regmap: Implementation for regmap_multi_reg_write

This is the implementation of regmap_multi_reg_write()

There is a new capability 'can_multi_write' that device drivers
must set in order to use this multi reg write mode.

This replaces the first definition, which just defined the API.

Signed-off-by: Anthony Olech <anthony.olech.opensource@diasemi.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/internal.h

@@ -134,6 +134,8 @@ struct regmap {
 
 	/* if set, converts bulk rw to single rw */
 	bool use_single_rw;
+	/* if set, the device supports multi write mode */
+	bool can_multi_write;
 
 	struct rb_root range_tree;
 	void *selector_work_buf;	/* Scratch buffer used for selector */

drivers/base/regmap/regmap.c

@@ -439,6 +439,7 @@ struct regmap *regmap_init(struct device *dev,
 	else
 		map->reg_stride = 1;
 	map->use_single_rw = config->use_single_rw;
+	map->can_multi_write = config->can_multi_write;
 	map->dev = dev;
 	map->bus = bus;
 	map->bus_context = bus_context;
@@ -1576,41 +1577,196 @@ out:
 }
 EXPORT_SYMBOL_GPL(regmap_bulk_write);
 
+/*
+ * _regmap_raw_multi_reg_write()
+ *
+ * the (register,newvalue) pairs in regs have not been formatted, but
+ * they are all in the same page and have been changed to being page
+ * relative. The page register has been written if that was neccessary.
+ */
+static int _regmap_raw_multi_reg_write(struct regmap *map,
+				       const struct reg_default *regs,
+				       size_t num_regs)
+{
+	int ret;
+	void *buf;
+	int i;
+	u8 *u8;
+	size_t val_bytes = map->format.val_bytes;
+	size_t reg_bytes = map->format.reg_bytes;
+	size_t pad_bytes = map->format.pad_bytes;
+	size_t pair_size = reg_bytes + pad_bytes + val_bytes;
+	size_t len = pair_size * num_regs;
+
+	buf = kzalloc(len, GFP_KERNEL);
+	if (!buf)
+		return -ENOMEM;
+
+	/* We have to linearise by hand. */
+
+	u8 = buf;
+
+	for (i = 0; i < num_regs; i++) {
+		int reg = regs[i].reg;
+		int val = regs[i].def;
+		trace_regmap_hw_write_start(map->dev, reg, 1);
+		map->format.format_reg(u8, reg, map->reg_shift);
+		u8 += reg_bytes + pad_bytes;
+		map->format.format_val(u8, val, 0);
+		u8 += val_bytes;
+	}
+	u8 = buf;
+	*u8 |= map->write_flag_mask;
+
+	ret = map->bus->write(map->bus_context, buf, len);
+
+	kfree(buf);
+
+	for (i = 0; i < num_regs; i++) {
+		int reg = regs[i].reg;
+		trace_regmap_hw_write_done(map->dev, reg, 1);
+	}
+	return ret;
+}
+
+static unsigned int _regmap_register_page(struct regmap *map,
+					  unsigned int reg,
+					  struct regmap_range_node *range)
+{
+	unsigned int win_page = (reg - range->range_min) / range->window_len;
+
+	return win_page;
+}
+
+static int _regmap_range_multi_paged_reg_write(struct regmap *map,
+					       struct reg_default *regs,
+					       size_t num_regs)
+{
+	int ret;
+	int i, n;
+	struct reg_default *base;
+	unsigned int this_page;
+	/*
+	 * the set of registers are not neccessarily in order, but
+	 * since the order of write must be preserved this algorithm
+	 * chops the set each time the page changes
+	 */
+	base = regs;
+	for (i = 0, n = 0; i < num_regs; i++, n++) {
+		unsigned int reg = regs[i].reg;
+		struct regmap_range_node *range;
+
+		range = _regmap_range_lookup(map, reg);
+		if (range) {
+			unsigned int win_page = _regmap_register_page(map, reg,
+								      range);
+
+			if (i == 0)
+				this_page = win_page;
+			if (win_page != this_page) {
+				this_page = win_page;
+				ret = _regmap_raw_multi_reg_write(map, base, n);
+				if (ret != 0)
+					return ret;
+				base += n;
+				n = 0;
+			}
+			ret = _regmap_select_page(map, &base[n].reg, range, 1);
+			if (ret != 0)
+				return ret;
+		}
+	}
+	if (n > 0)
+		return _regmap_raw_multi_reg_write(map, base, n);
+	return 0;
+}
+
 static int _regmap_multi_reg_write(struct regmap *map,
 				   const struct reg_default *regs,
-				   int num_regs)
+				   size_t num_regs)
 {
-	int i, ret;
+	int i;
+	int ret;
+
+	if (!map->can_multi_write) {
+		for (i = 0; i < num_regs; i++) {
+			ret = _regmap_write(map, regs[i].reg, regs[i].def);
+			if (ret != 0)
+				return ret;
+		}
+		return 0;
+	}
+
+	if (!map->format.parse_inplace)
+		return -EINVAL;
+
+	if (map->writeable_reg)
+		for (i = 0; i < num_regs; i++) {
+			int reg = regs[i].reg;
+			if (!map->writeable_reg(map->dev, reg))
+				return -EINVAL;
+			if (reg % map->reg_stride)
+				return -EINVAL;
+		}
+
+	if (!map->cache_bypass) {
+		for (i = 0; i < num_regs; i++) {
+			unsigned int val = regs[i].def;
+			unsigned int reg = regs[i].reg;
+			ret = regcache_write(map, reg, val);
+			if (ret) {
+				dev_err(map->dev,
+				"Error in caching of register: %x ret: %d\n",
+								reg, ret);
+				return ret;
+			}
+		}
+		if (map->cache_only) {
+			map->cache_dirty = true;
+			return 0;
+		}
+	}
+
+	WARN_ON(!map->bus);
 
