1 /*
2  * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
3  *
4  * Copyright (C) 2004, 2008 Jean Delvare <khali@linux-fr.org>
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  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software
18  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
19  */
20 
21 /*
22  * We select the channels by sending commands to the Philips
23  * PCA9556 chip at I2C address 0x18. The main adapter is used for
24  * the non-multiplexed part of the bus, and 4 virtual adapters
25  * are defined for the multiplexed addresses: 0x50-0x53 (memory
26  * module EEPROM) located on channels 1-4, and 0x4c (LM63)
27  * located on multiplexed channels 0 and 5-7. We define one
28  * virtual adapter per CPU, which corresponds to two multiplexed
29  * channels:
30  *   CPU0: virtual adapter 1, channels 1 and 0
31  *   CPU1: virtual adapter 2, channels 2 and 5
32  *   CPU2: virtual adapter 3, channels 3 and 6
33  *   CPU3: virtual adapter 4, channels 4 and 7
34  */
35 
36 #include <linux/module.h>
37 #include <linux/kernel.h>
38 #include <linux/slab.h>
39 #include <linux/init.h>
40 #include <linux/i2c.h>
41 #include <linux/mutex.h>
42 
43 extern struct i2c_adapter amd756_smbus;
44 
45 static struct i2c_adapter *s4882_adapter;
46 static struct i2c_algorithm *s4882_algo;
47 
48 /* Wrapper access functions for multiplexed SMBus */
49 static DEFINE_MUTEX(amd756_lock);
50 
51 static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
52 			       unsigned short flags, char read_write,
53 			       u8 command, int size,
54 			       union i2c_smbus_data * data)
55 {
56 	int error;
57 
58 	/* We exclude the multiplexed addresses */
59 	if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
60 	 || addr == 0x18)
61 		return -ENXIO;
62 
63 	mutex_lock(&amd756_lock);
64 
65 	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
66 					      command, size, data);
67 
68 	mutex_unlock(&amd756_lock);
69 
70 	return error;
71 }
72 
73 /* We remember the last used channels combination so as to only switch
74    channels when it is really needed. This greatly reduces the SMBus
75    overhead, but also assumes that nobody will be writing to the PCA9556
76    in our back. */
77 static u8 last_channels;
78 
79 static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
80 					unsigned short flags, char read_write,
81 					u8 command, int size,
82 					union i2c_smbus_data * data,
83 					u8 channels)
84 {
85 	int error;
86 
87 	/* We exclude the non-multiplexed addresses */
88 	if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
89 		return -ENXIO;
90 
91 	mutex_lock(&amd756_lock);
92 
93 	if (last_channels != channels) {
94 		union i2c_smbus_data mplxdata;
95 		mplxdata.byte = channels;
96 
97 		error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
98 						      I2C_SMBUS_WRITE, 0x01,
99 						      I2C_SMBUS_BYTE_DATA,
100 						      &mplxdata);
101 		if (error)
102 			goto UNLOCK;
103 		last_channels = channels;
104 	}
105 	error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
106 					      command, size, data);
107 
108 UNLOCK:
109 	mutex_unlock(&amd756_lock);
110 	return error;
111 }
112 
113 static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
114 			       unsigned short flags, char read_write,
115 			       u8 command, int size,
116 			       union i2c_smbus_data * data)
117 {
118 	/* CPU0: channels 1 and 0 enabled */
119 	return amd756_access_channel(adap, addr, flags, read_write, command,
120 				     size, data, 0x03);
121 }
122 
123 static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
124 			       unsigned short flags, char read_write,
125 			       u8 command, int size,
126 			       union i2c_smbus_data * data)
127 {
128 	/* CPU1: channels 2 and 5 enabled */
129 	return amd756_access_channel(adap, addr, flags, read_write, command,
130 				     size, data, 0x24);
131 }
132 
133 static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
