[v3,4/4] i2c: designware: add i2c gpio recovery option

Message ID 1504073857-122449-5-git-send-email-preid@electromag.com.au
State Changes Requested
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  • i2c: designware: add i2c gpio recovery option
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Commit Message

Phil Reid Aug. 30, 2017, 6:17 a.m.
From: Tim Sander <tim@krieglstein.org>

This patch contains much input from Phil Reid and has been tested
on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
SCL and SDA GPIO's. I am still a little unsure about the recover
in the timeout case (i2c-designware-core.c:770) as i could not
test this codepath.

Signed-off-by: Tim Sander <tim@krieglstein.org>
Signed-off-by: Phil Reid <preid@electromag.com.au>
---
 drivers/i2c/busses/i2c-designware-common.c | 11 ++++--
 drivers/i2c/busses/i2c-designware-core.h   |  1 +
 drivers/i2c/busses/i2c-designware-master.c | 57 ++++++++++++++++++++++++++++++
 3 files changed, 66 insertions(+), 3 deletions(-)

Comments

Andy Shevchenko Sept. 28, 2017, 10:58 a.m. | #1
On Wed, 2017-08-30 at 14:17 +0800, Phil Reid wrote:
> From: Tim Sander <tim@krieglstein.org>
> 
> This patch contains much input from Phil Reid and has been tested
> on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
> SCL and SDA GPIO's. I am still a little unsure about the recover
> in the timeout case (i2c-designware-core.c:770) as i could not
> test this codepath.

 
> -	if (abort_source & DW_IC_TX_ARB_LOST)
> +	if (abort_source & DW_IC_TX_ARB_LOST) {
> +		i2c_recover_bus(&dev->adapter);
>  		return -EAGAIN;

> -	else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
> +	} else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)

else is redundant.

>  		return -EINVAL; /* wrong msgs[] data */
>  	else

Ditto.

>  		return -EIO;

> +static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
> +{
> +	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
> +	struct i2c_adapter *adap = &dev->adapter;
> +	struct gpio_desc *gpio;
> +	int r;
> +
> +	gpio = devm_gpiod_get(dev->dev, "scl", GPIOD_OUT_HIGH);
> +	if (IS_ERR(gpio)) {
> +		r = PTR_ERR(gpio);

> +		if ((r == -ENOENT) || (r == -ENOENT))

Copy'n'paste typo?

> +			return 0;
> +		return r;
> +	}
> +	rinfo->scl_gpiod = gpio;
> +
> +	gpio = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
> +	if (IS_ERR(gpio))
> +		return PTR_ERR(gpio);
> +	rinfo->sda_gpiod = gpio;
> +
> +	rinfo->recover_bus = i2c_generic_scl_recovery;
> +	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
> +	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
> +	adap->bus_recovery_info = rinfo;
> +

> +	dev_info(dev->dev,
> +		"adapter: %s running with gpio recovery mode! scl:%i
> sda:%i\n",
> +		adap->name, !!rinfo->scl_gpiod, !!rinfo->sda_gpiod);

Instead of doing numbers, better just to list available descriptors,
e.g.

...("... %s scl\n", rinfo->sda_gpiod ? "sda,");

No need to explain that scl doesn't need any check here.

And I'm not sure why do you need adap->name here. Can you show an
example of output from your test platform?

> +	if (!ret)
> +		ret = i2c_dw_init_recovery_info(dev);

Better to 
if (ret)
 return ret;

return i2c...();

> +
>  	return ret;
Jarkko Nikula Sept. 28, 2017, 1:21 p.m. | #2
On 08/30/2017 09:17 AM, Phil Reid wrote:
> From: Tim Sander <tim@krieglstein.org>
> 
> This patch contains much input from Phil Reid and has been tested
> on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
> SCL and SDA GPIO's. I am still a little unsure about the recover
> in the timeout case (i2c-designware-core.c:770) as i could not
> test this codepath.
> 
> Signed-off-by: Tim Sander <tim@krieglstein.org>
> Signed-off-by: Phil Reid <preid@electromag.com.au>
> ---
>   drivers/i2c/busses/i2c-designware-common.c | 11 ++++--
>   drivers/i2c/busses/i2c-designware-core.h   |  1 +
>   drivers/i2c/busses/i2c-designware-master.c | 57 ++++++++++++++++++++++++++++++
>   3 files changed, 66 insertions(+), 3 deletions(-)
> 
While taking into account Andy's comments please modify the last 
sentence in the above commit log - i2c-designware-core.c doesn't exist 
anymore. Maybe better is to have the uncertainty documented as a 
"REVISIT:" comment in the code etc.

