Re: Re: [RFC PATCH 2/4] i2c: core: add generic I2C GPIO recovery
> I agree will all your suggestions, except with the removal of if > (bri->recover_bus) . If you agree with this, I can send the next version > and remove the RFC. Yes, sure. That was a brown paper bag thingie from my side. Please go ahead! signature.asc Description: PGP signature
Re: Re: [RFC PATCH 2/4] i2c: core: add generic I2C GPIO recovery
On 02.08.2020 19:54, Wolfram Sang wrote:
> On Fri, Jun 19, 2020 at 05:19:02PM +0300, Codrin Ciubotariu wrote:
>> Multiple I2C bus drivers use similar bindings to obtain information needed
>> for I2C recovery. For example, for platforms using device-tree, the
>> properties look something like this:
>>
>> {
>> ...
>> pinctrl-names = "default", "gpio";
>> // or pinctrl-names = "default", "recovery";
>> pinctrl-0 = <_i2c_default>;
>> pinctrl-1 = <_i2c_gpio>;
>> sda-gpios = < 0 GPIO_ACTIVE_HIGH>;
>> scl-gpios = < 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
>> ...
>> }
>>
>> For this reason, we can add this common initialization in the core. This
>> way, other I2C bus drivers will be able to support GPIO recovery just by
>> providing a pointer to platform's pinctrl and calling i2c_recover_bus()
>> when SDA is stuck low.
>>
>> Signed-off-by: Codrin Ciubotariu
>
> Thanks, it looks a lot like what I had in mind!
>
>> ---
>> drivers/i2c/i2c-core-base.c | 119
>> include/linux/i2c.h | 11
>> 2 files changed, 130 insertions(+)
>>
>> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
>> index d1f278f73011..4ee29fec4e93 100644
>> --- a/drivers/i2c/i2c-core-base.c
>> +++ b/drivers/i2c/i2c-core-base.c
>> @@ -32,6 +32,7 @@
>> #include
>> #include
>> #include
>> +#include
>> #include
>> #include
>> #include
>> @@ -179,6 +180,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
>> struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
>> int i = 0, scl = 1, ret = 0;
>>
>> +if (bri->pinctrl)
>> +pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
>
> I think this should come after 'prepare_recovery'. It may be that
> 'prepare_recovery' already needs to select the pinctrl state to avoid a
> glitch. In this version, there would be a glitch then. If we move it
> down, the doubled 'pinctrl_select_state' would be a noop then.
Agree
>
>> if (bri->prepare_recovery)
>> bri->prepare_recovery(adap);
>>
>> @@ -236,6 +239,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
>>
>> if (bri->unprepare_recovery)
>> bri->unprepare_recovery(adap);
>> +if (bri->pinctrl)
>> +pinctrl_select_state(bri->pinctrl, bri->pins_default);
>
> Here it is OK and will still work with the PXA version which needs to
> select the state on its own.
>
>>
>> return ret;
>> }
>> @@ -251,6 +256,118 @@ int i2c_recover_bus(struct i2c_adapter *adap)
>> }
>> EXPORT_SYMBOL_GPL(i2c_recover_bus);
>>
>> +static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
>> +{
>> +struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
>> +struct device *dev = >dev;
>> +struct pinctrl *p = bri->pinctrl;
>> +
>> +/*
>> + * we can't change states without pinctrl, so remove the states if
>> + * available
>
> s/available/populated/ ?
OK
>
>> + */
>> +if (!p) {
>> +bri->pins_default = NULL;
>> +bri->pins_gpio = NULL;
>> +return;
>> +}
>> +
>> +if (!bri->pins_default) {
>> +bri->pins_default = pinctrl_lookup_state(p,
>> + PINCTRL_STATE_DEFAULT);
>> +if (IS_ERR(bri->pins_default)) {
>> +dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found
>> for GPIO recovery\n");
>> +bri->pins_default = NULL;
>> +
>> +goto cleanup_pinctrl;
>
> I'd leave out the goto here. It is OK to check both parameters, I think.
since default state is missing, the next check can be skipped, but I
agree that removing the label makes things easier to read.
>
>> +}
>> +}
>> +if (!bri->pins_gpio) {
>> +bri->pins_gpio = pinctrl_lookup_state(p, "gpio");
>> +if (IS_ERR(bri->pins_gpio))
>> +bri->pins_gpio = pinctrl_lookup_state(p, "recovery");
>> +
>> +if (IS_ERR(bri->pins_gpio)) {
>> +dev_dbg(dev, "no gpio or recovery state found for GPIO
>> recovery\n");
>> +bri->pins_gpio = NULL;
>> +
>> +goto cleanup_pinctrl;
>
> This goto is not needed...
right
>
>> +}
>> +}
>> +
>> +cleanup_pinctrl:
>
> ... and this label can go then. Also nicer to read, I'd say.
I will remove it.
