mfd: Keep a cache of WM8350 volatile values

Due to the way that the WM8350 audio driver handles CODEC_ENA many of
the WM8350 audio registers are marked as volatile when they aren't
actually so. Allow the audio driver to see a cache of these values for
inspection during interrupt context.

To do this we need to stop satisfying any bits from volatile registers
from cache - there's no real benefit from doing so anyway, we did the
read already.

Signed-off-by: Mark Brown <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>

drivers/mfd/wm8350-core.c

···
 		/* Cache is CPU endian */
 		dest[i - reg] = be16_to_cpu(dest[i - reg]);
 
-		/* Satisfy non-volatile bits from cache */
-		dest[i - reg] &= wm8350_reg_io_map[i].vol;
-		dest[i - reg] |= wm8350->reg_cache[i];
-
 		/* Mask out non-readable bits */
 		dest[i - reg] &= wm8350_reg_io_map[i].readable;
 	}
···
 		wm8350->reg_cache[i] =
 			(wm8350->reg_cache[i] & ~wm8350_reg_io_map[i].writable)
 			| src[i - reg];
-
-		/* Don't store volatile bits */
-		wm8350->reg_cache[i] &= ~wm8350_reg_io_map[i].vol;
 
 		src[i - reg] = cpu_to_be16(src[i - reg]);
 	}
···
 		    (i < WM8350_CLOCK_CONTROL_1 || i > WM8350_AIF_TEST)) {
 			value = be16_to_cpu(wm8350->reg_cache[i]);
 			value &= wm8350_reg_io_map[i].readable;
-			value &= ~wm8350_reg_io_map[i].vol;
 			wm8350->reg_cache[i] = value;
 		} else
 			wm8350->reg_cache[i] = reg_map[i];