> @@ -254,9 +258,10 @@ int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
>   	for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
>   		dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);
>   
> -	if (abort_source & DW_IC_TX_ARB_LOST)
> +	if (abort_source & DW_IC_TX_ARB_LOST) {
> +		i2c_recover_bus(&dev->adapter);

Are you sure about doing recovery for arbitration lost case? To me it 
seems wrong to do it if another master is accessing the bus.
Phil Reid Sept. 29, 2017, 7 a.m. | #3
Thanks for the review.

On 28/09/2017 18:58, Andy Shevchenko wrote:
> On Wed, 2017-08-30 at 14:17 +0800, Phil Reid wrote:
>> From: Tim Sander <tim@krieglstein.org>
>>
>> This patch contains much input from Phil Reid and has been tested
>> on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
>> SCL and SDA GPIO's. I am still a little unsure about the recover
>> in the timeout case (i2c-designware-core.c:770) as i could not
>> test this codepath.
> 
>   
>> -	if (abort_source & DW_IC_TX_ARB_LOST)
>> +	if (abort_source & DW_IC_TX_ARB_LOST) {
>> +		i2c_recover_bus(&dev->adapter);
>>   		return -EAGAIN;
> 
>> -	else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
>> +	} else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
> 
> else is redundant.
> 
>>   		return -EINVAL; /* wrong msgs[] data */
>>   	else
> 
> Ditto.
Yep.
> 
>>   		return -EIO;
> 
>> +static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
>> +{
>> +	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
>> +	struct i2c_adapter *adap = &dev->adapter;
>> +	struct gpio_desc *gpio;
>> +	int r;
>> +
>> +	gpio = devm_gpiod_get(dev->dev, "scl", GPIOD_OUT_HIGH);
>> +	if (IS_ERR(gpio)) {
>> +		r = PTR_ERR(gpio);
> 
>> +		if ((r == -ENOENT) || (r == -ENOENT))
> 
> Copy'n'paste typo?
Yep.

> 
>> +			return 0;
>> +		return r;
>> +	}
>> +	rinfo->scl_gpiod = gpio;
>> +
>> +	gpio = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
>> +	if (IS_ERR(gpio))
>> +		return PTR_ERR(gpio);
>> +	rinfo->sda_gpiod = gpio;
>> +
>> +	rinfo->recover_bus = i2c_generic_scl_recovery;
>> +	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
>> +	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
>> +	adap->bus_recovery_info = rinfo;
>> +
> 
>> +	dev_info(dev->dev,
>> +		"adapter: %s running with gpio recovery mode! scl:%i
>> sda:%i\n",
>> +		adap->name, !!rinfo->scl_gpiod, !!rinfo->sda_gpiod);
> 
> Instead of doing numbers, better just to list available descriptors,
> e.g.
> 
> ...("... %s scl\n", rinfo->sda_gpiod ? "sda,");
Ok.

> 
> No need to explain that scl doesn't need any check here.
> 
> And I'm not sure why do you need adap->name here. Can you show an
> example of output from your test platform?

Good question. can't see a need.

> 
>> +	if (!ret)
>> +		ret = i2c_dw_init_recovery_info(dev);
> 
> Better to
> if (ret)
>   return ret;
> 
> return i2c...();
> 
>> +
>>   	return ret;
>
Phil Reid Oct. 6, 2017, 5:56 a.m. | #4
On 28/09/2017 21:21, Jarkko Nikula wrote:
> On 08/30/2017 09:17 AM, Phil Reid wrote:
>> From: Tim Sander <tim@krieglstein.org>
>>
>> This patch contains much input from Phil Reid and has been tested
>> on Intel/Altera Cyclone V SOC Hardware with Altera GPIO's for the
>> SCL and SDA GPIO's. I am still a little unsure about the recover
>> in the timeout case (i2c-designware-core.c:770) as i could not
>> test this codepath.
>>
>> Signed-off-by: Tim Sander <tim@krieglstein.org>
>> Signed-off-by: Phil Reid <preid@electromag.com.au>
>> ---
>>   drivers/i2c/busses/i2c-designware-common.c | 11 ++++--
>>   drivers/i2c/busses/i2c-designware-core.h   |  1 +
>>   drivers/i2c/busses/i2c-designware-master.c | 57 ++++++++++++++++++++++++++++++
>>   3 files changed, 66 insertions(+), 3 deletions(-)
>>
> While taking into account Andy's comments please modify the last sentence in the above commit log - i2c-designware-core.c doesn't exist anymore. Maybe better is 
> to have the uncertainty documented as a "REVISIT:" comment in the code etc.
> 
>> @@ -254,9 +258,10 @@ int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
>>       for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
>>           dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);
>> -    if (abort_source & DW_IC_TX_ARB_LOST)
>> +    if (abort_source & DW_IC_TX_ARB_LOST) {
>> +        i2c_recover_bus(&dev->adapter);
> 
> Are you sure about doing recovery for arbitration lost case? To me it seems wrong to do it if another master is accessing the bus.
> 
yes I think your right.

