regmap: Add support for register indirect addressing.

Devices with register paging or indirectly accessed registers can configure
register mapping to map those on virtual address range. During access to
virtually mapped register range, indirect addressing is processed
automatically, in following steps:
  1. selector for page or indirect register is updated (when needed);
  2. register in data window is accessed.

Configuration should provide minimum and maximum register for virtual range,
details of selector field for page selection, minimum and maximum register of
data window for indirect access.

Virtual range registers are managed by cache as well as direct access
registers. In order to make indirect access more efficient, selector register
should be declared as non-volatile, if possible.

struct regmap_config is extended with the following:
struct regmap_range_cfg	*ranges;
unsigned int		n_ranges;

[Also reordered debugfs init to later on since the cleanup code was
conflicting with the new cleanup code for ranges anyway -- broonie]

Signed-off-by: Krystian Garbaciak <krystian.garbaciak@diasemi.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

2 files changed, 213 insertions, 5 deletions

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index b986b86..80f9ab9 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -95,6 +95,9 @@ struct regmap {
 
 	/* if set, converts bulk rw to single rw */
 	bool use_single_rw;
+
+	struct rb_root range_tree;
+	void *selector_work_buf;	/* Scratch buffer used for selector */
 };
 
 struct regcache_ops {
@@ -115,6 +118,20 @@ bool regmap_precious(struct regmap *map, unsigned int reg);
 int _regmap_write(struct regmap *map, unsigned int reg,
 		  unsigned int val);
 
+struct regmap_range_node {
+	struct rb_node node;
+
+	unsigned int range_min;
+	unsigned int range_max;
+
+	unsigned int selector_reg;
+	unsigned int selector_mask;
+	int selector_shift;
+
+	unsigned int window_start;
+	unsigned int window_len;
+};
+
 #ifdef CONFIG_DEBUG_FS
 extern void regmap_debugfs_initcall(void);
 extern void regmap_debugfs_init(struct regmap *map, const char *name);
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 6520179..83a0166 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -15,12 +15,17 @@
 #include <linux/export.h>
 #include <linux/mutex.h>
 #include <linux/err.h>
+#include <linux/rbtree.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/regmap.h>
 
 #include "internal.h"
 
+static int _regmap_update_bits(struct regmap *map, unsigned int reg,
+			       unsigned int mask, unsigned int val,
+			       bool *change);
+
 bool regmap_writeable(struct regmap *map, unsigned int reg)
 {
 	if (map->max_register && reg > map->max_register)
@@ -208,6 +213,67 @@ static void dev_get_regmap_release(struct device *dev, void *res)
 	 */
 }
 
+static bool _regmap_range_add(struct regmap *map,
+			      struct regmap_range_node *data)
+{
+	struct rb_root *root = &map->range_tree;
+	struct rb_node **new = &(root->rb_node), *parent = NULL;
+
+	while (*new) {
+		struct regmap_range_node *this =
+			container_of(*new, struct regmap_range_node, node);
+
+		parent = *new;
+		if (data->range_max < this->range_min)
+			new = &((*new)->rb_left);
+		else if (data->range_min > this->range_max)
+			new = &((*new)->rb_right);
+		else
+			return false;
+	}
+
+	rb_link_node(&data->node, parent, new);
+	rb_insert_color(&data->node, root);
+
+	return true;
+}
+
+static struct regmap_range_node *_regmap_range_lookup(struct regmap *map,
+						      unsigned int reg)
+{
+	struct rb_node *node = map->range_tree.rb_node;
+
+	while (node) {
+		struct regmap_range_node *this =
+			container_of(node, struct regmap_range_node, node);
+
+		if (reg < this->range_min)
+			node = node->rb_left;
+		else if (reg > this->range_max)
+			node = node->rb_right;
+		else
+			return this;
+	}
+
+	return NULL;
+}
+
+static void regmap_range_exit(struct regmap *map)
+{
+	struct rb_node *next;
+	struct regmap_range_node *range_node;
+
+	next = rb_first(&map->range_tree);
+	while (next) {
+		range_node = rb_entry(next, struct regmap_range_node, node);
+		next = rb_next(&range_node->node);
+		rb_erase(&range_node->node, &map->range_tree);
+		kfree(range_node);
+	}
+
+	kfree(map->selector_work_buf);
+}
+
 /**
  * regmap_init(): Initialise register map
  *
@@ -227,6 +293,7 @@ struct regmap *regmap_init(struct device *dev,
 {
 	struct regmap *map, **m;
 	int ret = -EINVAL;
+	int i, j;
 
 	if (!bus || !config)
 		goto err;
@@ -364,27 +431,88 @@ struct regmap *regmap_init(struct device *dev,
 		goto err_map;
 	}
 