134 			       unsigned short flags, char read_write,
135 			       u8 command, int size,
136 			       union i2c_smbus_data * data)
137 {
138 	/* CPU2: channels 3 and 6 enabled */
139 	return amd756_access_channel(adap, addr, flags, read_write, command,
140 				     size, data, 0x48);
141 }
142 
143 static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
144 			       unsigned short flags, char read_write,
145 			       u8 command, int size,
146 			       union i2c_smbus_data * data)
147 {
148 	/* CPU3: channels 4 and 7 enabled */
149 	return amd756_access_channel(adap, addr, flags, read_write, command,
150 				     size, data, 0x90);
151 }
152 
153 static int __init amd756_s4882_init(void)
154 {
155 	int i, error;
156 	union i2c_smbus_data ioconfig;
157 
158 	if (!amd756_smbus.dev.parent)
159 		return -ENODEV;
160 
161 	/* Configure the PCA9556 multiplexer */
162 	ioconfig.byte = 0x00; /* All I/O to output mode */
163 	error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
164 			       I2C_SMBUS_BYTE_DATA, &ioconfig);
165 	if (error) {
166 		dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
167 		error = -EIO;
168 		goto ERROR0;
169 	}
170 
171 	/* Unregister physical bus */
172 	error = i2c_del_adapter(&amd756_smbus);
173 	if (error) {
174 		dev_err(&amd756_smbus.dev, "Physical bus removal failed\n");
175 		goto ERROR0;
176 	}
177 
178 	printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
179 	/* Define the 5 virtual adapters and algorithms structures */
180 	if (!(s4882_adapter = kzalloc(5 * sizeof(struct i2c_adapter),
181 				      GFP_KERNEL))) {
182 		error = -ENOMEM;
183 		goto ERROR1;
184 	}
185 	if (!(s4882_algo = kzalloc(5 * sizeof(struct i2c_algorithm),
186 				   GFP_KERNEL))) {
187 		error = -ENOMEM;
188 		goto ERROR2;
189 	}
190 
191 	/* Fill in the new structures */
192 	s4882_algo[0] = *(amd756_smbus.algo);
193 	s4882_algo[0].smbus_xfer = amd756_access_virt0;
194 	s4882_adapter[0] = amd756_smbus;
195 	s4882_adapter[0].algo = s4882_algo;
196 	s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
197 	for (i = 1; i < 5; i++) {
198 		s4882_algo[i] = *(amd756_smbus.algo);
199 		s4882_adapter[i] = amd756_smbus;
200 		snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
201 			 "SMBus 8111 adapter (CPU%d)", i-1);
202 		s4882_adapter[i].algo = s4882_algo+i;
203 		s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
204 	}
205 	s4882_algo[1].smbus_xfer = amd756_access_virt1;
206 	s4882_algo[2].smbus_xfer = amd756_access_virt2;
207 	s4882_algo[3].smbus_xfer = amd756_access_virt3;
208 	s4882_algo[4].smbus_xfer = amd756_access_virt4;
209 
210 	/* Register virtual adapters */
211 	for (i = 0; i < 5; i++) {
212 		error = i2c_add_adapter(s4882_adapter+i);
213 		if (error) {
214 			printk(KERN_ERR "i2c-amd756-s4882: "
215 			       "Virtual adapter %d registration "
216 			       "failed, module not inserted\n", i);
217 			for (i--; i >= 0; i--)
218 				i2c_del_adapter(s4882_adapter+i);
219 			goto ERROR3;
220 		}
221 	}
222 
223 	return 0;
224 
225 ERROR3:
226 	kfree(s4882_algo);
227 	s4882_algo = NULL;
228 ERROR2:
229 	kfree(s4882_adapter);
230 	s4882_adapter = NULL;
231 ERROR1:
232 	/* Restore physical bus */
233 	i2c_add_adapter(&amd756_smbus);
234 ERROR0:
235 	return error;
236 }
237 
238 static void __exit amd756_s4882_exit(void)
239 {
240 	if (s4882_adapter) {
241 		int i;
242 
243 		for (i = 0; i < 5; i++)
244 			i2c_del_adapter(s4882_adapter+i);
245 		kfree(s4882_adapter);
246 		s4882_adapter = NULL;
247 	}
248 	kfree(s4882_algo);
249 	s4882_algo = NULL;
250 
251 	/* Restore physical bus */
252 	if (i2c_add_adapter(&amd756_smbus))
253 		printk(KERN_ERR "i2c-amd756-s4882: "
254 		       "Physical bus restoration failed\n");
255 }
256 
257 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
258 MODULE_DESCRIPTION("S4882 SMBus multiplexing");
259 MODULE_LICENSE("GPL");
260 
261 module_init(amd756_s4882_init);
262 module_exit(amd756_s4882_exit);
263