[PATCH v5 01/11] i2c: Enhance i2c_new_ancillary_device API

[Biju Das <biju.das.jz@bp.renesas.com>]

Renesas PMIC RAA215300 exposes two separate i2c devices, one for the main
device and another for rtc device.

Enhance i2c_new_ancillary_device() to instantiate a real device.
(eg: Instantiate rtc device from PMIC driver)

Added helper function __i2c_new_dummy_device to share the code
between i2c_new_dummy_device and i2c_new_ancillary_device().

Also added helper function __i2c_new_client_device() to pass parent dev
parameter, so that the ancillary device can assign its parent during
creation.

Suggested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v4->v5:
 * Replaced parameter dev->parent in __i2c_new_client_device() and
   __i2c_new_dummy_device().
 * Improved error message in __i2c_new_dummy_device() by printing device name.
 * Updated comment for ancillary's device parent
 * Dropped aux_device_name check in i2c_new_ancillary_device().
v3->v4:
 * Dropped Rb tag from Geert as there are new changes.
 * Introduced __i2c_new_dummy_device() to share the code between
   i2c_new_dummy_device and i2c_new_ancillary_device().
 * Introduced __i2c_new_client_device() to pass parent dev
   parameter, so that the ancillary device can assign its parent during
   creation.
v3:
 * New patch

Ref:
 https://patchwork.kernel.org/project/linux-renesas-soc/patch/20230505172530.357455-5-biju.das.jz@bp.renesas.com/
---
 drivers/gpu/drm/bridge/adv7511/adv7511_drv.c |  6 +-
 drivers/i2c/i2c-core-base.c                  | 92 +++++++++++++-------
 drivers/media/i2c/adv748x/adv748x-core.c     |  2 +-
 drivers/media/i2c/adv7604.c                  |  3 +-
 include/linux/i2c.h                          |  3 +-
 5 files changed, 69 insertions(+), 37 deletions(-)

diff --git a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
index ddceafa7b637..86306b010a0a 100644
--- a/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
+++ b/drivers/gpu/drm/bridge/adv7511/adv7511_drv.c
@@ -1072,7 +1072,7 @@ static int adv7511_init_cec_regmap(struct adv7511 *adv)
 	int ret;
 
 	adv->i2c_cec = i2c_new_ancillary_device(adv->i2c_main, "cec",
-						ADV7511_CEC_I2C_ADDR_DEFAULT);
+				    ADV7511_CEC_I2C_ADDR_DEFAULT, NULL);
 	if (IS_ERR(adv->i2c_cec))
 		return PTR_ERR(adv->i2c_cec);
 
@@ -1261,7 +1261,7 @@ static int adv7511_probe(struct i2c_client *i2c)
 	adv7511_packet_disable(adv7511, 0xffff);
 
 	adv7511->i2c_edid = i2c_new_ancillary_device(i2c, "edid",
-					ADV7511_EDID_I2C_ADDR_DEFAULT);
+					ADV7511_EDID_I2C_ADDR_DEFAULT, NULL);
 	if (IS_ERR(adv7511->i2c_edid)) {
 		ret = PTR_ERR(adv7511->i2c_edid);
 		goto uninit_regulators;
@@ -1271,7 +1271,7 @@ static int adv7511_probe(struct i2c_client *i2c)
 		     adv7511->i2c_edid->addr << 1);
 
 	adv7511->i2c_packet = i2c_new_ancillary_device(i2c, "packet",
-					ADV7511_PACKET_I2C_ADDR_DEFAULT);
+					ADV7511_PACKET_I2C_ADDR_DEFAULT, NULL);
 	if (IS_ERR(adv7511->i2c_packet)) {
 		ret = PTR_ERR(adv7511->i2c_packet);
 		goto err_i2c_unregister_edid;
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index ae3af738b03f..3442aa80290f 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -893,24 +893,10 @@ int i2c_dev_irq_from_resources(const struct resource *resources,
 	return 0;
 }
 
