1/* 2 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard 3 * 4 * Copyright (C) 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. We define one virtual 27 * adapter per CPU, which corresponds to one multiplexed channel: 28 * CPU0: virtual adapter 1, channel 1 29 * CPU1: virtual adapter 2, channel 2 30 * CPU2: virtual adapter 3, channel 3 31 * CPU3: virtual adapter 4, channel 4 32 */ 33 34#include <linux/module.h> 35#include <linux/kernel.h> 36#include <linux/slab.h> 37#include <linux/init.h> 38#include <linux/i2c.h> 39#include <linux/mutex.h> 40 41extern struct i2c_adapter *nforce2_smbus; 42 43static struct i2c_adapter *s4985_adapter; 44static struct i2c_algorithm *s4985_algo; 45 46/* Wrapper access functions for multiplexed SMBus */ 47static DEFINE_MUTEX(nforce2_lock); 48 49static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr, 50 unsigned short flags, char read_write, 51 u8 command, int size, 52 union i2c_smbus_data *data) 53{ 54 int error; 55 56 /* We exclude the multiplexed addresses */ 57 if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30 58 || addr == 0x18) 59 return -ENXIO; 60 61 mutex_lock(&nforce2_lock); 62 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 63 command, size, data); 64 mutex_unlock(&nforce2_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. */ 73static u8 last_channels; 74 75static inline s32 nforce2_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 & 0xfc) != 0x50 && (addr & 0xfc) != 0x30) 85 return -ENXIO; 86 87 mutex_lock(&nforce2_lock); 88 if (last_channels != channels) { 89 union i2c_smbus_data mplxdata; 90 mplxdata.byte = channels; 91 92 error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0, 93 I2C_SMBUS_WRITE, 0x01, 94 I2C_SMBUS_BYTE_DATA, 95 &mplxdata); 96 if (error) 97 goto UNLOCK; 98 last_channels = channels; 99 } 100 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, 101 command, size, data); 102 103UNLOCK: 104 mutex_unlock(&nforce2_lock); 105 return error; 106} 107 108static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr, 109 unsigned short flags, char read_write, 110 u8 command, int size, 111 union i2c_smbus_data *data) 112{ 113 /* CPU0: channel 1 enabled */ 114 return nforce2_access_channel(adap, addr, flags, read_write, command, 115 size, data, 0x02); 116} 117 118static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr, 119 unsigned short flags, char read_write, 120 u8 command, int size, 121 union i2c_smbus_data *data) 122{ 123 /* CPU1: channel 2 enabled */ 124 return nforce2_access_channel(adap, addr, flags, read_write, command, 125 size, data, 0x04); 126} 127 128static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr, 129 unsigned short flags, char read_write, 130 u8 command, int size, 131 union i2c_smbus_data *data) 132{ 133 /* CPU2: channel 3 enabled */ 134 return nforce2_access_channel(adap, addr, flags, read_write, command, 135 size, data, 0x08); 136} 137 138static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr, 139 unsigned short flags, char read_write, 140 u8 command, int size, 141 union i2c_smbus_data *data) 142{ 143 /* CPU3: channel 4 enabled */ 144 return nforce2_access_channel(adap, addr, flags, read_write, command, 145 size, data, 0x10); 146} 147 148static int __init nforce2_s4985_init(void) 149{ 150 int i, error; 151 union i2c_smbus_data ioconfig; 152 153 if (!nforce2_smbus) 154 return -ENODEV; 155 156 /* Configure the PCA9556 multiplexer */ 157 ioconfig.byte = 0x00; /* All I/O to output mode */ 158 error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03, 159 I2C_SMBUS_BYTE_DATA, &ioconfig); 160 if (error) { 161 dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n"); 162 error = -EIO; 163 goto ERROR0; 164 } 165 166 /* Unregister physical bus */ 167 error = i2c_del_adapter(nforce2_smbus); 168 if (error) { 169 dev_err(&nforce2_smbus->dev, "Physical bus removal failed\n"); 170 goto ERROR0; 171 } 172 173 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n"); 174 /* Define the 5 virtual adapters and algorithms structures */ 175 s4985_adapter = kzalloc(5 * sizeof(struct i2c_adapter), GFP_KERNEL); 176 if (!s4985_adapter) { 177 error = -ENOMEM; 178 goto ERROR1; 179 } 180 s4985_algo = kzalloc(5 * sizeof(struct i2c_algorithm), GFP_KERNEL); 181 if (!s4985_algo) { 182 error = -ENOMEM; 183 goto ERROR2; 184 } 185 186 /* Fill in the new structures */ 187 s4985_algo[0] = *(nforce2_smbus->algo); 188 s4985_algo[0].smbus_xfer = nforce2_access_virt0; 189 s4985_adapter[0] = *nforce2_smbus; 190 s4985_adapter[0].algo = s4985_algo; 191 s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent; 192 for (i = 1; i < 5; i++) { 193 s4985_algo[i] = *(nforce2_smbus->algo); 194 s4985_adapter[i] = *nforce2_smbus; 195 snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name), 196 "SMBus nForce2 adapter (CPU%d)", i - 1); 197 s4985_adapter[i].algo = s4985_algo + i; 198 s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent; 199 } 200 s4985_algo[1].smbus_xfer = nforce2_access_virt1; 201 s4985_algo[2].smbus_xfer = nforce2_access_virt2; 202 s4985_algo[3].smbus_xfer = nforce2_access_virt3; 203 s4985_algo[4].smbus_xfer = nforce2_access_virt4; 204 205 /* Register virtual adapters */ 206 for (i = 0; i < 5; i++) { 207 error = i2c_add_adapter(s4985_adapter + i); 208 if (error) { 209 printk(KERN_ERR "i2c-nforce2-s4985: " 210 "Virtual adapter %d registration " 211 "failed, module not inserted\n", i); 212 for (i--; i >= 0; i--) 213 i2c_del_adapter(s4985_adapter + i); 214 goto ERROR3; 215 } 216 } 217 218 return 0; 219 220ERROR3: 221 kfree(s4985_algo); 222 s4985_algo = NULL; 223ERROR2: 224 kfree(s4985_adapter); 225 s4985_adapter = NULL; 226ERROR1: 227 /* Restore physical bus */ 228 i2c_add_adapter(nforce2_smbus); 229ERROR0: 230 return error; 231} 232 233static void __exit nforce2_s4985_exit(void) 234{ 235 if (s4985_adapter) { 236 int i; 237 238 for (i = 0; i < 5; i++) 239 i2c_del_adapter(s4985_adapter+i); 240 kfree(s4985_adapter); 241 s4985_adapter = NULL; 242 } 243 kfree(s4985_algo); 244 s4985_algo = NULL; 245 246 /* Restore physical bus */ 247 if (i2c_add_adapter(nforce2_smbus)) 248 printk(KERN_ERR "i2c-nforce2-s4985: " 249 "Physical bus restoration failed\n"); 250} 251 252MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); 253MODULE_DESCRIPTION("S4985 SMBus multiplexing"); 254MODULE_LICENSE("GPL"); 255 256module_init(nforce2_s4985_init); 257module_exit(nforce2_s4985_exit); 258