thermal: intel: int340x: Add module parameter for balanced Slider

By default, the SoC slider value for the "balanced" platform profile is
set to 3. This update introduces a new module parameter, allowing users
to modify this default value.

The module parameter can be specified during load time to set a custom
slider value for the "balanced" profile. If the module parameter is not
specified at load time and is updated later, the new value will only take
effect after the next write of "balanced" to the sysfs "profile"
attribute.

Signed-off-by: Srinivas Pandruvada <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
[ rjw: Minor adjustments of module param description ]
Signed-off-by: Rafael J. Wysocki <[e-mail]>

drivers/thermal/intel/int340x_thermal/processor_thermal_soc_slider.c

···
 	[SOC_POWER_SLIDER_POWERSAVE] = SOC_SLIDER_VALUE_MAXIMUM,
 };
 
+/* Lock to protect module param updates */
+static DEFINE_MUTEX(slider_param_lock);
+
+static int slider_balanced_param = SOC_SLIDER_VALUE_BALANCE;
+
+static int slider_def_balance_set(const char *arg, const struct kernel_param *kp)
+{
+	u8 slider_val;
+	int ret;
+
+	guard(mutex)(&slider_param_lock);
+
+	ret = kstrtou8(arg, 16, &slider_val);
+	if (!ret) {
+		if (slider_val > SOC_SLIDER_VALUE_MAXIMUM)
+			return -EINVAL;
+
+		slider_balanced_param = slider_val;
+	}
+
+	return ret;
+}
+
+static int slider_def_balance_get(char *buf, const struct kernel_param *kp)
+{
+	guard(mutex)(&slider_param_lock);
+	return sysfs_emit(buf, "%02x\n", slider_values[SOC_POWER_SLIDER_BALANCE]);
+}
+
+static const struct kernel_param_ops slider_def_balance_ops = {
+	.set = slider_def_balance_set,
+	.get = slider_def_balance_get,
+};
+
+module_param_cb(slider_balance, &slider_def_balance_ops, NULL, 0644);
+MODULE_PARM_DESC(slider_balance, "Set slider default value for balance");
+
 /* Convert from platform power profile option to SoC slider value */
 static int convert_profile_to_power_slider(enum platform_profile_option profile)
 {
···
 	proc_priv = dev_get_drvdata(dev);
 	if (!proc_priv)
 		return -EOPNOTSUPP;
+
+	guard(mutex)(&slider_param_lock);
+
+	slider_values[SOC_POWER_SLIDER_BALANCE] = slider_balanced_param;
 
 	slider = convert_profile_to_power_slider(profile);
 	if (slider < 0)