[PATCH v2 1/1] regmap: Synchronize cache for the page selector

[Andy Shevchenko <andriy.shevchenko@linux.intel.com>]

If the selector register is represented in each page, its value
in accordance to the debugfs is stale because it gets synchronized
only after the real page switch happens. Synchronize cache for
the page selector.

Before (offset followed by hexdump, the first byte is selector):

    // Real registers
    18: 05 ff 00 00 ff 0f 00 00 f0 00 00 00
    ...
    // Virtual (per port)
    40: 05 ff 00 00 e0 e0 00 00 00 00 00 1f
    50: 00 ff 00 00 e0 e0 00 00 00 00 00 1f
    60: 01 ff 00 00 ff ff 00 00 00 00 00 00
    70: 02 ff 00 00 cf f3 00 00 00 00 00 0c
    80: 03 ff 00 00 00 00 00 00 00 00 00 ff
    90: 04 ff 00 00 ff 0f 00 00 f0 00 00 00

After:

    // Real registers
    18: 05 ff 00 00 ff 0f 00 00 f0 00 00 00
    ...
    // Virtual (per port)
    40: 00 ff 00 00 e0 e0 00 00 00 00 00 1f
    50: 01 ff 00 00 e0 e0 00 00 00 00 00 1f
    60: 02 ff 00 00 ff ff 00 00 00 00 00 00
    70: 03 ff 00 00 cf f3 00 00 00 00 00 0c
    80: 04 ff 00 00 00 00 00 00 00 00 00 ff
    90: 05 ff 00 00 ff 0f 00 00 f0 00 00 00

Fixes: 6863ca622759 ("regmap: Add support for register indirect addressing.")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
v2: improved test for selector to be in the range window
 drivers/base/regmap/regmap.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 4ded93687c1f..6d3c69c68cad 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -1545,24 +1545,40 @@ static int _regmap_select_page(struct regmap *map, unsigned int *reg,
 			return -EINVAL;
 	}
 
-	/* It is possible to have selector register inside data window.
-	   In that case, selector register is located on every page and
-	   it needs no page switching, when accessed alone. */
+	/*
+	 * It is possible to have selector register inside data window.
+	 * In that case, selector register is located on every page and it
+	 * needs no page switching, when accessed alone.
+	 *
+	 * Nevertheless we should synchronize the cache values for it.
+	 */
 	if (val_num > 1 ||
 	    range->window_start + win_offset != range->selector_reg) {
+		unsigned int page_off = win_page * range->window_len;
+		unsigned int sel_offset = range->selector_reg - range->window_start;
+		unsigned int sel_register = range->range_min + page_off + sel_offset;
+		unsigned int val = win_page << range->selector_shift;
+		unsigned int mask = range->selector_mask;
+
 		/* Use separate work_buf during page switching */
 		orig_work_buf = map->work_buf;
 		map->work_buf = map->selector_work_buf;
 
-		ret = _regmap_update_bits(map, range->selector_reg,
-					  range->selector_mask,
-					  win_page << range->selector_shift,
+		ret = _regmap_update_bits(map, range->selector_reg, mask, val,
 					  &page_chg, false);
 
 		map->work_buf = orig_work_buf;
 
 		if (ret != 0)
 			return ret;
+
+		/*
+		 * If selector register has been just updated, update the respective
+		 * virtual copy as well.
+		 */
+		if (page_chg &&
+		    in_range(range->selector_reg, range->window_start, range->window_len))
+			_regmap_update_bits(map, sel_register, mask, val, NULL, false);
 	}
 
 	*reg = range->window_start + win_offset;
-- 
2.43.0.rc1.1336.g36b5255a03ac