1 // SPDX-License-Identifier: GPL-2.0-only
3  * max6875.c - driver for MAX6874/MAX6875
7  * Based on eeprom.c
9  * The MAX6875 has a bank of registers and two banks of EEPROM.
11  *  * 0x0000 - 0x0046 = configuration registers
12  *  * 0x8000 - 0x8046 = configuration EEPROM
13  *  * 0x8100 - 0x82FF = user EEPROM
15  * This driver makes the user EEPROM available for read.
17  * The registers & config EEPROM should be accessed via i2c-dev.
20  * two addresses - 0x50/0x51 and 0x52/0x53.
23  * address, so this driver is destructive if loaded for the wrong EEPROM chip.
36 /* USER EEPROM is at addresses 0x8100 - 0x82FF */
44 /* Each client has this additional data */
50 	u8			data[USER_EEPROM_SIZE];  member
56 	struct max6875_data *data = i2c_get_clientdata(client);  in max6875_update_slice()  local
63 	mutex_lock(&data->update_lock);  in max6875_update_slice()
65 	buf = &data->data[slice << SLICE_BITS];  in max6875_update_slice()
67 	if (!(data->valid & (1 << slice)) ||  in max6875_update_slice()
68 	    time_after(jiffies, data->last_updated[slice])) {  in max6875_update_slice()
70 		dev_dbg(&client->dev, "Starting update of slice %u\n", slice);  in max6875_update_slice()
72 		data->valid &= ~(1 << slice);  in max6875_update_slice()
76 		/* select the eeprom address */  in max6875_update_slice()
78 			dev_err(&client->dev, "address set failed\n");  in max6875_update_slice()
82 		if (i2c_check_functionality(client->adapter,  in max6875_update_slice()
99 		data->last_updated[slice] = jiffies;  in max6875_update_slice()
100 		data->valid |= (1 << slice);  in max6875_update_slice()
103 	mutex_unlock(&data->update_lock);  in max6875_update_slice()
111 	struct max6875_data *data = i2c_get_clientdata(client);  in max6875_read()  local
115 	max_slice = (off + count - 1) >> SLICE_BITS;  in max6875_read()
119 	memcpy(buf, &data->data[off], count);  in max6875_read()
126 		.name = "eeprom",
135 	struct i2c_adapter *adapter = client->adapter;  in max6875_probe()
136 	struct max6875_data *data;  in max6875_probe()  local
141 		return -ENODEV;  in max6875_probe()
144 	if (client->addr & 1)  in max6875_probe()
145 		return -ENODEV;  in max6875_probe()
147 	data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL);  in max6875_probe()
148 	if (!data)  in max6875_probe()
149 		return -ENOMEM;  in max6875_probe()
152 	data->fake_client = i2c_new_dummy_device(client->adapter, client->addr + 1);  in max6875_probe()
153 	if (IS_ERR(data->fake_client)) {  in max6875_probe()
154 		err = PTR_ERR(data->fake_client);  in max6875_probe()
159 	i2c_set_clientdata(client, data);  in max6875_probe()
160 	mutex_init(&data->update_lock);  in max6875_probe()
162 	err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr);  in max6875_probe()
169 	i2c_unregister_device(data->fake_client);  in max6875_probe()
171 	kfree(data);  in max6875_probe()
177 	struct max6875_data *data = i2c_get_clientdata(client);  in max6875_remove()  local
179 	i2c_unregister_device(data->fake_client);  in max6875_remove()
181 	sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);  in max6875_remove()
182 	kfree(data);  in max6875_remove()