On Monday, 18 June 2018 18:04:50 MSK Thierry Reding wrote:
> From: Thierry Reding <treding@xxxxxxxxxx>
>
> In order to support advanced features, the I2C FIFO interface was
> changed in the version of the Tegra I2C controller found in Tegra194.
> The changes are backwards incompatible, so the driver needs to be
> programmed in a slightly different way on new chips.
>
> Add support for MST FIFO programming and add an OF match entry for
> Tegra194. At the same time, mark all prior generations of this
> controller as not having the MST FIFO interface.
>
> Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
> ---
> drivers/i2c/busses/i2c-tegra.c | 99 +++++++++++++++++++++++++++++-----
> 1 file changed, 85 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
> index 5fccd1f1bca8..a2779e9af1ff 100644
> --- a/drivers/i2c/busses/i2c-tegra.c
> +++ b/drivers/i2c/busses/i2c-tegra.c
> @@ -115,6 +115,18 @@
>
> #define I2C_CONFIG_LOAD_TIMEOUT 1000000
>
> +#define I2C_MST_FIFO_CONTROL 0x0b4
> +#define I2C_MST_FIFO_CONTROL_RX_FLUSH BIT(0)
> +#define I2C_MST_FIFO_CONTROL_TX_FLUSH BIT(1)
> +#define I2C_MST_FIFO_CONTROL_RX_TRIG(x) (((x) - 1) << 4)
> +#define I2C_MST_FIFO_CONTROL_TX_TRIG(x) (((x) - 1) << 16)
> +
> +#define I2C_MST_FIFO_STATUS 0x0b8
> +#define I2C_MST_FIFO_STATUS_RX_MASK 0xff
> +#define I2C_MST_FIFO_STATUS_RX_SHIFT 0
> +#define I2C_MST_FIFO_STATUS_TX_MASK 0xff0000
> +#define I2C_MST_FIFO_STATUS_TX_SHIFT 16
> +
> /*
> * 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.
> @@ -154,6 +166,7 @@ struct tegra_i2c_hw_feature {
> u16 clk_divisor_fast_plus_mode;
> bool has_multi_master_mode;
> bool has_slcg_override_reg;
> + bool has_mst_fifo;
> };
>
> /**
> @@ -266,13 +279,24 @@ static void tegra_i2c_unmask_irq(struct tegra_i2c_dev
> *i2c_dev, u32 mask) static int tegra_i2c_flush_fifos(struct tegra_i2c_dev
> *i2c_dev)
> {
> unsigned long timeout = jiffies + HZ;
> - u32 val = i2c_readl(i2c_dev, I2C_FIFO_CONTROL);
> + unsigned int offset;
> + u32 mask, val;
> +
> + if (i2c_dev->hw->has_mst_fifo) {
> + mask = I2C_MST_FIFO_CONTROL_TX_FLUSH |
> + I2C_MST_FIFO_CONTROL_RX_FLUSH;
> + offset = I2C_MST_FIFO_CONTROL;
> + } else {
> + mask = I2C_FIFO_CONTROL_TX_FLUSH |
> + I2C_FIFO_CONTROL_RX_FLUSH;
> + offset = I2C_FIFO_CONTROL;
> + }
>
> - val |= I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH;
> - i2c_writel(i2c_dev, val, I2C_FIFO_CONTROL);
> + val = i2c_readl(i2c_dev, offset);
> + val |= mask;
> + i2c_writel(i2c_dev, val, offset);
>
> - while (i2c_readl(i2c_dev, I2C_FIFO_CONTROL) &
> - (I2C_FIFO_CONTROL_TX_FLUSH | I2C_FIFO_CONTROL_RX_FLUSH)) {
> + while (i2c_readl(i2c_dev, offset) & mask) {
> if (time_after(jiffies, timeout)) {
> dev_warn(i2c_dev->dev, "timeout waiting for fifo flush\n");
> return -ETIMEDOUT;
> @@ -290,9 +314,15 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev
> *i2c_dev) size_t buf_remaining = i2c_dev->msg_buf_remaining;
> int words_to_transfer;
>
> - val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
> - rx_fifo_avail = (val & I2C_FIFO_STATUS_RX_MASK) >>
> - I2C_FIFO_STATUS_RX_SHIFT;
> + if (i2c_dev->hw->has_mst_fifo) {
> + val = i2c_readl(i2c_dev, I2C_MST_FIFO_STATUS);
> + rx_fifo_avail = (val & I2C_MST_FIFO_STATUS_RX_MASK) >>
> + I2C_MST_FIFO_STATUS_RX_SHIFT;
> + } else {
> + val = i2c_readl(i2c_dev, I2C_FIFO_STATUS);
> + rx_fifo_avail = (val & I2C_FIFO_STATUS_RX_MASK) >>
> + I2C_FIFO_STATUS_RX_SHIFT;
> + }
>
> /* Rounds down to not include partial word at the end of buf */
> words_to_transfer = buf_remaining / BYTES_PER_FIFO_WORD;
> @@ -321,6 +351,16 @@ static int tegra_i2c_empty_rx_fifo(struct tegra_i2c_dev
> *i2c_dev) BUG_ON(rx_fifo_avail > 0 && buf_remaining > 0);
> i2c_dev->msg_buf_remaining = buf_remaining;
> i2c_dev->msg_buf = buf;
> +
> + /*
> + * All bytes received, mask RX_FIFO_DATA_REQ to prevent more
> + * interrupts from FIFO.
> + */
> + /*
> + if (i2c_dev->msg_buf_remaining == 0)
> + tegra_i2c_mask_irq(i2c_dev, I2C_INT_RX_FIFO_DATA_REQ);
> + */
Is it a deliberately commented out code?
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