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    Subject[PATCH V1 2/2] i2c: tegra: support for I2C_M_NOSTART protocol mangling
    Date
    Adding support for protocol mangling I2C_M_NOSTART.
    When multiple message transfer request made through i2c
    and if any message is flagged with I2C_M_NOSTART then
    it will not send the start/repeat start/address of that
    message i.e. send the data directly.

    Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
    ---
    drivers/i2c/busses/i2c-tegra.c | 32 +++++++++++++++++++++++++++-----
    1 files changed, 27 insertions(+), 5 deletions(-)

    diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
    index 18067b3..a50e4c4 100644
    --- a/drivers/i2c/busses/i2c-tegra.c
    +++ b/drivers/i2c/busses/i2c-tegra.c
    @@ -97,8 +97,21 @@
    #define I2C_HEADER_10BIT_ADDR (1<<18)
    #define I2C_HEADER_IE_ENABLE (1<<17)
    #define I2C_HEADER_REPEAT_START (1<<16)
    +#define I2C_HEADER_CONTINUE_XFER (1<<15)
    #define I2C_HEADER_MASTER_ADDR_SHIFT 12
    #define I2C_HEADER_SLAVE_ADDR_SHIFT 1
    +/*
    + * msg_end_type: The bus control which need to be send at end of transfer.
    + * @MSG_END_STOP: Send stop pulse at end of transfer.
    + * @MSG_END_REPEAT_START: Send repeat start at end of transfer.
    + * @MSG_END_CONTINUE: The following on message is coming and so do not send
    + * stop or repeat start.
    + */
    +enum msg_end_type {
    + MSG_END_STOP,
    + MSG_END_REPEAT_START,
    + MSG_END_CONTINUE,
    +};

    /**
    * struct tegra_i2c_dev - per device i2c context
    @@ -450,7 +463,7 @@ err:
    }

    static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
    - struct i2c_msg *msg, int stop)
    + struct i2c_msg *msg, enum msg_end_type end_state)
    {
    u32 packet_header;
    u32 int_mask;
    @@ -477,7 +490,9 @@ static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
    i2c_writel(i2c_dev, packet_header, I2C_TX_FIFO);

    packet_header = I2C_HEADER_IE_ENABLE;
    - if (!stop)
    + if (end_state == MSG_END_CONTINUE)
    + packet_header |= I2C_HEADER_CONTINUE_XFER;
    + else if (end_state == MSG_END_REPEAT_START)
    packet_header |= I2C_HEADER_REPEAT_START;
    if (msg->flags & I2C_M_TEN) {
    packet_header |= msg->addr;
    @@ -549,8 +564,14 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],

    clk_enable(i2c_dev->clk);
    for (i = 0; i < num; i++) {
    - int stop = (i == (num - 1)) ? 1 : 0;
    - ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], stop);
    + enum msg_end_type end_type = MSG_END_STOP;
    + if (i < (num - 1)) {
    + if (msgs[i + 1].flags & I2C_M_NOSTART)
    + end_type = MSG_END_CONTINUE;
    + else
    + end_type = MSG_END_REPEAT_START;
    + }
    + ret = tegra_i2c_xfer_msg(i2c_dev, &msgs[i], end_type);
    if (ret)
    break;
    }
    @@ -560,7 +581,8 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],

    static u32 tegra_i2c_func(struct i2c_adapter *adap)
    {
    - return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR;
    + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
    + I2C_FUNC_PROTOCOL_MANGLING;
    }

    static const struct i2c_algorithm tegra_i2c_algo = {
    --
    1.7.1.1


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