 	for (i = 0; i < num_regs; i++) {
-		if (regs[i].reg % map->reg_stride)
-			return -EINVAL;
-		ret = _regmap_write(map, regs[i].reg, regs[i].def);
-		if (ret != 0) {
-			dev_err(map->dev, "Failed to write %x = %x: %d\n",
-				regs[i].reg, regs[i].def, ret);
+		unsigned int reg = regs[i].reg;
+		struct regmap_range_node *range;
+		range = _regmap_range_lookup(map, reg);
+		if (range) {
+			size_t len = sizeof(struct reg_default)*num_regs;
+			struct reg_default *base = kmemdup(regs, len,
+							   GFP_KERNEL);
+			if (!base)
+				return -ENOMEM;
+			ret = _regmap_range_multi_paged_reg_write(map, base,
+								  num_regs);
+			kfree(base);
+
 			return ret;
 		}
 	}
-
-	return 0;
+	return _regmap_raw_multi_reg_write(map, regs, num_regs);
 }
 
 /*
  * regmap_multi_reg_write(): Write multiple registers to the device
  *
- * where the set of register are supplied in any order
+ * where the set of register,value pairs are supplied in any order,
+ * possibly not all in a single range.
  *
  * @map: Register map to write to
  * @regs: Array of structures containing register,value to be written
  * @num_regs: Number of registers to write
  *
- * This function is intended to be used for writing a large block of data
- * atomically to the device in single transfer for those I2C client devices
- * that implement this alternative block write mode.
+ * The 'normal' block write mode will send ultimately send data on the
+ * target bus as R,V1,V2,V3,..,Vn where successively higer registers are
+ * addressed. However, this alternative block multi write mode will send
+ * the data as R1,V1,R2,V2,..,Rn,Vn on the target bus. The target device
+ * must of course support the mode.
  *
- * A value of zero will be returned on success, a negative errno will
- * be returned in error cases.
+ * A value of zero will be returned on success, a negative errno will be
+ * returned in error cases.
  */
 int regmap_multi_reg_write(struct regmap *map, const struct reg_default *regs,
 			   int num_regs)

include/linux/regmap.h

@@ -164,6 +164,9 @@ typedef void (*regmap_unlock)(void *);
  * @use_single_rw: If set, converts the bulk read and write operations into
  *		    a series of single read and write operations. This is useful
  *		    for device that does not support bulk read and write.
+ * @can_multi_write: If set, the device supports the multi write mode of bulk
+ *                   write operations, if clear multi write requests will be
+ *                   split into individual write operations
  *
  * @cache_type: The actual cache type.
  * @reg_defaults_raw: Power on reset values for registers (for use with
@@ -215,6 +218,7 @@ struct regmap_config {
 	u8 write_flag_mask;
 
 	bool use_single_rw;
+	bool can_multi_write;
 
 	enum regmap_endian reg_format_endian;
 	enum regmap_endian val_format_endian;