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Subject[PATCH V5 3/3] i2c: i2c-qcom-geni: Add shutdown callback for i2c
Date
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 stop on-going transfer
and unmap DMA mappings during system "reboot" or "shutdown".

Fixes: 37692de5d523 ("i2c: i2c-qcom-geni: Add bus driver for the Qualcomm GENI I2C controller")
Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
---
Changes in V2:
- As per Stephen's comments added seperate function for stop transfer,
fixed minor nitpicks.
- As per Stephen's comments, changed commit text.

Changes in V3:
- As per Stephen's comments, squashed patch 1 into patch 2, added Fixes tag.
- As per Akash's comments, included FIFO case in stop_xfer, fixed minor nitpicks.

Changes in V4:
- As per Stephen's comments cleaned up geni_i2c_stop_xfer function,
added dma_buf in geni_i2c_dev struct to call i2c_put_dma_safe_msg_buf()
from other functions, removed "iova" check in geni_se_rx_dma_unprep()
and geni_se_tx_dma_unprep() functions.
- Added two helper functions geni_i2c_rx_one_msg_done() and
geni_i2c_tx_one_msg_done() to unwrap the things after rx/tx FIFO/DMA
transfers, so that the same can be used in geni_i2c_stop_xfer() function
during shutdown callback. Updated commit text accordingly.
- Checking whether it is tx/rx transfer using I2C_M_RD which is valid for both
FIFO and DMA cases, so dropped DMA_RX_ACTIVE and DMA_TX_ACTIVE bit checking

Changes in V5:
- As per Stephen's comments, added spin_lock_irqsave & spin_unlock_irqsave in
geni_i2c_stop_xfer() function.

drivers/i2c/busses/i2c-qcom-geni.c | 38 ++++++++++++++++++++++++++++++
1 file changed, 38 insertions(+)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index aee2a1dd2c62..56d3fbfe7eb6 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -380,6 +380,36 @@ static void geni_i2c_tx_msg_cleanup(struct geni_i2c_dev *gi2c,
}
}

+static void geni_i2c_stop_xfer(struct geni_i2c_dev *gi2c)
+{
+ int ret;
+ u32 geni_status;
+ unsigned long flags;
+ struct i2c_msg *cur;
+
+ /* Resume device, runtime suspend can happen anytime during transfer */
+ ret = pm_runtime_get_sync(gi2c->se.dev);
+ if (ret < 0) {
+ dev_err(gi2c->se.dev, "Failed to resume device: %d\n", ret);
+ return;
+ }
+
+ spin_lock_irqsave(&gi2c->lock, flags);
+ geni_status = readl_relaxed(gi2c->se.base + SE_GENI_STATUS);
+ if (!(geni_status & M_GENI_CMD_ACTIVE))
+ goto out;
+
+ cur = gi2c->cur;
+ geni_i2c_abort_xfer(gi2c);
+ if (cur->flags & I2C_M_RD)
+ geni_i2c_rx_msg_cleanup(gi2c, cur);
+ else
+ geni_i2c_tx_msg_cleanup(gi2c, cur);
+ spin_unlock_irqrestore(&gi2c->lock, flags);
+out:
+ pm_runtime_put_sync_suspend(gi2c->se.dev);
+}
+
static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
u32 m_param)
{
@@ -661,6 +691,13 @@ static int geni_i2c_remove(struct platform_device *pdev)
return 0;
}

+static void geni_i2c_shutdown(struct platform_device *pdev)
+{
+ struct geni_i2c_dev *gi2c = platform_get_drvdata(pdev);
+
+ geni_i2c_stop_xfer(gi2c);
+}
+
static int __maybe_unused geni_i2c_runtime_suspend(struct device *dev)
{
int ret;
@@ -725,6 +762,7 @@ 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,
--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member
of Code Aurora Forum, hosted by The Linux Foundation
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