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413 lines
9.8 KiB
413 lines
9.8 KiB
// SPDX-License-Identifier: GPL-2.0-or-later |
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/* |
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i2c-stub.c - I2C/SMBus chip emulator |
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Copyright (c) 2004 Mark M. Hoffman <[email protected]> |
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Copyright (C) 2007-2014 Jean Delvare <[email protected]> |
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*/ |
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#define pr_fmt(fmt) "i2c-stub: " fmt |
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#include <linux/errno.h> |
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#include <linux/i2c.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/list.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#define MAX_CHIPS 10 |
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/* |
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* Support for I2C_FUNC_SMBUS_BLOCK_DATA is disabled by default and must |
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* be enabled explicitly by setting the I2C_FUNC_SMBUS_BLOCK_DATA bits |
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* in the 'functionality' module parameter. |
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*/ |
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#define STUB_FUNC_DEFAULT \ |
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(I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | \ |
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I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ |
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I2C_FUNC_SMBUS_I2C_BLOCK) |
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#define STUB_FUNC_ALL \ |
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(STUB_FUNC_DEFAULT | I2C_FUNC_SMBUS_BLOCK_DATA) |
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static unsigned short chip_addr[MAX_CHIPS]; |
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module_param_array(chip_addr, ushort, NULL, S_IRUGO); |
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MODULE_PARM_DESC(chip_addr, |
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"Chip addresses (up to 10, between 0x03 and 0x77)"); |
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static unsigned long functionality = STUB_FUNC_DEFAULT; |
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module_param(functionality, ulong, S_IRUGO | S_IWUSR); |
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MODULE_PARM_DESC(functionality, "Override functionality bitfield"); |
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/* Some chips have banked register ranges */ |
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static u8 bank_reg[MAX_CHIPS]; |
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module_param_array(bank_reg, byte, NULL, S_IRUGO); |
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MODULE_PARM_DESC(bank_reg, "Bank register"); |
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static u8 bank_mask[MAX_CHIPS]; |
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module_param_array(bank_mask, byte, NULL, S_IRUGO); |
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MODULE_PARM_DESC(bank_mask, "Bank value mask"); |
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static u8 bank_start[MAX_CHIPS]; |
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module_param_array(bank_start, byte, NULL, S_IRUGO); |
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MODULE_PARM_DESC(bank_start, "First banked register"); |
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static u8 bank_end[MAX_CHIPS]; |
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module_param_array(bank_end, byte, NULL, S_IRUGO); |
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MODULE_PARM_DESC(bank_end, "Last banked register"); |
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struct smbus_block_data { |
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struct list_head node; |
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u8 command; |
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u8 len; |
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u8 block[I2C_SMBUS_BLOCK_MAX]; |
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}; |
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struct stub_chip { |
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u8 pointer; |
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u16 words[256]; /* Byte operations use the LSB as per SMBus |
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specification */ |
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struct list_head smbus_blocks; |
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/* For chips with banks, extra registers are allocated dynamically */ |
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u8 bank_reg; |
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u8 bank_shift; |
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u8 bank_mask; |
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u8 bank_sel; /* Currently selected bank */ |
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u8 bank_start; |
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u8 bank_end; |
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u16 bank_size; |
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u16 *bank_words; /* Room for bank_mask * bank_size registers */ |
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}; |
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static struct stub_chip *stub_chips; |
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static int stub_chips_nr; |
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static struct smbus_block_data *stub_find_block(struct device *dev, |
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struct stub_chip *chip, |
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u8 command, bool create) |
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{ |
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struct smbus_block_data *b, *rb = NULL; |
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list_for_each_entry(b, &chip->smbus_blocks, node) { |
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if (b->command == command) { |
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rb = b; |
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break; |
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} |
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} |
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if (rb == NULL && create) { |
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rb = devm_kzalloc(dev, sizeof(*rb), GFP_KERNEL); |
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if (rb == NULL) |
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return rb; |
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rb->command = command; |
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list_add(&rb->node, &chip->smbus_blocks); |
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} |
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return rb; |
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} |
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static u16 *stub_get_wordp(struct stub_chip *chip, u8 offset) |
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{ |
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if (chip->bank_sel && |
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offset >= chip->bank_start && offset <= chip->bank_end) |
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return chip->bank_words + |
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(chip->bank_sel - 1) * chip->bank_size + |
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offset - chip->bank_start; |
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else |
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return chip->words + offset; |
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} |
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/* Return negative errno on error. */ |
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static s32 stub_xfer(struct i2c_adapter *adap, u16 addr, unsigned short flags, |
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char read_write, u8 command, int size, union i2c_smbus_data *data) |
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{ |
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s32 ret; |
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int i, len; |
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struct stub_chip *chip = NULL; |
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struct smbus_block_data *b; |
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u16 *wordp; |
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/* Search for the right chip */ |
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for (i = 0; i < stub_chips_nr; i++) { |
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if (addr == chip_addr[i]) { |
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chip = stub_chips + i; |
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break; |
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} |
