1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
4 *
5 * Copyright (C) 2004, 2008 Jean Delvare <jdelvare@suse.de>
6 */
7
8 /*
9 * We select the channels by sending commands to the Philips
10 * PCA9556 chip at I2C address 0x18. The main adapter is used for
11 * the non-multiplexed part of the bus, and 4 virtual adapters
12 * are defined for the multiplexed addresses: 0x50-0x53 (memory
13 * module EEPROM) located on channels 1-4, and 0x4c (LM63)
14 * located on multiplexed channels 0 and 5-7. We define one
15 * virtual adapter per CPU, which corresponds to two multiplexed
16 * channels:
17 * CPU0: virtual adapter 1, channels 1 and 0
18 * CPU1: virtual adapter 2, channels 2 and 5
19 * CPU2: virtual adapter 3, channels 3 and 6
20 * CPU3: virtual adapter 4, channels 4 and 7
21 */
22
23 #include <linux/module.h>
24 #include <linux/kernel.h>
25 #include <linux/slab.h>
26 #include <linux/init.h>
27 #include <linux/i2c.h>
28 #include <linux/mutex.h>
29
30 extern struct i2c_adapter amd756_smbus;
31
32 static struct i2c_adapter *s4882_adapter;
33 static struct i2c_algorithm *s4882_algo;
34
35 /* Wrapper access functions for multiplexed SMBus */
36 static DEFINE_MUTEX(amd756_lock);
37
amd756_access_virt0(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)38 static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
39 unsigned short flags, char read_write,
40 u8 command, int size,
41 union i2c_smbus_data * data)
42 {
43 int error;
44
45 /* We exclude the multiplexed addresses */
46 if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
47 || addr == 0x18)
48 return -ENXIO;
49
50 mutex_lock(&amd756_lock);
51
52 error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
53 command, size, data);
54
55 mutex_unlock(&amd756_lock);
56
57 return error;
58 }
59
60 /* We remember the last used channels combination so as to only switch
61 channels when it is really needed. This greatly reduces the SMBus
62 overhead, but also assumes that nobody will be writing to the PCA9556
63 in our back. */
64 static u8 last_channels;
65
amd756_access_channel(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data,u8 channels)66 static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
67 unsigned short flags, char read_write,
68 u8 command, int size,
69 union i2c_smbus_data * data,
70 u8 channels)
71 {
72 int error;
73
74 /* We exclude the non-multiplexed addresses */
75 if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
76 return -ENXIO;
77
78 mutex_lock(&amd756_lock);
79
80 if (last_channels != channels) {
81 union i2c_smbus_data mplxdata;
82 mplxdata.byte = channels;
83
84 error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
85 I2C_SMBUS_WRITE, 0x01,
86 I2C_SMBUS_BYTE_DATA,
87 &mplxdata);
88 if (error)
89 goto UNLOCK;
90 last_channels = channels;
91 }
92 error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
93 command, size, data);
94
95 UNLOCK:
96 mutex_unlock(&amd756_lock);
97 return error;
98 }
99
amd756_access_virt1(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)100 static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
101 unsigned short flags, char read_write,
102 u8 command, int size,
103 union i2c_smbus_data * data)
104 {
105 /* CPU0: channels 1 and 0 enabled */
106 return amd756_access_channel(adap, addr, flags, read_write, command,
107 size, data, 0x03);
108 }
109
amd756_access_virt2(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)110 static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
111 unsigned short flags, char read_write,
112 u8 command, int size,
113 union i2c_smbus_data * data)
114 {
115 /* CPU1: channels 2 and 5 enabled */
116 return amd756_access_channel(adap, addr, flags, read_write, command,
117 size, data, 0x24);
118 }
119
amd756_access_virt3(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)120 static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
