wakeup(device) &&
+ priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)) {
+ err = pm_runtime_force_resume(device);
+ if (err)
+ return err;
+ }

if (device_may_wakeup(device))
flexcan_enable_wakeup_irq(priv, false);
diff --git a/drivers/net/can/flexcan/flexcan.h b/drivers/net/can/flexcan/flexcan.h
index 025c3417031f4..4933d8c7439e6 100644
--- a/drivers/net/can/flexcan/flexcan.h
+++ b/drivers/net/can/flexcan/flexcan.h
@@ -68,6 +68,8 @@
#define FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR BIT(15)
/* Device supports RX via FIFO */
#define FLEXCAN_QUIRK_SUPPORT_RX_FIFO BIT(16)
+/* Setup stop mode with ATF SCMI protocol to support wakeup */
+#define FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI BIT(17)

struct flexcan_devtype_data {
u32 quirks; /* quirks needed for different IP cores */

--
2.34.1