regmap: implement register striding

regmap_config.reg_stride is introduced. All extant register addresses
are a multiple of this value. Users of serial-oriented regmap busses will
typically set this to 1. Users of the MMIO regmap bus will typically set
this based on the value size of their registers, in bytes, so 4 for a
32-bit register.

Throughout the regmap code, actual register addresses are used. Wherever
the register address is used to index some array of values, the address
is divided by the stride to determine the index, or vice-versa. Error-
checking is added to all entry-points for register address data to ensure
that register addresses actually satisfy the specified stride. The MMIO
bus ensures that the specified stride is large enough for the register
size.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 99b28ff..d92e9b1 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -62,6 +62,7 @@
 
 	/* number of bits to (left) shift the reg value when formatting*/
 	int reg_shift;
+	int reg_stride;
 
 	/* regcache specific members */
 	const struct regcache_ops *cache_ops;
diff --git a/drivers/base/regmap/regcache-lzo.c b/drivers/base/regmap/regcache-lzo.c
index 483b06d..afd6aa9 100644
--- a/drivers/base/regmap/regcache-lzo.c
+++ b/drivers/base/regmap/regcache-lzo.c
@@ -108,7 +108,7 @@
 static inline int regcache_lzo_get_blkindex(struct regmap *map,
 					    unsigned int reg)
 {
-	return (reg * map->cache_word_size) /
+	return ((reg / map->reg_stride) * map->cache_word_size) /
 		DIV_ROUND_UP(map->cache_size_raw,
 			     regcache_lzo_block_count(map));
 }
@@ -116,9 +116,10 @@
 static inline int regcache_lzo_get_blkpos(struct regmap *map,
 					  unsigned int reg)
 {
-	return reg % (DIV_ROUND_UP(map->cache_size_raw,
-				   regcache_lzo_block_count(map)) /
-		      map->cache_word_size);
+	return (reg / map->reg_stride) %
+		    (DIV_ROUND_UP(map->cache_size_raw,
+				  regcache_lzo_block_count(map)) /
+		     map->cache_word_size);
 }
 
 static inline int regcache_lzo_get_blksize(struct regmap *map)
@@ -322,7 +323,7 @@
 	}
 
 	/* set the bit so we know we have to sync this register */
-	set_bit(reg, lzo_block->sync_bmp);
+	set_bit(reg / map->reg_stride, lzo_block->sync_bmp);
 	kfree(tmp_dst);
 	kfree(lzo_block->src);
 	return 0;
diff --git a/drivers/base/regmap/regcache-rbtree.c b/drivers/base/regmap/regcache-rbtree.c
index e49e71f..e6732cf 100644
--- a/drivers/base/regmap/regcache-rbtree.c
+++ b/drivers/base/regmap/regcache-rbtree.c
@@ -39,11 +39,12 @@
 };
 
 static inline void regcache_rbtree_get_base_top_reg(
+	struct regmap *map,
 	struct regcache_rbtree_node *rbnode,
 	unsigned int *base, unsigned int *top)
 {
 	*base = rbnode->base_reg;
-	*top = rbnode->base_reg + rbnode->blklen - 1;
+	*top = rbnode->base_reg + ((rbnode->blklen - 1) * map->reg_stride);
 }
 
 static unsigned int regcache_rbtree_get_register(
@@ -70,7 +71,8 @@
 
 	rbnode = rbtree_ctx->cached_rbnode;
 	if (rbnode) {
-		regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
+		regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
+						 &top_reg);
 		if (reg >= base_reg && reg <= top_reg)
 			return rbnode;
 	}
@@ -78,7 +80,8 @@
 	node = rbtree_ctx->root.rb_node;
 	while (node) {
 		rbnode = container_of(node, struct regcache_rbtree_node, node);
-		regcache_rbtree_get_base_top_reg(rbnode, &base_reg, &top_reg);
+		regcache_rbtree_get_base_top_reg(map, rbnode, &base_reg,
+						 &top_reg);
 		if (reg >= base_reg && reg <= top_reg) {
 			rbtree_ctx->cached_rbnode = rbnode;
 			return rbnode;
@@ -92,7 +95,7 @@
 	return NULL;
 }
 
