Add initial regmap support

This adds initial regmap support. Function prototypes are from
the Kernel, the implemention is mostly rewritten. Currently the
regmap support is limited to the bare minimum to get started.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

4 files changed, 374 insertions, 0 deletions

diff --git a/drivers/base/Makefile b/drivers/base/Makefile
index e1f1c7a0ad..4bd4217745 100644
--- a/drivers/base/Makefile
+++ b/drivers/base/Makefile
@@ -2,3 +2,4 @@ obj-y	+= bus.o
 obj-y	+= driver.o
 obj-y	+= platform.o
 obj-y	+= resource.o
+obj-y	+= regmap/
\ No newline at end of file
diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
new file mode 100644
index 0000000000..4dc3d8c510
--- /dev/null
+++ b/drivers/base/regmap/Makefile
@@ -0,0 +1 @@
+obj-y	+= regmap.o
\ No newline at end of file
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
new file mode 100644
index 0000000000..52df5290a1
--- /dev/null
+++ b/drivers/base/regmap/internal.h
@@ -0,0 +1,18 @@
+
+#include <linux/list.h>
+
+struct regmap {
+	struct device_d *dev;
+	const struct regmap_bus *bus;
+	const char *name;
+	void *bus_context;
+	struct list_head list;
+	int reg_bits;
+	int reg_stride;
+	int pad_bits;
+	int val_bits;
+	int val_bytes;
+	unsigned int max_register;
+
+	struct cdev cdev;
+};
\ No newline at end of file
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
new file mode 100644
index 0000000000..a042a1a24e
--- /dev/null
+++ b/drivers/base/regmap/regmap.c
@@ -0,0 +1,354 @@
+/*
+ * Register map access API
+ *
+ * Copyright 2016 Sascha Hauer <s.hauer@pengutronix.de>
+ *
+ * based on Kernel code:
+ *
+ * Copyright 2011 Wolfson Microelectronics plc
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; version 2.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include <common.h>
+#include <regmap.h>
+#include <malloc.h>
+#include <linux/log2.h>
+
+#include "internal.h"
+
+static LIST_HEAD(regmaps);
+
+/*
+ * regmap_init - initialize and register a regmap
+ *
+ * @dev:         The device the new regmap belongs to
+ * @bus:         The regmap_bus providing read/write access to the map
+ * @bus_context: Context pointer for the bus ops
+ * @config:      Configuration options for this map
+ *
+ * Returns a pointer to the new map or a ERR_PTR value on failure
+ */
+struct regmap *regmap_init(struct device_d *dev,
+			     const struct regmap_bus *bus,
+			     void *bus_context,
+			     const struct regmap_config *config)
+{
+	struct regmap *map;
+
+	map = xzalloc(sizeof(*map));
+	map->dev = dev;
+	map->bus = bus;
+	map->name = config->name;
+	map->bus_context = bus_context;
+	map->reg_bits = config->reg_bits;
+	map->reg_stride = config->reg_stride;
+	if (!map->reg_stride)
+		map->reg_stride = 1;
+	map->pad_bits = config->pad_bits;
+	map->val_bits = config->val_bits;
+	map->val_bytes = DIV_ROUND_UP(config->val_bits, 8);
+	map->max_register = config->max_register;
+
+	list_add_tail(&map->list, &regmaps);
+
+	return map;
+}
+
+/*
+ * regmap_init - initialize and register a regmap
+ *
+ * @dev:         The device the maps is attached to
+ * @name:        Optional name for the map. If given it must match.
+ *
+ * Returns a pointer to the regmap or a ERR_PTR value on failure
+ */
+struct regmap *dev_get_regmap(struct device_d *dev, const char *name)
+{
+	struct regmap *map;
+
+	list_for_each_entry(map, &regmaps, list) {
+		if (map->dev != dev)
+			continue;
+		if (!name)
+			return map;
+		if (!strcmp(map->name, name))
+			return map;
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+/*
+ * of_node_to_regmap - get a regmap from a device node
+ *
+ * node:         The device node
+ *
+ * Returns a pointer to the regmap or a ERR_PTR if the node has no
+ * regmap attached.
+ */
+struct regmap *of_node_to_regmap(struct device_node *node)
+{
+	struct regmap *map;
+
+	list_for_each_entry(map, &regmaps, list) {
+		if (map->dev->device_node == node)
+			return map;
+	}
+
+	return ERR_PTR(-ENOENT);
+}
+
+/*
+ * regmap_write - write a register in a map
+ *
+ * @map:	The map
+ * @reg:	The register offset of the register
+ * @val:	The value to be written
+ *
+ * Returns 0 for success or negative error code on failure
+ */
+int regmap_write(struct regmap *map, unsigned int reg, unsigned int val)
+{
+	return map->bus->reg_write(map->bus_context, reg, val);
+}
+
+/*
+ * regmap_write - read a register from a map
+ *
+ * @map:	The map
+ * @reg:	The register offset of the register
+ * @val:	pointer to value read
+ *
+ * Returns 0 for success or negative error code on failure
