1 files changed, 264 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-amd756-s4882.c b/drivers/i2c/busses/i2c-amd756-s4882.c
new file mode 100644
index 000000000000..4e553e8c5cba
--- /dev/null
+++ b/drivers/i2c/busses/i2c-amd756-s4882.c
@@ -0,0 +1,264 @@
+/*
+ * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
+ *
+ * Copyright (C) 2004 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, and 0x4c (LM63)
+ * located on multiplexed channels 0 and 5-7. We define one
+ * virtual adapter per CPU, which corresponds to two multiplexed
+ * channels:
+ *   CPU0: virtual adapter 1, channels 1 and 0
+ *   CPU1: virtual adapter 2, channels 2 and 5
+ *   CPU2: virtual adapter 3, channels 3 and 6
+ *   CPU3: virtual adapter 4, channels 4 and 7
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/init.h>
+#include <linux/i2c.h>
+
+extern struct i2c_adapter amd756_smbus;
+
+static struct i2c_adapter *s4882_adapter;
+static struct i2c_algorithm *s4882_algo;
+
+/* Wrapper access functions for multiplexed SMBus */
+static struct semaphore amd756_lock;
+
+static s32 amd756_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 == 0x4c || (addr & 0xfc) == 0x50 || (addr & 0xfc) == 0x30
+         || addr == 0x18)
+                return -1;
+
+        down(&amd756_lock);
+
+        error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
+                                              command, size, data);
+
+        up(&amd756_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 amd756_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 != 0x4c && (addr & 0xfc) != 0x50 && (addr & 0xfc) != 0x30)
+                return -1;
+
+        down(&amd756_lock);
+
+        if (last_channels != channels) {
+                union i2c_smbus_data mplxdata;
+                mplxdata.byte = channels;
+
+                error = amd756_smbus.algo->smbus_xfer(adap, 0x18, 0,
+                                                      I2C_SMBUS_WRITE, 0x01,
+                                                      I2C_SMBUS_BYTE_DATA,
+                                                      &mplxdata);
+                if (error)
+                        goto UNLOCK;
+                last_channels = channels;
+        }
+        error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
+                                              command, size, data);
+
+UNLOCK:
+        up(&amd756_lock);
+        return error;
+}
+
+static s32 amd756_access_virt1(struct i2c_adapter * adap, u16 addr,
+                               unsigned short flags, char read_write,
+                               u8 command, int size,
+                               union i2c_smbus_data * data)
+{
+        /* CPU0: channels 1 and 0 enabled */
+        return amd756_access_channel(adap, addr, flags, read_write, command,
+                                     size, data, 0x03);
+}
+
+static s32 amd756_access_virt2(struct i2c_adapter * adap, u16 addr,
+                               unsigned short flags, char read_write,
+                               u8 command, int size,
+                               union i2c_smbus_data * data)
+{
+        /* CPU1: channels 2 and 5 enabled */
+        return amd756_access_channel(adap, addr, flags, read_write, command,
+                                     size, data, 0x24);
+}
+
+static s32 amd756_access_virt3(struct i2c_adapter * adap, u16 addr,
+                               unsigned short flags, char read_write,
+                               u8 command, int size,
+                               union i2c_smbus_data * data)
+{
+        /* CPU2: channels 3 and 6 enabled */
+        return amd756_access_channel(adap, addr, flags, read_write, command,
+                                     size, data, 0x48);
+}
+
+static s32 amd756_access_virt4(struct i2c_adapter * adap, u16 addr,
+                               unsigned short flags, char read_write,
+                               u8 command, int size,
+                               union i2c_smbus_data * data)
+{
+        /* CPU3: channels 4 and 7 enabled */
