mfd: madera: Add special errata reset handling for cs47l15

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 <[e-mail]>
Signed-off-by: Lee Jones <[e-mail]>

drivers/mfd/madera-core.c

···
 #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",
···
 
 	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) {
···
 	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;
···
 	 */
 	switch (madera->type) {
 	case CS47L15:
+		madera->reset_errata = true;
+		break;
 	case CS47L35:
 	case CS47L90:
 	case CS47L91:
···
 		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);
···
 	 * 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;

include/linux/mfd/madera/core.h

···
 	struct regulator_bulk_data core_supplies[MADERA_MAX_CORE_SUPPLIES];
 	struct regulator *dcvdd;
 	bool internal_dcvdd;
+	bool reset_errata;
 
 	struct madera_pdata pdata;