-static int regcache_rbtree_insert(struct rb_root *root,
+static int regcache_rbtree_insert(struct regmap *map, struct rb_root *root,
 				  struct regcache_rbtree_node *rbnode)
 {
 	struct rb_node **new, *parent;
@@ -106,7 +109,7 @@
 		rbnode_tmp = container_of(*new, struct regcache_rbtree_node,
 					  node);
 		/* base and top registers of the current rbnode */
-		regcache_rbtree_get_base_top_reg(rbnode_tmp, &base_reg_tmp,
+		regcache_rbtree_get_base_top_reg(map, rbnode_tmp, &base_reg_tmp,
 						 &top_reg_tmp);
 		/* base register of the rbnode to be added */
 		base_reg = rbnode->base_reg;
@@ -138,7 +141,7 @@
 	unsigned int base, top;
 	int nodes = 0;
 	int registers = 0;
-	int average;
+	int this_registers, average;
 
 	map->lock(map);
 
@@ -146,11 +149,12 @@
 	     node = rb_next(node)) {
 		n = container_of(node, struct regcache_rbtree_node, node);
 
-		regcache_rbtree_get_base_top_reg(n, &base, &top);
-		seq_printf(s, "%x-%x (%d)\n", base, top, top - base + 1);
+		regcache_rbtree_get_base_top_reg(map, n, &base, &top);
+		this_registers = ((top - base) / map->reg_stride) + 1;
+		seq_printf(s, "%x-%x (%d)\n", base, top, this_registers);
 
 		nodes++;
-		registers += top - base + 1;
+		registers += this_registers;
 	}
 
 	if (nodes)
@@ -255,7 +259,7 @@
 
 	rbnode = regcache_rbtree_lookup(map, reg);
 	if (rbnode) {
-		reg_tmp = reg - rbnode->base_reg;
+		reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 		*value = regcache_rbtree_get_register(rbnode, reg_tmp,
 						      map->cache_word_size);
 	} else {
@@ -310,7 +314,7 @@
 	 */
 	rbnode = regcache_rbtree_lookup(map, reg);
 	if (rbnode) {
-		reg_tmp = reg - rbnode->base_reg;
+		reg_tmp = (reg - rbnode->base_reg) / map->reg_stride;
 		val = regcache_rbtree_get_register(rbnode, reg_tmp,
 						   map->cache_word_size);
 		if (val == value)
@@ -321,13 +325,15 @@
 		/* look for an adjacent register to the one we are about to add */
 		for (node = rb_first(&rbtree_ctx->root); node;
 		     node = rb_next(node)) {
-			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node, node);
+			rbnode_tmp = rb_entry(node, struct regcache_rbtree_node,
+					      node);
 			for (i = 0; i < rbnode_tmp->blklen; i++) {
-				reg_tmp = rbnode_tmp->base_reg + i;
-				if (abs(reg_tmp - reg) != 1)
+				reg_tmp = rbnode_tmp->base_reg +
+						(i * map->reg_stride);
+				if (abs(reg_tmp - reg) != map->reg_stride)
 					continue;
 				/* decide where in the block to place our register */
-				if (reg_tmp + 1 == reg)
+				if (reg_tmp + map->reg_stride == reg)
 					pos = i + 1;
 				else
 					pos = i;
@@ -357,7 +363,7 @@
 			return -ENOMEM;
 		}
 		regcache_rbtree_set_register(rbnode, 0, value, map->cache_word_size);
-		regcache_rbtree_insert(&rbtree_ctx->root, rbnode);
+		regcache_rbtree_insert(map, &rbtree_ctx->root, rbnode);
 		rbtree_ctx->cached_rbnode = rbnode;
 	}
 