>
>> +/* for pinctrl state changes, we need all the information */
>> +if (!bri->pins_default || !bri->pins_gpio) {
>> +bri->pinctrl = NULL;
>> +bri->pins_default = NULL;
>> +bri->pins_gpio = NULL;
>> +} else {
>> +dev_info(dev, "using pinctrl states for GPIO recovery");
>> +}
>> +}
>> +
>> +static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
>> +{
>> +struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
>> +struct
Re: [RFC PATCH 2/4] i2c: core: add generic I2C GPIO recovery
On Fri, Jun 19, 2020 at 05:19:02PM +0300, Codrin Ciubotariu wrote:
> Multiple I2C bus drivers use similar bindings to obtain information needed
> for I2C recovery. For example, for platforms using device-tree, the
> properties look something like this:
>
> {
> ...
> pinctrl-names = "default", "gpio";
> // or pinctrl-names = "default", "recovery";
> pinctrl-0 = <_i2c_default>;
> pinctrl-1 = <_i2c_gpio>;
> sda-gpios = < 0 GPIO_ACTIVE_HIGH>;
> scl-gpios = < 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
> ...
> }
>
> For this reason, we can add this common initialization in the core. This
> way, other I2C bus drivers will be able to support GPIO recovery just by
> providing a pointer to platform's pinctrl and calling i2c_recover_bus()
> when SDA is stuck low.
>
> Signed-off-by: Codrin Ciubotariu
Thanks, it looks a lot like what I had in mind!
> ---
> drivers/i2c/i2c-core-base.c | 119
> include/linux/i2c.h | 11
> 2 files changed, 130 insertions(+)
>
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index d1f278f73011..4ee29fec4e93 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -32,6 +32,7 @@
> #include
> #include
> #include
> +#include
> #include
> #include
> #include
> @@ -179,6 +180,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
> struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> int i = 0, scl = 1, ret = 0;
>
> + if (bri->pinctrl)
> + pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
I think this should come after 'prepare_recovery'. It may be that
'prepare_recovery' already needs to select the pinctrl state to avoid a
glitch. In this version, there would be a glitch then. If we move it
down, the doubled 'pinctrl_select_state' would be a noop then.
> if (bri->prepare_recovery)
> bri->prepare_recovery(adap);
>
> @@ -236,6 +239,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
>
> if (bri->unprepare_recovery)
> bri->unprepare_recovery(adap);
> + if (bri->pinctrl)
> + pinctrl_select_state(bri->pinctrl, bri->pins_default);
Here it is OK and will still work with the PXA version which needs to
select the state on its own.
>
> return ret;
> }
> @@ -251,6 +256,118 @@ int i2c_recover_bus(struct i2c_adapter *adap)
> }
> EXPORT_SYMBOL_GPL(i2c_recover_bus);
>
> +static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
> +{
> + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> + struct device *dev = >dev;
> + struct pinctrl *p = bri->pinctrl;
> +
> + /*
> + * we can't change states without pinctrl, so remove the states if
> + * available
s/available/populated/ ?
> + */
> + if (!p) {
> + bri->pins_default = NULL;
> + bri->pins_gpio = NULL;
> + return;
> + }
> +
> + if (!bri->pins_default) {
> + bri->pins_default = pinctrl_lookup_state(p,
> + PINCTRL_STATE_DEFAULT);
> + if (IS_ERR(bri->pins_default)) {
> + dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found
> for GPIO recovery\n");
> + bri->pins_default = NULL;
> +
> + goto cleanup_pinctrl;
I'd leave out the goto here. It is OK to check both parameters, I think.
> + }
> + }
> + if (!bri->pins_gpio) {
> + bri->pins_gpio = pinctrl_lookup_state(p, "gpio");
> + if (IS_ERR(bri->pins_gpio))
> + bri->pins_gpio = pinctrl_lookup_state(p, "recovery");
> +
> + if (IS_ERR(bri->pins_gpio)) {
> + dev_dbg(dev, "no gpio or recovery state found for GPIO
> recovery\n");
> + bri->pins_gpio = NULL;
> +
> + goto cleanup_pinctrl;
This goto is not needed...
> + }
> + }
> +
> +cleanup_pinctrl:
... and this label can go then. Also nicer to read, I'd say.
> + /* for pinctrl state changes, we need all the information */
> + if (!bri->pins_default || !bri->pins_gpio) {
> + bri->pinctrl = NULL;
> + bri->pins_default = NULL;
> + bri->pins_gpio = NULL;
> + } else {
> + dev_info(dev, "using pinctrl states for GPIO recovery");
> + }
> +}
> +
> +static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
> +{
> + struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
> + struct device *dev = >dev;
> + struct gpio_desc *gpiod;
> + int ret = 0;
> +
> + /* don't touch the recovery information if the driver is not using
> + * generic SCL recovery
> + */
Not kernel comment style.
