ASoC: codecs: wsa884x: Implement temperature reading and hwmon

Read temperature of the speaker and expose it via hwmon interface, which
will be later used during calibration of speaker protection algorithms.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://patch.msgid.link/20240809110122.137761-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/wsa884x.c

@@ -5,11 +5,14 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/cleanup.h>
 #include <linux/device.h>
 #include <linux/gpio/consumer.h>
+#include <linux/hwmon.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/pm_runtime.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
@@ -301,8 +304,28 @@
 #define WSA884X_PA_FSM_MSK1		(WSA884X_DIG_CTRL0_BASE + 0x3b)
 #define WSA884X_PA_FSM_BYP_CTL		(WSA884X_DIG_CTRL0_BASE + 0x3c)
 #define WSA884X_PA_FSM_BYP0		(WSA884X_DIG_CTRL0_BASE + 0x3d)
+#define WSA884X_PA_FSM_BYP0_DC_CAL_EN_MASK		0x01
+#define WSA884X_PA_FSM_BYP0_DC_CAL_EN_SHIFT		0
+#define WSA884X_PA_FSM_BYP0_CLK_WD_EN_MASK		0x02
+#define WSA884X_PA_FSM_BYP0_CLK_WD_EN_SHIFT		1
+#define WSA884X_PA_FSM_BYP0_BG_EN_MASK			0x04
+#define WSA884X_PA_FSM_BYP0_BG_EN_SHIFT			2
+#define WSA884X_PA_FSM_BYP0_BOOST_EN_MASK		0x08
+#define WSA884X_PA_FSM_BYP0_BOOST_EN_SHIFT		3
+#define WSA884X_PA_FSM_BYP0_PA_EN_MASK			0x10
+#define WSA884X_PA_FSM_BYP0_PA_EN_SHIFT			4
+#define WSA884X_PA_FSM_BYP0_D_UNMUTE_MASK		0x20
+#define WSA884X_PA_FSM_BYP0_D_UNMUTE_SHIFT		5
+#define WSA884X_PA_FSM_BYP0_SPKR_PROT_EN_MASK		0x40
+#define WSA884X_PA_FSM_BYP0_SPKR_PROT_EN_SHIFT		6
+#define WSA884X_PA_FSM_BYP0_TSADC_EN_MASK		0x80
+#define WSA884X_PA_FSM_BYP0_TSADC_EN_SHIFT		7
 #define WSA884X_PA_FSM_BYP1		(WSA884X_DIG_CTRL0_BASE + 0x3e)
 #define WSA884X_TADC_VALUE_CTL		(WSA884X_DIG_CTRL0_BASE + 0x50)
+#define WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_MASK	0x01
+#define WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_SHIFT	0
+#define WSA884X_TADC_VALUE_CTL_VBAT_VALUE_RD_EN_MASK	0x02
+#define WSA884X_TADC_VALUE_CTL_VBAT_VALUE_RD_EN_SHIFT	1
 #define WSA884X_TEMP_DETECT_CTL		(WSA884X_DIG_CTRL0_BASE + 0x51)
 #define WSA884X_TEMP_DIN_MSB		(WSA884X_DIG_CTRL0_BASE + 0x52)
 #define WSA884X_TEMP_DIN_LSB		(WSA884X_DIG_CTRL0_BASE + 0x53)
@@ -691,6 +714,17 @@
 		SNDRV_PCM_FMTBIT_S24_LE |\
 		SNDRV_PCM_FMTBIT_S24_3LE | SNDRV_PCM_FMTBIT_S32_LE)
 
+/* Two-point trimming for temperature calibration */
+#define WSA884X_T1_TEMP			-10L
+#define WSA884X_T2_TEMP			150L
+
+/*
+ * Device will report senseless data in many cases, so discard any measurements
+ * outside of valid range.
+ */
+#define WSA884X_LOW_TEMP_THRESHOLD	5
+#define WSA884X_HIGH_TEMP_THRESHOLD	45
+
 struct wsa884x_priv {
 	struct regmap *regmap;
 	struct device *dev;
@@ -706,6 +740,13 @@ struct wsa884x_priv {
 	int active_ports;
 	int dev_mode;
 	bool hw_init;
+	/*
+	 * Protects temperature reading code (related to speaker protection) and
+	 * fields: temperature and pa_on.
+	 */
+	struct mutex sp_lock;
+	unsigned int temperature;
+	bool pa_on;
 };
 
