2 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard
4 * Copyright (C) 2008 Jean Delvare <jdelvare@suse.de>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
18 * We select the channels by sending commands to the Philips
19 * PCA9556 chip at I2C address 0x18. The main adapter is used for
20 * the non-multiplexed part of the bus, and 4 virtual adapters
21 * are defined for the multiplexed addresses: 0x50-0x53 (memory
22 * module EEPROM) located on channels 1-4. We define one virtual
23 * adapter per CPU, which corresponds to one multiplexed channel:
24 * CPU0: virtual adapter 1, channel 1
25 * CPU1: virtual adapter 2, channel 2
26 * CPU2: virtual adapter 3, channel 3
27 * CPU3: virtual adapter 4, channel 4
30 #include <linux/module.h>
31 #include <linux/kernel.h>
32 #include <linux/slab.h>
33 #include <linux/init.h>
34 #include <linux/i2c.h>
35 #include <linux/mutex.h>
37 extern struct i2c_adapter
*nforce2_smbus
;
39 static struct i2c_adapter
*s4985_adapter
;
40 static struct i2c_algorithm
*s4985_algo
;
42 /* Wrapper access functions for multiplexed SMBus */
43 static DEFINE_MUTEX(nforce2_lock
);
45 static s32
nforce2_access_virt0(struct i2c_adapter
*adap
, u16 addr
,
46 unsigned short flags
, char read_write
,
48 union i2c_smbus_data
*data
)
52 /* We exclude the multiplexed addresses */
53 if ((addr
& 0xfc) == 0x50 || (addr
& 0xfc) == 0x30
57 mutex_lock(&nforce2_lock
);
58 error
= nforce2_smbus
->algo
->smbus_xfer(adap
, addr
, flags
, read_write
,
60 mutex_unlock(&nforce2_lock
);
65 /* We remember the last used channels combination so as to only switch
66 channels when it is really needed. This greatly reduces the SMBus
67 overhead, but also assumes that nobody will be writing to the PCA9556
69 static u8 last_channels
;
71 static inline s32
nforce2_access_channel(struct i2c_adapter
*adap
, u16 addr
,
72 unsigned short flags
, char read_write
,
74 union i2c_smbus_data
*data
,
79 /* We exclude the non-multiplexed addresses */
80 if ((addr
& 0xfc) != 0x50 && (addr
& 0xfc) != 0x30)
83 mutex_lock(&nforce2_lock
);
84 if (last_channels
!= channels
) {
85 union i2c_smbus_data mplxdata
;
86 mplxdata
.byte
= channels
;
88 error
= nforce2_smbus
->algo
->smbus_xfer(adap
, 0x18, 0,
89 I2C_SMBUS_WRITE
, 0x01,
94 last_channels
= channels
;
96 error
= nforce2_smbus
->algo
->smbus_xfer(adap
, addr
, flags
, read_write
,
100 mutex_unlock(&nforce2_lock
);
104 static s32
nforce2_access_virt1(struct i2c_adapter
*adap
, u16 addr
,
105 unsigned short flags
, char read_write
,
106 u8 command
, int size
,
107 union i2c_smbus_data
*data
)
109 /* CPU0: channel 1 enabled */
110 return nforce2_access_channel(adap
, addr
, flags
, read_write
, command
,
114 static s32
nforce2_access_virt2(struct i2c_adapter
*adap
, u16 addr
,
115 unsigned short flags
, char read_write
,
116 u8 command
, int size
,
117 union i2c_smbus_data
*data
)
119 /* CPU1: channel 2 enabled */
120 return nforce2_access_channel(adap
, addr
, flags
, read_write
, command
,
124 static s32
nforce2_access_virt3(struct i2c_adapter
*adap
, u16 addr
,
125 unsigned short flags
