1 | // SPDX-License-Identifier: GPL-2.0 |
2 | // Register map access API - SCCB support |
3 | |
4 | #include <linux/i2c.h> |
5 | #include <linux/module.h> |
6 | #include <linux/regmap.h> |
7 | |
8 | #include "internal.h" |
9 | |
10 | /** |
11 | * sccb_is_available - Check if the adapter supports SCCB protocol |
12 | * @adap: I2C adapter |
13 | * |
14 | * Return true if the I2C adapter is capable of using SCCB helper functions, |
15 | * false otherwise. |
16 | */ |
17 | static bool sccb_is_available(struct i2c_adapter *adap) |
18 | { |
19 | u32 needed_funcs = I2C_FUNC_SMBUS_BYTE | I2C_FUNC_SMBUS_WRITE_BYTE_DATA; |
20 | |
21 | /* |
22 | * If we ever want support for hardware doing SCCB natively, we will |
23 | * introduce a sccb_xfer() callback to struct i2c_algorithm and check |
24 | * for it here. |
25 | */ |
26 | |
27 | return (i2c_get_functionality(adap) & needed_funcs) == needed_funcs; |
28 | } |
29 | |
30 | /** |
31 | * regmap_sccb_read - Read data from SCCB slave device |
32 | * @context: Device that will be interacted with |
33 | * @reg: Register to be read from |
34 | * @val: Pointer to store read value |
35 | * |
36 | * This executes the 2-phase write transmission cycle that is followed by a |
37 | * 2-phase read transmission cycle, returning negative errno else zero on |
38 | * success. |
39 | */ |
40 | static int regmap_sccb_read(void *context, unsigned int reg, unsigned int *val) |
41 | { |
42 | struct device *dev = context; |
43 | struct i2c_client *i2c = to_i2c_client(dev); |
44 | int ret; |
45 | union i2c_smbus_data data; |
46 | |
47 | i2c_lock_bus(adapter: i2c->adapter, I2C_LOCK_SEGMENT); |
48 | |
49 | ret = __i2c_smbus_xfer(adapter: i2c->adapter, addr: i2c->addr, flags: i2c->flags, |
50 | I2C_SMBUS_WRITE, command: reg, I2C_SMBUS_BYTE, NULL); |
51 | if (ret < 0) |
52 | goto out; |
53 | |
54 | ret = __i2c_smbus_xfer(adapter: i2c->adapter, addr: i2c->addr, flags: i2c->flags, |
55 | I2C_SMBUS_READ, command: 0, I2C_SMBUS_BYTE, data: &data); |
56 | if (ret < 0) |
57 | goto out; |
58 | |
59 | *val = data.byte; |
60 | out: |
61 | i2c_unlock_bus(adapter: i2c->adapter, I2C_LOCK_SEGMENT); |
62 | |
63 | return ret; |
64 | } |
65 | |
66 | /** |
67 | * regmap_sccb_write - Write data to SCCB slave device |
68 | * @context: Device that will be interacted with |
69 | * @reg: Register to write to |
70 | * @val: Value to be written |
71 | * |
72 | * This executes the SCCB 3-phase write transmission cycle, returning negative |
73 | * errno else zero on success. |
74 | */ |
75 | static int regmap_sccb_write(void *context, unsigned int reg, unsigned int val) |
76 | { |
77 | struct device *dev = context; |
78 | struct i2c_client *i2c = to_i2c_client(dev); |
79 | |
80 | return i2c_smbus_write_byte_data(client: i2c, command: reg, value: val); |
81 | } |
82 | |
83 | static const struct regmap_bus regmap_sccb_bus = { |
84 | .reg_write = regmap_sccb_write, |
85 | .reg_read = regmap_sccb_read, |
86 | }; |
87 | |
88 | static const struct regmap_bus *regmap_get_sccb_bus(struct i2c_client *i2c, |
89 | const struct regmap_config *config) |
90 | { |
91 | if (config->val_bits == 8 && config->reg_bits == 8 && |
92 | sccb_is_available(adap: i2c->adapter)) |
93 | return ®map_sccb_bus; |
94 | |
95 | return ERR_PTR(error: -ENOTSUPP); |
96 | } |
97 | |
98 | struct regmap *__regmap_init_sccb(struct i2c_client *i2c, |
99 | const struct regmap_config *config, |
100 | struct lock_class_key *lock_key, |
101 | const char *lock_name) |
102 | { |
103 | const struct regmap_bus *bus = regmap_get_sccb_bus(i2c, config); |
104 | |
105 | if (IS_ERR(ptr: bus)) |
106 | return ERR_CAST(ptr: bus); |
107 | |
108 | return __regmap_init(dev: &i2c->dev, bus, bus_context: &i2c->dev, config, |
109 | lock_key, lock_name); |
110 | } |
111 | EXPORT_SYMBOL_GPL(__regmap_init_sccb); |
112 | |
113 | struct regmap *__devm_regmap_init_sccb(struct i2c_client *i2c, |
114 | const struct regmap_config *config, |
115 | struct lock_class_key *lock_key, |
116 | const char *lock_name) |
117 | { |
118 | const struct regmap_bus *bus = regmap_get_sccb_bus(i2c, config); |
119 | |
120 | if (IS_ERR(ptr: bus)) |
121 | return ERR_CAST(ptr: bus); |
122 | |
123 | return __devm_regmap_init(dev: &i2c->dev, bus, bus_context: &i2c->dev, config, |
124 | lock_key, lock_name); |
125 | } |
126 | EXPORT_SYMBOL_GPL(__devm_regmap_init_sccb); |
127 | |
128 | MODULE_LICENSE("GPL v2" ); |
129 | |