thermal: intel: int340x: Add module parameter to change slider offset

SoC slider value is set by the user (or the default when user has not
modified it). To enhance power efficiency dynamically, the firmware can
optionally auto-adjust the slider value based on the current workload.
This adjustment is governed by an additional parameter known as the
"slider offset". This offset permits the firmware to increase the slider
value up to and including "SoC slider + slider offset".

Add a module parameter to specify this "slier offset" value.

By default, the SoC slider offset is set to 0. This means that SoC is not
allowed to switch slider position.

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

drivers/thermal/intel/int340x_thermal/processor_thermal_soc_slider.c

···
 module_param_cb(slider_balance, &slider_def_balance_ops, NULL, 0644);
 MODULE_PARM_DESC(slider_balance, "Set slider default value for balance");
 
+static u8 slider_offset;
+
+static int slider_def_offset_set(const char *arg, const struct kernel_param *kp)
+{
+	u8 offset;
+	int ret;
+
+	guard(mutex)(&slider_param_lock);
+
+	ret = kstrtou8(arg, 16, &offset);
+	if (!ret) {
+		if (offset > SOC_SLIDER_VALUE_MAXIMUM)
+			return -EINVAL;
+
+		slider_offset = offset;
+	}
+
+	return ret;
+}
+
+static int slider_def_offset_get(char *buf, const struct kernel_param *kp)
+{
+	guard(mutex)(&slider_param_lock);
+	return sysfs_emit(buf, "%02x\n", slider_offset);
+}
+
+static const struct kernel_param_ops slider_offset_ops = {
+	.set = slider_def_offset_set,
+	.get = slider_def_offset_get,
+};
+
+/*
+ * To enhance power efficiency dynamically, the firmware can optionally
+ * auto-adjust the slider value based on the current workload. This
+ * adjustment is controlled by the "slider_offset" module parameter.
+ * This offset permits the firmware to increase the slider value
+ * up to and including "SoC slider + slider offset,".
+ */
+module_param_cb(slider_offset, &slider_offset_ops, NULL, 0644);
+MODULE_PARM_DESC(slider_offset, "Set slider offset");
+
 /* Convert from platform power profile option to SoC slider value */
 static int convert_profile_to_power_slider(enum platform_profile_option profile)
 {
···
 	writeq(val, proc_priv->mmio_base + SOC_POWER_SLIDER_OFFSET);
 }
 
+#define SLIDER_OFFSET_MASK	GENMASK_ULL(6, 4)
+
 static void set_soc_power_profile(struct proc_thermal_device *proc_priv, int slider)
 {
 	u64 val;
···
 	val = read_soc_slider(proc_priv);
 	val &= ~SLIDER_MASK;
 	val |= FIELD_PREP(SLIDER_MASK, slider) | BIT(SLIDER_ENABLE_BIT);
+
+	/* Set the slider offset from module params */
+	val &= ~SLIDER_OFFSET_MASK;
+	val |= FIELD_PREP(SLIDER_OFFSET_MASK, slider_offset);
+
 	write_soc_slider(proc_priv, val);
 }