+ */
+int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val)
+{
+	return map->bus->reg_read(map->bus_context, reg, val);
+}
+
+/**
+ * regmap_bulk_read(): Read data from the device
+ *
+ * @map: Register map to read from
+ * @reg: First register to be read from
+ * @val: Pointer to store read value
+ * @val_len: Size of data to read
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
+		     size_t val_len)
+{
+	size_t val_bytes = map->val_bytes;
+	size_t val_count = val_len / val_bytes;
+	unsigned int v;
+	int ret, i;
+
+	if (val_len % val_bytes)
+		return -EINVAL;
+	if (!IS_ALIGNED(reg, map->reg_stride))
+		return -EINVAL;
+	if (val_count == 0)
+		return -EINVAL;
+
+	for (i = 0; i < val_count; i++) {
+		u32 *u32 = val;
+		u16 *u16 = val;
+		u8 *u8 = val;
+
+		ret = regmap_read(map, reg + (i * map->reg_stride), &v);
+		if (ret != 0)
+			goto out;
+
+		switch (map->val_bytes) {
+		case 4:
+			u32[i] = v;
+			break;
+		case 2:
+			u16[i] = v;
+			break;
+		case 1:
+			u8[i] = v;
+			break;
+		default:
+			return -EINVAL;
+		}
+	}
+
+ out:
+	return ret;
+}
+
+/**
+ * regmap_bulk_write(): Write values to one or more registers
+ *
+ * @map: Register map to write to
+ * @reg: Initial register to write to
+ * @val: Block of data to be written, laid out for direct transmission to the
+ *       device
+ * @val_len: Length of data pointed to by val.
+ *
+ * A value of zero will be returned on success, a negative errno will
+ * be returned in error cases.
+ */
+int regmap_bulk_write(struct regmap *map, unsigned int reg,
+		     const void *val, size_t val_len)
+{
+	size_t val_bytes = map->val_bytes;
+	size_t val_count = val_len / val_bytes;
+	int ret, i;
+
+	if (val_len % val_bytes)
+		return -EINVAL;
+	if (!IS_ALIGNED(reg, map->reg_stride))
+		return -EINVAL;
+	if (val_count == 0)
+		return -EINVAL;
+
+	for (i = 0; i < val_count; i++) {
+		unsigned int ival;
+
+		switch (val_bytes) {
+		case 1:
+			ival = *(u8 *)(val + (i * val_bytes));
+			break;
+		case 2:
+			ival = *(u16 *)(val + (i * val_bytes));
+			break;
+		case 4:
+			ival = *(u32 *)(val + (i * val_bytes));
+			break;
+		default:
+			ret = -EINVAL;
+			goto out;
+		}
+
+		ret = regmap_write(map, reg + (i * map->reg_stride),
+				ival);
+		if (ret != 0)
+			goto out;
+	}
+
+ out:
+	return ret;
+}
+
+int regmap_get_val_bytes(struct regmap *map)
+{
+	return map->val_bytes;
+}
+
+int regmap_get_max_register(struct regmap *map)
+{
+	return map->max_register;
+}
+
+int regmap_get_reg_stride(struct regmap *map)
+{
+	return map->reg_stride;
+}
+
+static int regmap_round_val_bytes(struct regmap *map)
+{
+	int val_bytes;
+
+	val_bytes = roundup_pow_of_two(map->val_bits) >> 3;
+	if (!val_bytes)
+		val_bytes = 1;
+
+	return val_bytes;
+}
+
+static ssize_t regmap_cdev_read(struct cdev *cdev, void *buf, size_t count, loff_t offset,
+		       unsigned long flags)
+{
+	struct regmap *map = container_of(cdev, struct regmap, cdev);
+	int ret;
+
+	ret = regmap_bulk_read(map, offset, buf, count);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static ssize_t regmap_cdev_write(struct cdev *cdev, const void *buf, size_t count, loff_t offset,
+			unsigned long flags)
+{
+	struct regmap *map = container_of(cdev, struct regmap, cdev);
+	int ret;
+
+	ret = regmap_bulk_write(map, offset, buf, count);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+static struct file_operations regmap_fops = {
+	.lseek	= dev_lseek_default,
+	.read	= regmap_cdev_read,
+	.write	= regmap_cdev_write,
+};
+
+/*
+ * regmap_register_cdev - register a devfs file for a regmap
+ *
+ * @map:	The map
+ * @name:	Optional name of the device file
+ *
+ * Returns 0 for success or negative error code on failure
+ */
+int regmap_register_cdev(struct regmap *map, const char *name)
+{
+	int ret;
+
+	if (map->cdev.name)
+		return -EBUSY;
+
+	if (!map->max_register)
+		return -EINVAL;
+
+	if (name) {
+		map->cdev.name = xstrdup(name);
+	} else {
+		if (map->name)
+			map->cdev.name = xasprintf("%s-%s", dev_name(map->dev), map->name);
+		else
+			map->cdev.name = xstrdup(dev_name(map->dev));
+	}
+
+	map->cdev.size = regmap_round_val_bytes(map) * (map->max_register + 1) /
+			map->reg_stride;
+	map->cdev.dev = map->dev;
+	map->cdev.ops = &regmap_fops;
+
+	ret = devfs_create(&map->cdev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+void regmap_exit(struct regmap *map)
+{
+	list_del(&map->list);
+
+	if (map->cdev.name) {
+		devfs_remove(&map->cdev);
+		free(map->cdev.name);
+	}
+
+	free(map);
+}
\ No newline at end of file