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1/* SPDX-License-Identifier: GPL-2.0 */
2/*
3 * I2C Address Translator
4 *
5 * Copyright (c) 2019,2022 Luca Ceresoli <luca@lucaceresoli.net>
6 * Copyright (c) 2022,2023 Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
7 *
8 * Based on i2c-mux.h
9 */
10
11#ifndef _LINUX_I2C_ATR_H
12#define _LINUX_I2C_ATR_H
13
14#include <linux/i2c.h>
15#include <linux/types.h>
16
17struct device;
18struct fwnode_handle;
19struct i2c_atr;
20
21/**
22 * enum i2c_atr_flags - Flags for an I2C ATR driver
23 *
24 * @I2C_ATR_F_STATIC: ATR does not support dynamic mapping, use static mapping.
25 * Mappings will only be added or removed as a result of
26 * devices being added or removed from a child bus.
27 * The ATR pool will have to be big enough to accomodate all
28 * devices expected to be added to the child buses.
29 * @I2C_ATR_F_PASSTHROUGH: Allow unmapped incoming addresses to pass through
30 */
31enum i2c_atr_flags {
32 I2C_ATR_F_STATIC = BIT(0),
33 I2C_ATR_F_PASSTHROUGH = BIT(1),
34};
35
36/**
37 * struct i2c_atr_ops - Callbacks from ATR to the device driver.
38 * @attach_addr: Notify the driver of a new device connected on a child
39 * bus, with the alias assigned to it. The driver must
40 * configure the hardware to use the alias.
41 * @detach_addr: Notify the driver of a device getting disconnected. The
42 * driver must configure the hardware to stop using the
43 * alias.
44 *
45 * All these functions return 0 on success, a negative error code otherwise.
46 */
47struct i2c_atr_ops {
48 int (*attach_addr)(struct i2c_atr *atr, u32 chan_id,
49 u16 addr, u16 alias);
50 void (*detach_addr)(struct i2c_atr *atr, u32 chan_id,
51 u16 addr);
52};
53
54/**
55 * struct i2c_atr_adap_desc - An ATR downstream bus descriptor
56 * @chan_id: Index of the new adapter (0 .. max_adapters-1). This value is
57 * passed to the callbacks in `struct i2c_atr_ops`.
58 * @parent: The device used as the parent of the new i2c adapter, or NULL
59 * to use the i2c-atr device as the parent.
60 * @bus_handle: The fwnode handle that points to the adapter's i2c
61 * peripherals, or NULL.
62 * @num_aliases: The number of aliases in this adapter's private alias pool. Set
63 * to zero if this adapter uses the ATR's global alias pool.
64 * @aliases: An optional array of private aliases used by the adapter
65 * instead of the ATR's global pool of aliases. Must contain
66 * exactly num_aliases entries if num_aliases > 0, is ignored
67 * otherwise.
68 */
69struct i2c_atr_adap_desc {
70 u32 chan_id;
71 struct device *parent;
72 struct fwnode_handle *bus_handle;
73 size_t num_aliases;
74 u16 *aliases;
75};
76
77/**
78 * i2c_atr_new() - Allocate and initialize an I2C ATR helper.
79 * @parent: The parent (upstream) adapter
80 * @dev: The device acting as an ATR
81 * @ops: Driver-specific callbacks
82 * @max_adapters: Maximum number of child adapters
83 * @flags: Flags for ATR
84 *
85 * The new ATR helper is connected to the parent adapter but has no child
86 * adapters. Call i2c_atr_add_adapter() to add some.
87 *
88 * Call i2c_atr_delete() to remove.
89 *
90 * Return: pointer to the new ATR helper object, or ERR_PTR
91 */
92struct i2c_atr *i2c_atr_new(struct i2c_adapter *parent, struct device *dev,
93 const struct i2c_atr_ops *ops, int max_adapters,
94 u32 flags);
95
96/**
97 * i2c_atr_delete - Delete an I2C ATR helper.
98 * @atr: I2C ATR helper to be deleted.
99 *
100 * Precondition: all the adapters added with i2c_atr_add_adapter() must be
101 * removed by calling i2c_atr_del_adapter().
102 */
103void i2c_atr_delete(struct i2c_atr *atr);
104
105/**
106 * i2c_atr_add_adapter - Create a child ("downstream") I2C bus.
107 * @atr: The I2C ATR
108 * @desc: An ATR adapter descriptor
109 *
110 * After calling this function a new i2c bus will appear. Adding and removing
111 * devices on the downstream bus will result in calls to the
112 * &i2c_atr_ops->attach_client and &i2c_atr_ops->detach_client callbacks for the
113 * driver to assign an alias to the device.
114 *
115 * The adapter's fwnode is set to @bus_handle, or if @bus_handle is NULL the
116 * function looks for a child node whose 'reg' property matches the chan_id
117 * under the i2c-atr device's 'i2c-atr' node.
118 *
119 * Call i2c_atr_del_adapter() to remove the adapter.
120 *
121 * Return: 0 on success, a negative error code otherwise.
122 */
123int i2c_atr_add_adapter(struct i2c_atr *atr, struct i2c_atr_adap_desc *desc);
124
125/**
126 * i2c_atr_del_adapter - Remove a child ("downstream") I2C bus added by
127 * i2c_atr_add_adapter(). If no I2C bus has been added
128 * this function is a no-op.
129 * @atr: The I2C ATR
130 * @chan_id: Index of the adapter to be removed (0 .. max_adapters-1)
131 */
132void i2c_atr_del_adapter(struct i2c_atr *atr, u32 chan_id);
133
134/**
135 * i2c_atr_set_driver_data - Set private driver data to the i2c-atr instance.
136 * @atr: The I2C ATR
137 * @data: Pointer to the data to store
138 */
139void i2c_atr_set_driver_data(struct i2c_atr *atr, void *data);
140
141/**
142 * i2c_atr_get_driver_data - Get the stored drive data.
143 * @atr: The I2C ATR
144 *
145 * Return: Pointer to the stored data
146 */
147void *i2c_atr_get_driver_data(struct i2c_atr *atr);
148
149#endif /* _LINUX_I2C_ATR_H */