[PATCH V4 0/2] pinctrl: bcm2835: Implement pin_conf_get

[PATCH V4 0/2] pinctrl: bcm2835: Implement pin_conf_get

[Stefan Wahren]

For years, the Raspberry Pi users relied on userspace programs to read
the pin configuration. In the meantime, it has become apparent that this
approach has reached its limits for various reasons.

This patch series now attempts to improve the debugging possibilities on
the kernel side in order to reduce the dependency on these userspace
programs.

Changes in V4:
- drop PIN_CONFIG_INPUT_ENABLE & PIN_CONFIG_OUTPUT_ENABLE from
  bcm2835_pinconf_get as suggested by Chen-Yu Tsai
- add Florian's Reviewed-by and Tested-by

Changes in V3:
- convert changes to single return point of success as suggested by
  Andy Shevchenko
- justify ENOTSUPP checkpatch false positive

Changes in V2:
- adjust the BCM2711/7211 pull resistor value according to the Broadcom
  datasheet

Stefan Wahren (2):
  pinctrl: bcm2835: Implement bcm2835_pinconf_get
  pinctrl: bcm2835: Implement bcm2711_pinconf_get

 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 64 +++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 3 deletions(-)

--
2.34.1

[PATCH V4 0/2] pinctrl: bcm2835: Implement pin_conf_get

[Stefan Wahren]

For years, the Raspberry Pi users relied on userspace programs to read
the pin configuration. In the meantime, it has become apparent that this
approach has reached its limits for various reasons.

This patch series now attempts to improve the debugging possibilities on
the kernel side in order to reduce the dependency on these userspace
programs.

Changes in V4:
- drop PIN_CONFIG_INPUT_ENABLE & PIN_CONFIG_OUTPUT_ENABLE from
  bcm2835_pinconf_get as suggested by Chen-Yu Tsai
- add Florian's Reviewed-by and Tested-by

Changes in V3:
- convert changes to single return point of success as suggested by
  Andy Shevchenko
- justify ENOTSUPP checkpatch false positive

Changes in V2:
- adjust the BCM2711/7211 pull resistor value according to the Broadcom
  datasheet

Stefan Wahren (2):
  pinctrl: bcm2835: Implement bcm2835_pinconf_get
  pinctrl: bcm2835: Implement bcm2711_pinconf_get

 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 64 +++++++++++++++++++++++++--
 1 file changed, 61 insertions(+), 3 deletions(-)

--
2.34.1


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[PATCH V4 1/2] pinctrl: bcm2835: Implement bcm2835_pinconf_get

[Stefan Wahren]

Even the driver already has implemented pin_dbg_show, it could
be helpful to implement pin_conf_get for a more generic behavior.
Contrary to the BCM2711, the BCM2835 SOC doesn't allow to read
the bias config, so the implementation is limited to the basics.

Keep ENOTSUPP here, because it's only used internally.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
---
 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
index 1489191a213f..5d2b188a1ef4 100644
--- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
@@ -1003,8 +1003,27 @@ static const struct pinmux_ops bcm2835_pmx_ops = {
 static int bcm2835_pinconf_get(struct pinctrl_dev *pctldev,
 			unsigned pin, unsigned long *config)
 {
-	/* No way to read back config in HW */
-	return -ENOTSUPP;
+	enum pin_config_param param = pinconf_to_config_param(*config);
+	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
+	enum bcm2835_fsel fsel = bcm2835_pinctrl_fsel_get(pc, pin);
+	u32 val;
+
+	/* No way to read back bias config in HW */
+
+	switch (param) {
+	case PIN_CONFIG_OUTPUT:
+		if (fsel != BCM2835_FSEL_GPIO_OUT)
+			return -EINVAL;
+
+		val = bcm2835_gpio_get_bit(pc, GPLEV0, pin);
+		*config = pinconf_to_config_packed(param, val);
+		break;
+
+	default:
+		return -ENOTSUPP;
+	}
+
+	return 0;
 }

 static void bcm2835_pull_config_set(struct bcm2835_pinctrl *pc,
--
2.34.1

[PATCH V4 1/2] pinctrl: bcm2835: Implement bcm2835_pinconf_get

[Stefan Wahren]

Even the driver already has implemented pin_dbg_show, it could
be helpful to implement pin_conf_get for a more generic behavior.
Contrary to the BCM2711, the BCM2835 SOC doesn't allow to read
the bias config, so the implementation is limited to the basics.

