From: Jean Delvare <[email protected]> Subject: i2c-stub: Add support for bus multiplexing
Emulate a PCA9540 mux chip on request. There are two reasons for implementing this: * This makes it possible to emulate two chips at the same address. * This lets us test the multiplexing code. Signed-off-by: Jean Delvare <[email protected]> Cc: Michael Lawnick <[email protected]> Cc: Rodolfo Giometti <[email protected]> --- Documentation/i2c/i2c-stub | 9 ++ drivers/i2c/busses/i2c-stub.c | 179 +++++++++++++++++++++++++++++++++++++---- 2 files changed, 171 insertions(+), 17 deletions(-) --- linux-2.6.34-rc5.orig/drivers/i2c/busses/i2c-stub.c 2010-04-20 08:18:24.000000000 +0200 +++ linux-2.6.34-rc5/drivers/i2c/busses/i2c-stub.c 2010-04-20 13:42:53.000000000 +0200 @@ -2,7 +2,7 @@ i2c-stub.c - I2C/SMBus chip emulator Copyright (c) 2004 Mark M. Hoffman <[email protected]> - Copyright (C) 2007 Jean Delvare <[email protected]> + Copyright (C) 2007-2010 Jean Delvare <[email protected]> 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 @@ -33,11 +33,26 @@ I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | \ I2C_FUNC_SMBUS_I2C_BLOCK) +#define PCA9540_ADDR 0x70 +#define PCA9540_CHAN_MASK 0x07 +#define PCA9540_CHAN0_EN 0x04 +#define PCA9540_CHAN1_EN 0x05 + 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 short pca9540_addr_0[MAX_CHIPS]; +module_param_array(pca9540_addr_0, ushort, NULL, S_IRUGO); +MODULE_PARM_DESC(pca9540_addr_0, + "Chip addresses on PCA9540 mux branch 0 (up to 10)"); + +static unsigned short pca9540_addr_1[MAX_CHIPS]; +module_param_array(pca9540_addr_1, ushort, NULL, S_IRUGO); +MODULE_PARM_DESC(pca9540_addr_1, + "Chip addresses on PCA9540 mux branch 1 (up to 10)"); + static unsigned long functionality = STUB_FUNC; module_param(functionality, ulong, S_IRUGO | S_IWUSR); MODULE_PARM_DESC(functionality, "Override functionality bitfield"); @@ -49,10 +64,41 @@ struct stub_chip { }; static struct stub_chip *stub_chips; +static struct stub_chip *pca9540_chips_0; +static struct stub_chip *pca9540_chips_1; +static int have_pca9540; +static u8 pca9540_state; + +static struct stub_chip *pca9540_get_chip(u16 addr) +{ + const unsigned short *pca9540_addr; + struct stub_chip *pca9540_chips; + int i; + + switch (pca9540_state & PCA9540_CHAN_MASK) { + case PCA9540_CHAN0_EN: + pca9540_addr = pca9540_addr_0; + pca9540_chips = pca9540_chips_0; + break; + case PCA9540_CHAN1_EN: + pca9540_addr = pca9540_addr_1; + pca9540_chips = pca9540_chips_1; + break; + default: + return NULL; + } + + for (i = 0; i < MAX_CHIPS && pca9540_addr[i]; i++) { + if (addr == pca9540_addr[i]) + return pca9540_chips + i; + } + return NULL; +} /* 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) +static s32 stub_xfer_normal(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; @@ -65,6 +111,19 @@ static s32 stub_xfer(struct i2c_adapter break; } } + /* If a PCA9540 mux chip is emulated, check its state to find out + * which devices are reachable */ + if (have_pca9540) { + struct stub_chip *chip_muxed = pca9540_get_chip(addr); + if (chip_muxed) { + if (chip) { + dev_err(&adap->dev, "Bad bus topology, " + "duplicate address 0x%02x\n", addr); + return -EIO; + } + chip = chip_muxed; + } + } if (!chip) return -ENODEV; @@ -157,6 +216,39 @@ static s32 stub_xfer(struct i2c_adapter return ret; } +/* Emulate a PCA9540 mux chip */ +static s32 stub_xfer_pca9540(struct i2c_adapter *adap, u16 addr, + unsigned short flags, char read_write, u8 command, int size, + union i2c_smbus_data *data) +{ + if (size != I2C_SMBUS_BYTE) { + dev_dbg(&adap->dev, "Unsupported I2C/SMBus command\n"); + return -EOPNOTSUPP; + } + + if (read_write == I2C_SMBUS_WRITE) { + pca9540_state = command; + dev_dbg(&adap->dev, "PCA9540 - set to 0x%02x.\n", command); + } else { + data->byte = pca9540_state; + dev_dbg(&adap->dev, "PCA9540 - read 0x%02x.