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https://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson
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17a3a30e8e
Some I2C ATRs can have other I2C ATRs as children. The I2C messages of the child ATRs need to be forwarded as-is if the parent I2C ATR can only do static mapping. In the case of GMSL, the deserializer I2C ATR actually doesn't have I2C address remapping hardware capabilities, but it is able to select which GMSL link to talk to, allowing it to change the address of the serializer. The child ATRs need to have their alias pools defined in such a way to prevent overlapping addresses between them, but there's no way around this without orchestration between multiple ATR instances. To allow for this use-case, add a flag that allows unmapped addresses to be passed through, since they are already remapped by the child ATRs. There's no case where an address that has not been remapped by the child ATR will hit the parent ATR. Signed-off-by: Cosmin Tanislav <demonsingur@gmail.com> Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com> Reviewed-by: Romain Gantois <romain.gantois@bootlin.com> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
150 lines
5.2 KiB
C
150 lines
5.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* I2C Address Translator
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*
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* Copyright (c) 2019,2022 Luca Ceresoli <luca@lucaceresoli.net>
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* Copyright (c) 2022,2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
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*
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* Based on i2c-mux.h
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*/
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#ifndef _LINUX_I2C_ATR_H
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#define _LINUX_I2C_ATR_H
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#include <linux/i2c.h>
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#include <linux/types.h>
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struct device;
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struct fwnode_handle;
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struct i2c_atr;
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/**
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* enum i2c_atr_flags - Flags for an I2C ATR driver
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*
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* @I2C_ATR_F_STATIC: ATR does not support dynamic mapping, use static mapping.
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* Mappings will only be added or removed as a result of
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* devices being added or removed from a child bus.
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* The ATR pool will have to be big enough to accomodate all
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* devices expected to be added to the child buses.
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* @I2C_ATR_F_PASSTHROUGH: Allow unmapped incoming addresses to pass through
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*/
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enum i2c_atr_flags {
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I2C_ATR_F_STATIC = BIT(0),
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I2C_ATR_F_PASSTHROUGH = BIT(1),
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};
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/**
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* struct i2c_atr_ops - Callbacks from ATR to the device driver.
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* @attach_addr: Notify the driver of a new device connected on a child
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* bus, with the alias assigned to it. The driver must
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* configure the hardware to use the alias.
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* @detach_addr: Notify the driver of a device getting disconnected. The
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* driver must configure the hardware to stop using the
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* alias.
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*
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* All these functions return 0 on success, a negative error code otherwise.
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*/
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struct i2c_atr_ops {
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int (*attach_addr)(struct i2c_atr *atr, u32 chan_id,
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u16 addr, u16 alias);
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void (*detach_addr)(struct i2c_atr *atr, u32 chan_id,
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u16 addr);
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};
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/**
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* struct i2c_atr_adap_desc - An ATR downstream bus descriptor
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* @chan_id: Index of the new adapter (0 .. max_adapters-1). This value is
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* passed to the callbacks in `struct i2c_atr_ops`.
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* @parent: The device used as the parent of the new i2c adapter, or NULL
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* to use the i2c-atr device as the parent.
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* @bus_handle: The fwnode handle that points to the adapter's i2c
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* peripherals, or NULL.
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* @num_aliases: The number of aliases in this adapter's private alias pool. Set
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* to zero if this adapter uses the ATR's global alias pool.
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* @aliases: An optional array of private aliases used by the adapter
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* instead of the ATR's global pool of aliases. Must contain
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* exactly num_aliases entries if num_aliases > 0, is ignored
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* otherwise.
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*/
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struct i2c_atr_adap_desc {
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u32 chan_id;
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struct device *parent;
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struct fwnode_handle *bus_handle;
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size_t num_aliases;
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u16 *aliases;
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};
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/**
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* i2c_atr_new() - Allocate and initialize an I2C ATR helper.
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* @parent: The parent (upstream) adapter
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* @dev: The device acting as an ATR
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* @ops: Driver-specific callbacks
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* @max_adapters: Maximum number of child adapters
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* @flags: Flags for ATR
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*
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* The new ATR helper is connected to the parent adapter but has no child
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* adapters. Call i2c_atr_add_adapter() to add some.
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*
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* Call i2c_atr_delete() to remove.
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*
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* Return: pointer to the new ATR helper object, or ERR_PTR
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*/
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struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
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const struct i2c_atr_ops *ops, int max_adapters,
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u32 flags);
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/**
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* i2c_atr_delete - Delete an I2C ATR helper.
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* @atr: I2C ATR helper to be deleted.
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*
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* Precondition: all the adapters added with i2c_atr_add_adapter() must be
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* removed by calling i2c_atr_del_adapter().
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*/
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void i2c_atr_delete(struct i2c_atr *atr);
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/**
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* i2c_atr_add_adapter - Create a child ("downstream") I2C bus.
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* @atr: The I2C ATR
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* @desc: An ATR adapter descriptor
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*
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* After calling this function a new i2c bus will appear. Adding and removing
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* devices on the downstream bus will result in calls to the
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* &i2c_atr_ops->attach_client and &i2c_atr_ops->detach_client callbacks for the
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* driver to assign an alias to the device.
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*
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* The adapter's fwnode is set to @bus_handle, or if @bus_handle is NULL the
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* function looks for a child node whose 'reg' property matches the chan_id
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* under the i2c-atr device's 'i2c-atr' node.
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*
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* Call i2c_atr_del_adapter() to remove the adapter.
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*
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* Return: 0 on success, a negative error code otherwise.
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*/
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int i2c_atr_add_adapter(struct i2c_atr *atr, struct i2c_atr_adap_desc *desc);
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/**
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* i2c_atr_del_adapter - Remove a child ("downstream") I2C bus added by
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* i2c_atr_add_adapter(). If no I2C bus has been added
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* this function is a no-op.
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* @atr: The I2C ATR
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* @chan_id: Index of the adapter to be removed (0 .. max_adapters-1)
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*/
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void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id);
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/**
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* i2c_atr_set_driver_data - Set private driver data to the i2c-atr instance.
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* @atr: The I2C ATR
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* @data: Pointer to the data to store
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*/
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void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data);
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/**
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* i2c_atr_get_driver_data - Get the stored drive data.
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* @atr: The I2C ATR
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*
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* Return: Pointer to the stored data
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*/
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void *i2c_atr_get_driver_data(struct i2c_atr *atr);
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#endif /* _LINUX_I2C_ATR_H */
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