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i2c: stub: Add support for banked register ranges

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Some chips implement banked register ranges. This allows implementing
more registers than the limited 8-bit address space originally allows.
In order to access a register on these chips, you must first select
the proper bank. Add support for this mechanism to the i2c-stub driver
so that such chips can be emulated. All the bank settings are passed
as module parameters.

Signed-off-by: Jean Delvare <[email protected]>
Tested-by: Guenter Roeck <[email protected]>
Signed-off-by: Wolfram Sang <[email protected]>
This commit is contained in:
Jean Delvare 2014-07-10 12:56:59 +02:00 • committed by Wolfram Sang
commit 2408c17fce
2 changed files with 128 additions and 14 deletions
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131
drivers/i2c/i2c-stub.c
View file

@ -2,7 +2,7 @@
i2c-stub.c - I2C/SMBus chip emulator
Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com>
Copyright (C) 2007, 2012 Jean Delvare <jdelvare@suse.de>
Copyright (C) 2007-2014 Jean Delvare <jdelvare@suse.de>
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
@ -53,6 +53,24 @@ static unsigned long functionality = STUB_FUNC_DEFAULT;
module_param(functionality, ulong, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(functionality, "Override functionality bitfield");
/* Some chips have banked register ranges */
static u8 bank_reg[MAX_CHIPS];
module_param_array(bank_reg, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_reg, "Bank register");
static u8 bank_mask[MAX_CHIPS];
module_param_array(bank_mask, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_mask, "Bank value mask");
static u8 bank_start[MAX_CHIPS];
module_param_array(bank_start, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_start, "First banked register");
static u8 bank_end[MAX_CHIPS];
module_param_array(bank_end, byte, NULL, S_IRUGO);
MODULE_PARM_DESC(bank_end, "Last banked register");
struct smbus_block_data {
struct list_head node;
u8 command;
@ -65,6 +83,16 @@ struct stub_chip {
u16 words[256]; /* Byte operations use the LSB as per SMBus
specification */
struct list_head smbus_blocks;
/* For chips with banks, extra registers are allocated dynamically */
u8 bank_reg;
u8 bank_shift;
u8 bank_mask;
u8 bank_sel; /* Currently selected bank */
u8 bank_start;
u8 bank_end;
u16 bank_size;
u16 *bank_words; /* Room for bank_mask * bank_size registers */
};
static struct stub_chip *stub_chips;
@ -92,6 +120,17 @@ static struct smbus_block_data *stub_find_block(struct device *dev,
return rb;
}
static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset)
{
if (chip->bank_sel &&
offset >= chip->bank_start && offset <= chip->bank_end)
return chip->bank_words +
(chip->bank_sel - 1) * chip->bank_size +
offset - chip->bank_start;
else
return chip->words + offset;
}
/* Return negative errno on error. */
static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
char read_write, u8 command, int size, union i2c_smbus_data *data)
@ -100,6 +139,7 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
int i, len;
struct stub_chip *chip = NULL;
struct smbus_block_data *b;
u16 *wordp;
/* Search for the right chip */
for (i = 0; i < stub_chips_nr; i++) {
@ -125,7 +165,8 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
"smbus byte - addr 0x%02x, wrote 0x%02x.\n",
addr, command);
} else {
data->byte = chip->words[chip->pointer++] & 0xff;
wordp = stub_get_wordp(chip, chip->pointer++);
data->byte = *wordp & 0xff;
dev_dbg(&adap->dev,
"smbus byte - addr 0x%02x, read 0x%02x.\n",
addr, data->byte);
@ -135,14 +176,25 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
break;
case I2C_SMBUS_BYTE_DATA:
wordp = stub_get_wordp(chip, command);
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] &= 0xff00;
chip->words[command] |= data->byte;
*wordp &= 0xff00;
*wordp |= data->byte;
dev_dbg(&adap->dev,
"smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n",
addr, data->byte, command);
/* Set the bank as needed */
if (chip->bank_words && command == chip->bank_reg) {
chip->bank_sel =
(data->byte >> chip->bank_shift)
& chip->bank_mask;
dev_dbg(&adap->dev,
"switching to bank %u.\n",
chip->bank_sel);
}
} else {
data->byte = chip->words[command] & 0xff;
data->byte = *wordp & 0xff;
dev_dbg(&adap->dev,
"smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n",
addr, data->byte, command);
@ -153,13 +205,14 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
break;
case I2C_SMBUS_WORD_DATA:
wordp = stub_get_wordp(chip, command);
if (read_write == I2C_SMBUS_WRITE) {
chip->words[command] = data->word;
*wordp = data->word;
dev_dbg(&adap->dev,
"smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n",
addr, data->word, command);
} else {
data->word = chip->words[command];
data->word = *wordp;
dev_dbg(&adap->dev,
"smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n",
addr, data->word, command);
@ -169,6 +222,10 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
break;
case I2C_SMBUS_I2C_BLOCK_DATA:
/*
* We ignore banks here, because banked chips don't use I2C
* block transfers
*/
len = data->block[0];
if (read_write == I2C_SMBUS_WRITE) {
for (i = 0; i < len; i++) {
@ -192,6 +249,10 @@ static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags,
break;
case I2C_SMBUS_BLOCK_DATA:
/*
* We ignore banks here, because chips typically don't use both
* banks and SMBus block transfers
*/
b = stub_find_block(&adap->dev, chip, command, false);
if (read_write == I2C_SMBUS_WRITE) {
len = data->block[0];
@ -262,6 +323,43 @@ static struct i2c_adapter stub_adapter = {
.name = "SMBus stub driver",
};
static int __init i2c_stub_allocate_banks(int i)
{
struct stub_chip *chip = stub_chips + i;
chip->bank_reg = bank_reg[i];
chip->bank_start = bank_start[i];
chip->bank_end = bank_end[i];
chip->bank_size = bank_end[i] - bank_start[i] + 1;
/* We assume that all bits in the mask are contiguous */
chip->bank_mask = bank_mask[i];
while (!(chip->bank_mask & 1)) {
chip->bank_shift++;
chip->bank_mask >>= 1;
}
chip->bank_words = kzalloc(chip->bank_mask * chip->bank_size *
sizeof(u16), GFP_KERNEL);
if (!chip->bank_words)
return -ENOMEM;
pr_debug("i2c-stub: Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n",
chip->bank_mask, chip->bank_size, chip->bank_start,
chip->bank_end);
return 0;
}
static void i2c_stub_free(void)
{
int i;
for (i = 0; i < stub_chips_nr; i++)
kfree(stub_chips[i].bank_words);
kfree(stub_chips);
}
static int __init i2c_stub_init(void)
{
int i, ret;
@ -289,19 +387,32 @@ static int __init i2c_stub_init(void)
pr_err("i2c-stub: Out of memory\n");
return -ENOMEM;
}
for (i = 0; i < stub_chips_nr; i++)
for (i = 0; i < stub_chips_nr; i++) {
INIT_LIST_HEAD(&stub_chips[i].smbus_blocks);
/* Allocate extra memory for banked register ranges */
if (bank_mask[i]) {
ret = i2c_stub_allocate_banks(i);
if (ret)
goto fail_free;
}
}
ret = i2c_add_adapter(&stub_adapter);
if (ret)
kfree(stub_chips);
goto fail_free;
return 0;
fail_free:
i2c_stub_free();
return ret;
}
static void __exit i2c_stub_exit(void)
{
i2c_del_adapter(&stub_adapter);
kfree(stub_chips);
i2c_stub_free();
}
MODULE_AUTHOR("Mark M. Hoffman <[email protected]>");