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i2c-nforce2: Add support for multiplexing on the Tyan S4985
Just like the Tyan S4882, the S4985 uses a multiplexer to give access to all 16 memory module SPD EEPROMs. This specific i2c-nforce2-s4985 driver adds support for this. It is heavily based on the older i2c-amd756-s4882 driver. As more mainboards will use multiplexer chips, we will have to find a way to support them without having to write a new specfic driver for each. The recent changes to the i2c subsystem should help us, and the new gpio subsystem might help, too. Signed-off-by: Jean Delvare <khali@linux-fr.org>
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,257 @@ | ||
| /* | ||
| * i2c-nforce2-s4985.c - i2c-nforce2 extras for the Tyan S4985 motherboard | ||
| * | ||
| * Copyright (C) 2008 Jean Delvare <khali@linux-fr.org> | ||
| * | ||
| * This program is free software; you can redistribute it and/or modify | ||
| * it under the terms of the GNU General Public License as published by | ||
| * the Free Software Foundation; either version 2 of the License, or | ||
| * (at your option) any later version. | ||
| * | ||
| * This program is distributed in the hope that it will be useful, | ||
| * but WITHOUT ANY WARRANTY; without even the implied warranty of | ||
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | ||
| * GNU General Public License for more details. | ||
| * | ||
| * You should have received a copy of the GNU General Public License | ||
| * along with this program; if not, write to the Free Software | ||
| * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. | ||
| */ | ||
|
|
||
| /* | ||
| * We select the channels by sending commands to the Philips | ||
| * PCA9556 chip at I2C address 0x18. The main adapter is used for | ||
| * the non-multiplexed part of the bus, and 4 virtual adapters | ||
| * are defined for the multiplexed addresses: 0x50-0x53 (memory | ||
| * module EEPROM) located on channels 1-4. We define one virtual | ||
| * adapter per CPU, which corresponds to one multiplexed channel: | ||
| * CPU0: virtual adapter 1, channel 1 | ||
| * CPU1: virtual adapter 2, channel 2 | ||
| * CPU2: virtual adapter 3, channel 3 | ||
| * CPU3: virtual adapter 4, channel 4 | ||
| */ | ||
|
|
||
| #include <linux/module.h> | ||
| #include <linux/kernel.h> | ||
| #include <linux/slab.h> | ||
| #include <linux/init.h> | ||
| #include <linux/i2c.h> | ||
| #include <linux/mutex.h> | ||
|
|
||
| extern struct i2c_adapter *nforce2_smbus; | ||
|
|
||
| static struct i2c_adapter *s4985_adapter; | ||
| static struct i2c_algorithm *s4985_algo; | ||
|
|
||
| /* Wrapper access functions for multiplexed SMBus */ | ||
| static DEFINE_MUTEX(nforce2_lock); | ||
|
|
||
| static s32 nforce2_access_virt0(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data) | ||
| { | ||
| int error; | ||
|
|
||
| /* We exclude the multiplexed addresses */ | ||
| if ((addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30 | ||
| || addr == 0x18) | ||
| return -ENXIO; | ||
|
|
||
| mutex_lock(&nforce2_lock); | ||
| error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, | ||
| command, size, data); | ||
| mutex_unlock(&nforce2_lock); | ||
|
|
||
| return error; | ||
| } | ||
|
|
||
| /* We remember the last used channels combination so as to only switch | ||
| channels when it is really needed. This greatly reduces the SMBus | ||
| overhead, but also assumes that nobody will be writing to the PCA9556 | ||
| in our back. */ | ||
| static u8 last_channels; | ||
|
|
||
| static inline s32 nforce2_access_channel(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data, | ||
| u8 channels) | ||
| { | ||
| int error; | ||
|
|
||
| /* We exclude the non-multiplexed addresses */ | ||
| if ((addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30) | ||
| return -ENXIO; | ||
|
|
||
| mutex_lock(&nforce2_lock); | ||
| if (last_channels != channels) { | ||
| union i2c_smbus_data mplxdata; | ||
| mplxdata.byte = channels; | ||
|
|
||
| error = nforce2_smbus->algo->smbus_xfer(adap, 0x18, 0, | ||
| I2C_SMBUS_WRITE, 0x01, | ||
| I2C_SMBUS_BYTE_DATA, | ||
| &mplxdata); | ||
| if (error) | ||
| goto UNLOCK; | ||
| last_channels = channels; | ||
| } | ||
| error = nforce2_smbus->algo->smbus_xfer(adap, addr, flags, read_write, | ||
| command, size, data); | ||
|
|
||
| UNLOCK: | ||
| mutex_unlock(&nforce2_lock); | ||
| return error; | ||
| } | ||
|
|
||
| static s32 nforce2_access_virt1(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data) | ||
| { | ||
| /* CPU0: channel 1 enabled */ | ||
