i2c: stub: Add support for banked register ranges

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 <jdelvare@suse.de>
Tested-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/Documentation/i2c/i2c-stub b/Documentation/i2c/i2c-stub
index a0fe7a0..a16924f 100644 (file)
--- a/Documentation/i2c/i2c-stub
+++ b/Documentation/i2c/i2c-stub
@@ -47,15 +47,18 @@ unsigned long functionality:
        value 0x1f0000 would only enable the quick, byte and byte data
        commands.
 
+u8 bank_reg[10]
+u8 bank_mask[10]
+u8 bank_start[10]
+u8 bank_end[10]:
+       Optional bank settings. They tell which bits in which register
+       select the active bank, as well as the range of banked registers.
+
 CAVEATS:
 
 If your target driver polls some byte or word waiting for it to change, the
 stub could lock it up.  Use i2cset to unlock it.
 
-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.
-
 If you spam it hard enough, printk can be lossy.  This module really wants
 something like relayfs.
 

diff --git a/drivers/i2c/i2c-stub.c b/drivers/i2c/i2c-stub.c
index ad52f07..e815c60 100644 (file)
--- a/drivers/i2c/i2c-stub.c
+++ b/drivers/i2c/i2c-stub.c
@@ -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 <mhoffman@lightlink.com>");