Message-Id: <20180809101533.CAF5E1124347@debutante.sirena.org.uk>
Date:   Thu,  9 Aug 2018 11:15:33 +0100 (BST)
From:   Mark Brown <broonie@...nel.org>
To:     Crestez Dan Leonard <leonard.crestez@...el.com>
Cc:     Stefan Popa <stefan.popa@...log.com>,
        Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org
Subject: Applied "regmap: Add regmap_noinc_read API" to the regmap tree

The patch

   regmap: Add regmap_noinc_read API

has been applied to the regmap tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 74fe7b551f3385fa585d92616c85b3a575b2b2cb Mon Sep 17 00:00:00 2001
From: Crestez Dan Leonard <leonard.crestez@...el.com>
Date: Tue, 7 Aug 2018 17:52:17 +0300
Subject: [PATCH] regmap: Add regmap_noinc_read API

The regmap API usually assumes that bulk read operations will read a
range of registers but some I2C/SPI devices have certain registers for
which a such a read operation will return data from an internal FIFO
instead. Add an explicit API to support bulk read without range semantics.

Some linux drivers use regmap_bulk_read or regmap_raw_read for such
registers, for example mpu6050 or bmi150 from IIO. This only happens to
work because when caching is disabled a single regmap read op will map
to a single bus read op (as desired). This breaks if caching is enabled and
reg+1 happens to be a cacheable register.

Without regmap support refactoring a driver to enable regmap caching
requires separate I2C and SPI paths. This is exactly what regmap is
supposed to help avoid.

Suggested-by: Jonathan Cameron <jic23@...nel.org>
Signed-off-by: Crestez Dan Leonard <leonard.crestez@...el.com>
Signed-off-by: Stefan Popa <stefan.popa@...log.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 drivers/base/regmap/internal.h |  3 ++
 drivers/base/regmap/regmap.c   | 79 +++++++++++++++++++++++++++++++++-
 include/linux/regmap.h         | 19 ++++++++
 3 files changed, 100 insertions(+), 1 deletion(-)

diff --git a/drivers/base/regmap/internal.h b/drivers/base/regmap/internal.h
index 53785e0e297a..a6bf34d6394e 100644
--- a/drivers/base/regmap/internal.h
+++ b/drivers/base/regmap/internal.h
@@ -94,10 +94,12 @@ struct regmap {
 	bool (*readable_reg)(struct device *dev, unsigned int reg);
 	bool (*volatile_reg)(struct device *dev, unsigned int reg);
 	bool (*precious_reg)(struct device *dev, unsigned int reg);
+	bool (*readable_noinc_reg)(struct device *dev, unsigned int reg);
 	const struct regmap_access_table *wr_table;
 	const struct regmap_access_table *rd_table;
 	const struct regmap_access_table *volatile_table;
 	const struct regmap_access_table *precious_table;
+	const struct regmap_access_table *rd_noinc_table;
 
 	int (*reg_read)(void *context, unsigned int reg, unsigned int *val);
 	int (*reg_write)(void *context, unsigned int reg, unsigned int val);
@@ -181,6 +183,7 @@ bool regmap_writeable(struct regmap *map, unsigned int reg);
 bool regmap_readable(struct regmap *map, unsigned int reg);
 bool regmap_volatile(struct regmap *map, unsigned int reg);
 bool regmap_precious(struct regmap *map, unsigned int reg);
+bool regmap_readable_noinc(struct regmap *map, unsigned int reg);
 
 int _regmap_write(struct regmap *map, unsigned int reg,
 		  unsigned int val);
diff --git a/drivers/base/regmap/regmap.c b/drivers/base/regmap/regmap.c
index 3bc84885eb91..0360a90ad6b6 100644
--- a/drivers/base/regmap/regmap.c
+++ b/drivers/base/regmap/regmap.c
@@ -168,6 +168,17 @@ bool regmap_precious(struct regmap *map, unsigned int reg)
 	return false;
 }
 
+bool regmap_readable_noinc(struct regmap *map, unsigned int reg)
+{
+	if (map->readable_noinc_reg)
+		return map->readable_noinc_reg(map->dev, reg);
+
+	if (map->rd_noinc_table)
+		return regmap_check_range_table(map, reg, map->rd_noinc_table);
+
+	return true;
+}
+
 static bool regmap_volatile_range(struct regmap *map, unsigned int reg,
 	size_t num)
 {
@@ -766,10 +777,12 @@ struct regmap *__regmap_init(struct device *dev,
 	map->rd_table = config->rd_table;
 	map->volatile_table = config->volatile_table;
 	map->precious_table = config->precious_table;
+	map->rd_noinc_table = config->rd_noinc_table;
 	map->writeable_reg = config->writeable_reg;
 	map->readable_reg = config->readable_reg;
 	map->volatile_reg = config->volatile_reg;
 	map->precious_reg = config->precious_reg;
+	map->readable_noinc_reg = config->readable_noinc_reg;
 	map->cache_type = config->cache_type;
 
 	spin_lock_init(&map->async_lock);
@@ -1285,6 +1298,7 @@ int regmap_reinit_cache(struct regmap *map, const struct regmap_config *config)
 	map->readable_reg = config->readable_reg;
 	map->volatile_reg = config->volatile_reg;
 	map->precious_reg = config->precious_reg;
+	map->readable_noinc_reg = config->readable_noinc_reg;
 	map->cache_type = config->cache_type;
 
 	regmap_debugfs_init(map, config->name);
@@ -2564,7 +2578,70 @@ int regmap_raw_read(struct regmap *map, unsigned int reg, void *val,
 EXPORT_SYMBOL_GPL(regmap_raw_read);
 
