24.01.2019 23:51, Sowjanya Komatineni пишет:
> This patch prepares the buffer with the message bytes to be
> transmitted along with the packet header information and then
> performs i2c transfer in PIO mode.
>
> Signed-off-by: Sowjanya Komatineni <skomatin...@nvidia.com>
> ---
> [V2] : DMA support changes include preparing buffer with message bytes and
> and header before sending them through DMA. So splitted the whole
> change into 2 seperate patches in this series.
>
> drivers/i2c/busses/i2c-tegra.c | 97
> +++++++++++++++++++++++++++++-------------
> 1 file changed, 68 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index ef854be4c837..13bce1411ddc 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -117,6 +117,9 @@
> #define I2C_MST_FIFO_STATUS_TX_MASK 0xff0000
> #define I2C_MST_FIFO_STATUS_TX_SHIFT 16
>
> +/* Packet header size in bytes */
> +#define I2C_PACKET_HEADER_SIZE 12
> +
> /*
> * 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.
> @@ -677,35 +680,69 @@ static irqreturn_t tegra_i2c_isr(int irq, void *dev_id)
> return IRQ_HANDLED;
> }
>
> +static int tegra_i2c_start_pio_xfer(struct tegra_i2c_dev *i2c_dev)
> +{
> + u32 *buffer = (u32 *)i2c_dev->msg_buf;
> + unsigned long flags;
> + u32 int_mask;
> +
> + spin_lock_irqsave(&i2c_dev->xfer_lock, flags);
> +
> + int_mask = I2C_INT_NO_ACK | I2C_INT_ARBITRATION_LOST;
> + tegra_i2c_unmask_irq(i2c_dev, int_mask);
> +
> + i2c_writel(i2c_dev, *(buffer++), I2C_TX_FIFO);
> + i2c_writel(i2c_dev, *(buffer++), I2C_TX_FIFO);
> + i2c_writel(i2c_dev, *(buffer++), I2C_TX_FIFO);
> +
> + i2c_dev->msg_buf = (u8 *) buffer;
> +
> + if (!i2c_dev->msg_read)
> + tegra_i2c_fill_tx_fifo(i2c_dev);
> +
> + if (i2c_dev->hw->has_per_pkt_xfer_complete_irq)
> + int_mask |= I2C_INT_PACKET_XFER_COMPLETE;
> + if (i2c_dev->msg_read)
> + int_mask |= I2C_INT_RX_FIFO_DATA_REQ;
> + else if (i2c_dev->msg_buf_remaining)
> + int_mask |= I2C_INT_TX_FIFO_DATA_REQ;
> +
> + tegra_i2c_unmask_irq(i2c_dev, int_mask);
> + spin_unlock_irqrestore(&i2c_dev->xfer_lock, flags);
> + dev_dbg(i2c_dev->dev, "unmasked irq: %02x\n",
> + i2c_readl(i2c_dev, I2C_INT_MASK));
> +
> + return 0;
> +}
> +
> static int tegra_i2c_xfer_msg(struct tegra_i2c_dev *i2c_dev,
> struct i2c_msg *msg, enum msg_end_type end_state)
> {
> u32 packet_header;
> u32 int_mask;
> unsigned long time_left;
> - unsigned long flags;
> + u32 *buffer;
> + int ret = 0;
> +
> + buffer = kmalloc(ALIGN(msg->len, BYTES_PER_FIFO_WORD) +
> + I2C_PACKET_HEADER_SIZE, GFP_KERNEL);
> + if (!buffer)
> + return -ENOMEM;
Isn't it possible to avoid "buffer" allocation / copying overhead and keep code
as-is for the PIO mode?
[snip]