121 unsigned short flags, char read_write,
122 u8 command, int size,
123 union i2c_smbus_data * data)
124 {
125 /* CPU2: channels 3 and 6 enabled */
126 return amd756_access_channel(adap, addr, flags, read_write, command,
127 size, data, 0x48);
128 }
129
amd756_access_virt4(struct i2c_adapter * adap,u16 addr,unsigned short flags,char read_write,u8 command,int size,union i2c_smbus_data * data)130 static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
131 unsigned short flags, char read_write,
132 u8 command, int size,
133 union i2c_smbus_data * data)
134 {
135 /* CPU3: channels 4 and 7 enabled */
136 return amd756_access_channel(adap, addr, flags, read_write, command,
137 size, data, 0x90);
138 }
139
amd756_s4882_init(void)140 static int __init amd756_s4882_init(void)
141 {
142 int i, error;
143 union i2c_smbus_data ioconfig;
144
145 if (!amd756_smbus.dev.parent)
146 return -ENODEV;
147
148 /* Configure the PCA9556 multiplexer */
149 ioconfig.byte = 0x00; /* All I/O to output mode */
150 error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
151 I2C_SMBUS_BYTE_DATA, &ioconfig);
152 if (error) {
153 dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
154 error = -EIO;
155 goto ERROR0;
156 }
157
158 /* Unregister physical bus */
159 i2c_del_adapter(&amd756_smbus);
160
161 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
162 /* Define the 5 virtual adapters and algorithms structures */
163 if (!(s4882_adapter = kcalloc(5, sizeof(struct i2c_adapter),
164 GFP_KERNEL))) {
165 error = -ENOMEM;
166 goto ERROR1;
167 }
168 if (!(s4882_algo = kcalloc(5, sizeof(struct i2c_algorithm),
169 GFP_KERNEL))) {
170 error = -ENOMEM;
171 goto ERROR2;
172 }
173
174 /* Fill in the new structures */
175 s4882_algo[0] = *(amd756_smbus.algo);
176 s4882_algo[0].smbus_xfer = amd756_access_virt0;
177 s4882_adapter[0] = amd756_smbus;
178 s4882_adapter[0].algo = s4882_algo;
179 s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
180 for (i = 1; i < 5; i++) {
181 s4882_algo[i] = *(amd756_smbus.algo);
182 s4882_adapter[i] = amd756_smbus;
183 snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
184 "SMBus 8111 adapter (CPU%d)", i-1);
185 s4882_adapter[i].algo = s4882_algo+i;
186 s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
187 }
188 s4882_algo[1].smbus_xfer = amd756_access_virt1;
189 s4882_algo[2].smbus_xfer = amd756_access_virt2;
190 s4882_algo[3].smbus_xfer = amd756_access_virt3;
191 s4882_algo[4].smbus_xfer = amd756_access_virt4;
192
193 /* Register virtual adapters */
194 for (i = 0; i < 5; i++) {
195 error = i2c_add_adapter(s4882_adapter+i);
196 if (error) {
197 printk(KERN_ERR "i2c-amd756-s4882: "
198 "Virtual adapter %d registration "
199 "failed, module not inserted\n", i);
200 for (i--; i >= 0; i--)
201 i2c_del_adapter(s4882_adapter+i);
202 goto ERROR3;
203 }
204 }
205
206 return 0;
207
208 ERROR3:
209 kfree(s4882_algo);
210 s4882_algo = NULL;
211 ERROR2:
212 kfree(s4882_adapter);
213 s4882_adapter = NULL;
214 ERROR1:
215 /* Restore physical bus */
216 i2c_add_adapter(&amd756_smbus);
217 ERROR0:
218 return error;
219 }
220
amd756_s4882_exit(void)221 static void __exit amd756_s4882_exit(void)
222 {
223 if (s4882_adapter) {
224 int i;
225
226 for (i = 0; i < 5; i++)
227 i2c_del_adapter(s4882_adapter+i);
228 kfree(s4882_adapter);
229 s4882_adapter = NULL;
230 }
231 kfree(s4882_algo);
232 s4882_algo = NULL;
233
234 /* Restore physical bus */
235 if (i2c_add_adapter(&amd756_smbus))
236 printk(KERN_ERR "i2c-amd756-s4882: "
237 "Physical bus restoration failed\n");
238 }
239
240 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
241 MODULE_DESCRIPTION("S4882 SMBus multiplexing");
242 MODULE_LICENSE("GPL");
243
244 module_init(amd756_s4882_init);
245 module_exit(amd756_s4882_exit);
246
