[PATCH V2 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c
Akash Asthana
akashast at codeaurora.org
Wed Aug 26 11:56:30 UTC 2020
Hi Roja,
On 8/20/2020 4:05 PM, Roja Rani Yarubandi wrote:
> If the hardware is still accessing memory after SMMU translation
> is disabled (as part of smmu shutdown callback), then the
> IOVAs (I/O virtual address) which it was using will go on the bus
> as the physical addresses which will result in unknown crashes
> like NoC/interconnect errors.
>
> So, implement shutdown callback to i2c driver to unmap DMA mappings
> during system "reboot" or "shutdown".
>
> Signed-off-by: Roja Rani Yarubandi <rojay at codeaurora.org>
> ---
> Changes in V2:
> - As per Stephen's comments added seperate function for stop transfer,
> fixed minor nitpicks.
>
> drivers/i2c/busses/i2c-qcom-geni.c | 43 ++++++++++++++++++++++++++++++
> include/linux/qcom-geni-se.h | 5 ++++
> 2 files changed, 48 insertions(+)
>
> diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
> index 1fda5c7c2cfc..d07f2f33bb75 100644
> --- a/drivers/i2c/busses/i2c-qcom-geni.c
> +++ b/drivers/i2c/busses/i2c-qcom-geni.c
> @@ -486,6 +486,28 @@ static int geni_i2c_xfer(struct i2c_adapter *adap,
> return ret;
> }
>
> +static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
> +{
> + u32 val;
> + struct geni_se *se = &gi2c->se;
> +
> + val = readl_relaxed(gi2c->se.base + SE_DMA_DEBUG_REG0);
> + if (val & DMA_TX_ACTIVE) {
> + geni_i2c_abort_xfer(gi2c);
> + gi2c->cur_wr = 0;
> + if (gi2c->err)
> + geni_i2c_tx_fsm_rst(gi2c);
> + geni_se_tx_dma_unprep(se, gi2c->tx_dma, gi2c->xfer_len);
> + }
should be 'else if', because TX and RX can't happen parallel.
> + if (val & DMA_RX_ACTIVE) {
> + geni_i2c_abort_xfer(gi2c);
> + gi2c->cur_rd = 0;
> + if (gi2c->err)
> + geni_i2c_rx_fsm_rst(gi2c);
> + geni_se_rx_dma_unprep(se, gi2c->rx_dma, gi2c->xfer_len);
> + }
> +}
> +
> static u32 geni_i2c_func(struct i2c_adapter *adap)
> {
> return I2C_FUNC_I2C | (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK);
> @@ -617,6 +639,26 @@ static int geni_i2c_remove(struct platform_device *pdev)
> return 0;
> }
>
> +static void geni_i2c_shutdown(struct platform_device *pdev)
> +{
> + int ret;
> + u32 dma;
> + struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
> + struct geni_se *se = &gi2c->se;
> +
> + ret = pm_runtime_get_sync(gi2c->se.dev);
> + if (ret < 0) {
> + dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
> + return;
> + }
> +
> + dma = readl_relaxed(se->base + SE_GENI_DMA_MODE_EN);
Wrt to current issue context it may be suffice to stop just DMA mode
transfers but why not stop all mode of active transfer during shutdown
in a generic way.
Regards,
Akash
> + if (dma)
> + geni_i2c_stop_xfer(gi2c);
> +
> + pm_runtime_put_sync_suspend(gi2c->se.dev);
> +}
> +
> static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
> {
> int ret;
> @@ -677,6 +719,7 @@ MODULE_DEVICE_TABLE(of, geni_i2c_dt_match);
> static struct platform_driver geni_i2c_driver = {
> .probe = geni_i2c_probe,
> .remove = geni_i2c_remove,
> + .shutdown = geni_i2c_shutdown,
> .driver = {
> .name = "geni_i2c",
> .pm = &geni_i2c_pm_ops,
> diff --git a/include/linux/qcom-geni-se.h b/include/linux/qcom-geni-se.h
> index dd464943f717..c3c016496d98 100644
> --- a/include/linux/qcom-geni-se.h
> +++ b/include/linux/qcom-geni-se.h
> @@ -77,6 +77,7 @@ struct geni_se {
> #define SE_DMA_RX_FSM_RST 0xd58
> #define SE_HW_PARAM_0 0xe24
> #define SE_HW_PARAM_1 0xe28
> +#define SE_DMA_DEBUG_REG0 0xe40
>
> /* GENI_FORCE_DEFAULT_REG fields */
> #define FORCE_DEFAULT BIT(0)
> @@ -207,6 +208,10 @@ struct geni_se {
> #define RX_GENI_CANCEL_IRQ BIT(11)
> #define RX_GENI_GP_IRQ_EXT GENMASK(13, 12)
>
> +/* SE_DMA_DEBUG_REG0 Register fields */
> +#define DMA_TX_ACTIVE BIT(0)
> +#define DMA_RX_ACTIVE BIT(1)
> +
> /* SE_HW_PARAM_0 fields */
> #define TX_FIFO_WIDTH_MSK GENMASK(29, 24)
> #define TX_FIFO_WIDTH_SHFT 24
--
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