linux-kernel - [PATCH v2 3/9] hwmon: (dell-smm) Move whitelist handling to module init

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Message-Id: <20231104155559.11842-4-W_Armin@gmx.de>
Date:   Sat,  4 Nov 2023 16:55:53 +0100
From:   Armin Wolf <W_Armin@....de>
To:     pali@...nel.org
Cc:     hdegoede@...hat.com, markgross@...nel.org,
        ilpo.jarvinen@...ux.intel.com, jdelvare@...e.com,
        linux@...ck-us.net, platform-driver-x86@...r.kernel.org,
        linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 3/9] hwmon: (dell-smm) Move whitelist handling to module init

Future SMM calling backends will not be able to probe during
module init, meaning the DMI tables used for whitelisting
features would have to drop their __initconst attribute.
Prevent this by moving the whitelist handling to module init.

Signed-off-by: Armin Wolf <W_Armin@....de>
---
 drivers/hwmon/dell-smm-hwmon.c | 31 +++++++++++++++++--------------
 1 file changed, 17 insertions(+), 14 deletions(-)

diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c
index ccb3fcff4f60..3a792faf2369 100644
--- a/drivers/hwmon/dell-smm-hwmon.c
+++ b/drivers/hwmon/dell-smm-hwmon.c
@@ -90,8 +90,6 @@ struct dell_smm_data {
 	uint i8k_fan_mult;
 	uint i8k_pwm_mult;
 	uint i8k_fan_max;
-	unsigned int manual_fan;
-	unsigned int auto_fan;
 	int temp_type[DELL_SMM_NO_TEMP];
 	bool fan[DELL_SMM_NO_FANS];
 	int fan_type[DELL_SMM_NO_FANS];
@@ -138,6 +136,8 @@ MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)"

 static bool disallow_fan_type_call, disallow_fan_support;

+static unsigned int manual_fan, auto_fan;
+
 static const char * const temp_labels[] = {
 	"CPU",
 	"GPU",
@@ -329,7 +329,7 @@ static int i8k_enable_fan_auto_mode(const struct dell_smm_data *data, bool enabl
 	if (disallow_fan_support)
 		return -EINVAL;

-	regs.eax = enable ? data->auto_fan : data->manual_fan;
+	regs.eax = enable ? auto_fan : manual_fan;
 	return dell_smm_call(data->ops, &regs);
 }

@@ -741,7 +741,7 @@ static umode_t dell_smm_is_visible(const void *drvdata, enum hwmon_sensor_types

 			break;
 		case hwmon_pwm_enable:
-			if (data->auto_fan)
+			if (auto_fan)
 				/*
 				 * There is no command for retrieve the current status
 				 * from BIOS, and userspace/firmware itself can change
@@ -1370,7 +1370,7 @@ static const struct dmi_system_id i8k_whitelist_fan_control[] __initconst = {
 static int __init dell_smm_probe(struct platform_device *pdev)
 {
 	struct dell_smm_data *data;
-	const struct dmi_system_id *id, *fan_control;
+	const struct dmi_system_id *id;
 	int ret;

 	data = devm_kzalloc(&pdev->dev, sizeof(struct dell_smm_data), GFP_KERNEL);
@@ -1406,15 +1406,6 @@ static int __init dell_smm_probe(struct platform_device *pdev)
 	data->i8k_fan_max = fan_max ? : I8K_FAN_HIGH;
 	data->i8k_pwm_mult = DIV_ROUND_UP(255, data->i8k_fan_max);

-	fan_control = dmi_first_match(i8k_whitelist_fan_control);
-	if (fan_control && fan_control->driver_data) {
-		const struct i8k_fan_control_data *control = fan_control->driver_data;
-
-		data->manual_fan = control->manual_fan;
-		data->auto_fan = control->auto_fan;
-		dev_info(&pdev->dev, "enabling support for setting automatic/manual fan control\n");
-	}
-
 	ret = dell_smm_init_hwmon(&pdev->dev);
 	if (ret)
 		return ret;
@@ -1437,6 +1428,9 @@ static struct platform_device *dell_smm_device;
  */
 static void __init dell_smm_init_dmi(void)
 {
+	struct i8k_fan_control_data *control;
+	const struct dmi_system_id *id;
+
 	if (dmi_check_system(i8k_blacklist_fan_support_dmi_table)) {
 		if (!force) {
 			pr_notice("Disabling fan support due to BIOS bugs\n");
@@ -1454,6 +1448,15 @@ static void __init dell_smm_init_dmi(void)
 			pr_warn("Enabling fan type call despite BIOS bugs\n");
 		}
 	}
+
+	id = dmi_first_match(i8k_whitelist_fan_control);
+	if (id && id->driver_data) {
+		control = id->driver_data;
+		manual_fan = control->manual_fan;
+		auto_fan = control->auto_fan;
+
+		pr_info("Enabling support for setting automatic/manual fan control\n");
+	}
 }

 static int __init i8k_init(void)
--
2.39.2