ASoC: sta32x: add workaround for ESD reset issue

sta32x resets and loses all configuration during ESD test.
Work around by polling the CONFA register once a second
and restore all coeffcients and registers when CONFA
changes unexpectedly.

Signed-off-by: Johannes Stezenbach <js@sig21.net>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

1 files changed, 49 insertions, 1 deletions

diff --git a/sound/soc/codecs/sta32x.c b/sound/soc/codecs/sta32x.c
index 97091e3b9a0b..3b0deafd766b 100644
--- a/sound/soc/codecs/sta32x.c
+++ b/sound/soc/codecs/sta32x.c
@@ -27,6 +27,7 @@
 #include <linux/platform_device.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/pcm_params.h>
@@ -80,6 +81,8 @@ struct sta32x_priv {
         unsigned int format;
 
         u32 coef_shadow[STA32X_COEF_COUNT];
+        struct delayed_work watchdog_work;
+        int shutdown;
 };
 
 static const DECLARE_TLV_DB_SCALE(mvol_tlv, -12700, 50, 1);
@@ -304,6 +307,46 @@ int sta32x_cache_sync(struct snd_soc_codec *codec)
         return rc;
 }
 
+/* work around ESD issue where sta32x resets and loses all configuration */
+static void sta32x_watchdog(struct work_struct *work)
+{
+        struct sta32x_priv *sta32x = container_of(work, struct sta32x_priv,
+                                                  watchdog_work.work);
+        struct snd_soc_codec *codec = sta32x->codec;
+        unsigned int confa, confa_cached;
+
+        /* check if sta32x has reset itself */
+        confa_cached = snd_soc_read(codec, STA32X_CONFA);
+        codec->cache_bypass = 1;
+        confa = snd_soc_read(codec, STA32X_CONFA);
+        codec->cache_bypass = 0;
+        if (confa != confa_cached) {
+                codec->cache_sync = 1;
+                sta32x_cache_sync(codec);
+        }
+
+        if (!sta32x->shutdown)
+                schedule_delayed_work(&sta32x->watchdog_work,
+                                      round_jiffies_relative(HZ));
+}
+
+static void sta32x_watchdog_start(struct sta32x_priv *sta32x)
+{
+        if (sta32x->pdata->needs_esd_watchdog) {
+                sta32x->shutdown = 0;
+                schedule_delayed_work(&sta32x->watchdog_work,
+                                      round_jiffies_relative(HZ));
+        }
+}
+
+static void sta32x_watchdog_stop(struct sta32x_priv *sta32x)
+{
+        if (sta32x->pdata->needs_esd_watchdog) {
+                sta32x->shutdown = 1;
+                cancel_delayed_work_sync(&sta32x->watchdog_work);
+        }
+}
+
 #define SINGLE_COEF(xname, index) \
 {       .iface = SNDRV_CTL_ELEM_IFACE_MIXER, .name = xname, \
         .info = sta32x_coefficient_info, \
@@ -714,6 +757,7 @@ static int sta32x_set_bias_level(struct snd_soc_codec *codec,
                         }
 
                         sta32x_cache_sync(codec);
+                        sta32x_watchdog_start(sta32x);
                 }
 
                 /* Power up to mute */
@@ -730,7 +774,7 @@ static int sta32x_set_bias_level(struct snd_soc_codec *codec,
                                     STA32X_CONFF_PWDN | STA32X_CONFF_EAPD,
                                     STA32X_CONFF_PWDN);
                 msleep(300);
-
+                sta32x_watchdog_stop(sta32x);
                 regulator_bulk_disable(ARRAY_SIZE(sta32x->supplies),
                                        sta32x->supplies);
                 break;
@@ -863,6 +907,9 @@ static int sta32x_probe(struct snd_soc_codec *codec)
         sta32x->coef_shadow[60] = 0x400000;
         sta32x->coef_shadow[61] = 0x400000;
 
+        if (sta32x->pdata->needs_esd_watchdog)
+                INIT_DELAYED_WORK(&sta32x->watchdog_work, sta32x_watchdog);
+
         sta32x_set_bias_level(codec, SND_SOC_BIAS_STANDBY);
         /* Bias level configuration will have done an extra enable */
         regulator_bulk_disable(ARRAY_SIZE(sta32x->supplies), sta32x->supplies);
@@ -879,6 +926,7 @@ static int sta32x_remove(struct snd_soc_codec *codec)
 {
         struct sta32x_priv *sta32x = snd_soc_codec_get_drvdata(codec);
 
+        sta32x_watchdog_stop(sta32x);
         sta32x_set_bias_level(codec, SND_SOC_BIAS_OFF);
         regulator_bulk_disable(ARRAY_SIZE(sta32x->supplies), sta32x->supplies);
         regulator_bulk_free(ARRAY_SIZE(sta32x->supplies), sta32x->supplies);