Keep ENOTSUPP here, because it's only used internally.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
---
 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 23 +++++++++++++++++++++--
 1 file changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
index 1489191a213f..5d2b188a1ef4 100644
--- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
@@ -1003,8 +1003,27 @@ static const struct pinmux_ops bcm2835_pmx_ops = {
 static int bcm2835_pinconf_get(struct pinctrl_dev *pctldev,
 			unsigned pin, unsigned long *config)
 {
-	/* No way to read back config in HW */
-	return -ENOTSUPP;
+	enum pin_config_param param = pinconf_to_config_param(*config);
+	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
+	enum bcm2835_fsel fsel = bcm2835_pinctrl_fsel_get(pc, pin);
+	u32 val;
+
+	/* No way to read back bias config in HW */
+
+	switch (param) {
+	case PIN_CONFIG_OUTPUT:
+		if (fsel != BCM2835_FSEL_GPIO_OUT)
+			return -EINVAL;
+
+		val = bcm2835_gpio_get_bit(pc, GPLEV0, pin);
+		*config = pinconf_to_config_packed(param, val);
+		break;
+
+	default:
+		return -ENOTSUPP;
+	}
+
+	return 0;
 }

 static void bcm2835_pull_config_set(struct bcm2835_pinctrl *pc,
--
2.34.1


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[PATCH V4 2/2] pinctrl: bcm2835: Implement bcm2711_pinconf_get

[Stefan Wahren]

The BCM2711 allows to read the bias config. So implement pin_conf_get
accordingly. The pull resistor values has been taken from the
BCM2711/7211 datasheet.

This implementation assumes that BCM7211 behaves the same way.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 41 ++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
index 5d2b188a1ef4..f5a9372d43bd 100644
--- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
@@ -1098,6 +1098,45 @@ static const struct pinconf_ops bcm2835_pinconf_ops = {
 	.pin_config_set = bcm2835_pinconf_set,
 };

+static int bcm2711_pinconf_get(struct pinctrl_dev *pctldev, unsigned pin,
+			       unsigned long *config)
+{
+	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
+	enum pin_config_param param = pinconf_to_config_param(*config);
+	u32 offset, shift, val;
+
+	offset = PUD_2711_REG_OFFSET(pin);
+	shift = PUD_2711_REG_SHIFT(pin);
+	val = bcm2835_gpio_rd(pc, GP_GPIO_PUP_PDN_CNTRL_REG0 + (offset * 4));
+
+	switch (param) {
+	case PIN_CONFIG_BIAS_DISABLE:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_NONE)
+			return -EINVAL;
+
+		break;
+
+	case PIN_CONFIG_BIAS_PULL_UP:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_UP)
+			return -EINVAL;
+
+		*config = pinconf_to_config_packed(param, 50000);
+		break;
+
+	case PIN_CONFIG_BIAS_PULL_DOWN:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_DOWN)
+			return -EINVAL;
+
+		*config = pinconf_to_config_packed(param, 50000);
+		break;
+
+	default:
+		return bcm2835_pinconf_get(pctldev, pin, config);
+	}
+
+	return 0;
+}
+
 static void bcm2711_pull_config_set(struct bcm2835_pinctrl *pc,
 				    unsigned int pin, unsigned int arg)
 {
@@ -1165,7 +1204,7 @@ static int bcm2711_pinconf_set(struct pinctrl_dev *pctldev,

 static const struct pinconf_ops bcm2711_pinconf_ops = {
 	.is_generic = true,
-	.pin_config_get = bcm2835_pinconf_get,
+	.pin_config_get = bcm2711_pinconf_get,
 	.pin_config_set = bcm2711_pinconf_set,
 };

--
2.34.1

[PATCH V4 2/2] pinctrl: bcm2835: Implement bcm2711_pinconf_get

[Stefan Wahren]

The BCM2711 allows to read the bias config. So implement pin_conf_get
accordingly. The pull resistor values has been taken from the
BCM2711/7211 datasheet.

