241 lines · c
1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard4 *5 * Copyright (C) 2008 Jean Delvare <jdelvare@suse.de>6 */7 8/*9 * We select the channels by sending commands to the Philips10 * PCA9556 chip at I2C address 0x18. The main adapter is used for11 * the non-multiplexed part of the bus, and 4 virtual adapters12 * are defined for the multiplexed addresses: 0x50-0x53 (memory13 * module EEPROM) located on channels 1-4. We define one virtual14 * adapter per CPU, which corresponds to one multiplexed channel:15 * CPU0: virtual adapter 1, channel 116 * CPU1: virtual adapter 2, channel 217 * CPU2: virtual adapter 3, channel 318 * CPU3: virtual adapter 4, channel 419 */20 21#include <linux/module.h>22#include <linux/kernel.h>23#include <linux/slab.h>24#include <linux/init.h>25#include <linux/i2c.h>26#include <linux/mutex.h>27 28extern struct i2c_adapter *nforce2_smbus;29 30static struct i2c_adapter *s4985_adapter;31static struct i2c_algorithm *s4985_algo;32 33/* Wrapper access functions for multiplexed SMBus */34static DEFINE_MUTEX(nforce2_lock);35 36static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr,37 unsigned short flags, char read_write,38 u8 command, int size,39 union i2c_smbus_data *data)40{41 int error;42 43 /* We exclude the multiplexed addresses */44 if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x3045 || addr == 0x18)46 return -ENXIO;47 48 mutex_lock(&nforce2_lock);49 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,50 command, size, data);51 mutex_unlock(&nforce2_lock);52 53 return error;54}55 56/* We remember the last used channels combination so as to only switch57 channels when it is really needed. This greatly reduces the SMBus58 overhead, but also assumes that nobody will be writing to the PCA955659 in our back. */60static u8 last_channels;61 62static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr,63 unsigned short flags, char read_write,64 u8 command, int size,65 union i2c_smbus_data *data,66 u8 channels)67{68 int error;69 70 /* We exclude the non-multiplexed addresses */71 if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)72 return -ENXIO;73 74 mutex_lock(&nforce2_lock);75 if (last_channels != channels) {76 union i2c_smbus_data mplxdata;77 mplxdata.byte = channels;78 79 error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0,80 I2C_SMBUS_WRITE, 0x01,81 I2C_SMBUS_BYTE_DATA,82 &mplxdata);83 if (error)84 goto UNLOCK;85 last_channels = channels;86 }87 error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write,88 command, size, data);89 90UNLOCK:91 mutex_unlock(&nforce2_lock);92 return error;93}94 95static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr,96 unsigned short flags, char read_write,97 u8 command, int size,98 union i2c_smbus_data *data)99{100 /* CPU0: channel 1 enabled */101 return nforce2_access_channel(adap, addr, flags, read_write, command,102 size, data, 0x02);103}104 105static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr,106 unsigned short flags, char read_write,107 u8 command, int size,108 union i2c_smbus_data *data)109{110 /* CPU1: channel 2 enabled */111 return nforce2_access_channel(adap, addr, flags, read_write, command,112 size, data, 0x04);113}114 115static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr,116 unsigned short flags, char read_write,117 u8 command, int size,118 union i2c_smbus_data *data)119{120 /* CPU2: channel 3 enabled */121 return nforce2_access_channel(adap, addr, flags, read_write, command,122 size, data, 0x08);123}124 125static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr,126 unsigned short flags, char read_write,127 u8 command, int size,128 union i2c_smbus_data *data)129{130 /* CPU3: channel 4 enabled */131 return nforce2_access_channel(adap, addr, flags, read_write, command,132 size, data, 0x10);133}134 135static int __init nforce2_s4985_init(void)136{137 int i, error;138 union i2c_smbus_data ioconfig;139 140 if (!nforce2_smbus)141 return -ENODEV;142 143 /* Configure the PCA9556 multiplexer */144 ioconfig.byte = 0x00; /* All I/O to output mode */145 error = i2c_smbus_xfer(nforce2_smbus, 0x18, 0, I2C_SMBUS_WRITE, 0x03,146 I2C_SMBUS_BYTE_DATA, &ioconfig);147 if (error) {148 dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n");149 error = -EIO;150 goto ERROR0;151 }152 153 /* Unregister physical bus */154 i2c_del_adapter(nforce2_smbus);155 156 printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n");157 /* Define the 5 virtual adapters and algorithms structures */158 s4985_adapter = kcalloc(5, sizeof(struct i2c_adapter), GFP_KERNEL);159 if (!s4985_adapter) {160 error = -ENOMEM;161 goto ERROR1;162 }163 s4985_algo = kcalloc(5, sizeof(struct i2c_algorithm), GFP_KERNEL);164 if (!s4985_algo) {165 error = -ENOMEM;166 goto ERROR2;167 }168 169 /* Fill in the new structures */170 s4985_algo[0] = *(nforce2_smbus->algo);171 s4985_algo[0].smbus_xfer = nforce2_access_virt0;172 s4985_adapter[0] = *nforce2_smbus;173 s4985_adapter[0].algo = s4985_algo;174 s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent;175 for (i = 1; i < 5; i++) {176 s4985_algo[i] = *(nforce2_smbus->algo);177 s4985_adapter[i] = *nforce2_smbus;178 snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name),179 "SMBus nForce2 adapter (CPU%d)", i - 1);180 s4985_adapter[i].algo = s4985_algo + i;181 s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent;182 }183 s4985_algo[1].smbus_xfer = nforce2_access_virt1;184 s4985_algo[2].smbus_xfer = nforce2_access_virt2;185 s4985_algo[3].smbus_xfer = nforce2_access_virt3;186 s4985_algo[4].smbus_xfer = nforce2_access_virt4;187 188 /* Register virtual adapters */189 for (i = 0; i < 5; i++) {190 error = i2c_add_adapter(s4985_adapter + i);191 if (error) {192 printk(KERN_ERR "i2c-nforce2-s4985: "193 "Virtual adapter %d registration "194 "failed, module not inserted\n", i);195 for (i--; i >= 0; i--)196 i2c_del_adapter(s4985_adapter + i);197 goto ERROR3;198 }199 }200 201 return 0;202 203ERROR3:204 kfree(s4985_algo);205 s4985_algo = NULL;206ERROR2:207 kfree(s4985_adapter);208 s4985_adapter = NULL;209ERROR1:210 /* Restore physical bus */211 i2c_add_adapter(nforce2_smbus);212ERROR0:213 return error;214}215 216static void __exit nforce2_s4985_exit(void)217{218 if (s4985_adapter) {219 int i;220 221 for (i = 0; i < 5; i++)222 i2c_del_adapter(s4985_adapter+i);223 kfree(s4985_adapter);224 s4985_adapter = NULL;225 }226 kfree(s4985_algo);227 s4985_algo = NULL;228 229 /* Restore physical bus */230 if (i2c_add_adapter(nforce2_smbus))231 printk(KERN_ERR "i2c-nforce2-s4985: "232 "Physical bus restoration failed\n");233}234 235MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");236MODULE_DESCRIPTION("S4985 SMBus multiplexing");237MODULE_LICENSE("GPL");238 239module_init(nforce2_s4985_init);240module_exit(nforce2_s4985_exit);241