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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
   4  *
   5  * Copyright (C) 2004, 2008 Jean Delvare <jdelvare@suse.de>
   6  */
   7
   8 /*
   9  * We select the channels by sending commands to the Philips
  10  * PCA9556 chip at I2C address 0x18. The main adapter is used for
  11  * the non-multiplexed part of the bus, and 4 virtual adapters
  12  * are defined for the multiplexed addresses: 0x50-0x53 (memory
  13  * module EEPROM) located on channels 1-4, and 0x4c (LM63)
  14  * located on multiplexed channels 0 and 5-7. We define one
  15  * virtual adapter per CPU, which corresponds to two multiplexed
  16  * channels:
  17  *   CPU0: virtual adapter 1, channels 1 and 0
  18  *   CPU1: virtual adapter 2, channels 2 and 5
  19  *   CPU2: virtual adapter 3, channels 3 and 6
  20  *   CPU3: virtual adapter 4, channels 4 and 7
  21  */
  22
  23 #include <linux/module.h>
  24 #include <linux/kernel.h>
  25 #include <linux/slab.h>
  26 #include <linux/init.h>
  27 #include <linux/i2c.h>
  28 #include <linux/mutex.h>
  29
  30 extern struct i2c_adapter amd756_smbus;
  31
  32 static struct i2c_adapter *s4882_adapter;
  33 static struct i2c_algorithm *s4882_algo;
  34
  35 /* Wrapper access functions for multiplexed SMBus */
  36 static DEFINE_MUTEX(amd756_lock);
  37
  38 static s32 amd756_access_virt0(struct i2c_adapter * adap, u16 addr,
  39                                unsigned short flags, char read_write,
  40                                u8 command, int size,
  41                                union i2c_smbus_data * data)
  42 {
  43         int error;
  44
  45         /* We exclude the multiplexed addresses */
  46         if (addr == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
  47          || addr == 0x18)
  48                 return -ENXIO;
  49
  50         mutex_lock(&amd756_lock);
  51
  52         error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
  53                                               command, size, data);
  54
  55         mutex_unlock(&amd756_lock);
  56
  57         return error;
  58 }
  59
  60 /* We remember the last used channels combination so as to only switch
  61    channels when it is really needed. This greatly reduces the SMBus
  62    overhead, but also assumes that nobody will be writing to the PCA9556
  63    in our back. */
  64 static u8 last_channels;
  65
  66 static inline s32 amd756_access_channel(struct i2c_adapter * adap, u16 addr,
  67                                         unsigned short flags, char read_write,
  68                                         u8 command, int size,
  69                                         union i2c_smbus_data * data,
  70                                         u8 channels)
  71 {
  72         int error;
  73
  74         /* We exclude the non-multiplexed addresses */
  75         if (addr != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
  76                 return -ENXIO;
  77
  78         mutex_lock(&amd756_lock);
  79
  80         if (last_channels != channels) {
  81                 union i2c_smbus_data mplxdata;
  82                 mplxdata.byte = channels;
  83
  84                 error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
  85                                                       I2C_SMBUS_WRITE, 0x01,
  86                                                       I2C_SMBUS_BYTE_DATA,
  87                                                       &mplxdata);
  88                 if (error)
  89                         goto UNLOCK;
  90                 last_channels = channels;
  91         }
  92         error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
  93                                               command, size, data);
  94
  95 UNLOCK:
  96         mutex_unlock(&amd756_lock);
  97         return error;
  98 }
  99
 100 static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
 101                                unsigned short flags, char read_write,
 102                                u8 command, int size,
 103                                union i2c_smbus_data * data)
 104 {
 105         /* CPU0: channels 1 and 0 enabled */
 106         return amd756_access_channel(adap, addr, flags, read_write, command,
 107                                      size, data, 0x03);
 108 }
 109
 110 static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
 111                                unsigned short flags, char read_write,
 112                                u8 command, int size,
 113                                union i2c_smbus_data * data)
 114 {
 115         /* CPU1: channels 2 and 5 enabled */
 116         return amd756_access_channel(adap, addr, flags, read_write, command,
 117                                      size, data, 0x24);
 118 }
 119
 120 static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
 121                                unsigned short flags, char read_write,