 enum {
@@ -1660,6 +1701,10 @@ static int wsa884x_spkr_event(struct snd_soc_dapm_widget *w,
 
 	switch (event) {
 	case SND_SOC_DAPM_POST_PMU:
+		mutex_lock(&wsa884x->sp_lock);
+		wsa884x->pa_on = true;
+		mutex_unlock(&wsa884x->sp_lock);
+
 		wsa884x_spkr_post_pmu(component, wsa884x);
 
 		snd_soc_component_write_field(component, WSA884X_PDM_WD_CTL,
@@ -1671,6 +1716,10 @@ static int wsa884x_spkr_event(struct snd_soc_dapm_widget *w,
 		snd_soc_component_write_field(component, WSA884X_PDM_WD_CTL,
 					      WSA884X_PDM_WD_CTL_PDM_WD_EN_MASK,
 					      0x0);
+
+		mutex_lock(&wsa884x->sp_lock);
+		wsa884x->pa_on = false;
+		mutex_unlock(&wsa884x->sp_lock);
 		break;
 	}
 
@@ -1810,6 +1859,144 @@ static struct snd_soc_dai_driver wsa884x_dais[] = {
 	},
 };
 
+static int wsa884x_get_temp(struct wsa884x_priv *wsa884x, long *temp)
+{
+	unsigned int d1_msb = 0, d1_lsb = 0, d2_msb = 0, d2_lsb = 0;
+	unsigned int dmeas_msb = 0, dmeas_lsb = 0;
+	int d1, d2, dmeas;
+	unsigned int mask;
+	long val;
+	int ret;
+
+	guard(mutex)(&wsa884x->sp_lock);
+
+	if (wsa884x->pa_on) {
+		/*
+		 * Reading temperature is possible only when Power Amplifier is
+		 * off. Report last cached data.
+		 */
+		*temp = wsa884x->temperature;
+		return 0;
+	}
+
+	ret = pm_runtime_resume_and_get(wsa884x->dev);
+	if (ret < 0)
+		return ret;
+
+	mask = WSA884X_PA_FSM_BYP0_DC_CAL_EN_MASK |
+	       WSA884X_PA_FSM_BYP0_CLK_WD_EN_MASK |
+	       WSA884X_PA_FSM_BYP0_BG_EN_MASK |
+	       WSA884X_PA_FSM_BYP0_D_UNMUTE_MASK |
+	       WSA884X_PA_FSM_BYP0_SPKR_PROT_EN_MASK |
+	       WSA884X_PA_FSM_BYP0_TSADC_EN_MASK;
+	/*
+	 * Here and further do not care about read or update failures.
+	 * For example, before turning on Power Amplifier for the first
+	 * time, reading WSA884X_TEMP_DIN_MSB will always return 0.
+	 * Instead, check if returned value is within reasonable
+	 * thresholds.
+	 */
+	regmap_update_bits(wsa884x->regmap, WSA884X_PA_FSM_BYP0, mask, mask);
+
+	regmap_update_bits(wsa884x->regmap, WSA884X_TADC_VALUE_CTL,
+			   WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_MASK,
+			   FIELD_PREP(WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_MASK, 0x0));
+
+	regmap_read(wsa884x->regmap, WSA884X_TEMP_DIN_MSB, &dmeas_msb);
+	regmap_read(wsa884x->regmap, WSA884X_TEMP_DIN_LSB, &dmeas_lsb);
+
+	regmap_update_bits(wsa884x->regmap, WSA884X_TADC_VALUE_CTL,
+			   WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_MASK,
+			   FIELD_PREP(WSA884X_TADC_VALUE_CTL_TEMP_VALUE_RD_EN_MASK, 0x1));
+
+	regmap_read(wsa884x->regmap, WSA884X_OTP_REG_1, &d1_msb);
+	regmap_read(wsa884x->regmap, WSA884X_OTP_REG_2, &d1_lsb);
+	regmap_read(wsa884x->regmap, WSA884X_OTP_REG_3, &d2_msb);
+	regmap_read(wsa884x->regmap, WSA884X_OTP_REG_4, &d2_lsb);
+
