[PATCH] mfd: macsmc: Fix key count endianness annotation

[Sven Peter]

SMC firmware returns the value of the #KEY key in big-endian unlike most
other keys. Reading it through apple_smc_read_u32() into a plain u32
and then converting with be32_to_cpu() makes sparse complain:

  drivers/mfd/macsmc.c:462:26: sparse: cast to restricted __be32

Read the raw value into a __be32 using apple_smc_read() instead.

Fixes: e038d985c982 ("mfd: Add Apple Silicon System Management Controller")
Reported-by: kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202607181046.OANjIoqR-lkp@xxxxxxxxx/
Signed-off-by: Sven Peter <sven@xxxxxxxxxx>
---
 drivers/mfd/macsmc.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/mfd/macsmc.c b/drivers/mfd/macsmc.c
index 358feec2d088..514cba7dc897 100644
--- a/drivers/mfd/macsmc.c
+++ b/drivers/mfd/macsmc.c
@@ -410,7 +410,7 @@ static int apple_smc_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct apple_smc *smc;
-	u32 count;
+	__be32 count;
 	int ret;
 
 	smc = devm_kzalloc(dev, sizeof(*smc), GFP_KERNEL);
@@ -461,8 +461,10 @@ static int apple_smc_probe(struct platform_device *pdev)
 	dev_set_drvdata(&pdev->dev, smc);
 	BLOCKING_INIT_NOTIFIER_HEAD(&smc->event_handlers);
 
-	ret = apple_smc_read_u32(smc, SMC_KEY(#KEY), &count);
-	if (ret)
+	ret = apple_smc_read(smc, SMC_KEY(#KEY), &count, sizeof(count));
+	if (ret >= 0 && ret != sizeof(count))
+		ret = -EINVAL;
+	if (ret < 0)
 		return dev_err_probe(smc->dev, ret, "Failed to get key count");
 	smc->key_count = be32_to_cpu(count);
 

---
base-commit: dc59e4fea9d83f03bad6bddf3fa2e52491777482
change-id: 20260719-b4-macsmc-be32-fix-637e8bb1692a

Best regards,
--  
Sven Peter <sven@xxxxxxxxxx>