Patch

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index 3d684c6..e3120987 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -230,7 +230,11 @@  int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev)
 	while (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY) {
 		if (timeout <= 0) {
 			dev_warn(dev->dev, "timeout waiting for bus ready\n");
-			return -ETIMEDOUT;
+			i2c_recover_bus(&dev->adapter);
+
+			if (dw_readl(dev, DW_IC_STATUS) & DW_IC_STATUS_ACTIVITY)
+				return -ETIMEDOUT;
+			return 0;
 		}
 		timeout--;
 		usleep_range(1000, 1100);
@@ -254,9 +258,10 @@  int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
 	for_each_set_bit(i, &abort_source, ARRAY_SIZE(abort_sources))
 		dev_err(dev->dev, "%s: %s\n", __func__, abort_sources[i]);
 
-	if (abort_source & DW_IC_TX_ARB_LOST)
+	if (abort_source & DW_IC_TX_ARB_LOST) {
+		i2c_recover_bus(&dev->adapter);
 		return -EAGAIN;
-	else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
+	} else if (abort_source & DW_IC_TX_ABRT_GCALL_READ)
 		return -EINVAL; /* wrong msgs[] data */
 	else
 		return -EIO;
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index fef44b5..8707c76 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -284,6 +284,7 @@  struct dw_i2c_dev {
 	void			(*disable_int)(struct dw_i2c_dev *dev);
 	int			(*init)(struct dw_i2c_dev *dev);
 	int			mode;
+	struct i2c_bus_recovery_info rinfo;
 };
 
 #define ACCESS_SWAP		0x00000001
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 418c233..07e34fe 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -25,11 +25,13 @@ 
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/export.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 
 #include "i2c-designware-core.h"
 
@@ -443,6 +445,7 @@  static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)
 	if (!wait_for_completion_timeout(&dev->cmd_complete, adap->timeout)) {
 		dev_err(dev->dev, "controller timed out\n");
 		/* i2c_dw_init implicitly disables the adapter */
+		i2c_recover_bus(&dev->adapter);
 		i2c_dw_init_master(dev);
 		ret = -ETIMEDOUT;
 		goto done;
@@ -613,6 +616,57 @@  static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
+static void i2c_dw_prepare_recovery(struct i2c_adapter *adap)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	i2c_dw_disable(dev);
+	reset_control_assert(dev->rst);
+	i2c_dw_prepare_clk(dev, false);
+}
+
+static void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
+
+	i2c_dw_prepare_clk(dev, true);
+	reset_control_deassert(dev->rst);
+	i2c_dw_init_master(dev);
+}
+
+static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
+{
+	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
+	struct i2c_adapter *adap = &dev->adapter;
+	struct gpio_desc *gpio;
+	int r;
+
+	gpio = devm_gpiod_get(dev->dev, "scl", GPIOD_OUT_HIGH);
+	if (IS_ERR(gpio)) {
+		r = PTR_ERR(gpio);
+		if ((r == -ENOENT) || (r == -ENOENT))
+			return 0;
+		return r;
+	}
+	rinfo->scl_gpiod = gpio;
+
+	gpio = devm_gpiod_get_optional(dev->dev, "sda", GPIOD_IN);
+	if (IS_ERR(gpio))
+		return PTR_ERR(gpio);
+	rinfo->sda_gpiod = gpio;
+
+	rinfo->recover_bus = i2c_generic_scl_recovery;
+	rinfo->prepare_recovery = i2c_dw_prepare_recovery;
+	rinfo->unprepare_recovery = i2c_dw_unprepare_recovery;
+	adap->bus_recovery_info = rinfo;
+
+	dev_info(dev->dev,
+		"adapter: %s running with gpio recovery mode! scl:%i sda:%i\n",
+		adap->name, !!rinfo->scl_gpiod, !!rinfo->sda_gpiod);
+
+	return 0;
+}
+
 int i2c_dw_probe(struct dw_i2c_dev *dev)
 {
 	struct i2c_adapter *adap = &dev->adapter;
@@ -664,6 +718,9 @@  int i2c_dw_probe(struct dw_i2c_dev *dev)
 		dev_err(dev->dev, "failure adding adapter: %d\n", ret);
 	pm_runtime_put_noidle(dev->dev);
 
+	if (!ret)
+		ret = i2c_dw_init_recovery_info(dev);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(i2c_dw_probe);