1 /* 2 * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard 3 * 4 * Copyright (C) 2004 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 -1; 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 -1; 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 /* Unregister physical bus */ 159 error = i2c_del_adapter(&amd756_smbus); 160 if (error) { 161 if (error == -EINVAL) 162 error = -ENODEV; 163 else 164 dev_err(&amd756_smbus.dev, "Physical bus removal " 165 "failed\n"); 166 goto ERROR0; 167 } 168 169 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n"); 170 /* Define the 5 virtual adapters and algorithms structures */ 171 if (!(s4882_adapter = kzalloc(5 * sizeof(struct i2c_adapter), 172 GFP_KERNEL))) { 173 error = -ENOMEM; 174 goto ERROR1; 175 } 176 if (!(s4882_algo = kzalloc(5 * sizeof(struct i2c_algorithm), 177 GFP_KERNEL))) { 178 error = -ENOMEM; 179 goto ERROR2; 180 } 181 182 /* Fill in the new structures */ 183 s4882_algo[0] = *(amd756_smbus.algo); 184 s4882_algo[0].smbus_xfer = amd756_access_virt0; 185 s4882_adapter[0] = amd756_smbus; 186 s4882_adapter[0].algo = s4882_algo; 187 s4882_adapter[0].dev.parent = amd756_smbus.dev.parent; 188 for (i = 1; i < 5; i++) { 189 s4882_algo[i] = *(amd756_smbus.algo); 190 s4882_adapter[i] = amd756_smbus; 191 sprintf(s4882_adapter[i].name, 192 "SMBus 8111 adapter (CPU%d)", i-1); 193 s4882_adapter[i].algo = s4882_algo+i; 194 s4882_adapter[i].dev.parent = amd756_smbus.dev.parent; 195 } 196 s4882_algo[1].smbus_xfer = amd756_access_virt1; 197 s4882_algo[2].smbus_xfer = amd756_access_virt2; 198 s4882_algo[3].smbus_xfer = amd756_access_virt3; 199 s4882_algo[4].smbus_xfer = amd756_access_virt4; 200 201 /* Configure the PCA9556 multiplexer */ 202 ioconfig.byte = 0x00; /* All I/O to output mode */ 203 error = amd756_smbus.algo->smbus_xfer(&amd756_smbus, 0x18, 0, 204 I2C_SMBUS_WRITE, 0x03, 205 I2C_SMBUS_BYTE_DATA, &ioconfig); 206 if (error) { 207 dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n"); 208 error = -EIO; 209 goto ERROR3; 210 } 211 212 /* Register virtual adapters */ 213 for (i = 0; i < 5; i++) { 214 error = i2c_add_adapter(s4882_adapter+i); 215 if (error) { 216 dev_err(&amd756_smbus.dev, 217 "Virtual adapter %d registration " 218 "failed, module not inserted\n", i); 219 for (i--; i >= 0; i--) 220 i2c_del_adapter(s4882_adapter+i); 221 goto ERROR3; 222 } 223 } 224 225 return 0; 226 227 ERROR3: 228 kfree(s4882_algo); 229 s4882_algo = NULL; 230 ERROR2: 231 kfree(s4882_adapter); 232 s4882_adapter = NULL; 233 ERROR1: 234 i2c_del_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 dev_err(&amd756_smbus.dev, "Physical bus restoration " 255 "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