> + if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery)
> + return 0;
No
[RFC PATCH 2/4] i2c: core: add generic I2C GPIO recovery
Multiple I2C bus drivers use similar bindings to obtain information needed
for I2C recovery. For example, for platforms using device-tree, the
properties look something like this:
{
...
pinctrl-names = "default", "gpio";
// or pinctrl-names = "default", "recovery";
pinctrl-0 = <_i2c_default>;
pinctrl-1 = <_i2c_gpio>;
sda-gpios = < 0 GPIO_ACTIVE_HIGH>;
scl-gpios = < 1 (GPIO_ACTIVE_HIGH | GPIO_OPEN_DRAIN)>;
...
}
For this reason, we can add this common initialization in the core. This
way, other I2C bus drivers will be able to support GPIO recovery just by
providing a pointer to platform's pinctrl and calling i2c_recover_bus()
when SDA is stuck low.
Signed-off-by: Codrin Ciubotariu
---
drivers/i2c/i2c-core-base.c | 119
include/linux/i2c.h | 11
2 files changed, 130 insertions(+)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index d1f278f73011..4ee29fec4e93 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -32,6 +32,7 @@
#include
#include
#include
+#include
#include
#include
#include
@@ -179,6 +180,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
int i = 0, scl = 1, ret = 0;
+ if (bri->pinctrl)
+ pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
if (bri->prepare_recovery)
bri->prepare_recovery(adap);
@@ -236,6 +239,8 @@ int i2c_generic_scl_recovery(struct i2c_adapter *adap)
if (bri->unprepare_recovery)
bri->unprepare_recovery(adap);
+ if (bri->pinctrl)
+ pinctrl_select_state(bri->pinctrl, bri->pins_default);
return ret;
}
@@ -251,6 +256,118 @@ int i2c_recover_bus(struct i2c_adapter *adap)
}
EXPORT_SYMBOL_GPL(i2c_recover_bus);
+static void i2c_gpio_init_pinctrl_recovery(struct i2c_adapter *adap)
+{
+ struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+ struct device *dev = >dev;
+ struct pinctrl *p = bri->pinctrl;
+
+ /*
+* we can't change states without pinctrl, so remove the states if
+* available
+*/
+ if (!p) {
+ bri->pins_default = NULL;
+ bri->pins_gpio = NULL;
+ return;
+ }
+
+ if (!bri->pins_default) {
+ bri->pins_default = pinctrl_lookup_state(p,
+PINCTRL_STATE_DEFAULT);
+ if (IS_ERR(bri->pins_default)) {
+ dev_dbg(dev, PINCTRL_STATE_DEFAULT " state not found
for GPIO recovery\n");
+ bri->pins_default = NULL;
+
+ goto cleanup_pinctrl;
+ }
+ }
+ if (!bri->pins_gpio) {
+ bri->pins_gpio = pinctrl_lookup_state(p, "gpio");
+ if (IS_ERR(bri->pins_gpio))
+ bri->pins_gpio = pinctrl_lookup_state(p, "recovery");
+
+ if (IS_ERR(bri->pins_gpio)) {
+ dev_dbg(dev, "no gpio or recovery state found for GPIO
recovery\n");
+ bri->pins_gpio = NULL;
+
+ goto cleanup_pinctrl;
+ }
+ }
+
+cleanup_pinctrl:
+ /* for pinctrl state changes, we need all the information */
+ if (!bri->pins_default || !bri->pins_gpio) {
+ bri->pinctrl = NULL;
+ bri->pins_default = NULL;
+ bri->pins_gpio = NULL;
+ } else {
+ dev_info(dev, "using pinctrl states for GPIO recovery");
+ }
+}
+
+static int i2c_gpio_init_generic_recovery(struct i2c_adapter *adap)
+{
+ struct i2c_bus_recovery_info *bri = adap->bus_recovery_info;
+ struct device *dev = >dev;
+ struct gpio_desc *gpiod;
+ int ret = 0;
+
+ /* don't touch the recovery information if the driver is not using
+* generic SCL recovery
+*/
+ if (bri->recover_bus && bri->recover_bus != i2c_generic_scl_recovery)
+ return 0;
+
+ /*
+* pins might be taken as GPIO, so we might as well inform pinctrl about
+* this and move the state to GPIO
+*/
+ if (bri->pinctrl)
+ pinctrl_select_state(bri->pinctrl, bri->pins_gpio);
+
+ /*
+* if there is incomplete or no recovery information, see if generic
+* GPIO recovery is available
+*/
+ if (!bri->scl_gpiod) {
+ gpiod = devm_gpiod_get(dev, "scl", GPIOD_OUT_HIGH_OPEN_DRAIN);
+ if (PTR_ERR(gpiod) == -EPROBE_DEFER) {
+ ret = -EPROBE_DEFER;
+ goto cleanup_pinctrl_state;
+ }
+ if (!IS_ERR(gpiod)) {
+ bri->scl_gpiod = gpiod;
+ bri->recover_bus = i2c_generic_scl_recovery;
+