 122                                u8 command, int size,
 123                                union i2c_smbus_data * data)
 124 {
 125         /* CPU2: channels 3 and 6 enabled */
 126         return amd756_access_channel(adap, addr, flags, read_write, command,
 127                                      size, data, 0x48);
 128 }
 129
 130 static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
 131                                unsigned short flags, char read_write,
 132                                u8 command, int size,
 133                                union i2c_smbus_data * data)
 134 {
 135         /* CPU3: channels 4 and 7 enabled */
 136         return amd756_access_channel(adap, addr, flags, read_write, command,
 137                                      size, data, 0x90);
 138 }
 139
 140 static int __init amd756_s4882_init(void)
 141 {
 142         int i, error;
 143         union i2c_smbus_data ioconfig;
 144
 145         if (!amd756_smbus.dev.parent)
 146                 return -ENODEV;
 147
 148         /* Configure the PCA9556 multiplexer */
 149         ioconfig.byte = 0x00; /* All I/O to output mode */
 150         error = i2c_smbus_xfer(&amd756_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,
 151                                I2C_SMBUS_BYTE_DATA, &ioconfig);
 152         if (error) {
 153                 dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
 154                 error = -EIO;
 155                 goto ERROR0;
 156         }
 157
 158         /* Unregister physical bus */
 159         i2c_del_adapter(&amd756_smbus);
 160
 161         printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
 162         /* Define the 5 virtual adapters and algorithms structures */
 163         if (!(s4882_adapter = kcalloc(5, sizeof(struct i2c_adapter),
 164                                       GFP_KERNEL))) {
 165                 error = -ENOMEM;
 166                 goto ERROR1;
 167         }
 168         if (!(s4882_algo = kcalloc(5, sizeof(struct i2c_algorithm),
 169                                    GFP_KERNEL))) {
 170                 error = -ENOMEM;
 171                 goto ERROR2;
 172         }
 173
 174         /* Fill in the new structures */
 175         s4882_algo[0] = *(amd756_smbus.algo);
 176         s4882_algo[0].smbus_xfer = amd756_access_virt0;
 177         s4882_adapter[0] = amd756_smbus;
 178         s4882_adapter[0].algo = s4882_algo;
 179         s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
 180         for (i = 1; i < 5; i++) {
 181                 s4882_algo[i] = *(amd756_smbus.algo);
 182                 s4882_adapter[i] = amd756_smbus;
 183                 snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
 184                          "SMBus 8111 adapter (CPU%d)", i-1);
 185                 s4882_adapter[i].algo = s4882_algo+i;
 186                 s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
 187         }
 188         s4882_algo[1].smbus_xfer = amd756_access_virt1;
 189         s4882_algo[2].smbus_xfer = amd756_access_virt2;
 190         s4882_algo[3].smbus_xfer = amd756_access_virt3;
 191         s4882_algo[4].smbus_xfer = amd756_access_virt4;
 192
 193         /* Register virtual adapters */
 194         for (i = 0; i < 5; i++) {
 195                 error = i2c_add_adapter(s4882_adapter+i);
 196                 if (error) {
 197                         printk(KERN_ERR "i2c-amd756-s4882: "
 198                                "Virtual adapter %d registration "
 199                                "failed, module not inserted\n", i);
 200                         for (i--; i >= 0; i--)
 201                                 i2c_del_adapter(s4882_adapter+i);
 202                         goto ERROR3;
 203                 }
 204         }
 205
 206         return 0;
 207
 208 ERROR3:
 209         kfree(s4882_algo);
 210         s4882_algo = NULL;
 211 ERROR2:
 212         kfree(s4882_adapter);
 213         s4882_adapter = NULL;
 214 ERROR1:
 215         /* Restore physical bus */
 216         i2c_add_adapter(&amd756_smbus);
 217 ERROR0:
 218         return error;
 219 }
 220
 221 static void __exit amd756_s4882_exit(void)
 222 {
 223         if (s4882_adapter) {
 224                 int i;
 225
 226                 for (i = 0; i < 5; i++)
 227                         i2c_del_adapter(s4882_adapter+i);
 228                 kfree(s4882_adapter);
 229                 s4882_adapter = NULL;
 230         }
 231         kfree(s4882_algo);
 232         s4882_algo = NULL;
 233
 234         /* Restore physical bus */
 235         if (i2c_add_adapter(&amd756_smbus))
 236                 printk(KERN_ERR "i2c-amd756-s4882: "
 237                        "Physical bus restoration failed\n");
 238 }
 239
 240 MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
 241 MODULE_DESCRIPTION("S4882 SMBus multiplexing");
 242 MODULE_LICENSE("GPL");
 243
 244 module_init(amd756_s4882_init);
 245 module_exit(amd756_s4882_exit);