Add basic support for i3c bus.
This is a simple implementation that only give support
for SDR Read and Write commands.

Signed-off-by: Vitor Soares <vitor.soa...@synopsys.com>
---
Changes in v2:
  None

 drivers/base/regmap/Kconfig      |  6 +++-
 drivers/base/regmap/Makefile     |  1 +
 drivers/base/regmap/regmap-i3c.c | 60 ++++++++++++++++++++++++++++++++++++++++
 include/linux/regmap.h           | 20 ++++++++++++++
 4 files changed, 86 insertions(+), 1 deletion(-)
 create mode 100644 drivers/base/regmap/regmap-i3c.c

diff --git a/drivers/base/regmap/Kconfig b/drivers/base/regmap/Kconfig
index 6ad5ef4..c8bbf53 100644
--- a/drivers/base/regmap/Kconfig
+++ b/drivers/base/regmap/Kconfig
@@ -4,7 +4,7 @@
 # subsystems should select the appropriate symbols.
 
 config REGMAP
-       default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_W1 || 
REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ)
+       default y if (REGMAP_I2C || REGMAP_SPI || REGMAP_SPMI || REGMAP_W1 || 
REGMAP_AC97 || REGMAP_MMIO || REGMAP_IRQ || REGMAP_I3C)
        select IRQ_DOMAIN if REGMAP_IRQ
        bool
 
@@ -49,3 +49,7 @@ config REGMAP_SOUNDWIRE
 config REGMAP_SCCB
        tristate
        depends on I2C
+
+config REGMAP_I3C
+       tristate
+       depends on I3C
diff --git a/drivers/base/regmap/Makefile b/drivers/base/regmap/Makefile
index f5b4e88..ff6c7d8 100644
--- a/drivers/base/regmap/Makefile
+++ b/drivers/base/regmap/Makefile
@@ -16,3 +16,4 @@ obj-$(CONFIG_REGMAP_IRQ) += regmap-irq.o
 obj-$(CONFIG_REGMAP_W1) += regmap-w1.o
 obj-$(CONFIG_REGMAP_SOUNDWIRE) += regmap-sdw.o
 obj-$(CONFIG_REGMAP_SCCB) += regmap-sccb.o
+obj-$(CONFIG_REGMAP_I3C) += regmap-i3c.o
diff --git a/drivers/base/regmap/regmap-i3c.c b/drivers/base/regmap/regmap-i3c.c
new file mode 100644
index 0000000..1578fb5
--- /dev/null
+++ b/drivers/base/regmap/regmap-i3c.c
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2018 Synopsys, Inc. and/or its affiliates.
+
+#include <linux/regmap.h>
+#include <linux/i3c/device.h>
+#include <linux/i3c/master.h>
+#include <linux/module.h>
+
+static int regmap_i3c_write(void *context, const void *data, size_t count)
+{
+       struct device *dev = context;
+       struct i3c_device *i3c = dev_to_i3cdev(dev);
+       struct i3c_priv_xfer xfers[] = {
+               {
+                       .rnw = false,
+                       .len = count,
+                       .data.out = data,
+               },
+       };
+
+       return i3c_device_do_priv_xfers(i3c, xfers, 1);
+}
+
+static int regmap_i3c_read(void *context,
+                          const void *reg, size_t reg_size,
+                          void *val, size_t val_size)
+{
+       struct device *dev = context;
+       struct i3c_device *i3c = dev_to_i3cdev(dev);
+       struct i3c_priv_xfer xfers[2];
+
+       xfers[0].rnw = false;
+       xfers[0].len = reg_size;
+       xfers[0].data.out = reg;
+
+       xfers[1].rnw = true;
+       xfers[1].len = val_size;
+       xfers[1].data.in = val;
+
+       return i3c_device_do_priv_xfers(i3c, xfers, 2);
+}
+
+static struct regmap_bus regmap_i3c = {
+       .write = regmap_i3c_write,
+       .read = regmap_i3c_read,
+};
+
+struct regmap *__devm_regmap_init_i3c(struct i3c_device *i3c,
+                                     const struct regmap_config *config,
+                                     struct lock_class_key *lock_key,
+                                     const char *lock_name)
+{
+       return __devm_regmap_init(&i3c->dev, &regmap_i3c, &i3c->dev, config,
+                                 lock_key, lock_name);
+}
+EXPORT_SYMBOL_GPL(__devm_regmap_init_i3c);
+
+MODULE_AUTHOR("Vitor Soares <vitor.soa...@synopsys.com>");
+MODULE_DESCRIPTION("Regmap I3C Module");
+MODULE_LICENSE("GPL v2");
diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index daeec7d..f65984d 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -25,6 +25,7 @@ struct module;
 struct clk;
 struct device;
 struct i2c_client;
+struct i3c_device;
 struct irq_domain;
 struct slim_device;
 struct spi_device;
@@ -624,6 +625,10 @@ struct regmap *__devm_regmap_init_slimbus(struct 
slim_device *slimbus,
                                 const struct regmap_config *config,
                                 struct lock_class_key *lock_key,
                                 const char *lock_name);
+struct regmap *__devm_regmap_init_i3c(struct i3c_device *i3c,
+                                const struct regmap_config *config,
+                                struct lock_class_key *lock_key,
+                                const char *lock_name);
 /*
  * Wrapper for regmap_init macros to include a unique lockdep key and name
  * for each call. No-op if CONFIG_LOCKDEP is not set.
@@ -982,6 +987,21 @@ bool regmap_ac97_default_volatile(struct device *dev, 
unsigned int reg);
 #define devm_regmap_init_slimbus(slimbus, config)                      \
        __regmap_lockdep_wrapper(__devm_regmap_init_slimbus, #config,   \
                                slimbus, config)
+
+/**
+ * devm_regmap_init_i3c() - Initialise managed register map
+ *
+ * @i3c: Device that will be interacted with
+ * @config: Configuration for register map
+ *
+ * The return value will be an ERR_PTR() on error or a valid pointer
+ * to a struct regmap.  The regmap will be automatically freed by the
+ * device management code.
+ */
+#define devm_regmap_init_i3c(i3c, config)                              \
+       __regmap_lockdep_wrapper(__devm_regmap_init_i3c, #config,       \
+                               i3c, config)
+
 int regmap_mmio_attach_clk(struct regmap *map, struct clk *clk);
 void regmap_mmio_detach_clk(struct regmap *map);
 void regmap_exit(struct regmap *map);
-- 
2.7.4

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