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} |
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if (!chip) |
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return -ENODEV; |
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switch (size) { |
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case I2C_SMBUS_QUICK: |
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dev_dbg(&adap->dev, "smbus quick - addr 0x%02x\n", addr); |
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ret = 0; |
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break; |
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case I2C_SMBUS_BYTE: |
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if (read_write == I2C_SMBUS_WRITE) { |
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chip->pointer = command; |
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dev_dbg(&adap->dev, |
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"smbus byte - addr 0x%02x, wrote 0x%02x.\n", |
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addr, command); |
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} else { |
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wordp = stub_get_wordp(chip, chip->pointer++); |
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data->byte = *wordp & 0xff; |
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dev_dbg(&adap->dev, |
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"smbus byte - addr 0x%02x, read 0x%02x.\n", |
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addr, data->byte); |
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} |
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ret = 0; |
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break; |
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case I2C_SMBUS_BYTE_DATA: |
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wordp = stub_get_wordp(chip, command); |
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if (read_write == I2C_SMBUS_WRITE) { |
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*wordp &= 0xff00; |
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*wordp |= data->byte; |
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dev_dbg(&adap->dev, |
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"smbus byte data - addr 0x%02x, wrote 0x%02x at 0x%02x.\n", |
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addr, data->byte, command); |
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/* Set the bank as needed */ |
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if (chip->bank_words && command == chip->bank_reg) { |
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chip->bank_sel = |
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(data->byte >> chip->bank_shift) |
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& chip->bank_mask; |
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dev_dbg(&adap->dev, |
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"switching to bank %u.\n", |
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chip->bank_sel); |
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} |
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} else { |
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data->byte = *wordp & 0xff; |
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dev_dbg(&adap->dev, |
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"smbus byte data - addr 0x%02x, read 0x%02x at 0x%02x.\n", |
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addr, data->byte, command); |
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} |
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chip->pointer = command + 1; |
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ret = 0; |
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break; |
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case I2C_SMBUS_WORD_DATA: |
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wordp = stub_get_wordp(chip, command); |
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if (read_write == I2C_SMBUS_WRITE) { |
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*wordp = data->word; |
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dev_dbg(&adap->dev, |
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"smbus word data - addr 0x%02x, wrote 0x%04x at 0x%02x.\n", |
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addr, data->word, command); |
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} else { |
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data->word = *wordp; |
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dev_dbg(&adap->dev, |
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"smbus word data - addr 0x%02x, read 0x%04x at 0x%02x.\n", |
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addr, data->word, command); |
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} |
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ret = 0; |
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break; |
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case I2C_SMBUS_I2C_BLOCK_DATA: |
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/* |
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* We ignore banks here, because banked chips don't use I2C |
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* block transfers |
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*/ |
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if (data->block[0] > 256 - command) /* Avoid overrun */ |
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data->block[0] = 256 - command; |
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len = data->block[0]; |
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if (read_write == I2C_SMBUS_WRITE) { |
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for (i = 0; i < len; i++) { |
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chip->words[command + i] &= 0xff00; |
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chip->words[command + i] |= data->block[1 + i]; |
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} |
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dev_dbg(&adap->dev, |
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"i2c block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", |
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addr, len, command); |
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} else { |
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for (i = 0; i < len; i++) { |
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data->block[1 + i] = |
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chip->words[command + i] & 0xff; |
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} |
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dev_dbg(&adap->dev, |
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"i2c block data - addr 0x%02x, read %d bytes at 0x%02x.\n", |
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addr, len, command); |
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} |
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ret = 0; |
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break; |
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case I2C_SMBUS_BLOCK_DATA: |
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/* |
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* We ignore banks here, because chips typically don't use both |
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* banks and SMBus block transfers |
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*/ |
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b = stub_find_block(&adap->dev, chip, command, false); |
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if (read_write == I2C_SMBUS_WRITE) { |
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len = data->block[0]; |
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if (len == 0 || len > I2C_SMBUS_BLOCK_MAX) { |
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ret = -EINVAL; |
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break; |
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} |
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if (b == NULL) { |
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b = stub_find_block(&adap->dev, chip, command, |
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true); |
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if (b == NULL) { |
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ret = -ENOMEM; |
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break; |
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} |
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} |
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/* Largest write sets read block length */ |
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if (len > b->len) |
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b->len = len; |
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for (i = 0; i < len; i++) |
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b->block[i] = data->block[i + 1]; |
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/* update for byte and word commands */ |
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chip->words[command] = (b->block[0] << 8) | b->len; |
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dev_dbg(&adap->dev, |
