[PATCH v4 2/2] can: flexcan: add wakeup support for imx95

From: Frank Li
Date: Wed Jul 31 2024 - 20:01:41 EST

From: Haibo Chen <haibo.chen@xxxxxxx>

iMX95 defines a bit in GPR that sets/unsets the IPG_STOP signal to the
FlexCAN module, controlling its entry into STOP mode. Wakeup should work
even if FlexCAN is in STOP mode.

Due to iMX95 architecture design, the A-Core cannot access GPR; only the
system manager (SM) can configure GPR. To support the wakeup feature,
follow these steps:

- For suspend:
1) During Linux suspend, when CAN suspends, do nothing for GPR and keep
CAN-related clocks on.
2) In ATF, check whether CAN needs to support wakeup; if yes, send a
request to SM through the SCMI protocol.
3) In SM, configure the GPR and unset IPG_STOP.
4) A-Core suspends.

- For wakeup and resume:
1) A-Core wakeup event arrives.
2) In SM, deassert IPG_STOP.
3) Linux resumes.

Add a new fsl_imx95_devtype_data and FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI to
reflect this.

Reviewed-by: Han Xu <han.xu@xxxxxxx>
Signed-off-by: Haibo Chen <haibo.chen@xxxxxxx>
Reviewed-by: Vincent Mailhol <mailhol.vincent@xxxxxxxxxx>
Signed-off-by: Frank Li <Frank.Li@xxxxxxx>
---
Change from v1 to v2
- fsl_imx95_devtype_data keep order by value
- Add empty line after fsl_imx95_devtype_data
- suspend/resume code look symmetrical
---
drivers/net/can/flexcan/flexcan-core.c | 50 +++++++++++++++++++++++++++++-----
drivers/net/can/flexcan/flexcan.h | 2 ++
2 files changed, 45 insertions(+), 7 deletions(-)

diff --git a/drivers/net/can/flexcan/flexcan-core.c b/drivers/net/can/flexcan/flexcan-core.c
index f6e609c388d55..3c98231e25898 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 const 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_SUPPORT_FD |
+ FLEXCAN_QUIRK_SUPPORT_ECC | FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX |
+ FLEXCAN_QUIRK_SUPPORT_RX_MAILBOX_RTR | FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI,
+};
+
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, },
@@ -2314,9 +2337,19 @@ static int __maybe_unused flexcan_noirq_suspend(struct device *device)
if (device_may_wakeup(device))
flexcan_enable_wakeup_irq(priv, true);

- err = pm_runtime_force_suspend(device);
- if (err)
- return err;
+ /* For FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI, it need ATF to send
+ * 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 (!(device_may_wakeup(device) &&
+ priv->devtype_data.quirks & FLEXCAN_QUIRK_SETUP_STOP_MODE_SCMI)) {
+ err = pm_runtime_force_suspend(device);
+ if (err)
+ return err;
+ }
}

return 0;
@@ -2330,9 +2363,12 @@ 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