-	regmap_debugfs_init(map, config->name);
+	map->range_tree = RB_ROOT;
+	for (i = 0; i < config->n_ranges; i++) {
+		const struct regmap_range_cfg *range_cfg = &config->ranges[i];
+		struct regmap_range_node *new;
+
+		/* Sanity check */
+		if (range_cfg->range_max < range_cfg->range_min ||
+		    range_cfg->range_max > map->max_register ||
+		    range_cfg->selector_reg > map->max_register ||
+		    range_cfg->window_len == 0)
+			goto err_range;
+
+		/* Make sure, that this register range has no selector
+		   or data window within its boundary */
+		for (j = 0; j < config->n_ranges; j++) {
+			unsigned sel_reg = config->ranges[j].selector_reg;
+			unsigned win_min = config->ranges[j].window_start;
+			unsigned win_max = win_min +
+					   config->ranges[j].window_len - 1;
+
+			if (range_cfg->range_min <= sel_reg &&
+			    sel_reg <= range_cfg->range_max) {
+				goto err_range;
+			}
+
+			if (!(win_max < range_cfg->range_min ||
+			      win_min > range_cfg->range_max)) {
+				goto err_range;
+			}
+		}
+
+		new = kzalloc(sizeof(*new), GFP_KERNEL);
+		if (new == NULL) {
+			ret = -ENOMEM;
+			goto err_range;
+		}
+
+		new->range_min = range_cfg->range_min;
+		new->range_max = range_cfg->range_max;
+		new->selector_reg = range_cfg->selector_reg;
+		new->selector_mask = range_cfg->selector_mask;
+		new->selector_shift = range_cfg->selector_shift;
+		new->window_start = range_cfg->window_start;
+		new->window_len = range_cfg->window_len;
+
+		if (_regmap_range_add(map, new) == false) {
+			kfree(new);
+			goto err_range;
+		}
+
+		if (map->selector_work_buf == NULL) {
+			map->selector_work_buf =
+				kzalloc(map->format.buf_size, GFP_KERNEL);
+			if (map->selector_work_buf == NULL) {
+				ret = -ENOMEM;
+				goto err_range;
+			}
+		}
+	}
 
 	ret = regcache_init(map, config);
 	if (ret < 0)
-		goto err_debugfs;
+		goto err_range;
+
+	regmap_debugfs_init(map, config->name);
 
 	/* Add a devres resource for dev_get_regmap() */
 	m = devres_alloc(dev_get_regmap_release, sizeof(*m), GFP_KERNEL);
 	if (!m) {
 		ret = -ENOMEM;
-		goto err_cache;
+		goto err_debugfs;
 	}
 	*m = map;
 	devres_add(dev, m);
 
 	return map;
 
-err_cache:
-	regcache_exit(map);
 err_debugfs:
 	regmap_debugfs_exit(map);
+	regcache_exit(map);
+err_range:
+	regmap_range_exit(map);
 	kfree(map->work_buf);
 err_map:
 	kfree(map);
@@ -481,6 +609,7 @@ void regmap_exit(struct regmap *map)
 {
 	regcache_exit(map);
 	regmap_debugfs_exit(map);
+	regmap_range_exit(map);
 	if (map->bus->free_context)
 		map->bus->free_context(map->bus_context);
 	kfree(map->work_buf);
@@ -526,6 +655,56 @@ struct regmap *dev_get_regmap(struct device *dev, const char *name)
 }
 EXPORT_SYMBOL_GPL(dev_get_regmap);
 
+static int _regmap_select_page(struct regmap *map, unsigned int *reg,
+			       unsigned int val_num)
+{
+	struct regmap_range_node *range;
+	void *orig_work_buf;
+	unsigned int win_offset;
+	unsigned int win_page;
+	bool page_chg;
+	int ret;
+
+	range = _regmap_range_lookup(map, *reg);
+	if (range) {
+		win_offset = (*reg - range->range_min) % range->window_len;
+		win_page = (*reg - range->range_min) / range->window_len;
+
+		if (val_num > 1) {
+			/* Bulk write shouldn't cross range boundary */
+			if (*reg + val_num - 1 > range->range_max)
+				return -EINVAL;
+
+			/* ... or single page boundary */
+			if (val_num > range->window_len - win_offset)
+				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. */
+		if (val_num > 1 ||
+		    range->window_start + win_offset != range->selector_reg) {
+			/* 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,
+					&page_chg);
+			if (ret < 0)
+				return ret;
+
+			map->work_buf = orig_work_buf;
+		}
+
+		*reg = range->window_start + win_offset;
+	}
+
+	return 0;
+}
+
 static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 			     const void *val, size_t val_len)
 {
@@ -563,6 +742,10 @@ static int _regmap_raw_write(struct regmap *map, unsigned int reg,
 		}
 	}
 
+	ret = _regmap_select_page(map, &reg, val_len / map->format.val_bytes);
+	if (ret < 0)
+		return ret;
+
 	map->format.format_reg(map->work_buf, reg, map->reg_shift);
 
 	u8[0] |= map->write_flag_mask;
@@ -626,6 +809,10 @@ int _regmap_write(struct regmap *map, unsigned int reg,
 	trace_regmap_reg_write(map->dev, reg, val);
 
 	if (map->format.format_write) {
+		ret = _regmap_select_page(map, &reg, 1);
+		if (ret < 0)
+			return ret;
+
 		map->format.format_write(map, reg, val);
 
 		trace_regmap_hw_write_start(map->dev, reg, 1);
@@ -783,6 +970,10 @@ static int _regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 	u8 *u8 = map->work_buf;
 	int ret;
 
+	ret = _regmap_select_page(map, &reg, val_len / map->format.val_bytes);
+	if (ret < 0)
+		return ret;
+
 	map->format.format_reg(map->work_buf, reg, map->reg_shift);
 
 	/*