1 /*
2  * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
3  *
4  * Copyright (C) 2004, 2008 Jean Delvare <jdelvare@suse.de>
5  *
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.
10  *
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.
15  */
16 
17 /*
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, and 0x4c (LM63)
23  * located on multiplexed channels 0 and 5-7. We define one
24  * virtual adapter per CPU, which corresponds to two multiplexed
25  * channels:
26  *   CPU0: virtual adapter 1, channels 1 and 0
27  *   CPU1: virtual adapter 2, channels 2 and 5
28  *   CPU2: virtual adapter 3, channels 3 and 6
29  *   CPU3: virtual adapter 4, channels 4 and 7
30  */
31 
32 #include <linux/module.h>
33 #include <linux/kernel.h>
34 #include <linux/slab.h>
35 #include <linux/init.h>
36 #include <linux/i2c.h>
37 #include <linux/mutex.h>
38 
39 extern struct i2c_adapter amd756_smbus;
40 
41 static struct i2c_adapter *s4882_adapter;
42 static struct i2c_algorithm *s4882_algo;
43 
44 /* Wrapper access functions for multiplexed SMBus */
45 static DEFINE_MUTEX(amd756_lock);
46 
47 static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
48 			       unsigned short flags, char read_write,
49 			       u8 command, int size,
50 			       union i2c_smbus_data * data)
51 {
52 	int error;
53 
54 	/* We exclude the multiplexed addresses */
55 	if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
56 	 || addr == 0x18)
57 		return -ENXIO;
58 
59 	mutex_lock(&amd756_lock);
60 
61 	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
62 					      command, size, data);
63 
64 	mutex_unlock(&amd756_lock);
65 
66 	return error;
67 }
68 
69 /* We remember the last used channels combination so as to only switch
70    channels when it is really needed. This greatly reduces the SMBus
71    overhead, but also assumes that nobody will be writing to the PCA9556
72    in our back. */
73 static u8 last_channels;
74 
75 static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
76 					unsigned short flags, char read_write,
77 					u8 command, int size,
78 					union i2c_smbus_data * data,
79 					u8 channels)
80 {
81 	int error;
82 
83 	/* We exclude the non-multiplexed addresses */
84 	if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
85 		return -ENXIO;
86 
87 	mutex_lock(&amd756_lock);
88 
89 	if (last_channels != channels) {
90 		union i2c_smbus_data mplxdata;
91 		mplxdata.byte = channels;
92 
93 		error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
94 						      I2C_SMBUS_WRITE, 0x01,
95 						      I2C_SMBUS_BYTE_DATA,
96 						      &mplxdata);
97 		if (error)
98 			goto UNLOCK;
99 		last_channels = channels;
100 	}
101 	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
102 					      command, size, data);
103 
104 UNLOCK:
105 	mutex_unlock(&amd756_lock);
106 	return error;
107 }
108 
109 static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
110 			       unsigned short flags, char read_write,
111 			       u8 command, int size,
112 			       union i2c_smbus_data * data)
113 {
114 	/* CPU0: channels 1 and 0 enabled */
115 	return amd756_access_channel(adap, addr, flags, read_write, command,
116 				     size, data, 0x03);
117 }
118 
119 static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
120 			       unsigned short flags, char read_write,
121 			       u8 command, int size,
122 			       union i2c_smbus_data * data)
123 {
124 	/* CPU1: channels 2 and 5 enabled */
125 	return amd756_access_channel(adap, addr, flags, read_write, command,
126 				     size, data, 0x24);
127 }
128 
129 static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
130 			       unsigned short flags, char read_write,
131 			       u8 command, int size,