-/**
- * i2c_new_client_device - instantiate an i2c device
- * @adap: the adapter managing the device
- * @info: describes one I2C device; bus_num is ignored
- * Context: can sleep
- *
- * Create an i2c device. Binding is handled through driver model
- * probe()/remove() methods.  A driver may be bound to this device when we
- * return from this function, or any later moment (e.g. maybe hotplugging will
- * load the driver module).  This call is not appropriate for use by mainboard
- * initialization logic, which usually runs during an arch_initcall() long
- * before any i2c_adapter could exist.
- *
- * This returns the new i2c client, which may be saved for later use with
- * i2c_unregister_device(); or an ERR_PTR to describe the error.
- */
-struct i2c_client *
-i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
+static struct i2c_client *
+__i2c_new_client_device(struct i2c_adapter *adap,
+			struct i2c_board_info const *info,
+			struct device *parent)
 {
 	struct i2c_client	*client;
 	int			status;
@@ -944,7 +930,7 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 	if (status)
 		goto out_err;
 
-	client->dev.parent = &client->adapter->dev;
+	client->dev.parent = parent ? parent : &client->adapter->dev;
 	client->dev.bus = &i2c_bus_type;
 	client->dev.type = &i2c_client_type;
 	client->dev.of_node = of_node_get(info->of_node);
@@ -984,6 +970,28 @@ i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *inf
 	kfree(client);
 	return ERR_PTR(status);
 }
+
+/**
+ * i2c_new_client_device - instantiate an i2c device
+ * @adap: the adapter managing the device
+ * @info: describes one I2C device; bus_num is ignored
+ * Context: can sleep
+ *
+ * Create an i2c device. Binding is handled through driver model
+ * probe()/remove() methods.  A driver may be bound to this device when we
+ * return from this function, or any later moment (e.g. maybe hotplugging will
+ * load the driver module).  This call is not appropriate for use by mainboard
+ * initialization logic, which usually runs during an arch_initcall() long
+ * before any i2c_adapter could exist.
+ *
+ * This returns the new i2c client, which may be saved for later use with
+ * i2c_unregister_device(); or an ERR_PTR to describe the error.
+ */
+struct i2c_client *
+i2c_new_client_device(struct i2c_adapter *adap, struct i2c_board_info const *info)
+{
+	return __i2c_new_client_device(adap, info, NULL);
+}
 EXPORT_SYMBOL_GPL(i2c_new_client_device);
 
 /**
@@ -1054,6 +1062,26 @@ static struct i2c_driver dummy_driver = {
 	.id_table	= dummy_id,
 };
 
+static struct i2c_client *__i2c_new_dummy_device(struct i2c_adapter *adapter,
+						 u16 address, const char *name,
+						 struct device *parent)
+{
+	struct i2c_board_info info = {
+		I2C_BOARD_INFO("dummy", address),
+	};
+
+	if (name) {
+		ssize_t ret = strscpy(info.type, name, sizeof(info.type));
+
+		if (ret < 0)
+			return ERR_PTR(dev_err_probe(&adapter->dev, ret,
+						     "Invalid device name: %s\n",
+						     name));
+	}
+
+	return __i2c_new_client_device(adapter, &info, parent);
+}
+
 /**
  * i2c_new_dummy_device - return a new i2c device bound to a dummy driver
  * @adapter: the adapter managing the device
@@ -1074,11 +1102,7 @@ static struct i2c_driver dummy_driver = {
  */
 struct i2c_client *i2c_new_dummy_device(struct i2c_adapter *adapter, u16 address)
 {
-	struct i2c_board_info info = {
-		I2C_BOARD_INFO("dummy", address),
-	};
-
-	return i2c_new_client_device(adapter, &info);
+	return __i2c_new_dummy_device(adapter, address, NULL, NULL);
 }
 EXPORT_SYMBOL_GPL(i2c_new_dummy_device);
 
