1 /* 2 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard 3 * 4 * Copyright (C) 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. We define one virtual 23 * adapter per CPU, which corresponds to one multiplexed channel: 24 * CPU0: virtual adapter 1, channel 1 25 * CPU1: virtual adapter 2, channel 2 26 * CPU2: virtual adapter 3, channel 3 27 * CPU3: virtual adapter 4, channel 4 28 */ 29 30 #include <linux/module.h> 31 #include <linux/kernel.h> 32 #include <linux/slab.h> 33 #include <linux/init.h> 34 #include <linux/i2c.h> 35 #include <linux/mutex.h> 36 37 extern struct i2c_adapter *nforce2_smbus; 38 39 static struct i2c_adapter *s4985_adapter; 40 static struct i2c_algorithm *s4985_algo; 41 42 /* Wrapper access functions for multiplexed SMBus */ 43 static DEFINE_MUTEX(nforce2_lock); 44 45 static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr, 46 unsigned short flags, char read_write, 47 u8 command, int size, 48 union i2c_smbus_data *data) 49 { 50 int error; 51 52 /* We exclude the multiplexed addresses */ 53 if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30 54 || addr == 0x18) 55 return -ENXIO; 56 57 mutex_lock(&nforce2_lock); 58 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 59 command, size, data); 60 mutex_unlock(&nforce2_lock); 61 62 return error; 63 } 64 65 /* We remember the last used channels combination so as to only switch 66 channels when it is really needed. This greatly reduces the SMBus 67 overhead, but also assumes that nobody will be writing to the PCA9556 68 in our back. */ 69 static u8 last_channels; 70 71 static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr, 72 unsigned short flags, char read_write, 73 u8 command, int size, 74 union i2c_smbus_data *data, 75 u8 channels) 76 { 77 int error; 78 79 /* We exclude the non-multiplexed addresses */ 80 if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30) 81 return -ENXIO; 82 83 mutex_lock(&nforce2_lock); 84 if (last_channels != channels) { 85 union i2c_smbus_data mplxdata; 86 mplxdata.byte = channels; 87 88 error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0, 89 I2C_SMBUS_WRITE, 0x01, 90 I2C_SMBUS_BYTE_DATA, 91 &mplxdata); 92 if (error) 93 goto UNLOCK; 94 last_channels = channels; 95 } 96 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 97 command, size, data); 98 99 UNLOCK: 100 mutex_unlock(&nforce2_lock); 101 return error; 102 } 103 104 static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr, 105 unsigned short flags, char read_write, 106 u8 command, int size, 107 union i2c_smbus_data *data) 108 { 109 /* CPU0: channel 1 enabled */ 110 return nforce2_access_channel(adap, addr, flags, read_write, command, 111 size, data, 0x02); 112 } 113 114 static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr, 115 unsigned short flags, char read_write, 116 u8 command, int size, 117 union i2c_smbus_data *data) 118 { 119 /* CPU1: channel 2 enabled */ 120 return nforce2_access_channel(adap, addr, flags, read_write, command, 121 size, data, 0x04); 122 } 123 124 static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr, 125 unsigned short flags, char read_write, 126 u8 command, int size, 127 union i2c_smbus_data *data) 128 { 129 /* CPU2: channel 3 enabled */ 130 return nforce2_access_channel(adap, addr, flags, read_write, command, 131 size, data, 0x08); 132 } 133 134 static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr, 135 unsigned short flags, char read_write, 136 u8 command, int size, 137 union i2c_smbus_data *data) 138 { 139 /* CPU3: channel 4 enabled */ 140 return nforce2_access_channel(adap, addr, flags, read_write, command, 141 size, data, 0x10); 142 } 143 144 static int __init nforce2_s4985_init(void) 145 { 146 int i, error; 147 union i2c_smbus_data ioconfig; 148 149 if (!nforce2_smbus) 150 return -ENODEV; 151 152 /* Configure the PCA9556 multiplexer */ 153 ioconfig.byte = 0x00; /* All I/O to output mode */ 154 error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03, 155 I2C_SMBUS_BYTE_DATA, &ioconfig); 156 if (error) { 157 dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n"); 158 error = -EIO; 159 goto ERROR0; 160 } 161 162 /* Unregister physical bus */ 163 i2c_del_adapter(nforce2_smbus); 164 165 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n"); 166 /* Define the 5 virtual adapters and algorithms structures */ 167 s4985_adapter = kcalloc(5, sizeof(struct i2c_adapter), GFP_KERNEL); 168 if (!s4985_adapter) { 169 error = -ENOMEM; 170 goto ERROR1; 171 } 172 s4985_algo = kcalloc(5, sizeof(struct i2c_algorithm), GFP_KERNEL); 173 if (!s4985_algo) { 174 error = -ENOMEM; 175 goto ERROR2; 176 } 177 178 /* Fill in the new structures */ 179 s4985_algo[0] = *(nforce2_smbus->algo); 180 s4985_algo[0].smbus_xfer = nforce2_access_virt0; 181 s4985_adapter[0] = *nforce2_smbus; 182 s4985_adapter[0].algo = s4985_algo; 183 s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent; 184 for (i = 1; i < 5; i++) { 185 s4985_algo[i] = *(nforce2_smbus->algo); 186 s4985_adapter[i] = *nforce2_smbus; 187 snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name), 188 "SMBus nForce2 adapter (CPU%d)", i - 1); 189 s4985_adapter[i].algo = s4985_algo + i; 190 s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent; 191 } 192 s4985_algo[1].smbus_xfer = nforce2_access_virt1; 193 s4985_algo[2].smbus_xfer = nforce2_access_virt2; 194 s4985_algo[3].smbus_xfer = nforce2_access_virt3; 195 s4985_algo[4].smbus_xfer = nforce2_access_virt4; 196 197 /* Register virtual adapters */ 198 for (i = 0; i < 5; i++) { 199 error = i2c_add_adapter(s4985_adapter + i); 200 if (error) { 201 printk(KERN_ERR "i2c-nforce2-s4985: " 202 "Virtual adapter %d registration " 203 "failed, module not inserted\n", i); 204 for (i--; i >= 0; i--) 205 i2c_del_adapter(s4985_adapter + i); 206 goto ERROR3; 207 } 208 } 209 210 return 0; 211 212 ERROR3: 213 kfree(s4985_algo); 214 s4985_algo = NULL; 215 ERROR2: 216 kfree(s4985_adapter); 217 s4985_adapter = NULL; 218 ERROR1: 219 /* Restore physical bus */ 220 i2c_add_adapter(nforce2_smbus); 221 ERROR0: 222 return error; 223 } 224 225 static void __exit nforce2_s4985_exit(void) 226 { 227 if (s4985_adapter) { 228 int i; 229 230 for (i = 0; i < 5; i++) 231 i2c_del_adapter(s4985_adapter+i); 232 kfree(s4985_adapter); 233 s4985_adapter = NULL; 234 } 235 kfree(s4985_algo); 236 s4985_algo = NULL; 237 238 /* Restore physical bus */ 239 if (i2c_add_adapter(nforce2_smbus)) 240 printk(KERN_ERR "i2c-nforce2-s4985: " 241 "Physical bus restoration failed\n"); 242 } 243 244 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>"); 245 MODULE_DESCRIPTION("S4985 SMBus multiplexing"); 246 MODULE_LICENSE("GPL"); 247 248 module_init(nforce2_s4985_init); 249 module_exit(nforce2_s4985_exit); 250