linux-kernel - [PATCH 3/3] mfd: macsmc: Support variable app endpoint start

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Message-Id: <20251223-rtkit-v10-v1-3-12b4783d6403@gmail.com>
Date: Tue, 23 Dec 2025 22:13:44 +0800
From: Nick Chan <towinchenmi@...il.com>
To: Sven Peter <sven@...nel.org>, Janne Grunau <j@...nau.net>, 
 Neal Gompa <neal@...pa.dev>, Lee Jones <lee@...nel.org>
Cc: asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 linux-kernel@...r.kernel.org, Nick Chan <towinchenmi@...il.com>
Subject: [PATCH 3/3] mfd: macsmc: Support variable app endpoint start

Instead of hardcoding the SMC endpoint number, use
apple_rtkit_app_ep_to_ep() to convert a relative endpoint number to
an absolute endpoint number in order to support protocol versions
with a different start of app endpoint number.

Signed-off-by: Nick Chan <towinchenmi@...il.com>
---
 drivers/mfd/macsmc.c       | 18 +++++++++++-------
 include/linux/mfd/macsmc.h |  2 ++
 2 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
index e3893e255ce5e4bb4832d80ad1fc002d413a291a..4e0fc5ddf9293ee7281680e964fc5f9b80260b3d 100644
--- a/drivers/mfd/macsmc.c
+++ b/drivers/mfd/macsmc.c
@@ -21,7 +21,7 @@
 #include <linux/soc/apple/rtkit.h>
 #include <linux/unaligned.h>
 
-#define SMC_ENDPOINT			0x20
+#define SMC_APP_ENDPOINT		0
 
 /* We don't actually know the true size here but this seem reasonable */
 #define SMC_SHMEM_SIZE			0x1000
@@ -72,7 +72,7 @@ static int apple_smc_cmd_locked(struct apple_smc *smc, u64 cmd, u64 arg,
 	       FIELD_PREP(SMC_ID, smc->msg_id) |
 	       FIELD_PREP(SMC_DATA, arg));
 
-	ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT, msg, NULL, false);
+	ret = apple_rtkit_send_message(smc->rtk, smc->ep, msg, NULL, false);
 	if (ret) {
 		dev_err(smc->dev, "Failed to send command\n");
 		return ret;
@@ -262,7 +262,7 @@ int apple_smc_write_atomic(struct apple_smc *smc, smc_key key, const void *buf,
 	       FIELD_PREP(SMC_DATA, key));
 	smc->atomic_pending = true;
 
-	ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT, msg, NULL, true);
+	ret = apple_rtkit_send_message(smc->rtk, smc->ep, msg, NULL, true);
 	if (ret < 0) {
 		dev_err(smc->dev, "Failed to send command (%d)\n", ret);
 		return ret;
@@ -330,7 +330,7 @@ static bool apple_smc_rtkit_recv_early(void *cookie, u8 endpoint, u64 message)
 {
 	struct apple_smc *smc = cookie;
 
-	if (endpoint != SMC_ENDPOINT) {
+	if (endpoint != smc->ep) {
 		dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
 		return false;
 	}
@@ -366,7 +366,7 @@ static void apple_smc_rtkit_recv(void *cookie, u8 endpoint, u64 message)
 {
 	struct apple_smc *smc = cookie;
 
-	if (endpoint != SMC_ENDPOINT) {
+	if (endpoint != smc->ep) {
 		dev_warn(smc->dev, "Received message for unknown endpoint 0x%x\n", endpoint);
 		return;
 	}
@@ -427,18 +427,22 @@ static int apple_smc_probe(struct platform_device *pdev)
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to wake up SMC");
 
+	smc->ep = apple_rtkit_app_ep_to_ep(smc->rtk, SMC_APP_ENDPOINT);
+	if (!smc->ep)
+		return dev_err_probe(dev, ret, "Failed to get SMC endpoint");
+
 	ret = devm_add_action_or_reset(dev, apple_smc_rtkit_shutdown, smc);
 	if (ret)
 		return ret;
 
-	ret = apple_rtkit_start_ep(smc->rtk, SMC_ENDPOINT);
+	ret = apple_rtkit_start_ep(smc->rtk, smc->ep);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to start SMC endpoint");
 
 	init_completion(&smc->init_done);
 	init_completion(&smc->cmd_done);
 
-	ret = apple_rtkit_send_message(smc->rtk, SMC_ENDPOINT,
+	ret = apple_rtkit_send_message(smc->rtk, smc->ep,
 				       FIELD_PREP(SMC_MSG, SMC_MSG_INITIALIZE), NULL, false);
 	if (ret)
 		return dev_err_probe(dev, ret, "Failed to send init message");
diff --git a/include/linux/mfd/macsmc.h b/include/linux/mfd/macsmc.h
index cc09ecce0df7424b288d4248d869f4c9bed3e188..1a462baae0e38ac099f90988afda0f3f5ad968b9 100644
--- a/include/linux/mfd/macsmc.h
+++ b/include/linux/mfd/macsmc.h
@@ -93,6 +93,7 @@ enum apple_smc_boot_stage {
  * @sram: Pointer to SRAM resource
  * @sram_base: SRAM base address
  * @shmem: RTKit shared memory structure for SRAM
+ * @ep: SMC endpoint number
  * @msg_id: Current message id for commands, will be incremented for each command
  * @atomic_mode: Flag set when atomic mode is entered
  * @atomic_pending: Flag indicating pending atomic command
@@ -118,6 +119,7 @@ struct apple_smc {
 	struct resource *sram;
 	void __iomem *sram_base;
 	struct apple_rtkit_shmem shmem;
+	u8 ep;
 
 	unsigned int msg_id;
 

-- 
2.52.0