linux-kernel - [PATCH 1/2] regmap: ram: support noinc semantics

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Date:   Thu,  2 Nov 2023 16:30:38 -0400
From:   Ben Wolsieffer <ben.wolsieffer@...ring.com>
To:     linux-kernel@...r.kernel.org
Cc:     Mark Brown <broonie@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Ben Wolsieffer <ben.wolsieffer@...ring.com>
Subject: [PATCH 1/2] regmap: ram: support noinc semantics

Support noinc semantics in RAM backed regmaps, for testing purposes. Add
a new callback that selects registers which should have noinc behavior.
Bulk writes to a noinc register will cause the last value in the buffer
to be assigned to the register, while bulk reads will copy the same
value repeatedly into the buffer.

This patch only adds support to regmap-raw-ram, since regmap-ram does
not support bulk operations.

Signed-off-by: Ben Wolsieffer <ben.wolsieffer@...ring.com>
---
 drivers/base/regmap/internal.h       |  1 +
 drivers/base/regmap/regmap-raw-ram.c | 27 +++++++++++++++++++--------
 2 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 9a9ea514c2d8..583dd5d7d46b 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -318,6 +318,7 @@ struct regmap_ram_data {
 	bool *read;
 	bool *written;
 	enum regmap_endian reg_endian;
+	bool (*noinc_reg)(struct regmap_ram_data *data, unsigned int reg);
 };
 
 /*
diff --git a/drivers/base/regmap/regmap-raw-ram.c b/drivers/base/regmap/regmap-raw-ram.c
index c9b800885f3b..463adafa9532 100644
--- a/drivers/base/regmap/regmap-raw-ram.c
+++ b/drivers/base/regmap/regmap-raw-ram.c
@@ -41,10 +41,15 @@ static int regmap_raw_ram_gather_write(void *context,
 		return -EINVAL;
 
 	r = decode_reg(data->reg_endian, reg);
-	memcpy(&our_buf[r], val, val_len);
-
-	for (i = 0; i < val_len / 2; i++)
-		data->written[r + i] = true;
+	if (data->noinc_reg && data->noinc_reg(data, r)) {
+		memcpy(&our_buf[r], val + val_len - 2, 2);
+		data->written[r] = true;
+	} else {
+		memcpy(&our_buf[r], val, val_len);
+
+		for (i = 0; i < val_len / 2; i++)
+			data->written[r + i] = true;
+	}
 	
 	return 0;
 }
@@ -70,10 +75,16 @@ static int regmap_raw_ram_read(void *context,
 		return -EINVAL;
 
 	r = decode_reg(data->reg_endian, reg);
-	memcpy(val, &our_buf[r], val_len);
-
-	for (i = 0; i < val_len / 2; i++)
-		data->read[r + i] = true;
+	if (data->noinc_reg && data->noinc_reg(data, r)) {
+		for (i = 0; i < val_len; i += 2)
+			memcpy(val + i, &our_buf[r], 2);
+		data->read[r] = true;
+	} else {
+		memcpy(val, &our_buf[r], val_len);
+
+		for (i = 0; i < val_len / 2; i++)
+			data->read[r + i] = true;
+	}
 
 	return 0;
 }
-- 
2.42.0