i2c-stub: Support multiple chips (9d90c1fd) · Commits · e / devices / android_kernel_teracube_2e

Documentation/i2c/i2c-stub

+8 −10

Original line number	Diff line number	Diff line
		@@ -6,13 +6,14 @@ This module is a very simple fake I2C/SMBus driver. It implements four
		types of SMBus commands: write quick, (r/w) byte, (r/w) byte data, and
		(r/w) word data.

		You need to provide a chip address as a module parameter when loading
		this driver, which will then only react to SMBus commands to this address.
		You need to provide chip addresses as a module parameter when loading this
		driver, which will then only react to SMBus commands to these addresses.

		No hardware is needed nor associated with this module. It will accept write
		quick commands to one address; it will respond to the other commands (also
		to one address) by reading from or writing to an array in memory. It will
		also spam the kernel logs for every command it handles.
		quick commands to the specified addresses; it will respond to the other
		commands (also to the specified addresses) by reading from or writing to
		arrays in memory. It will also spam the kernel logs for every command it
		handles.

		A pointer register with auto-increment is implemented for all byte
		operations. This allows for continuous byte reads like those supported by
		@@ -26,8 +27,8 @@ The typical use-case is like this:

		PARAMETERS:

		int chip_addr:
		The SMBus address to emulate a chip at.
		int chip_addr[10]:
		The SMBus addresses to emulate chips at.

		CAVEATS:

		@@ -41,9 +42,6 @@ If the hardware for your driver has banked registers (e.g. Winbond sensors
		chips) this module will not work well - although it could be extended to
		support that pretty easily.

		Only one chip address is supported - although this module could be
		extended to support more.

		If you spam it hard enough, printk can be lossy. This module really wants
		something like relayfs.

drivers/i2c/busses/i2c-stub.c

+57 −22

Original line number	Diff line number	Diff line
		@@ -24,24 +24,41 @@
		#include <linux/init.h>
		#include <linux/module.h>
		#include <linux/kernel.h>
		#include <linux/slab.h>
		#include <linux/errno.h>
		#include <linux/i2c.h>

		static unsigned short chip_addr;
		module_param(chip_addr, ushort, S_IRUGO);
		MODULE_PARM_DESC(chip_addr, "Chip address (between 0x03 and 0x77)\n");
		#define MAX_CHIPS 10

		static u8 stub_pointer;
		static u8 stub_bytes[256];
		static u16 stub_words[256];
		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)\n");

		struct stub_chip {
		u8 pointer;
		u8 bytes[256];
		u16 words[256];
		};

		static struct stub_chip *stub_chips;

		/* Return -1 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;
		struct stub_chip *chip = NULL;

		if (addr != chip_addr)
		/* Search for the right chip */
		for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
		if (addr == chip_addr[i]) {
		chip = stub_chips + i;
		break;
		}
		}
		if (!chip)
		return -ENODEV;

		switch (size) {
		@@ -53,12 +70,12 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,

		case I2C_SMBUS_BYTE:
		if (read_write == I2C_SMBUS_WRITE) {
		stub_pointer = command;
		chip->pointer = command;
		dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
		"wrote 0x%02x.\n",
		addr, command);
		} else {
		data->byte = stub_bytes[stub_pointer++];
		data->byte = chip->bytes[chip->pointer++];
		dev_dbg(&adap->dev, "smbus byte - addr 0x%02x, "
		"read 0x%02x.\n",
		addr, data->byte);
		@@ -69,29 +86,29 @@ static s32 stub_xfer(struct i2c_adapter * adap, u16 addr, unsigned short flags,

		case I2C_SMBUS_BYTE_DATA:
		if (read_write == I2C_SMBUS_WRITE) {
		stub_bytes[command] = data->byte;
		chip->bytes[command] = data->byte;
		dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
		"wrote 0x%02x at 0x%02x.\n",
		addr, data->byte, command);
		} else {
		data->byte = stub_bytes[command];
		data->byte = chip->bytes[command];
		dev_dbg(&adap->dev, "smbus byte data - addr 0x%02x, "
		"read 0x%02x at 0x%02x.\n",
		addr, data->byte, command);
		}
		stub_pointer = command + 1;
		chip->pointer = command + 1;

		ret = 0;
		break;

		case I2C_SMBUS_WORD_DATA:
		if (read_write == I2C_SMBUS_WRITE) {
		stub_words[command] = data->word;
		chip->words[command] = 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 = stub_words[command];
		data->word = chip->words[command];
		dev_dbg(&adap->dev, "smbus word data - addr 0x%02x, "
		"read 0x%04x at 0x%02x.\n",
		addr, data->word, command);
		@@ -129,23 +146,41 @@ static struct i2c_adapter stub_adapter = {

		static int __init i2c_stub_init(void)
		{
		if (!chip_addr) {
		int i, ret;

		if (!chip_addr[0]) {
		printk(KERN_ERR "i2c-stub: Please specify a chip address\n");
		return -ENODEV;
		}
		if (chip_addr < 0x03 \|\| chip_addr > 0x77) {
		printk(KERN_ERR "i2c-stub: Invalid chip address 0x%02x\n",
		chip_addr);

		for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) {
		if (chip_addr[i] < 0x03 \|\| chip_addr[i] > 0x77) {
		printk(KERN_ERR "i2c-stub: Invalid chip address "
		"0x%02x\n", chip_addr[i]);
		return -EINVAL;
		}

		printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", chip_addr);
		return i2c_add_adapter(&stub_adapter);
		printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n",
		chip_addr[i]);
		}

		/* Allocate memory for all chips at once */
		stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL);
		if (!stub_chips) {
		printk(KERN_ERR "i2c-stub: Out of memory\n");
		return -ENOMEM;
		}

		ret = i2c_add_adapter(&stub_adapter);
		if (ret)
		kfree(stub_chips);
		return ret;
		}

		static void __exit i2c_stub_exit(void)
		{
		i2c_del_adapter(&stub_adapter);
		kfree(stub_chips);
		}

		MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");