[PATCH] ASoC: cs35l56: Fix illegal writes to OTP_MEM registers

[Richard Fitzgerald <rf@opensource.cirrus.com>]

Mark the OTP_MEM registers as volatile so that regcache_sync() will not
attempt to write to them.

These registers hold a constant, and originally they were marked as
readable non-volatile so that this value would be read into the regmap
cache. The problem with this is regcache_sync() issues a write for any
cached register that does not have a reg_default.

Though these registers are constants and writing them in normal use
cannot change OTP, it is illegal for the host to write to them.

Fixes: e1830f66f6c6 ("ASoC: cs35l56: Add helper functions for amp calibration")
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
---
 sound/soc/codecs/cs35l56-shared.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/sound/soc/codecs/cs35l56-shared.c b/sound/soc/codecs/cs35l56-shared.c
index e05d975ba794..033e56d5e9db 100644
--- a/sound/soc/codecs/cs35l56-shared.c
+++ b/sound/soc/codecs/cs35l56-shared.c
@@ -108,8 +108,6 @@ int cs35l56_set_patch(struct cs35l56_base *cs35l56_base)
 EXPORT_SYMBOL_NS_GPL(cs35l56_set_patch, "SND_SOC_CS35L56_SHARED");
 
 static const struct reg_default cs35l56_reg_defaults[] = {
-	/* no defaults for OTP_MEM - first read populates cache */
-
 	{ CS35L56_ASP1_ENABLES1,		0x00000000 },
 	{ CS35L56_ASP1_CONTROL1,		0x00000028 },
 	{ CS35L56_ASP1_CONTROL2,		0x18180200 },
@@ -138,8 +136,6 @@ static const struct reg_default cs35l56_reg_defaults[] = {
 };
 
 static const struct reg_default cs35l63_reg_defaults[] = {
-	/* no defaults for OTP_MEM - first read populates cache */
-
 	{ CS35L56_ASP1_ENABLES1,		0x00000000 },
 	{ CS35L56_ASP1_CONTROL1,		0x00000028 },
 	{ CS35L56_ASP1_CONTROL2,		0x18180200 },
@@ -282,6 +278,9 @@ static bool cs35l56_common_volatile_reg(unsigned int reg)
 	case CS35L56_GLOBAL_ENABLES:		   /* owned by firmware */
 	case CS35L56_BLOCK_ENABLES:		   /* owned by firmware */
 	case CS35L56_BLOCK_ENABLES2:		   /* owned by firmware */
+	case CS35L56_OTP_MEM_53:
+	case CS35L56_OTP_MEM_54:
+	case CS35L56_OTP_MEM_55:
 	case CS35L56_SYNC_GPIO1_CFG ... CS35L56_ASP2_DIO_GPIO13_CFG:
 	case CS35L56_UPDATE_REGS:
 	case CS35L56_REFCLK_INPUT:		   /* owned by firmware */
-- 
2.47.3