linux-kernel - [PATCH 3.16 006/366] regmap: Support bulk reads for devices without raw formatting

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Date:   Sun, 14 Oct 2018 16:25:40 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Mark Brown" <broonie@...nel.org>
Subject: [PATCH 3.16 006/366] regmap: Support bulk reads for devices
 without raw formatting

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Mark Brown <broonie@...nel.org>

commit d5b98eb12420ce856caaf57dc5256eedc56a3747 upstream.

When doing a bulk read from a device which lacks raw I/O support we fall
back to doing register at a time reads but we still use the raw
formatters in order to render the data into the word size used by the
device (since bulk reads still operate on the device word size rather
than unsigned ints).  This means that devices without raw formatting
such as those that provide reg_read() are not supported.  Provide
handling for them by copying the values read into native endian values
of the appropriate size.

Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/base/regmap/regmap.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -2246,7 +2246,34 @@ int regmap_bulk_read(struct regmap *map,
 					  &ival);
 			if (ret != 0)
 				return ret;
-			map->format.format_val(val + (i * val_bytes), ival, 0);
+
+			if (map->format.format_val) {
+				map->format.format_val(val + (i * val_bytes), ival, 0);
+			} else {
+				/* Devices providing read and write
+				 * operations can use the bulk I/O
+				 * functions if they define a val_bytes,
+				 * we assume that the values are native
+				 * endian.
+				 */
+				u32 *u32 = val;
+				u16 *u16 = val;
+				u8 *u8 = val;
+
+				switch (map->format.val_bytes) {
+				case 4:
+					u32[i] = ival;
+					break;
+				case 2:
+					u16[i] = ival;
+					break;
+				case 1:
+					u8[i] = ival;
+					break;
+				default:
+					return -EINVAL;
+				}
+			}
 		}
 	}