I2C修改支持ALPAR协议

IC读卡芯片是一个完全单芯片、低成本、低功耗、功能强大的智能读卡器。它具有多种用来减少功耗的模式以及宽的电源电压范围，使之非常适合使用在便携式 设备中。由于具有特殊的多用途硬件，小嵌入式软件程序能够控制市场上的大部份卡。

由于我们产品的串口都已经被占用，IC读卡芯片支持非标准I2C方式访问数据，所以我们改用I2C方式。CPU的I2C有标准I2C和GPIO I2C两种方式。由于IC读卡芯片的I2C协议不是标准I2C，需要进行修改。所以我们选择从GPIO I2C方式中进行简单修改以支持ALPAR协议访问格式。

下面是ALPAR协议格式：
由上图可知，协议发送或接收的数据长度在数据的第二第三字节定义。因此，我们只需要在读取数据过程中先得出数据长度即可。

以下部分是修改的代码, +为添加部分：

Index: include/linux/i2c.h
===================================================================
--- include/linux/i2c.h    (版本 986)
+++ include/linux/i2c.h    (版本 988)
@@ -90,6 +90,12 @@
                      u8 command, u8 *values);
 extern s32 i2c_smbus_write_block_data(struct i2c_client *client,
                       u8 command, u8 length, const u8 *values);
+/*
+*    iUnin add for tda8029 ALPAR protocol. by yang.yuanming.
+*    data: ACK(1) + length(2) + code(1) + data(n) +LRC(1) = n+5     n=0~506
+*/
+extern s32 i2c_smbus_read_alpar_data(struct i2c_client *client, u8 *values);
+extern s32 i2c_smbus_write_alpar_data(struct i2c_client *client, u8 length, const u8 *values);
 /* Returns the number of read bytes */
 extern s32 i2c_smbus_read_i2c_block_data(struct i2c_client *client,
                      u8 command, u8 length, u8 *values);
@@ -511,6 +517,7 @@
 #define I2C_M_IGNORE_NAK    0x1000    /* if I2C_FUNC_PROTOCOL_MANGLING */
 #define I2C_M_NO_RD_ACK        0x0800    /* if I2C_FUNC_PROTOCOL_MANGLING */
 #define I2C_M_RECV_LEN        0x0400    /* length will be first received byte */
+#define I2C_M_ALPAR_RECV_LEN        0x0200    /* length will be n2&0xFF+n3+5 received byte */
     __u16 len;        /* msg length                */
     __u8 *buf;        /* pointer to msg data            */
 };
@@ -566,6 +573,18 @@
              /* and one more for user-space compatibility */
 };

+/*
+*    iUnin add for tda8029 ALPAR protocol. by yang.yuanming.
+*    data: ACK(1) + length(2) + code(1) + data(n) +LRC(1) = n+5     n=0~506
+*/
+#define I2C_SMBUS_ALPAR_MAX    512    /* As specified in SMBus standard */
+union i2c_alpar_data {
+    __u8 byte;
+    __u16 word;
+    __u8 block[I2C_SMBUS_ALPAR_MAX]; /* block[0] is used for length */
+             /* and one more for user-space compatibility */
+};
+
 /* i2c_smbus_xfer read or write markers */
 #define I2C_SMBUS_READ    1
 #define I2C_SMBUS_WRITE    0
@@ -581,5 +600,5 @@
 #define I2C_SMBUS_I2C_BLOCK_BROKEN  6
 #define I2C_SMBUS_BLOCK_PROC_CALL   7        /* SMBus 2.0 */
 #define I2C_SMBUS_I2C_BLOCK_DATA    8
-
+#define I2C_SMBUS_ALPAR_DATA       9
 #endif /* _LINUX_I2C_H */
Index: drivers/i2c/i2c-core.c
===================================================================
--- drivers/i2c/i2c-core.c    (版本 986)
+++ drivers/i2c/i2c-core.c    (版本 988)
@@ -1803,6 +1803,70 @@
 }
 EXPORT_SYMBOL(i2c_smbus_write_i2c_block_data);

