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