@@ -397,7 +403,7 @@
 			end = rbnode->blklen;
 
 		for (i = base; i < end; i++) {
-			regtmp = rbnode->base_reg + i;
+			regtmp = rbnode->base_reg + (i * map->reg_stride);
 			val = regcache_rbtree_get_register(rbnode, i,
 							   map->cache_word_size);
 
diff --git a/drivers/base/regmap/regcache.c b/drivers/base/regmap/regcache.c
index d4368e8..835883b 100644
--- a/drivers/base/regmap/regcache.c
+++ b/drivers/base/regmap/regcache.c
@@ -59,7 +59,7 @@
 	for (count = 0, i = 0; i < map->num_reg_defaults_raw; i++) {
 		val = regcache_get_val(map->reg_defaults_raw,
 				       i, map->cache_word_size);
-		if (regmap_volatile(map, i))
+		if (regmap_volatile(map, i * map->reg_stride))
 			continue;
 		count++;
 	}
@@ -76,9 +76,9 @@
 	for (i = 0, j = 0; i < map->num_reg_defaults_raw; i++) {
 		val = regcache_get_val(map->reg_defaults_raw,
 				       i, map->cache_word_size);
-		if (regmap_volatile(map, i))
+		if (regmap_volatile(map, i * map->reg_stride))
 			continue;
-		map->reg_defaults[j].reg = i;
+		map->reg_defaults[j].reg = i * map->reg_stride;
 		map->reg_defaults[j].def = val;
 		j++;
 	}
@@ -98,6 +98,10 @@
 	int i;
 	void *tmp_buf;
 
+	for (i = 0; i < config->num_reg_defaults; i++)
+		if (config->reg_defaults[i].reg % map->reg_stride)
+			return -EINVAL;
+
 	if (map->cache_type == REGCACHE_NONE) {
 		map->cache_bypass = true;
 		return 0;
@@ -278,6 +282,10 @@
 	/* Apply any patch first */
 	map->cache_bypass = 1;
 	for (i = 0; i < map->patch_regs; i++) {
+		if (map->patch[i].reg % map->reg_stride) {
+			ret = -EINVAL;
+			goto out;
+		}
 		ret = _regmap_write(map, map->patch[i].reg, map->patch[i].def);
 		if (ret != 0) {
 			dev_err(map->dev, "Failed to write %x = %x: %d\n",
diff --git a/drivers/base/regmap/regmap-debugfs.c b/drivers/base/regmap/regmap-debugfs.c
index df97c93..bb1ff17 100644
--- a/drivers/base/regmap/regmap-debugfs.c
+++ b/drivers/base/regmap/regmap-debugfs.c
@@ -80,7 +80,7 @@
 	val_len = 2 * map->format.val_bytes;
 	tot_len = reg_len + val_len + 3;      /* : \n */
 
-	for (i = 0; i < map->max_register + 1; i++) {
+	for (i = 0; i <= map->max_register; i += map->reg_stride) {
 		if (!regmap_readable(map, i))
 			continue;
 
@@ -197,7 +197,7 @@
 	reg_len = regmap_calc_reg_len(map->max_register, buf, count);
 	tot_len = reg_len + 10; /* ': R W V P\n' */
 
-	for (i = 0; i < map->max_register + 1; i++) {
+	for (i = 0; i <= map->max_register; i += map->reg_stride) {
 		/* Ignore registers which are neither readable nor writable */
 		if (!regmap_readable(map, i) && !regmap_writeable(map, i))
 			continue;
diff --git a/drivers/base/regmap/regmap-irq.c b/drivers/base/regmap/regmap-irq.c
index 1befaa7..56b8136 100644
--- a/drivers/base/regmap/regmap-irq.c
+++ b/drivers/base/regmap/regmap-irq.c
@@ -58,11 +58,12 @@
 	 * suppress pointless writes.
 	 */
 	for (i = 0; i < d->chip->num_regs; i++) {
-		ret = regmap_update_bits(d->map, d->chip->mask_base + i,
+		ret = regmap_update_bits(d->map, d->chip->mask_base +
+						(i * map->map->reg_stride),
 					 d->mask_buf_def[i], d->mask_buf[i]);
 		if (ret != 0)
 			dev_err(d->map->dev, "Failed to sync masks in %x\n",
-				d->chip->mask_base + i);
+				d->chip->mask_base + (i * map->reg_stride));
 	}
 
 	mutex_unlock(&d->lock);
@@ -73,7 +74,7 @@
 	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
 	const struct regmap_irq *irq_data = irq_to_regmap_irq(d, data->irq);
 