This implementation assumes that BCM7211 behaves the same way.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Tested-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/pinctrl/bcm/pinctrl-bcm2835.c | 41 ++++++++++++++++++++++++++-
 1 file changed, 40 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/bcm/pinctrl-bcm2835.c b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
index 5d2b188a1ef4..f5a9372d43bd 100644
--- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
+++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
@@ -1098,6 +1098,45 @@ static const struct pinconf_ops bcm2835_pinconf_ops = {
 	.pin_config_set = bcm2835_pinconf_set,
 };

+static int bcm2711_pinconf_get(struct pinctrl_dev *pctldev, unsigned pin,
+			       unsigned long *config)
+{
+	struct bcm2835_pinctrl *pc = pinctrl_dev_get_drvdata(pctldev);
+	enum pin_config_param param = pinconf_to_config_param(*config);
+	u32 offset, shift, val;
+
+	offset = PUD_2711_REG_OFFSET(pin);
+	shift = PUD_2711_REG_SHIFT(pin);
+	val = bcm2835_gpio_rd(pc, GP_GPIO_PUP_PDN_CNTRL_REG0 + (offset * 4));
+
+	switch (param) {
+	case PIN_CONFIG_BIAS_DISABLE:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_NONE)
+			return -EINVAL;
+
+		break;
+
+	case PIN_CONFIG_BIAS_PULL_UP:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_UP)
+			return -EINVAL;
+
+		*config = pinconf_to_config_packed(param, 50000);
+		break;
+
+	case PIN_CONFIG_BIAS_PULL_DOWN:
+		if (((val >> shift) & PUD_2711_MASK) != BCM2711_PULL_DOWN)
+			return -EINVAL;
+
+		*config = pinconf_to_config_packed(param, 50000);
+		break;
+
+	default:
+		return bcm2835_pinconf_get(pctldev, pin, config);
+	}
+
+	return 0;
+}
+
 static void bcm2711_pull_config_set(struct bcm2835_pinctrl *pc,
 				    unsigned int pin, unsigned int arg)
 {
@@ -1165,7 +1204,7 @@ static int bcm2711_pinconf_set(struct pinctrl_dev *pctldev,

 static const struct pinconf_ops bcm2711_pinconf_ops = {
 	.is_generic = true,
-	.pin_config_get = bcm2835_pinconf_get,
+	.pin_config_get = bcm2711_pinconf_get,
 	.pin_config_set = bcm2711_pinconf_set,
 };

--
2.34.1


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Re: [PATCH V4 1/2] pinctrl: bcm2835: Implement bcm2835_pinconf_get

[Chen-Yu Tsai]

On Thu, Mar 7, 2024 at 3:02 PM Stefan Wahren <wahrenst@gmx.net> wrote:
>
> Even the driver already has implemented pin_dbg_show, it could
> be helpful to implement pin_conf_get for a more generic behavior.
> Contrary to the BCM2711, the BCM2835 SOC doesn't allow to read
> the bias config, so the implementation is limited to the basics.
>
> Keep ENOTSUPP here, because it's only used internally.
>
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>

Reviewed-by: Chen-Yu Tsai <wens@csie.org>

Re: [PATCH V4 1/2] pinctrl: bcm2835: Implement bcm2835_pinconf_get

[Chen-Yu Tsai]

On Thu, Mar 7, 2024 at 3:02 PM Stefan Wahren <wahrenst@gmx.net> wrote:
>
> Even the driver already has implemented pin_dbg_show, it could
> be helpful to implement pin_conf_get for a more generic behavior.
> Contrary to the BCM2711, the BCM2835 SOC doesn't allow to read
> the bias config, so the implementation is limited to the basics.
>
> Keep ENOTSUPP here, because it's only used internally.
>
> Signed-off-by: Stefan Wahren <wahrenst@gmx.net>

Reviewed-by: Chen-Yu Tsai <wens@csie.org>

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Re: [PATCH V4 0/2] pinctrl: bcm2835: Implement pin_conf_get

[Linus Walleij]

On Thu, Mar 7, 2024 at 8:01 AM Stefan Wahren <wahrenst@gmx.net> wrote:

> For years, the Raspberry Pi users relied on userspace programs to read
> the pin configuration. In the meantime, it has become apparent that this
> approach has reached its limits for various reasons.
>
> This patch series now attempts to improve the debugging possibilities on
> the kernel side in order to reduce the dependency on these userspace
> programs.

This v4 version applied for kernel v6.10!

Yours,
Linus Walleij

Re: [PATCH V4 0/2] pinctrl: bcm2835: Implement pin_conf_get

[Linus Walleij]

On Thu, Mar 7, 2024 at 8:01 AM Stefan Wahren <wahrenst@gmx.net> wrote:

> For years, the Raspberry Pi users relied on userspace programs to read
> the pin configuration. In the meantime, it has become apparent that this
> approach has reached its limits for various reasons.
>
> This patch series now attempts to improve the debugging possibilities on
> the kernel side in order to reduce the dependency on these userspace
> programs.

This v4 version applied for kernel v6.10!

Yours,
Linus Walleij

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