ASoC: rt5651: Allow specifying the OVCD scale-factor through a device-property

OVer-Current-Detection (OVCD) for the micbias current is used to detect if
an inserted jack is a headset or headphones (mic shorted to ground).

The threshold for at which current the OVCD triggers on the rt5651 is not
only controlled by setting the absolute current limit, but also by setting
a scale factor which applies to the limit. Testing has shown that we need
to set both (depending on the board).

This commit adds support for the sofar unused OVCD scale-factor register
and adds support for specifying non-default values for it through the
"realtek,over-current-scale-factor" device-property.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

include/sound/rt5651.h

@@ -22,4 +22,15 @@ enum rt5651_jd_src {
 	RT5651_JD2,
 };
 
+/*
+ * Note these MUST match the values from the DT binding:
+ * Documentation/devicetree/bindings/sound/rt5651.txt
+ */
+enum rt5651_ovcd_sf {
+	RT5651_OVCD_SF_0P5,
+	RT5651_OVCD_SF_0P75,
+	RT5651_OVCD_SF_1P0,
+	RT5651_OVCD_SF_1P5,
+};
+
 #endif

sound/soc/codecs/rt5651.c

@@ -1632,6 +1632,10 @@ static int rt5651_set_jack(struct snd_soc_component *component,
 	snd_soc_component_update_bits(component, RT5651_PWR_ANLG2,
 		RT5651_PWR_JD_M, RT5651_PWR_JD_M);
 
+	/* Set OVCD threshold current and scale-factor */
+	snd_soc_component_write(component, RT5651_PR_BASE + RT5651_BIAS_CUR4,
+				0xa800 | rt5651->ovcd_sf);
+
 	snd_soc_component_update_bits(component, RT5651_MICBIAS,
 				      RT5651_MIC1_OVCD_MASK |
 				      RT5651_MIC1_OVTH_MASK |
@@ -1685,7 +1689,13 @@ static void rt5651_apply_properties(struct snd_soc_component *component)
 				     "realtek,jack-detect-source", &val) == 0)
 		rt5651->jd_src = val;
 
+	/*
+	 * Testing on various boards has shown that good defaults for the OVCD
+	 * threshold and scale-factor are 2000µA and 0.75. For an effective
+	 * limit of 1500µA, this seems to be more reliable then 1500µA and 1.0.
+	 */
 	rt5651->ovcd_th = RT5651_MIC1_OVTH_2000UA;
+	rt5651->ovcd_sf = RT5651_MIC_OVCD_SF_0P75;
 
 	if (device_property_read_u32(component->dev,
 			"realtek,over-current-threshold-microamp", &val) == 0) {
@@ -1704,6 +1714,15 @@ static void rt5651_apply_properties(struct snd_soc_component *component)
 				 val);
 		}
 	}
+
+	if (device_property_read_u32(component->dev,
+			"realtek,over-current-scale-factor", &val) == 0) {
+		if (val <= RT5651_OVCD_SF_1P5)
+			rt5651->ovcd_sf = val << RT5651_MIC_OVCD_SF_SFT;
+		else
+			dev_warn(component->dev, "Warning: Invalid over-current-scale-factor value: %d, defaulting to 0.75\n",
+				 val);
+	}
 }
 
 static int rt5651_probe(struct snd_soc_component *component)

sound/soc/codecs/rt5651.h

@@ -138,6 +138,7 @@
 /* Index of Codec Private Register definition */
 #define RT5651_BIAS_CUR1			0x12
 #define RT5651_BIAS_CUR3			0x14
+#define RT5651_BIAS_CUR4			0x15
 #define RT5651_CLSD_INT_REG1			0x1c
 #define RT5651_CHPUMP_INT_REG1			0x24
 #define RT5651_MAMP_INT_REG2			0x37
@@ -1966,6 +1967,15 @@
 #define RT5651_D_GATE_EN_SFT			0
 
 /* Codec Private Register definition */
+
+/* MIC Over current threshold scale factor (0x15) */
+#define RT5651_MIC_OVCD_SF_MASK			(0x3 << 8)
+#define RT5651_MIC_OVCD_SF_SFT			8
+#define RT5651_MIC_OVCD_SF_0P5			(0x0 << 8)
+#define RT5651_MIC_OVCD_SF_0P75			(0x1 << 8)
+#define RT5651_MIC_OVCD_SF_1P0			(0x2 << 8)
+#define RT5651_MIC_OVCD_SF_1P5			(0x3 << 8)
+
 /* 3D Speaker Control (0x63) */
 #define RT5651_3D_SPK_MASK			(0x1 << 15)
 #define RT5651_3D_SPK_SFT			15
@@ -2065,6 +2075,7 @@ struct rt5651_priv {
 	struct delayed_work jack_detect_work;
 	enum rt5651_jd_src jd_src;
 	unsigned int ovcd_th;
+	unsigned int ovcd_sf;
 
 	int irq;
 	int sysclk;