@@ -1122,15 +1146,19 @@ EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
  * @client: Handle to the primary client
  * @name: Handle to specify which secondary address to get
  * @default_addr: Used as a fallback if no secondary address was specified
+ * @aux_device_name: Ancillary device name
  * Context: can sleep
  *
  * I2C clients can be composed of multiple I2C slaves bound together in a single
  * component. The I2C client driver then binds to the master I2C slave and needs
- * to create I2C dummy clients to communicate with all the other slaves.
+ * to create I2C ancillary clients to communicate with all the other slaves.
  *
- * This function creates and returns an I2C dummy client whose I2C address is
- * retrieved from the platform firmware based on the given slave name. If no
- * address is specified by the firmware default_addr is used.
+ * This function creates and returns an I2C ancillary client whose I2C address
+ * is retrieved from the platform firmware based on the given slave name. if
+ * aux_device_name is specified by the firmware, the ancillary's device parent
+ * will be set to the primary device. If no address is specified by the firmware
+ * default_addr is used. If no aux_device_name is specified by the firmware, it
+ * will create an I2C dummy client.
  *
  * On DT-based platforms the address is retrieved from the "reg" property entry
  * cell whose "reg-names" value matches the slave name.
@@ -1139,8 +1167,9 @@ EXPORT_SYMBOL_GPL(devm_i2c_new_dummy_device);
  * i2c_unregister_device(); or an ERR_PTR to describe the error.
  */
 struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client,
-						const char *name,
-						u16 default_addr)
+					    const char *name,
+					    u16 default_addr,
+					    const char *aux_device_name)
 {
 	struct device_node *np = client->dev.of_node;
 	u32 addr = default_addr;
@@ -1153,7 +1182,8 @@ struct i2c_client *i2c_new_ancillary_device(struct i2c_client *client,
 	}
 
 	dev_dbg(&client->adapter->dev, "Address for %s : 0x%x\n", name, addr);
-	return i2c_new_dummy_device(client->adapter, addr);
+	return __i2c_new_dummy_device(client->adapter, addr, aux_device_name,
+				      &client->dev);
 }
 EXPORT_SYMBOL_GPL(i2c_new_ancillary_device);
 
diff --git a/drivers/media/i2c/adv748x/adv748x-core.c b/drivers/media/i2c/adv748x/adv748x-core.c
index 4498d78a2357..5bdf7b0c6bf3 100644
--- a/drivers/media/i2c/adv748x/adv748x-core.c
+++ b/drivers/media/i2c/adv748x/adv748x-core.c
@@ -186,7 +186,7 @@ static int adv748x_initialise_clients(struct adv748x_state *state)
 		state->i2c_clients[i] = i2c_new_ancillary_device(
 				state->client,
 				adv748x_default_addresses[i].name,
-				adv748x_default_addresses[i].default_addr);
+				adv748x_default_addresses[i].default_addr, NULL);
 
 		if (IS_ERR(state->i2c_clients[i])) {
 			adv_err(state, "failed to create i2c client %u\n", i);
diff --git a/drivers/media/i2c/adv7604.c b/drivers/media/i2c/adv7604.c
index 3d0898c4175e..63fa44c9d27c 100644
--- a/drivers/media/i2c/adv7604.c
+++ b/drivers/media/i2c/adv7604.c
@@ -2935,7 +2935,8 @@ static struct i2c_client *adv76xx_dummy_client(struct v4l2_subdev *sd,
 	else
 		new_client = i2c_new_ancillary_device(client,
 				adv76xx_default_addresses[page].name,
-				adv76xx_default_addresses[page].default_addr);
+				adv76xx_default_addresses[page].default_addr,
+				NULL);
 
 	if (!IS_ERR(new_client))
 		io_write(sd, io_reg, new_client->addr << 1);
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 13a1ce38cb0c..0ce344724209 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -489,7 +489,8 @@ devm_i2c_new_dummy_device(struct device *dev, struct i2c_adapter *adap, u16 addr
 struct i2c_client *
 i2c_new_ancillary_device(struct i2c_client *client,
 			 const char *name,
-			 u16 default_addr);
+			 u16 default_addr,
+			 const char *aux_device_name);
 
 void i2c_unregister_device(struct i2c_client *client);
 
-- 
2.25.1