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@xxxxxxxxxxxxxx>
---
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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