 /**
- * regmap_field_read() - Read a value to a single register field
+ * regmap_noinc_read(): Read data from a register without incrementing the
+ *			register number
+ *
+ * @map: Register map to read from
+ * @reg: Register to read from
+ * @val: Pointer to data buffer
+ * @val_len: Length of output buffer in bytes.
+ *
+ * The regmap API usually assumes that bulk bus read operations will read a
+ * range of registers. Some devices have certain registers for which a read
+ * operation read will read from an internal FIFO.
+ *
+ * The target register must be volatile but registers after it can be
+ * completely unrelated cacheable registers.
+ *
+ * This will attempt multiple reads as required to read val_len bytes.
+ *
+ * A value of zero will be returned on success, a negative errno will be
+ * returned in error cases.
+ */
+int regmap_noinc_read(struct regmap *map, unsigned int reg,
+		      void *val, size_t val_len)
+{
+	size_t read_len;
+	int ret;
+
+	if (!map->bus)
+		return -EINVAL;
+	if (!map->bus->read)
+		return -ENOTSUPP;
+	if (val_len % map->format.val_bytes)
+		return -EINVAL;
+	if (!IS_ALIGNED(reg, map->reg_stride))
+		return -EINVAL;
+	if (val_len == 0)
+		return -EINVAL;
+
+	map->lock(map->lock_arg);
+
+	if (!regmap_volatile(map, reg) || !regmap_readable_noinc(map, reg)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	while (val_len) {
+		if (map->max_raw_read && map->max_raw_read < val_len)
+			read_len = map->max_raw_read;
+		else
+			read_len = val_len;
+		ret = _regmap_raw_read(map, reg, val, read_len);
+		if (ret)
+			goto out_unlock;
+		val = ((u8 *)val) + read_len;
+		val_len -= read_len;
+	}
+
+out_unlock:
+	map->unlock(map->lock_arg);
+	return ret;
+}
+EXPORT_SYMBOL_GPL(regmap_noinc_read);
+
+/**
+ * regmap_field_read(): Read a value to a single register field
  *
  * @field: Register field to read from
  * @val: Pointer to store read value
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 4f38068ffb71..19df946499d2 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -268,6 +268,13 @@ typedef void (*regmap_unlock)(void *);
  *                field is NULL but precious_table (see below) is not, the
  *                check is performed on such table (a register is precious if
  *                it belongs to one of the ranges specified by precious_table).
+ * @readable_noinc_reg: Optional callback returning true if the register
+ *			supports multiple read operations without incrementing
+ *			the register number. If this field is NULL but
+ *			rd_noinc_table (see below) is not, the check is
+ *			performed on such table (a register is no increment
+ *			readable if it belongs to one of the ranges specified
+ *			by rd_noinc_table).
  * @disable_locking: This regmap is either protected by external means or
  *                   is guaranteed not be be accessed from multiple threads.
  *                   Don't use any locking mechanisms.
@@ -295,6 +302,7 @@ typedef void (*regmap_unlock)(void *);
  * @rd_table:     As above, for read access.
  * @volatile_table: As above, for volatile registers.
  * @precious_table: As above, for precious registers.
+ * @rd_noinc_table: As above, for no increment readable registers.
  * @reg_defaults: Power on reset values for registers (for use with
  *                register cache support).
  * @num_reg_defaults: Number of elements in reg_defaults.
@@ -344,6 +352,7 @@ struct regmap_config {
 	bool (*readable_reg)(struct device *dev, unsigned int reg);
 	bool (*volatile_reg)(struct device *dev, unsigned int reg);
 	bool (*precious_reg)(struct device *dev, unsigned int reg);
+	bool (*readable_noinc_reg)(struct device *dev, unsigned int reg);
 
 	bool disable_locking;
 	regmap_lock lock;
@@ -360,6 +369,7 @@ struct regmap_config {
 	const struct regmap_access_table *rd_table;
 	const struct regmap_access_table *volatile_table;
 	const struct regmap_access_table *precious_table;
+	const struct regmap_access_table *rd_noinc_table;
 	const struct reg_default *reg_defaults;
 	unsigned int num_reg_defaults;
 	enum regcache_type cache_type;
@@ -946,6 +956,8 @@ int regmap_raw_write_async(struct regmap *map, unsigned int reg,
 int regmap_read(struct regmap *map, unsigned int reg, unsigned int *val);
 int regmap_raw_read(struct regmap *map, unsigned int reg,
 		    void *val, size_t val_len);
+int regmap_noinc_read(struct regmap *map, unsigned int reg,
+		      void *val, size_t val_len);
 int regmap_bulk_read(struct regmap *map, unsigned int reg, void *val,
 		     size_t val_count);
 int regmap_update_bits_base(struct regmap *map, unsigned int reg,
@@ -1196,6 +1208,13 @@ static inline int regmap_raw_read(struct regmap *map, unsigned int reg,
 	return -EINVAL;
 }
 
+static inline int regmap_noinc_read(struct regmap *map, unsigned int reg,
+				    void *val, size_t val_len)
+{
+	WARN_ONCE(1, "regmap API is disabled");
+	return -EINVAL;
+}
+
 static inline int regmap_bulk_read(struct regmap *map, unsigned int reg,
 				   void *val, size_t val_count)
 {
-- 
2.18.0

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