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 /* Configure the PCA9556 multiplexer */ 159 ioconfig.byte = 0x00; /* All I/O to output mode */ 160 error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03, 161 I2C_SMBUS_BYTE_DATA, &ioconfig); 162 if (error) { 163 dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n"); 164 error = -EIO; 165 goto ERROR0; 166 } 167 168 /* Unregister physical bus */ 169 error = i2c_del_adapter(&amd756_smbus); 170 if (error) { 171 if (error == -EINVAL) 172 error = -ENODEV; 173 else 174 dev_err(&amd756_smbus.dev, "Physical bus removal " 175 "failed\n"); 176 goto ERROR0; 177 } 178 179 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n"); 180 /* Define the 5 virtual adapters and algorithms structures */ 181 if (!(s4882_adapter = kzalloc(5 * sizeof(struct i2c_adapter), 182 GFP_KERNEL))) { 183 error = -ENOMEM; 184 goto ERROR1; 185 } 186 if (!(s4882_algo = kzalloc(5 * sizeof(struct i2c_algorithm), 187 GFP_KERNEL))) { 188 error = -ENOMEM; 189 goto ERROR2; 190 } 191 192 /* Fill in the new structures */ 193 s4882_algo[0] = *(amd756_smbus.algo); 194 s4882_algo[0].smbus_xfer = amd756_access_virt0; 195 s4882_adapter[0] = amd756_smbus; 196 s4882_adapter[0].algo = s4882_algo; 197 s4882_adapter[0].dev.parent = amd756_smbus.dev.parent; 198 for (i = 1; i < 5; i++) { 199 s4882_algo[i] = *(amd756_smbus.algo); 200 s4882_adapter[i] = amd756_smbus; 201 sprintf(s4882_adapter[i].name, 202 "SMBus 8111 adapter (CPU%d)", i-1); 203 s4882_adapter[i].algo = s4882_algo+i; 204 s4882_adapter[i].dev.parent = amd756_smbus.dev.parent; 205 } 206 s4882_algo[1].smbus_xfer = amd756_access_virt1; 207 s4882_algo[2].smbus_xfer = amd756_access_virt2; 208 s4882_algo[3].smbus_xfer = amd756_access_virt3; 209 s4882_algo[4].smbus_xfer = amd756_access_virt4; 210 211 /* Register virtual adapters */ 212 for (i = 0; i < 5; i++) { 213 error = i2c_add_adapter(s4882_adapter+i); 214 if (error) { 215 printk(KERN_ERR "i2c-amd756-s4882: " 216 "Virtual adapter %d registration " 217 "failed, module not inserted\n", i); 218 for (i--; i >= 0; i--) 219 i2c_del_adapter(s4882_adapter+i); 220 goto ERROR3; 221 } 222 } 223 224 return 0; 225 226 ERROR3: 227 kfree(s4882_algo); 228 s4882_algo = NULL; 229 ERROR2: 230 kfree(s4882_adapter); 231 s4882_adapter = NULL; 232 ERROR1: 233 /* Restore physical bus */ 234 i2c_add_adapter(&amd756_smbus); 235 ERROR0: 236 return error; 237 } 238 239 static void __exit amd756_s4882_exit(void) 240 { 241 if (s4882_adapter) { 242 int i; 243 244 for (i = 0; i < 5; i++) 245 i2c_del_adapter(s4882_adapter+i); 246 kfree(s4882_adapter); 247 s4882_adapter = NULL; 248 } 249 kfree(s4882_algo); 250 s4882_algo = NULL; 251 252 /* Restore physical bus */ 253 if (i2c_add_adapter(&amd756_smbus)) 254 printk(KERN_ERR "i2c-amd756-s4882: " 255 "Physical bus restoration failed\n"); 256 } 257 258 MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 259 MODULE_DESCRIPTION("S4882 SMBus multiplexing"); 260 MODULE_LICENSE("GPL"); 261 262 module_init(amd756_s4882_init); 263 module_exit(amd756_s4882_exit); 264