[PATCH V7 0/2] Implement Shutdown callback for geni-i2c

[PATCH V7 0/2] Implement Shutdown callback for geni-i2c

[Roja Rani Yarubandi]

Hi,

Posting V7 with comments answering.

Roja Rani Yarubandi (2):
  i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct
  i2c: i2c-qcom-geni: Add shutdown callback for i2c

 drivers/i2c/busses/i2c-qcom-geni.c | 94 +++++++++++++++++++++++++-----
 1 file changed, 78 insertions(+), 16 deletions(-)

-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member 
of Code Aurora Forum, hosted by The Linux Foundation

[PATCH V7 1/2] i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct

[Roja Rani Yarubandi]

Store DMA mapping data in geni_i2c_dev struct to enhance DMA mapping
data scope. For example during shutdown callback to unmap DMA mapping,
this stored DMA mapping data can be used to call geni_se_tx_dma_unprep
and geni_se_rx_dma_unprep functions.

Add two helper functions geni_i2c_rx_msg_cleanup and
geni_i2c_tx_msg_cleanup 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.

Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
---
Changes in V5:
 - As per Stephen's comments separated this patch from shutdown
   callback patch, gi2c->cur = NULL is not removed from
   geni_i2c_abort_xfer(), and made a copy of gi2c->cur and passed
   to cleanup functions.

Changes in V6:
 - Added spin_lock/unlock in geni_i2c_rx_msg_cleanup() and
   geni_i2c_tx_msg_cleanup() functions.

Changes in V7:
 - As per Akash's comments analysed the race chances and removed
   spin lock in cleanup functions.

 drivers/i2c/busses/i2c-qcom-geni.c | 59 ++++++++++++++++++++++--------
 1 file changed, 43 insertions(+), 16 deletions(-)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 046d241183c5..214b4c913a13 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -86,6 +86,9 @@ struct geni_i2c_dev {
 	u32 clk_freq_out;
 	const struct geni_i2c_clk_fld *clk_fld;
 	int suspended;
+	void *dma_buf;
+	size_t xfer_len;
+	dma_addr_t dma_addr;
 };
 
 struct geni_i2c_err_log {
@@ -348,14 +351,39 @@ static void geni_i2c_tx_fsm_rst(struct geni_i2c_dev *gi2c)
 		dev_err(gi2c->se.dev, "Timeout resetting TX_FSM\n");
 }
 
+static void geni_i2c_rx_msg_cleanup(struct geni_i2c_dev *gi2c,
+				     struct i2c_msg *cur)
+{
+	gi2c->cur_rd = 0;
+	if (gi2c->dma_buf) {
+		if (gi2c->err)
+			geni_i2c_rx_fsm_rst(gi2c);
+		geni_se_rx_dma_unprep(&gi2c->se, gi2c->dma_addr, gi2c->xfer_len);
+		i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
+	}
+}
+
+static void geni_i2c_tx_msg_cleanup(struct geni_i2c_dev *gi2c,
+				     struct i2c_msg *cur)
+{
+	gi2c->cur_wr = 0;
+	if (gi2c->dma_buf) {
+		if (gi2c->err)
+			geni_i2c_tx_fsm_rst(gi2c);
+		geni_se_tx_dma_unprep(&gi2c->se, gi2c->dma_addr, gi2c->xfer_len);
+		i2c_put_dma_safe_msg_buf(gi2c->dma_buf, cur, !gi2c->err);
+	}
+}
+
 static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 				u32 m_param)
 {
-	dma_addr_t rx_dma;
+	dma_addr_t rx_dma = 0;
 	unsigned long time_left;
 	void *dma_buf;
 	struct geni_se *se = &gi2c->se;
 	size_t len = msg->len;
+	struct i2c_msg *cur;
 
 	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
 	if (dma_buf)
@@ -370,19 +398,18 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 		geni_se_select_mode(se, GENI_SE_FIFO);
 		i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
 		dma_buf = NULL;
+	} else {
+		gi2c->xfer_len = len;
+		gi2c->dma_addr = rx_dma;
+		gi2c->dma_buf = dma_buf;
 	}
 
+	cur = gi2c->cur;
 	time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
 	if (!time_left)
 		geni_i2c_abort_xfer(gi2c);
 
-	gi2c->cur_rd = 0;
-	if (dma_buf) {
-		if (gi2c->err)
-			geni_i2c_rx_fsm_rst(gi2c);
-		geni_se_rx_dma_unprep(se, rx_dma, len);
-		i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
-	}
+	geni_i2c_rx_msg_cleanup(gi2c, cur);
 
 	return gi2c->err;
 }
@@ -390,11 +417,12 @@ static int geni_i2c_rx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 				u32 m_param)
 {
-	dma_addr_t tx_dma;
+	dma_addr_t tx_dma = 0;
 	unsigned long time_left;
 	void *dma_buf;
 	struct geni_se *se = &gi2c->se;
 	size_t len = msg->len;
+	struct i2c_msg *cur;
 
 	dma_buf = i2c_get_dma_safe_msg_buf(msg, 32);
 	if (dma_buf)
@@ -409,22 +437,21 @@ static int geni_i2c_tx_one_msg(struct geni_i2c_dev *gi2c, struct i2c_msg *msg,
 		geni_se_select_mode(se, GENI_SE_FIFO);
 		i2c_put_dma_safe_msg_buf(dma_buf, msg, false);
 		dma_buf = NULL;
+	} else {
+		gi2c->xfer_len = len;
+		gi2c->dma_addr = tx_dma;
+		gi2c->dma_buf = dma_buf;
 	}
 
 	if (!dma_buf) /* Get FIFO IRQ */
 		writel_relaxed(1, se->base + SE_GENI_TX_WATERMARK_REG);
 