+
+/*
+*    iUnin add for tda8029 ALPAR protocol. by yang.yuanming.
+*    data: ACK(1) + length(2) + code(1) + data(n) +LRC(1) = n+5
+*/
+s32 i2c_smbus_read_alpar_data(struct i2c_client *client, u8 *values)
+{
+    union i2c_alpar_data data;
+    int status;
+    unsigned char msgbuf0[I2C_SMBUS_ALPAR_MAX];
+    int num = 1;
+    struct i2c_msg msg[1] = {{ client->addr, client->flags | I2C_M_RD, 0, msgbuf0 }
+     };
+
+    int i, alpar_len;
+    u8 partial_pec = 0;
+
+    msg[0].flags |= I2C_M_ALPAR_RECV_LEN;
+    msg[0].len = 5; /* block length will be added by the underlying bus driver */
+
+    status = i2c_transfer(client->adapter, msg, num);
+    if (status < 0)
+        return status;
+
+    /* Check PEC if last message is a read */
+    if (i && (msg[num-1].flags & I2C_M_RD)) {
+        status = i2c_smbus_check_pec(partial_pec, &msg[num-1]);
+        if (status < 0)
+            return status;
+    }
+
+    alpar_len = (msgbuf0[1]*256 +msgbuf0[2] + 5);
+    for (i = 0; i < alpar_len; i++)
+        data.block[i] = msgbuf0[i];
+
+    memcpy(values, &data.block[0], alpar_len);
+
+    return alpar_len;
+}
+EXPORT_SYMBOL(i2c_smbus_read_alpar_data);
+
+/*
+*    iUnin add for tda8029 ALPAR protocol. by yang.yuanming.
+*    data: ACK(1) + length(2) + code(1) + data(n) +LRC(1) = n+5
+*/
+s32 i2c_smbus_write_alpar_data(struct i2c_client *client, u8 length, const u8 *values)
+{
+    int status;
+
+    if (length > I2C_SMBUS_ALPAR_MAX)
+        length = I2C_SMBUS_ALPAR_MAX;
+
+    struct i2c_msg msg[1] = {{ client->addr, 0, length, values }
+     };
+
+    status = i2c_transfer(client->adapter, msg, 1);
+    if (status < 0)
+        return status;
+
+    return 0;
+}
+EXPORT_SYMBOL(i2c_smbus_write_alpar_data);
+
+
 /* Simulate a SMBus command using the i2c protocol
    No checking of parameters is */
 static s32 i2c_smbus_xfer_emulated(struct i2c_adapter *adapter, u16 addr,
Index: drivers/i2c/algos/i2c-algo-bit.c
===================================================================
--- drivers/i2c/algos/i2c-algo-bit.c    (版本 986)
+++ drivers/i2c/algos/i2c-algo-bit.c    (版本 988)
@@ -417,6 +417,25 @@
         temp++;
         count--;

+    /*
+    *    iUnin add for tda8029 ALPAR protocol. by yang.yuanming.
+    *    data: ACK(1) + length(2) + code(1) + data(n) +LRC(1) = n+5
+    */
+        if ((rdcount == 2 || rdcount == 3) && (flags & I2C_M_ALPAR_RECV_LEN)) {
+            /* The original count value accounts for the extra
+               bytes, that is, either 1 for a regular transaction,
+             or 2 for a PEC transaction. */
+             if(rdcount == 2){
+                count += (inval*256);
+                msg->len += (inval*256);
+             }
+             if(rdcount == 3){
+                count += inval;
+                msg->len += inval;
+             }
+
+        }
+
         /* Some SMBus transactions require that we receive the
            transaction length as the first read byte. */
         if (rdcount == 1 && (flags & I2C_M_RECV_LEN)) {

在完成协议小小修改部分后，IC读卡芯片驱动则相对简单了。真正的工作在上层的各种IC卡的协议访问过程。这就是下部分的事情了。。。