drivers/i2c/busses/i2c-amd756-s4882.c

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