+	regmap_update_bits(wsa884x->regmap, WSA884X_PA_FSM_BYP0, mask, 0x0);
+
+	dmeas = (((dmeas_msb & 0xff) << 0x8) | (dmeas_lsb & 0xff)) >> 0x6;
+	d1 = (((d1_msb & 0xff) << 0x8) | (d1_lsb & 0xff)) >> 0x6;
+	d2 = (((d2_msb & 0xff) << 0x8) | (d2_lsb & 0xff)) >> 0x6;
+
+	if (d1 == d2) {
+		/* Incorrect data in OTP? */
+		ret = -EINVAL;
+		goto out;
+	}
+
+	val = WSA884X_T1_TEMP + (((dmeas - d1) * (WSA884X_T2_TEMP - WSA884X_T1_TEMP))/(d2 - d1));
+
+	dev_dbg(wsa884x->dev, "Measured temp %ld (dmeas=%d, d1=%d, d2=%d)\n",
+		val, dmeas, d1, d2);
+
+	if ((val > WSA884X_LOW_TEMP_THRESHOLD) &&
+	    (val < WSA884X_HIGH_TEMP_THRESHOLD)) {
+		wsa884x->temperature = val;
+		*temp = val;
+		ret = 0;
+	} else {
+		ret = -EAGAIN;
+	}
+
+out:
+	pm_runtime_mark_last_busy(wsa884x->dev);
+	pm_runtime_put_autosuspend(wsa884x->dev);
+
+	return ret;
+}
+
+static umode_t wsa884x_hwmon_is_visible(const void *data,
+					enum hwmon_sensor_types type, u32 attr,
+					int channel)
+{
+	if (type != hwmon_temp)
+		return 0;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		return 0444;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int wsa884x_hwmon_read(struct device *dev,
+			      enum hwmon_sensor_types type,
+			      u32 attr, int channel, long *temp)
+{
+	int ret;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		ret = wsa884x_get_temp(dev_get_drvdata(dev), temp);
+		break;
+	default:
+		ret = -EOPNOTSUPP;
+		break;
+	}
+
+	return ret;
+}
+
+static const struct hwmon_channel_info *const wsa884x_hwmon_info[] = {
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	NULL
+};
+
+static const struct hwmon_ops wsa884x_hwmon_ops = {
+	.is_visible	= wsa884x_hwmon_is_visible,
+	.read		= wsa884x_hwmon_read,
+};
+
+static const struct hwmon_chip_info wsa884x_hwmon_chip_info = {
+	.ops	= &wsa884x_hwmon_ops,
+	.info	= wsa884x_hwmon_info,
+};
+
 static void wsa884x_reset_powerdown(void *data)
 {
 	struct wsa884x_priv *wsa884x = data;
@@ -1866,6 +2053,8 @@ static int wsa884x_probe(struct sdw_slave *pdev,
 	if (!wsa884x)
 		return -ENOMEM;
 
+	mutex_init(&wsa884x->sp_lock);
+
 	for (i = 0; i < WSA884X_SUPPLIES_NUM; i++)
 		wsa884x->supplies[i].supply = wsa884x_supply_name[i];
 
@@ -1923,6 +2112,18 @@ static int wsa884x_probe(struct sdw_slave *pdev,
 	regcache_cache_only(wsa884x->regmap, true);
 	wsa884x->hw_init = true;
 
+	if (IS_REACHABLE(CONFIG_HWMON)) {
+		struct device *hwmon;
+
+		hwmon = devm_hwmon_device_register_with_info(dev, "wsa884x",
+							     wsa884x,
+							     &wsa884x_hwmon_chip_info,
+							     NULL);
+		if (IS_ERR(hwmon))
+			return dev_err_probe(dev, PTR_ERR(hwmon),
+					     "Failed to register hwmon sensor\n");
+	}
+
 	pm_runtime_set_autosuspend_delay(dev, 3000);
 	pm_runtime_use_autosuspend(dev);
 	pm_runtime_mark_last_busy(dev);