regmap: Provide a ram backed regmap with raw support

Provide a simple, 16 bit only, RAM backed regmap which supports raw I/O for
use in testing.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230610-regcache-raw-kunit-v1-1-583112cd28ac@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: broonie

drivers/base/regmap/Makefile

@@ -8,7 +8,7 @@ obj-$(CONFIG_DEBUG_FS) += regmap-debugfs.o
 obj-$(CONFIG_REGMAP_KUNIT) += regmap-kunit.o
 obj-$(CONFIG_REGMAP_AC97) += regmap-ac97.o
 obj-$(CONFIG_REGMAP_I2C) += regmap-i2c.o
-obj-$(CONFIG_REGMAP_RAM) += regmap-ram.o
+obj-$(CONFIG_REGMAP_RAM) += regmap-ram.o regmap-raw-ram.o
 obj-$(CONFIG_REGMAP_SLIMBUS) += regmap-slimbus.o
 obj-$(CONFIG_REGMAP_SPI) += regmap-spi.o
 obj-$(CONFIG_REGMAP_SPMI) += regmap-spmi.o

drivers/base/regmap/internal.h

@@ -312,6 +312,7 @@ struct regmap_ram_data {
 	unsigned int *vals;  /* Allocatd by caller */
 	bool *read;
 	bool *written;
+	enum regmap_endian reg_endian;
 };
 
 /*
@@ -326,5 +327,12 @@ struct regmap *__regmap_init_ram(const struct regmap_config *config,
 #define regmap_init_ram(config, data)					\
 	__regmap_lockdep_wrapper(__regmap_init_ram, #config, config, data)
 
+struct regmap *__regmap_init_raw_ram(const struct regmap_config *config,
+				     struct regmap_ram_data *data,
+				     struct lock_class_key *lock_key,
+				     const char *lock_name);
+
+#define regmap_init_raw_ram(config, data)				\
+	__regmap_lockdep_wrapper(__regmap_init_raw_ram, #config, config, data)
 
 #endif

drivers/base/regmap/regmap-raw-ram.c

@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// Register map access API - Memory region with raw access
+//
+// This is intended for testing only
+//
+// Copyright (c) 2023, Arm Ltd
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/regmap.h>
+#include <linux/slab.h>
+#include <linux/swab.h>
+
+#include "internal.h"
+
+static unsigned int decode_reg(enum regmap_endian endian, const void *reg)
+{
+	const u16 *r = reg;
+
+	if (endian == REGMAP_ENDIAN_BIG)
+		return be16_to_cpu(*r);
+	else
+		return le16_to_cpu(*r);
+}
+
+static int regmap_raw_ram_gather_write(void *context,
+				       const void *reg, size_t reg_len,
+				       const void *val, size_t val_len)
+{
+	struct regmap_ram_data *data = context;
+	unsigned int r;
+	u16 *our_buf = (u16 *)data->vals;
+	int i;
+
+	if (reg_len != 2)
+		return -EINVAL;
+	if (val_len % 2)
+		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;
+	
+	return 0;
+}
+
+static int regmap_raw_ram_write(void *context, const void *data, size_t count)
+{
+	return regmap_raw_ram_gather_write(context, data, 2,
+					   data + 2, count - 2);
+}
+
+static int regmap_raw_ram_read(void *context,
+			       const void *reg, size_t reg_len,
+			       void *val, size_t val_len)
+{
+	struct regmap_ram_data *data = context;
+	unsigned int r;
+	u16 *our_buf = (u16 *)data->vals;
+	int i;
+
+	if (reg_len != 2)
+		return -EINVAL;
+	if (val_len % 2)
+		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;
+
+	return 0;
+}
+
+static void regmap_raw_ram_free_context(void *context)
+{
+	struct regmap_ram_data *data = context;
+
+	kfree(data->vals);
+	kfree(data->read);
+	kfree(data->written);
+	kfree(data);
+}
+
+static const struct regmap_bus regmap_raw_ram = {
+	.fast_io = true,
+	.write = regmap_raw_ram_write,
+	.gather_write = regmap_raw_ram_gather_write,
+	.read = regmap_raw_ram_read,
+	.free_context = regmap_raw_ram_free_context,
+};
+
+struct regmap *__regmap_init_raw_ram(const struct regmap_config *config,
+				     struct regmap_ram_data *data,
+				     struct lock_class_key *lock_key,
+				     const char *lock_name)
+{
+	struct regmap *map;
+
+	if (config->reg_bits != 16)
+		return ERR_PTR(-EINVAL);
+
+	if (!config->max_register) {
+		pr_crit("No max_register specified for RAM regmap\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	data->read = kcalloc(sizeof(bool), config->max_register + 1,
+			     GFP_KERNEL);
+	if (!data->read)
+		return ERR_PTR(-ENOMEM);
+
+	data->written = kcalloc(sizeof(bool), config->max_register + 1,
+				GFP_KERNEL);
+	if (!data->written)
+		return ERR_PTR(-ENOMEM);
+
+	data->reg_endian = config->reg_format_endian;
+
+	map = __regmap_init(NULL, &regmap_raw_ram, data, config,
+			    lock_key, lock_name);
+
+	return map;
+}
+EXPORT_SYMBOL_GPL(__regmap_init_raw_ram);
+
+MODULE_LICENSE("GPL v2");