+        return amd756_access_channel(adap, addr, flags, read_write, command,
+                                     size, data, 0x90);
+}
+
+static int __init amd756_s4882_init(void)
+{
+        int i, error;
+        union i2c_smbus_data ioconfig;
+
+        /* Unregister physical bus */
+        error = i2c_del_adapter(&amd756_smbus);
+        if (error) {
+                if (error == -EINVAL)
+                        error = -ENODEV;
+                else
+                        dev_err(&amd756_smbus.dev, "Physical bus removal "
+                                "failed\n");
+                goto ERROR0;
+        }
+
+        printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
+        init_MUTEX(&amd756_lock);
+
+        /* Define the 5 virtual adapters and algorithms structures */
+        if (!(s4882_adapter = kmalloc(5 * sizeof(struct i2c_adapter),
+                                      GFP_KERNEL))) {
+                error = -ENOMEM;
+                goto ERROR1;
+        }
+        if (!(s4882_algo = kmalloc(5 * sizeof(struct i2c_algorithm),
+                                   GFP_KERNEL))) {
+                error = -ENOMEM;
+                goto ERROR2;
+        }
+
+        /* Fill in the new structures */
+        s4882_algo[0] = *(amd756_smbus.algo);
+        s4882_algo[0].smbus_xfer = amd756_access_virt0;
+        s4882_adapter[0] = amd756_smbus;
+        s4882_adapter[0].algo = s4882_algo;
+        for (i = 1; i < 5; i++) {
+                s4882_algo[i] = *(amd756_smbus.algo);
+                s4882_adapter[i] = amd756_smbus;
+                sprintf(s4882_adapter[i].name,
+                        "SMBus 8111 adapter (CPU%d)", i-1);
+                s4882_adapter[i].algo = s4882_algo+i;
+        }
+        s4882_algo[1].smbus_xfer = amd756_access_virt1;
+        s4882_algo[2].smbus_xfer = amd756_access_virt2;
+        s4882_algo[3].smbus_xfer = amd756_access_virt3;
+        s4882_algo[4].smbus_xfer = amd756_access_virt4;
+
+        /* Configure the PCA9556 multiplexer */
+        ioconfig.byte = 0x00; /* All I/O to output mode */
+        error = amd756_smbus.algo->smbus_xfer(&amd756_smbus, 0x18, 0,
+                                              I2C_SMBUS_WRITE, 0x03,
+                                              I2C_SMBUS_BYTE_DATA, &ioconfig);
+        if (error) {
+                dev_err(&amd756_smbus.dev, "PCA9556 configuration failed\n");
+                error = -EIO;
+                goto ERROR3;
+        }
+
+        /* Register virtual adapters */
+        for (i = 0; i < 5; i++) {
+                error = i2c_add_adapter(s4882_adapter+i);
+                if (error) {
+                        dev_err(&amd756_smbus.dev,
+                               "Virtual adapter %d registration "
+                               "failed, module not inserted\n", i);
+                        for (i--; i >= 0; i--)
+                                i2c_del_adapter(s4882_adapter+i);
+                        goto ERROR3;
+                }
+        }
+
+        return 0;
+
+ERROR3:
+        kfree(s4882_algo);
+        s4882_algo = NULL;
+ERROR2:
+        kfree(s4882_adapter);
+        s4882_adapter = NULL;
+ERROR1:
+        i2c_del_adapter(&amd756_smbus);
+ERROR0:
+        return error;
+}
+
+static void __exit amd756_s4882_exit(void)
+{
+        if (s4882_adapter) {
+                int i;
+
+                for (i = 0; i < 5; i++)
+                        i2c_del_adapter(s4882_adapter+i);
+                kfree(s4882_adapter);
+                s4882_adapter = NULL;
+        }
+        if (s4882_algo) {
+                kfree(s4882_algo);
+                s4882_algo = NULL;
+        }
+
+        /* Restore physical bus */
+        if (i2c_add_adapter(&amd756_smbus))
+                dev_err(&amd756_smbus.dev, "Physical bus restoration "
+                        "failed\n");
+}
+
+MODULE_AUTHOR("Jean Delvare <khali@linux-fr.org>");
+MODULE_DESCRIPTION("S4882 SMBus multiplexing");
+MODULE_LICENSE("GPL");
+
+module_init(amd756_s4882_init);
+module_exit(amd756_s4882_exit);