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Diffstat (limited to 'drivers/i2c/busses/i2c-amd756-s4882.c')
-rw-r--r--drivers/i2c/busses/i2c-amd756-s4882.c245
1 files changed, 245 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 0000000000..063274388a
--- /dev/null
+++ b/drivers/i2c/busses/i2c-amd756-s4882.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * i2c-amd756-s4882.c - i2c-amd756 extras for the Tyan S4882 motherboard
+ *
+ * Copyright (C) 2004, 2008 Jean Delvare <jdelvare@suse.de>
+ */
+
+/*
+ * 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>
+#include <linux/mutex.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 DEFINE_MUTEX(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 -ENXIO;
+
+ mutex_lock(&amd756_lock);
+
+ error = amd756_smbus.algo->smbus_xfer(adap, addr, flags, read_write,
+ command, size, data);
+
+ mutex_unlock(&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 -ENXIO;
+
+ mutex_lock(&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:
+ mutex_unlock(&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;
+
+ if (!amd756_smbus.dev.parent)
+ return -ENODEV;
+
+ /* Configure the PCA9556 multiplexer */
+ ioconfig.byte = 0x00; /* All I/O to output mode */
+ error = i2c_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 ERROR0;
+ }
+
+ /* Unregister physical bus */
+ i2c_del_adapter(&amd756_smbus);
+
+ printk(KERN_INFO "Enabling SMBus multiplexing for Tyan S4882\n");
+ /* Define the 5 virtual adapters and algorithms structures */
+ if (!(s4882_adapter = kcalloc(5, sizeof(struct i2c_adapter),
+ GFP_KERNEL))) {
+ error = -ENOMEM;
+ goto ERROR1;
+ }
+ if (!(s4882_algo = kcalloc(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;
+ s4882_adapter[0].dev.parent = amd756_smbus.dev.parent;
+ for (i = 1; i < 5; i++) {
+ s4882_algo[i] = *(amd756_smbus.algo);
+ s4882_adapter[i] = amd756_smbus;
+ snprintf(s4882_adapter[i].name, sizeof(s4882_adapter[i].name),
+ "SMBus 8111 adapter (CPU%d)", i-1);
+ s4882_adapter[i].algo = s4882_algo+i;
+ s4882_adapter[i].dev.parent = amd756_smbus.dev.parent;
+ }
+ 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;
+
+ /* Register virtual adapters */
+ for (i = 0; i < 5; i++) {
+ error = i2c_add_adapter(s4882_adapter+i);
+ if (error) {
+ printk(KERN_ERR "i2c-amd756-s4882: "
+ "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:
+ /* Restore physical bus */
+ i2c_add_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;
+ }
+ kfree(s4882_algo);
+ s4882_algo = NULL;
+
+ /* Restore physical bus */
+ if (i2c_add_adapter(&amd756_smbus))
+ printk(KERN_ERR "i2c-amd756-s4882: "
+ "Physical bus restoration failed\n");
+}
+
+MODULE_AUTHOR("Jean Delvare <jdelvare@suse.de>");
+MODULE_DESCRIPTION("S4882 SMBus multiplexing");
+MODULE_LICENSE("GPL");
+
+module_init(amd756_s4882_init);
+module_exit(amd756_s4882_exit);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-12 05:29:11 +0000