[PATCH] power: reset: th1520-aon: send RPCs from sleepable handlers

[Han Gao]

The AON RPC takes a mutex and waits for mailbox interrupts. The final
sys-off handlers run on atomic notifier chains, where this can sleep
with interrupts disabled.

Send the requests from the preparation handlers before syscore shutdown.
Retain a final power-off handler to advertise capability and report
failure without issuing another RPC. Let other providers handle
fallback.

Report RPC errors and allow one second after a successful return for the
asynchronous operation to take effect. This is a software fallback
timeout, not a hardware timing requirement.

Fixes: 2d81a24a74e5 ("driver: reset: th1520-aon: add driver for poweroff/reboot via AON FW")
Signed-off-by: Han Gao <gaohan at iscas.ac.cn>
---
 drivers/power/reset/th1520-aon-reboot.c | 49 +++++++++++++++++++++++----------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/drivers/power/reset/th1520-aon-reboot.c b/drivers/power/reset/th1520-aon-reboot.c
index ec249667a0ffd74829357d57b9e63c3524ea3759..ace70491834dc9a63ed543427e40e4cbc0a9388f 100644
--- a/drivers/power/reset/th1520-aon-reboot.c
+++ b/drivers/power/reset/th1520-aon-reboot.c
@@ -6,6 +6,7 @@
  */
 
 #include <linux/auxiliary_bus.h>
+#include <linux/delay.h>
 #include <linux/firmware/thead/thead,th1520-aon.h>
 #include <linux/module.h>
 #include <linux/notifier.h>
@@ -14,37 +15,46 @@
 #include <linux/slab.h>
 
 #define TH1520_AON_REBOOT_PRIORITY 200
+/* Allow an accepted asynchronous command to take effect before fallback. */
+#define TH1520_AON_REBOOT_TIMEOUT_MS 1000
 
 struct th1520_aon_msg_empty_body {
 	struct th1520_aon_rpc_msg_hdr hdr;
 	u16 reserved[12];
 } __packed __aligned(1);
 
-static int th1520_aon_pwroff_handler(struct sys_off_data *data)
+static int th1520_aon_reboot_request(struct sys_off_data *data, u8 func)
 {
 	struct th1520_aon_chan *aon_chan = data->cb_data;
 	struct th1520_aon_msg_empty_body msg = {};
+	int ret;
 
 	msg.hdr.svc = TH1520_AON_RPC_SVC_WDG;
-	msg.hdr.func = TH1520_AON_WDG_FUNC_POWER_OFF;
+	msg.hdr.func = func;
 	msg.hdr.size = TH1520_AON_RPC_MSG_NUM;
 
-	th1520_aon_call_rpc(aon_chan, &msg);
+	ret = th1520_aon_call_rpc(aon_chan, &msg);
+	if (ret)
+		dev_err(data->dev, "AON WDG command %u failed: %d\n", func, ret);
+	else
+		msleep(TH1520_AON_REBOOT_TIMEOUT_MS);
 
 	return NOTIFY_DONE;
 }
 
-static int th1520_aon_restart_handler(struct sys_off_data *data)
+static int th1520_aon_pwroff_handler(struct sys_off_data *data)
 {
-	struct th1520_aon_chan *aon_chan = data->cb_data;
-	struct th1520_aon_msg_empty_body msg = {};
-
-	msg.hdr.svc = TH1520_AON_RPC_SVC_WDG;
-	msg.hdr.func = TH1520_AON_WDG_FUNC_RESTART;
-	msg.hdr.size = TH1520_AON_RPC_MSG_NUM;
+	return th1520_aon_reboot_request(data, TH1520_AON_WDG_FUNC_POWER_OFF);
+}
 
-	th1520_aon_call_rpc(aon_chan, &msg);
+static int th1520_aon_restart_handler(struct sys_off_data *data)
+{
+	return th1520_aon_reboot_request(data, TH1520_AON_WDG_FUNC_RESTART);
+}
 
+static int th1520_aon_pwroff_failed(struct sys_off_data *data)
+{
+	dev_err(data->dev, "AON did not power off the system\n");
 	return NOTIFY_DONE;
 }
 
@@ -54,8 +64,11 @@ static int th1520_aon_reboot_probe(struct auxiliary_device *adev,
 	struct device *dev = &adev->dev;
 	int ret;
 
-	/* Expect struct th1520_aon_chan to be passed via platform_data */
-	ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF,
+	/*
+	 * RPC takes a mutex and waits for mailbox interrupts. Send after device
+	 * shutdown, but before syscore shutdown and the final atomic callbacks.
+	 */
+	ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF_PREPARE,
 					    TH1520_AON_REBOOT_PRIORITY,
 					    th1520_aon_pwroff_handler,
 					    adev->dev.platform_data);
@@ -65,7 +78,7 @@ static int th1520_aon_reboot_probe(struct auxiliary_device *adev,
 		return ret;
 	}
 
-	ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART,
+	ret = devm_register_sys_off_handler(dev, SYS_OFF_MODE_RESTART_PREPARE,
 					    TH1520_AON_REBOOT_PRIORITY,
 					    th1520_aon_restart_handler,
 					    adev->dev.platform_data);
@@ -75,7 +88,13 @@ static int th1520_aon_reboot_probe(struct auxiliary_device *adev,
 		return ret;
 	}
 
-	return 0;
+	/*
+	 * Advertise power-off capability to kernel_can_power_off(). This final
+	 * callback must not send RPCs; let other providers try if AON failed.
+	 */
+	return devm_register_sys_off_handler(dev, SYS_OFF_MODE_POWER_OFF,
+					     TH1520_AON_REBOOT_PRIORITY,
+					     th1520_aon_pwroff_failed, dev_get_platdata(dev));
 }
 
 static const struct auxiliary_device_id th1520_aon_reboot_id_table[] = {

---
base-commit: fd73f4a6659897191fa0d40695fe370925dd3780
change-id: 20260916-fix-xuantieaon-1ea016a22526

Best regards,
-- 
Han Gao <gaohan at iscas.ac.cn>