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"smbus block data - addr 0x%02x, wrote %d bytes at 0x%02x.\n", |
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addr, len, command); |
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} else { |
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if (b == NULL) { |
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dev_dbg(&adap->dev, |
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"SMBus block read command without prior block write not supported\n"); |
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ret = -EOPNOTSUPP; |
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break; |
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} |
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len = b->len; |
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data->block[0] = len; |
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for (i = 0; i < len; i++) |
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data->block[i + 1] = b->block[i]; |
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dev_dbg(&adap->dev, |
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"smbus block data - addr 0x%02x, read %d bytes at 0x%02x.\n", |
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addr, len, command); |
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} |
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ret = 0; |
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break; |
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default: |
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dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); |
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ret = -EOPNOTSUPP; |
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break; |
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} /* switch (size) */ |
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return ret; |
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} |
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static u32 stub_func(struct i2c_adapter *adapter) |
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{ |
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return STUB_FUNC_ALL & functionality; |
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} |
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static const struct i2c_algorithm smbus_algorithm = { |
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.functionality = stub_func, |
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.smbus_xfer = stub_xfer, |
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}; |
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static struct i2c_adapter stub_adapter = { |
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.owner = THIS_MODULE, |
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.class = I2C_CLASS_HWMON | I2C_CLASS_SPD, |
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.algo = &smbus_algorithm, |
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.name = "SMBus stub driver", |
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}; |
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static int __init i2c_stub_allocate_banks(int i) |
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{ |
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struct stub_chip *chip = stub_chips + i; |
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chip->bank_reg = bank_reg[i]; |
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chip->bank_start = bank_start[i]; |
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chip->bank_end = bank_end[i]; |
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chip->bank_size = bank_end[i] - bank_start[i] + 1; |
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/* We assume that all bits in the mask are contiguous */ |
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chip->bank_mask = bank_mask[i]; |
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while (!(chip->bank_mask & 1)) { |
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chip->bank_shift++; |
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chip->bank_mask >>= 1; |
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} |
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chip->bank_words = kcalloc(chip->bank_mask * chip->bank_size, |
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sizeof(u16), |
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GFP_KERNEL); |
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if (!chip->bank_words) |
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return -ENOMEM; |
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pr_debug("Allocated %u banks of %u words each (registers 0x%02x to 0x%02x)\n", |
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chip->bank_mask, chip->bank_size, chip->bank_start, |
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chip->bank_end); |
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return 0; |
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} |
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static void i2c_stub_free(void) |
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{ |
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int i; |
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for (i = 0; i < stub_chips_nr; i++) |
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kfree(stub_chips[i].bank_words); |
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kfree(stub_chips); |
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} |
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static int __init i2c_stub_init(void) |
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{ |
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int i, ret; |
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if (!chip_addr[0]) { |
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pr_err("Please specify a chip address\n"); |
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return -ENODEV; |
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} |
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for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { |
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if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { |
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pr_err("Invalid chip address 0x%02x\n", |
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chip_addr[i]); |
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return -EINVAL; |
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} |
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pr_info("Virtual chip at 0x%02x\n", chip_addr[i]); |
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} |
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/* Allocate memory for all chips at once */ |
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stub_chips_nr = i; |
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stub_chips = kcalloc(stub_chips_nr, sizeof(struct stub_chip), |
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GFP_KERNEL); |
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if (!stub_chips) |
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return -ENOMEM; |
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for (i = 0; i < stub_chips_nr; i++) { |
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INIT_LIST_HEAD(&stub_chips[i].smbus_blocks); |
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/* Allocate extra memory for banked register ranges */ |
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if (bank_mask[i]) { |
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ret = i2c_stub_allocate_banks(i); |
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if (ret) |
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goto fail_free; |
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} |
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} |
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ret = i2c_add_adapter(&stub_adapter); |
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if (ret) |
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goto fail_free; |
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return 0; |
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fail_free: |
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i2c_stub_free(); |
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return ret; |
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} |
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static void __exit i2c_stub_exit(void) |
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{ |
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i2c_del_adapter(&stub_adapter); |
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i2c_stub_free(); |
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} |
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MODULE_AUTHOR("Mark M. Hoffman <[email protected]>"); |
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MODULE_DESCRIPTION("I2C stub driver"); |
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MODULE_LICENSE("GPL"); |
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module_init(i2c_stub_init); |
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module_exit(i2c_stub_exit);
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