\n", data->byte); + } + + return 0; +} + +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) +{ + if (have_pca9540 && addr == PCA9540_ADDR) { + return stub_xfer_pca9540(adap, addr, flags, read_write, + command, size, data); + } else { + return stub_xfer_normal(adap, addr, flags, read_write, + command, size, data); + } +} + static u32 stub_func(struct i2c_adapter *adapter) { return STUB_FUNC & functionality; @@ -174,36 +266,89 @@ static struct i2c_adapter stub_adapter = .name = "SMBus stub driver", }; -static int __init i2c_stub_init(void) +static int __init i2c_stub_parse_addresses(const unsigned short *addr, + struct stub_chip **chipsp, const char *suffix) { - int i, ret; + int i; - if (!chip_addr[0]) { - printk(KERN_ERR "i2c-stub: Please specify a chip address\n"); - return -ENODEV; - } + /* Nothing to do if the address list is empty */ + if (!addr[0]) + return 0; - for (i = 0; i < MAX_CHIPS && chip_addr[i]; i++) { - if (chip_addr[i] < 0x03 || chip_addr[i] > 0x77) { + for (i = 0; i < MAX_CHIPS && addr[i]; i++) { + if (addr[i] < 0x03 || addr[i] > 0x77) { printk(KERN_ERR "i2c-stub: Invalid chip address " - "0x%02x\n", chip_addr[i]); + "0x%02x\n", addr[i]); + return -EINVAL; + } + if (have_pca9540 && addr[i] == PCA9540_ADDR) { + printk(KERN_ERR "i2c-stub: Address 0x%02x reserved " + "for PCA9540 mux\n", addr[i]); return -EINVAL; } - printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x\n", - chip_addr[i]); + printk(KERN_INFO "i2c-stub: Virtual chip at 0x%02x%s\n", + addr[i], suffix); } /* Allocate memory for all chips at once */ - stub_chips = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL); - if (!stub_chips) { + *chipsp = kzalloc(i * sizeof(struct stub_chip), GFP_KERNEL); + if (!*chipsp) { printk(KERN_ERR "i2c-stub: Out of memory\n"); return -ENOMEM; } + return 0; +} + +static int __init i2c_stub_init(void) +{ + int ret; + + have_pca9540 = pca9540_addr_0[0] || pca9540_addr_1[0]; + if (!chip_addr[0] && !have_pca9540) { + printk(KERN_ERR "i2c-stub: Please specify a chip address\n"); + return -ENODEV; + } + + ret = i2c_stub_parse_addresses(chip_addr, &stub_chips, ""); + if (ret) + goto err_free; + + ret = i2c_stub_parse_addresses(pca9540_addr_0, &pca9540_chips_0, + " on PCA9540 mux branch 0"); + if (ret) + goto err_free; + + ret = i2c_stub_parse_addresses(pca9540_addr_1, &pca9540_chips_1, + " on PCA9540 mux branch 1"); + if (ret) + goto err_free; + + /* Bus multiplexing isn't compatible with device auto-detection */ + if (have_pca9540) + stub_adapter.class = 0; + ret = i2c_add_adapter(&stub_adapter); if (ret) - kfree(stub_chips); + goto err_free; + + /* Instantiate PCA9540 multiplexer chip if requested */ + if (have_pca9540) { + struct i2c_board_info info; + + memset(&info, 0, sizeof(struct i2c_board_info)); + strlcpy(info.type, "pca9540", I2C_NAME_SIZE); + info.addr = PCA9540_ADDR; + i2c_new_device(&stub_adapter, &info); + } + + return 0; + + err_free: + kfree(stub_chips); + kfree(pca9540_chips_0); + kfree(pca9540_chips_1); return ret; } --- linux-2.6.34-rc5.orig/Documentation/i2c/i2c-stub 2010-03-05 11:08:47.000000000 +0100 +++ linux-2.6.34-rc5/Documentation/i2c/i2c-stub 2010-04-20 14:05:17.000000000 +0200 @@ -33,6 +33,15 @@ PARAMETERS: int chip_addr[10]: The SMBus addresses to emulate chips at. +int pca9540_addr_0[10]: +int pca9540_addr_1[10]: + The SMBus addresses to emulate chips at on the two branches + of an emulated PCA9540 mux chip. The PCA9540 chip is emulated + at address 0x70 if and only if at least one address is provided + for either parameter. Also note that the adapter class is reset + in this case, so you always have to explicitly instantiate your + devices, auto-detection will no longer work. + unsigned long functionality: Functionality override, to disable some commands. See I2C_FUNC_* constants in <linux/i2c.h> for the suitable values. For example, -- Jean Delvare -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
