diff options
Diffstat (limited to 'drivers/i2c/i2c-stub.c')
| -rw-r--r-- | drivers/i2c/i2c-stub.c | 422 |
1 files changed, 422 insertions, 0 deletions
diff --git a/drivers/i2c/i2c-stub.c b/drivers/i2c/i2c-stub.c new file mode 100644 index 000000000..f31ec0861 --- /dev/null +++ b/drivers/i2c/i2c-stub.c @@ -0,0 +1,422 @@ +/* + i2c-stub.c - I2C/SMBus chip emulator + + Copyright (c) 2004 Mark M. Hoffman <mhoffman@lightlink.com> + 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 + 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. +*/ + +#define DEBUG 1 +#define pr_fmt(fmt) "i2c-stub: " fmt + +#include <linux/errno.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/kernel.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/slab.h> + +#define MAX_CHIPS 10 + +/* + * Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must + * be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits + * in the 'functionality' module parameter. + */ +#define STUB_FUNC_DEFAULT \ + (I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ + I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ + I2C_FUNC_SMBUS_I2C_BLOCK) + +#define STUB_FUNC_ALL \ + (STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) + +static unsigned short chip_addr[MAX_CHIPS]; +module_param_array(chip_addr, ushort, NULL, S_IRUGO); +MODULE_PARM_DESC(chip_addr, + "Chip addresses (up to 10, between 0x03 and 0x77)"); + +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; + u8 len; + u8 block[I2C_SMBUS_BLOCK_MAX]; +}; + +struct stub_chip { + u8 pointer; + 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; +static int stub_chips_nr; + +static struct smbus_block_data *stub_find_block(struct device *dev, + struct stub_chip *chip, + u8 command, bool create) +{ + struct smbus_block_data *b, *rb = NULL; + + list_for_each_entry(b, &chip->smbus_blocks, node) { + if (b->command == command) { + rb = b; + break; + } + } + if (rb == NULL && create) { + rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); + if (rb == NULL) + return rb; + rb->command = command; + list_add(&rb->node, &chip->smbus_blocks); + } + 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) +{ + s32 ret; + 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++) { + if (addr == chip_addr[i]) { + chip = stub_chips + i; + break; + } + } + if (!chip) + return -ENODEV; + + switch (size) { + + case I2C_SMBUS_QUICK: + dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); + ret = 0; + break; + + case I2C_SMBUS_BYTE: + if (read_write == I2C_SMBUS_WRITE) { + chip->pointer = command; + dev_dbg(&adap->dev, + "smbus byte - addr 0x%02x, wrote 0x%02x.\n", + addr, command); + } else { + 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); + } + + ret = 0; + break; + + case I2C_SMBUS_BYTE_DATA: + wordp = stub_get_wordp(chip, command); + if (read_write == I2C_SMBUS_WRITE) { + *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 = *wordp & 0xff; + dev_dbg(&adap->dev, + "smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", + addr, data->byte, command); + } + chip->pointer = command + 1; + + ret = 0; + break; + + case I2C_SMBUS_WORD_DATA: + wordp = stub_get_wordp(chip, command); + if (read_write == I2C_SMBUS_WRITE) { + *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 = *wordp; + dev_dbg(&adap->dev, + "smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", + addr, data->word, command); + } + + ret = 0; + break; + + case I2C_SMBUS_I2C_BLOCK_DATA: + /* + * We ignore banks here, because banked chips don't use I2C + * block transfers + */ + if (data->block[0] > 256 - command) /* Avoid overrun */ + data->block[0] = 256 - command; + len = data->block[0]; + if (read_write == I2C_SMBUS_WRITE) { + for (i = 0; i < len; i++) { + chip->words[command + i] &= 0xff00; + chip->words[command + i] |= data->block[1 + i]; + } + dev_dbg(&adap->dev, + "i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", + addr, len, command); + } else { + for (i = 0; i < len; i++) { + data->block[1 + i] = + chip->words[command + i] & 0xff; + } + dev_dbg(&adap->dev, + "i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", + addr, len, command); + } + + ret = 0; + 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]; + if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { + ret = -EINVAL; + break; + } + if (b == NULL) { + b = stub_find_block(&adap->dev, chip, command, + true); + if (b == NULL) { + ret = -ENOMEM; + break; + } + } + /* Largest write sets read block length */ + if (len > b->len) + b->len = len; + for (i = 0; i < len; i++) + b->block[i] = data->block[i + 1]; + /* update for byte and word commands */ + chip->words[command] = (b->block[0] << 8) | b->len; + dev_dbg(&adap->dev, + "smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", + addr, len, command); + } else { + if (b == NULL) { + dev_dbg(&adap->dev, + "SMBus block read command without prior block write not supported\n"); + ret = -EOPNOTSUPP; + break; + } + len = b->len; + data->block[0] = len; + for (i = 0; i < len; i++) + data->block[i + 1] = b->block[i]; + dev_dbg(&adap->dev, + "smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", + addr, len, command); + } + + ret = 0; + break; + + default: + dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); + ret = -EOPNOTSUPP; + break; + } /* switch (size) */ + + return ret; +} + +static u32 stub_func(struct i2c_adapter *adapter) +{ + return STUB_FUNC_ALL & functionality; +} + +static const struct i2c_algorithm smbus_algorithm = { + .functionality = stub_func, + .smbus_xfer = stub_xfer, +}; + +static struct i2c_adapter stub_adapter = { + .owner = THIS_MODULE, + .class = I2C_CLASS_HWMON | I2C_CLASS_SPD, + .algo = &smbus_algorithm, + .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 = kcalloc(chip->bank_mask * chip->bank_size, + sizeof(u16), + GFP_KERNEL); + if (!chip->bank_words) + return -ENOMEM; + + pr_debug("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; + + if (!chip_addr[0]) { + pr_err("Please specify a chip address\n"); + return -ENODEV; + } + + for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { + if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { + pr_err("Invalid chip address 0x%02x\n", + chip_addr[i]); + return -EINVAL; + } + + pr_info("Virtual chip at 0x%02x\n", chip_addr[i]); + } + + /* Allocate memory for all chips at once */ + stub_chips_nr = i; + stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), + GFP_KERNEL); + if (!stub_chips) + return -ENOMEM; + + 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) + goto fail_free; + + return 0; + + fail_free: + i2c_stub_free(); + return ret; +} + +static void __exit i2c_stub_exit(void) +{ + i2c_del_adapter(&stub_adapter); + i2c_stub_free(); +} + +MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>"); +MODULE_DESCRIPTION("I2C stub driver"); +MODULE_LICENSE("GPL"); + +module_init(i2c_stub_init); +module_exit(i2c_stub_exit); |