132 			       union i2c_smbus_data * data)
133 {
134 	/* CPU2: channels 3 and 6 enabled */
135 	return amd756_access_channel(adap, addr, flags, read_write, command,
136 				     size, data, 0x48);
137 }
138 
139 static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
140 			       unsigned short flags, char read_write,
141 			       u8 command, int size,
142 			       union i2c_smbus_data * data)
143 {
144 	/* CPU3: channels 4 and 7 enabled */
145 	return amd756_access_channel(adap, addr, flags, read_write, command,
146 				     size, data, 0x90);
147 }
148 
149 static int __init amd756_s4882_init(void)
150 {
151 	int i, error;
152 	union i2c_smbus_data ioconfig;
153 
154 	if (!amd756_smbus.dev.parent)
155 		return -ENODEV;
156 
157 	/* Configure the PCA9556 multiplexer */
158 	ioconfig.byte = 0x00; /* All I/O to output mode */
159 	error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
160 			       I2C_SMBUS_BYTE_DATA, &ioconfig);
161 	if (error) {
162 		dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
163 		error = -EIO;
164 		goto ERROR0;
165 	}
166 
167 	/* Unregister physical bus */
168 	i2c_del_adapter(&amd756_smbus);
169 
170 	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
171 	/* Define the 5 virtual adapters and algorithms structures */
172 	if (!(s4882_adapter = kcalloc(5, sizeof(struct i2c_adapter),
173 				      GFP_KERNEL))) {
174 		error = -ENOMEM;
175 		goto ERROR1;
176 	}
177 	if (!(s4882_algo = kcalloc(5, sizeof(struct i2c_algorithm),
178 				   GFP_KERNEL))) {
179 		error = -ENOMEM;
180 		goto ERROR2;
181 	}
182 
183 	/* Fill in the new structures */
184 	s4882_algo[0] = *(amd756_smbus.algo);
185 	s4882_algo[0].smbus_xfer = amd756_access_virt0;
186 	s4882_adapter[0] = amd756_smbus;
187 	s4882_adapter[0].algo = s4882_algo;
188 	s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
189 	for (i = 1; i < 5; i++) {
190 		s4882_algo[i] = *(amd756_smbus.algo);
191 		s4882_adapter[i] = amd756_smbus;
192 		snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
193 			 "SMBus 8111 adapter (CPU%d)", i-1);
194 		s4882_adapter[i].algo = s4882_algo+i;
195 		s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
196 	}
197 	s4882_algo[1].smbus_xfer = amd756_access_virt1;
198 	s4882_algo[2].smbus_xfer = amd756_access_virt2;
199 	s4882_algo[3].smbus_xfer = amd756_access_virt3;
200 	s4882_algo[4].smbus_xfer = amd756_access_virt4;
201 
202 	/* Register virtual adapters */
203 	for (i = 0; i < 5; i++) {
204 		error = i2c_add_adapter(s4882_adapter+i);
205 		if (error) {
206 			printk(KERN_ERR "i2c-amd756-s4882: "
207 			       "Virtual adapter %d registration "
208 			       "failed, module not inserted\n", i);
209 			for (i--; i >= 0; i--)
210 				i2c_del_adapter(s4882_adapter+i);
211 			goto ERROR3;
212 		}
213 	}
214 
215 	return 0;
216 
217 ERROR3:
218 	kfree(s4882_algo);
219 	s4882_algo = NULL;
220 ERROR2:
221 	kfree(s4882_adapter);
222 	s4882_adapter = NULL;
223 ERROR1:
224 	/* Restore physical bus */
225 	i2c_add_adapter(&amd756_smbus);
226 ERROR0:
227 	return error;
228 }
229 
230 static void __exit amd756_s4882_exit(void)
231 {
232 	if (s4882_adapter) {
233 		int i;
234 
235 		for (i = 0; i < 5; i++)
236 			i2c_del_adapter(s4882_adapter+i);
237 		kfree(s4882_adapter);
238 		s4882_adapter = NULL;
239 	}
240 	kfree(s4882_algo);
241 	s4882_algo = NULL;
242 
243 	/* Restore physical bus */
244 	if (i2c_add_adapter(&amd756_smbus))
245 		printk(KERN_ERR "i2c-amd756-s4882: "
246 		       "Physical bus restoration failed\n");
247 }
248 
249 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
250 MODULE_DESCRIPTION("S4882 SMBus multiplexing");
251 MODULE_LICENSE("GPL");
252 
253 module_init(amd756_s4882_init);
254 module_exit(amd756_s4882_exit);
255