[PATCH 2/2] mfd: madera: Add special errata reset handling for cs47l15

[Charles Keepax]

An errata exists for cs47l15 where the reset must be handled
differently and removed before DCVDD is applied. A soft reset is used
for situations where a reset is required to reset state. This does
however, make this part unsuitable for DCVDD supplies with a rise time
greater than 2mS.

Signed-off-by: Charles Keepax <ckeepax@xxxxxxxxxxxxxxxxxxxxx>
---
 drivers/mfd/madera-core.c       | 25 ++++++++++++++++++++-----
 include/linux/mfd/madera/core.h |  1 +
 2 files changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/mfd/madera-core.c b/drivers/mfd/madera-core.c
index a9c6f0833f327..a2abc0094def7 100644
--- a/drivers/mfd/madera-core.c
+++ b/drivers/mfd/madera-core.c
@@ -38,6 +38,9 @@
 #define MADERA_RESET_MIN_US	2000
 #define MADERA_RESET_MAX_US	3000
 
+#define ERRATA_DCVDD_MIN_US	10000
+#define ERRATA_DCVDD_MAX_US	15000
+
 static const char * const madera_core_supplies[] = {
 	"AVDD",
 	"DBVDD1",
@@ -291,7 +294,8 @@ static int __maybe_unused madera_runtime_resume(struct device *dev)
 
 	dev_dbg(dev, "Leaving sleep mode\n");
 
-	madera_enable_hard_reset(madera);
+	if (!madera->reset_errata)
+		madera_enable_hard_reset(madera);
 
 	ret = regulator_enable(madera->dcvdd);
 	if (ret) {
@@ -302,9 +306,12 @@ static int __maybe_unused madera_runtime_resume(struct device *dev)
 	regcache_cache_only(madera->regmap, false);
 	regcache_cache_only(madera->regmap_32bit, false);
 
-	madera_disable_hard_reset(madera);
+	if (madera->reset_errata)
+		usleep_range(ERRATA_DCVDD_MIN_US, ERRATA_DCVDD_MAX_US);
+	else
+		madera_disable_hard_reset(madera);
 
-	if (!madera->pdata.reset) {
+	if (!madera->pdata.reset || madera->reset_errata) {
 		ret = madera_wait_for_boot(madera);
 		if (ret)
 			goto err;
@@ -503,6 +510,8 @@ int madera_dev_init(struct madera *madera)
 	 */
 	switch (madera->type) {
 	case CS47L15:
+		madera->reset_errata = true;
+		break;
 	case CS47L35:
 	case CS47L90:
 	case CS47L91:
@@ -553,13 +562,19 @@ int madera_dev_init(struct madera *madera)
 		goto err_dcvdd;
 	}
 
+	if (madera->reset_errata)
+		madera_disable_hard_reset(madera);
+
 	ret = regulator_enable(madera->dcvdd);
 	if (ret) {
 		dev_err(dev, "Failed to enable DCVDD: %d\n", ret);
 		goto err_enable;
 	}
 
-	madera_disable_hard_reset(madera);
+	if (madera->reset_errata)
+		usleep_range(ERRATA_DCVDD_MIN_US, ERRATA_DCVDD_MAX_US);
+	else
+		madera_disable_hard_reset(madera);
 
 	regcache_cache_only(madera->regmap, false);
 	regcache_cache_only(madera->regmap_32bit, false);
@@ -667,7 +682,7 @@ int madera_dev_init(struct madera *madera)
 	 * It looks like a device we support. If we don't have a hard reset
 	 * we can now attempt a soft reset.
 	 */
-	if (!madera->pdata.reset) {
+	if (!madera->pdata.reset || madera->reset_errata) {
 		ret = madera_soft_reset(madera);
 		if (ret)
 			goto err_reset;
diff --git a/include/linux/mfd/madera/core.h b/include/linux/mfd/madera/core.h
index ad2c138105d4b..03a8a788424a2 100644
--- a/include/linux/mfd/madera/core.h
+++ b/include/linux/mfd/madera/core.h
@@ -186,6 +186,7 @@ struct madera {
 	struct regulator_bulk_data core_supplies[MADERA_MAX_CORE_SUPPLIES];
 	struct regulator *dcvdd;
 	bool internal_dcvdd;
+	bool reset_errata;
 
 	struct madera_pdata pdata;
 
-- 
2.11.0