, char read_write
,
126 u8 command
, int size
,
127 union i2c_smbus_data
*data
)
129 /* CPU2: channel 3 enabled */
130 return nforce2_access_channel(adap
, addr
, flags
, read_write
, command
,
134 static s32
nforce2_access_virt4(struct i2c_adapter
*adap
, u16 addr
,
135 unsigned short flags
, char read_write
,
136 u8 command
, int size
,
137 union i2c_smbus_data
*data
)
139 /* CPU3: channel 4 enabled */
140 return nforce2_access_channel(adap
, addr
, flags
, read_write
, command
,
144 static int __init
nforce2_s4985_init(void)
147 union i2c_smbus_data ioconfig
;
152 /* Configure the PCA9556 multiplexer */
153 ioconfig
.byte
= 0x00; /* All I/O to output mode */
154 error
= i2c_smbus_xfer(nforce2_smbus
, 0x18, 0, I2C_SMBUS_WRITE
, 0x03,
155 I2C_SMBUS_BYTE_DATA
, &ioconfig
);
157 dev_err(&nforce2_smbus
->dev
, "PCA9556 configuration failed\n");
162 /* Unregister physical bus */
163 i2c_del_adapter(nforce2_smbus
);
165 printk(KERN_INFO
"Enabling SMBus multiplexing for Tyan S4985\n");
166 /* Define the 5 virtual adapters and algorithms structures */
167 s4985_adapter
= kzalloc(5 * sizeof(struct i2c_adapter
), GFP_KERNEL
);
168 if (!s4985_adapter
) {
172 s4985_algo
= kzalloc(5 * sizeof(struct i2c_algorithm
), GFP_KERNEL
);
178 /* Fill in the new structures */
179 s4985_algo
[0] = *(nforce2_smbus
->algo
);
180 s4985_algo
[0].smbus_xfer
= nforce2_access_virt0
;
181 s4985_adapter
[0] = *nforce2_smbus
;
182 s4985_adapter
[0].algo
= s4985_algo
;
183 s4985_adapter
[0].dev
.parent
= nforce2_smbus
->dev
.parent
;
184 for (i
= 1; i
< 5; i
++) {
185 s4985_algo
[i
] = *(nforce2_smbus
->algo
);
186 s4985_adapter
[i
] = *nforce2_smbus
;
187 snprintf(s4985_adapter
[i
].name
, sizeof(s4985_adapter
[i
].name
),
188 "SMBus nForce2 adapter (CPU%d)", i
- 1);
189 s4985_adapter
[i
].algo
= s4985_algo
+ i
;
190 s4985_adapter
[i
].dev
.parent
= nforce2_smbus
->dev
.parent
;
192 s4985_algo
[1].smbus_xfer
= nforce2_access_virt1
;
193 s4985_algo
[2].smbus_xfer
= nforce2_access_virt2
;
194 s4985_algo
[3].smbus_xfer
= nforce2_access_virt3
;
195 s4985_algo
[4].smbus_xfer
= nforce2_access_virt4
;
197 /* Register virtual adapters */
198 for (i
= 0; i
< 5; i
++) {
199 error
= i2c_add_adapter(s4985_adapter
+ i
);
201 printk(KERN_ERR
"i2c-nforce2-s4985: "
202 "Virtual adapter %d registration "
203 "failed, module not inserted\n", i
);
204 for (i
--; i
>= 0; i
--)
205 i2c_del_adapter(s4985_adapter
+ i
);
216 kfree(s4985_adapter
);
217 s4985_adapter
= NULL
;
219 /* Restore physical bus */
220 i2c_add_adapter(nforce2_smbus
);
225 static void __exit
nforce2_s4985_exit(void)
230 for (i
= 0; i
< 5; i
++)
231 i2c_del_adapter(s4985_adapter
+i
);
232 kfree(s4985_adapter
);
233 s4985_adapter
= NULL
;
238 /* Restore physical bus */
239 if (i2c_add_adapter(nforce2_smbus
))
240 printk(KERN_ERR
"i2c-nforce2-s4985: "
241 "Physical bus restoration failed\n");
244 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
245 MODULE_DESCRIPTION("S4985 SMBus multiplexing");
246 MODULE_LICENSE("GPL");
248 module_init(nforce2_s4985_init
);
249 module_exit(nforce2_s4985_exit
);