| return nforce2_access_channel(adap, addr, flags, read_write, command, | ||
| size, data, 0x02); | ||
| } | ||
|
|
||
| static s32 nforce2_access_virt2(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data) | ||
| { | ||
| /* CPU1: channel 2 enabled */ | ||
| return nforce2_access_channel(adap, addr, flags, read_write, command, | ||
| size, data, 0x04); | ||
| } | ||
|
|
||
| static s32 nforce2_access_virt3(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data) | ||
| { | ||
| /* CPU2: channel 3 enabled */ | ||
| return nforce2_access_channel(adap, addr, flags, read_write, command, | ||
| size, data, 0x08); | ||
| } | ||
|
|
||
| static s32 nforce2_access_virt4(struct i2c_adapter *adap, u16 addr, | ||
| unsigned short flags, char read_write, | ||
| u8 command, int size, | ||
| union i2c_smbus_data *data) | ||
| { | ||
| /* CPU3: channel 4 enabled */ | ||
| return nforce2_access_channel(adap, addr, flags, read_write, command, | ||
| size, data, 0x10); | ||
| } | ||
|
|
||
| static int __init nforce2_s4985_init(void) | ||
| { | ||
| int i, error; | ||
| union i2c_smbus_data ioconfig; | ||
|
|
||
| /* Unregister physical bus */ | ||
| if (!nforce2_smbus) | ||
| return -ENODEV; | ||
| error = i2c_del_adapter(nforce2_smbus); | ||
| if (error) { | ||
| dev_err(&nforce2_smbus->dev, "Physical bus removal failed\n"); | ||
| goto ERROR0; | ||
| } | ||
|
|
||
| printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4985\n"); | ||
| /* Define the 5 virtual adapters and algorithms structures */ | ||
| s4985_adapter = kzalloc(5 * sizeof(struct i2c_adapter), GFP_KERNEL); | ||
| if (!s4985_adapter) { | ||
| error = -ENOMEM; | ||
| goto ERROR1; | ||
| } | ||
| s4985_algo = kzalloc(5 * sizeof(struct i2c_algorithm), GFP_KERNEL); | ||
| if (!s4985_algo) { | ||
| error = -ENOMEM; | ||
| goto ERROR2; | ||
| } | ||
|
|
||
| /* Fill in the new structures */ | ||
| s4985_algo[0] = *(nforce2_smbus->algo); | ||
| s4985_algo[0].smbus_xfer = nforce2_access_virt0; | ||
| s4985_adapter[0] = *nforce2_smbus; | ||
| s4985_adapter[0].algo = s4985_algo; | ||
| s4985_adapter[0].dev.parent = nforce2_smbus->dev.parent; | ||
| for (i = 1; i < 5; i++) { | ||
| s4985_algo[i] = *(nforce2_smbus->algo); | ||
| s4985_adapter[i] = *nforce2_smbus; | ||
| snprintf(s4985_adapter[i].name, sizeof(s4985_adapter[i].name), | ||
| "SMBus nForce2 adapter (CPU%d)", i - 1); | ||
| s4985_adapter[i].algo = s4985_algo + i; | ||
| s4985_adapter[i].dev.parent = nforce2_smbus->dev.parent; | ||
| } | ||
| s4985_algo[1].smbus_xfer = nforce2_access_virt1; | ||
| s4985_algo[2].smbus_xfer = nforce2_access_virt2; | ||
| s4985_algo[3].smbus_xfer = nforce2_access_virt3; | ||
| s4985_algo[4].smbus_xfer = nforce2_access_virt4; | ||
|
|
||
| /* Configure the PCA9556 multiplexer */ | ||
| ioconfig.byte = 0x00; /* All I/O to output mode */ | ||
| error = nforce2_smbus->algo->smbus_xfer(nforce2_smbus, 0x18, 0, | ||
| I2C_SMBUS_WRITE, 0x03, | ||
| I2C_SMBUS_BYTE_DATA, &ioconfig); | ||
| if (error) { | ||
| dev_err(&nforce2_smbus->dev, "PCA9556 configuration failed\n"); | ||
| error = -EIO; | ||
| goto ERROR3; | ||
| } | ||
|
|
||
| /* Register virtual adapters */ | ||
| for (i = 0; i < 5; i++) { | ||
| error = i2c_add_adapter(s4985_adapter + i); | ||
| if (error) { | ||
| dev_err(&nforce2_smbus->dev, | ||
| "Virtual adapter %d registration " | ||
| "failed, module not inserted\n", i); | ||
| for (i--; i >= 0; i--) | ||
| i2c_del_adapter(s4985_adapter + i); | ||
| goto ERROR3; | ||
| } | ||
| } | ||
|
|
||
| return 0; | ||
|
|
||
| ERROR3: | ||
| kfree(s4985_algo); | ||
| s4985_algo = NULL; | ||
| ERROR2: | ||
| kfree(s4985_adapter); | ||
| s4985_adapter = NULL; | ||
| ERROR1: | ||
| /* Restore physical bus */ | ||
| i2c_add_adapter(nforce2_smbus); | ||
| ERROR0: | ||
| return error; | ||
| } | ||
|
|
||
| static void __exit nforce2_s4985_exit(void) | ||
| { | ||
| if (s4985_adapter) { | ||
| int i; | ||
|
|
||
| for (i = 0; i < 5; i++) | ||
| i2c_del_adapter(s4985_adapter+i); | ||
| kfree(s4985_adapter); | ||
| s4985_adapter = NULL; | ||
| } | ||
| kfree(s4985_algo); | ||
| s4985_algo = NULL; | ||
|
|
||
| /* Restore physical bus */ | ||
| if (i2c_add_adapter(nforce2_smbus)) | ||
| dev_err(&nforce2_smbus->dev, "Physical bus restoration " | ||
| "failed\n"); | ||
| } | ||
|
|
||
| MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>"); | ||
| MODULE_DESCRIPTION("S4985 SMBus multiplexing"); | ||
| MODULE_LICENSE("GPL"); | ||
|
|
||
| module_init(nforce2_s4985_init); | ||
| module_exit(nforce2_s4985_exit); |
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