-	d->mask_buf[irq_data->reg_offset] &= ~irq_data->mask;
+	d->mask_buf[irq_data->reg_offset / map->reg_stride] &= ~irq_data->mask;
 }
 
 static void regmap_irq_disable(struct irq_data *data)
@@ -81,7 +82,7 @@
 	struct regmap_irq_chip_data *d = irq_data_get_irq_chip_data(data);
 	const struct regmap_irq *irq_data = irq_to_regmap_irq(d, data->irq);
 
-	d->mask_buf[irq_data->reg_offset] |= irq_data->mask;
+	d->mask_buf[irq_data->reg_offset / map->reg_stride] |= irq_data->mask;
 }
 
 static struct irq_chip regmap_irq_chip = {
@@ -136,17 +137,19 @@
 		data->status_buf[i] &= ~data->mask_buf[i];
 
 		if (data->status_buf[i] && chip->ack_base) {
-			ret = regmap_write(map, chip->ack_base + i,
+			ret = regmap_write(map, chip->ack_base +
+						(i * map->reg_stride),
 					   data->status_buf[i]);
 			if (ret != 0)
 				dev_err(map->dev, "Failed to ack 0x%x: %d\n",
-					chip->ack_base + i, ret);
+					chip->ack_base + (i * map->reg_stride),
+					ret);
 		}
 	}
 
 	for (i = 0; i < chip->num_irqs; i++) {
-		if (data->status_buf[chip->irqs[i].reg_offset] &
-		    chip->irqs[i].mask) {
+		if (data->status_buf[chip->irqs[i].reg_offset /
+				     map->reg_stride] & chip->irqs[i].mask) {
 			handle_nested_irq(data->irq_base + i);
 			handled = true;
 		}
@@ -181,6 +184,14 @@
 	int cur_irq, i;
 	int ret = -ENOMEM;
 
+	for (i = 0; i < chip->num_irqs; i++) {
+		if (chip->irqs[i].reg_offset % map->reg_stride)
+			return -EINVAL;
+		if (chip->irqs[i].reg_offset / map->reg_stride >=
+		    chip->num_regs)
+			return -EINVAL;
+	}
+
 	irq_base = irq_alloc_descs(irq_base, 0, chip->num_irqs, 0);
 	if (irq_base < 0) {
 		dev_warn(map->dev, "Failed to allocate IRQs: %d\n",
@@ -218,16 +229,17 @@
 	mutex_init(&d->lock);
 
 	for (i = 0; i < chip->num_irqs; i++)
-		d->mask_buf_def[chip->irqs[i].reg_offset]
+		d->mask_buf_def[chip->irqs[i].reg_offset / map->reg_stride]
 			|= chip->irqs[i].mask;
 
 	/* Mask all the interrupts by default */
 	for (i = 0; i < chip->num_regs; i++) {
 		d->mask_buf[i] = d->mask_buf_def[i];
-		ret = regmap_write(map, chip->mask_base + i, d->mask_buf[i]);
+		ret = regmap_write(map, chip->mask_base + (i * map->reg_stride),
+				   d->mask_buf[i]);
 		if (ret != 0) {
 			dev_err(map->dev, "Failed to set masks in 0x%x: %d\n",
-				chip->mask_base + i, ret);
+				chip->mask_base + (i * map->reg_stride), ret);
 			goto err_alloc;
 		}
 	}
diff --git a/drivers/base/regmap/regmap-mmio.c b/drivers/base/regmap/regmap-mmio.c
index bdf4dc8..febd6de 100644
--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -130,6 +130,7 @@
 					const struct regmap_config *config)
 {
 	struct regmap_mmio_context *ctx;
+	int min_stride;
 