+	cur = gi2c->cur;
 	time_left = wait_for_completion_timeout(&gi2c->done, XFER_TIMEOUT);
 	if (!time_left)
 		geni_i2c_abort_xfer(gi2c);
 
-	gi2c->cur_wr = 0;
-	if (dma_buf) {
-		if (gi2c->err)
-			geni_i2c_tx_fsm_rst(gi2c);
-		geni_se_tx_dma_unprep(se, tx_dma, len);
-		i2c_put_dma_safe_msg_buf(dma_buf, msg, !gi2c->err);
-	}
+	geni_i2c_tx_msg_cleanup(gi2c, cur);
 
 	return gi2c->err;
 }
-- 
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member 
of Code Aurora Forum, hosted by The Linux Foundation

Re: [PATCH V7 1/2] i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct

[Akash Asthana]

On 12/21/2020 6:08 PM, Roja Rani Yarubandi wrote:
> Store DMA mapping data in geni_i2c_dev struct to enhance DMA mapping
> data scope. For example during shutdown callback to unmap DMA mapping,
> this stored DMA mapping data can be used to call geni_se_tx_dma_unprep
> and geni_se_rx_dma_unprep functions.
>
> Add two helper functions geni_i2c_rx_msg_cleanup and
> geni_i2c_tx_msg_cleanup 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.
>
> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>
Reviewed-by: Akash Asthana <akashast@codeaurora.org>

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project

Re: [PATCH V7 1/2] i2c: i2c-qcom-geni: Store DMA mapping data in geni_i2c_dev struct

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 663 bytes --]

On Mon, Dec 21, 2020 at 06:08:00PM +0530, Roja Rani Yarubandi wrote:
> Store DMA mapping data in geni_i2c_dev struct to enhance DMA mapping
> data scope. For example during shutdown callback to unmap DMA mapping,
> this stored DMA mapping data can be used to call geni_se_tx_dma_unprep
> and geni_se_rx_dma_unprep functions.
> 
> Add two helper functions geni_i2c_rx_msg_cleanup and
> geni_i2c_tx_msg_cleanup 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.
> 
> Signed-off-by: Roja Rani Yarubandi <rojay@codeaurora.org>

Applied to for-next, thanks!


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[PATCH V7 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

[Roja Rani Yarubandi]

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.

Changes in V6:
 - As per Stephen's comments, taken care of unsafe lock order in
   geni_i2c_stop_xfer().
 - Moved spin_lock/unlock to geni_i2c_rx_msg_cleanup() and
   geni_i2c_tx_msg_cleanup() functions.

Changes in V7:
 - No changes 

 drivers/i2c/busses/i2c-qcom-geni.c | 35 ++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/i2c/busses/i2c-qcom-geni.c b/drivers/i2c/busses/i2c-qcom-geni.c
index 214b4c913a13..7903e6145543 100644
--- a/drivers/i2c/busses/i2c-qcom-geni.c
+++ b/drivers/i2c/busses/i2c-qcom-geni.c
@@ -375,6 +375,33 @@ 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;
+	struct i2c_msg *cur;
+
+	/* Resume device, as 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;
+	}
+
+	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);
+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)
 {
@@ -650,6 +677,13 @@ 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;
@@ -714,6 +748,7 @@ 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

Re: [PATCH V7 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

[Akash Asthana]

On 12/21/2020 6:08 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 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>
Reviewed-by: Akash Asthana <akashast@codeaurora.org>

-- 
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,\na Linux Foundation Collaborative Project

Re: [PATCH V7 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 696 bytes --]


> +	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);
> +out:
> +	pm_runtime_put_sync_suspend(gi2c->se.dev);
> +}

The use of 'goto' is not needed here IMHO. I think:

	if (geni_status & M_GENI_CMD_ACTIVE) {
		do_the_stuff
	}

	pm_runtime_put_sync_suspend(...);

is more readable, in fact. Also, I don't think we really need the 'cur'
variable and just use 'gi2c->cur' but that's very minor and you can keep
it if you like it.

Reset looks good!


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Re: [PATCH V7 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

[rojay]

Hi Wolfram,

On 2021-01-05 20:57, Wolfram Sang wrote:
>> +	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);
>> +out:
>> +	pm_runtime_put_sync_suspend(gi2c->se.dev);
>> +}
> 
> The use of 'goto' is not needed here IMHO. I think:
> 
> 	if (geni_status & M_GENI_CMD_ACTIVE) {
> 		do_the_stuff
> 	}
> 
> 	pm_runtime_put_sync_suspend(...);
> 
> is more readable, in fact.
> 

In context to the previous comment [1], I have implemented this way.
But, yeah anything is fine for me.

> Also, I don't think we really need the 'cur'
> variable and just use 'gi2c->cur' but that's very minor and you can 
> keep
> it if you like it.
> 

In geni_i2c_abort_xfer() function gi2c->cur will be made NULL, so 
copying it before to "cur" is needed here.

> Reset looks good!

[1] 
https://patchwork.kernel.org/project/linux-arm-msm/patch/20200820103522.26242-3-rojay@codeaurora.org/#23560541

Thanks,
Roja

Re: [PATCH V7 2/2] i2c: i2c-qcom-geni: Add shutdown callback for i2c

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 359 bytes --]


> > The use of 'goto' is not needed here IMHO. I think:
...
> In context to the previous comment [1], I have implemented this way.
> But, yeah anything is fine for me.

Thanks, I really think it is better.

> In geni_i2c_abort_xfer() function gi2c->cur will be made NULL, so copying it
> before to "cur" is needed here.

Okay then, thanks for the heads up!


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