 	if (config->reg_bits != 32)
 		return ERR_PTR(-EINVAL);
@@ -139,16 +140,28 @@
 
 	switch (config->val_bits) {
 	case 8:
+		/* The core treats 0 as 1 */
+		min_stride = 0;
+		break;
 	case 16:
+		min_stride = 2;
+		break;
 	case 32:
+		min_stride = 4;
+		break;
 #ifdef CONFIG_64BIT
 	case 64:
+		min_stride = 8;
+		break;
 #endif
 		break;
 	default:
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (config->reg_stride < min_stride)
+		return ERR_PTR(-EINVAL);
+
 	ctx = kzalloc(GFP_KERNEL, sizeof(*ctx));
 	if (!ctx)
 		return ERR_PTR(-ENOMEM);
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 40f9101..8a25006 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -243,6 +243,10 @@
 	map->format.val_bytes = DIV_ROUND_UP(config->val_bits, 8);
 	map->format.buf_size += map->format.pad_bytes;
 	map->reg_shift = config->pad_bits % 8;
+	if (config->reg_stride)
+		map->reg_stride = config->reg_stride;
+	else
+		map->reg_stride = 1;
 	map->dev = dev;
 	map->bus = bus;
 	map->bus_context = bus_context;
@@ -469,7 +473,8 @@
 	/* Check for unwritable registers before we start */
 	if (map->writeable_reg)
 		for (i = 0; i < val_len / map->format.val_bytes; i++)
-			if (!map->writeable_reg(map->dev, reg + i))
+			if (!map->writeable_reg(map->dev,
+						reg + (i * map->reg_stride)))
 				return -EINVAL;
 
 	if (!map->cache_bypass && map->format.parse_val) {
@@ -478,7 +483,8 @@
 		for (i = 0; i < val_len / val_bytes; i++) {
 			memcpy(map->work_buf, val + (i * val_bytes), val_bytes);
 			ival = map->format.parse_val(map->work_buf);
-			ret = regcache_write(map, reg + i, ival);
+			ret = regcache_write(map, reg + (i * map->reg_stride),
+					     ival);
 			if (ret) {
 				dev_err(map->dev,
 				   "Error in caching of register: %u ret: %d\n",
@@ -590,6 +596,9 @@
 {
 	int ret;
 
+	if (reg % map->reg_stride)
+		return -EINVAL;
+
 	map->lock(map);
 
 	ret = _regmap_write(map, reg, val);
@@ -623,6 +632,8 @@
 
 	if (val_len % map->format.val_bytes)
 		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
 
 	map->lock(map);
 
@@ -657,6 +668,8 @@
 
 	if (!map->format.parse_val)
 		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
 
 	map->lock(map);
 
@@ -753,6 +766,9 @@
 {
 	int ret;
 
+	if (reg % map->reg_stride)
+		return -EINVAL;
+
 	map->lock(map);
 
 	ret = _regmap_read(map, reg, val);
@@ -784,6 +800,8 @@
 
 	if (val_len % map->format.val_bytes)
 		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
 
 	map->lock(map);
 
@@ -797,7 +815,8 @@
 		 * cost as we expect to hit the cache.
 		 */
 		for (i = 0; i < val_count; i++) {
-			ret = _regmap_read(map, reg + i, &v);
+			ret = _regmap_read(map, reg + (i * map->reg_stride),
+					   &v);
 			if (ret != 0)
 				goto out;
 
@@ -832,6 +851,8 @@
 
 	if (!map->format.parse_val)
 		return -EINVAL;
+	if (reg % map->reg_stride)
+		return -EINVAL;
 
 	if (vol || map->cache_type == REGCACHE_NONE) {
 		ret = regmap_raw_read(map, reg, val, val_bytes * val_count);
@@ -842,7 +863,8 @@
 			map->format.parse_val(val + i);
 	} else {
 		for (i = 0; i < val_count; i++) {
-			ret = regmap_read(map, reg + i, val + (i * val_bytes));
+			ret = regmap_read(map, reg + (i * map->reg_stride),
+					  val + (i * val_bytes));
 			if (ret != 0)
 				return ret;
 		}
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 680ddd7..0258bcd 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -50,6 +50,9 @@
  *        register regions.
  *
  * @reg_bits: Number of bits in a register address, mandatory.
+ * @reg_stride: The register address stride. Valid register addresses are a
+ *              multiple of this value. If set to 0, a value of 1 will be
+ *              used.
  * @pad_bits: Number of bits of padding between register and value.
  * @val_bits: Number of bits in a register value, mandatory.
  *
@@ -83,6 +86,7 @@
 	const char *name;
 
 	int reg_bits;
+	int reg_stride;
 	int pad_bits;
 	int val_bits;