[PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

[PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

[Helmut Grohne]

The DA9062 can be the device used to power the CPU. In that case, it can
be used to power off the system. In the CONTROL_A register, the M_*_EN
bits must be zero for the corresponding *_EN bits to have an effect. We
zero them all to turn off the system.

Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
---
 drivers/mfd/da9062-core.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

This series effectively is a rebased resend. The earlier posting was
https://lore.kernel.org/all/20200107120559.GA700@laureti-dev/. At that time,
Adam Thomson critisized the use of regmap and i2c inside a pm_power_off hook
since irqs are disabled. He reached out to Lee Jones, who asked Mark Brown and
Wolfram Sang, but never got any reply. I noted that a fair number of other
drivers do use regmap and i2c despite this issue. In the mean time, more
instances were added:
 * drivers/mfd/acer-ec-a500.c uses i2c
 * drivers/mfd/ntxec.c uses i2c
 * drivers/mfd/rk808.c uses regmap and i2c
Given that we proceeded with accepting the use of i2c and regmap inside
pm_power_off hooks, I think we can proceed with this patch as well.

Helmut

diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c
index 2774b2cbaea6..e7af5b5f16e0 100644
--- a/drivers/mfd/da9062-core.c
+++ b/drivers/mfd/da9062-core.c
@@ -620,6 +620,23 @@ static const struct of_device_id da9062_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, da9062_dt_ids);
 
+/* Hold client since pm_power_off is global. */
+static struct i2c_client *da9062_i2c_client;
+
+static void da9062_power_off(void)
+{
+	struct da9062 *chip = i2c_get_clientdata(da9062_i2c_client);
+	const unsigned int mask = DA9062AA_SYSTEM_EN_MASK |
+		DA9062AA_POWER_EN_MASK | DA9062AA_POWER1_EN_MASK |
+		DA9062AA_M_SYSTEM_EN_MASK | DA9062AA_M_POWER_EN_MASK |
+		DA9062AA_M_POWER1_EN_MASK;
+	int ret = regmap_update_bits(chip->regmap, DA9062AA_CONTROL_A, mask, 0);
+
+	if (ret < 0)
+		dev_err(&da9062_i2c_client->dev,
+			"DA9062AA_CONTROL_A update failed, %d\n", ret);
+}
+
 static int da9062_i2c_probe(struct i2c_client *i2c,
 	const struct i2c_device_id *id)
 {
@@ -720,6 +737,15 @@ static int da9062_i2c_probe(struct i2c_client *i2c,
 		return ret;
 	}
 
+	if (of_device_is_system_power_controller(i2c->dev.of_node)) {
+		if (!pm_power_off) {
+			da9062_i2c_client = i2c;
+			pm_power_off = da9062_power_off;
+		} else {
+			dev_warn(&i2c->dev, "Poweroff callback already assigned\n");
+		}
+	}
+
 	return ret;
 }
 
@@ -727,6 +753,11 @@ static int da9062_i2c_remove(struct i2c_client *i2c)
 {
 	struct da9062 *chip = i2c_get_clientdata(i2c);
 
+	if (pm_power_off == da9062_power_off)
+		pm_power_off = NULL;
+	if (da9062_i2c_client)
+		da9062_i2c_client = NULL;
+
 	mfd_remove_devices(chip->dev);
 	regmap_del_irq_chip(i2c->irq, chip->regmap_irq);
 
-- 
2.20.1

Dipl.-Inf. Helmut Grohne
Research and Development
Application Engineering
 
Phone: +49 (371) 24354 0 ∙ Fax:  +49 (371) 24354 020
helmut.grohne@intenta.de ∙ https://www.intenta.de
 
Intenta GmbH ∙ Ahornstraße 55 ∙ 09112 Chemnitz, Germany
Managing Director: Dr.-Ing. Basel Fardi ∙ VAT/USt-IdNr.: DE 275745394
Commercial register: HRB 26404 Amtsgericht Chemnitz

[PATCH v2 2/2] dt-bindings: mfd: da9062 can be a system power controller

[Helmut Grohne]

The DA9062 can be used to power off a system if it is appropriately
wired.

Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
---
 Documentation/devicetree/bindings/mfd/da9062.txt | 1 +
 1 file changed, 1 insertion(+)

This series effectively is a rebased resend. The earlier posting was
https://lore.kernel.org/all/20200107120613.GA746@laureti-dev/. Back then, this
patch was Acked-by: Rob Herring, but I'm not including that ack here, because
this patch required a non-trivial rebase.

Helmut

diff --git a/Documentation/devicetree/bindings/mfd/da9062.txt b/Documentation/devicetree/bindings/mfd/da9062.txt
index bab0d0e66cb3..4861c3ad97e9 100644
--- a/Documentation/devicetree/bindings/mfd/da9062.txt
+++ b/Documentation/devicetree/bindings/mfd/da9062.txt
@@ -41,6 +41,7 @@ further information on IRQ bindings.
 
 Optional properties:
 
+- system-power-controller
 - gpio-controller : Marks the device as a gpio controller.
 - #gpio-cells     : Should be two. The first cell is the pin number and the
                     second cell is used to specify the gpio polarity.
-- 
2.20.1

Dipl.-Inf. Helmut Grohne
Research and Development
Application Engineering
 
Phone: +49 (371) 24354 0 ∙ Fax:  +49 (371) 24354 020
helmut.grohne@intenta.de ∙ https://www.intenta.de
 
Intenta GmbH ∙ Ahornstraße 55 ∙ 09112 Chemnitz, Germany
Managing Director: Dr.-Ing. Basel Fardi ∙ VAT/USt-IdNr.: DE 275745394
Commercial register: HRB 26404 Amtsgericht Chemnitz

Re: [PATCH v2 2/2] dt-bindings: mfd: da9062 can be a system power controller

[Rob Herring]

On Fri, 22 Apr 2022 08:16:55 +0200, Helmut Grohne wrote:
> The DA9062 can be used to power off a system if it is appropriately
> wired.
> 
> Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
> ---
>  Documentation/devicetree/bindings/mfd/da9062.txt | 1 +
>  1 file changed, 1 insertion(+)
> 
> This series effectively is a rebased resend. The earlier posting was
> https://lore.kernel.org/all/20200107120613.GA746@laureti-dev/. Back then, this
> patch was Acked-by: Rob Herring, but I'm not including that ack here, because
> this patch required a non-trivial rebase.
> 
> Helmut
> 

Acked-by: Rob Herring <robh@kernel.org>

RE: [PATCH v2 2/2] dt-bindings: mfd: da9062 can be a system power controller

[DLG Adam Thomson]

On 22 April 2022 07:17, Helmut Grohne wrote:

> The DA9062 can be used to power off a system if it is appropriately
> wired.
> 
> Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>

Reviewed-by: Adam Thomson <DLG-Adam.Thomson.Opensource@dm.renesas.com>

RE: [PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

[DLG Adam Thomson]

On 22 April 2022 07:17, Helmut Grohne wrote:

> The DA9062 can be the device used to power the CPU. In that case, it can
> be used to power off the system. In the CONTROL_A register, the M_*_EN
> bits must be zero for the corresponding *_EN bits to have an effect. We
> zero them all to turn off the system.
> 
> Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
> ---
>  drivers/mfd/da9062-core.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> This series effectively is a rebased resend. The earlier posting was
> https://lore.kernel.org/all/20200107120559.GA700@laureti-dev/. At that time,
> Adam Thomson critisized the use of regmap and i2c inside a pm_power_off hook
> since irqs are disabled. He reached out to Lee Jones, who asked Mark Brown and
> Wolfram Sang, but never got any reply. I noted that a fair number of other
> drivers do use regmap and i2c despite this issue. In the mean time, more
> instances were added:
>  * drivers/mfd/acer-ec-a500.c uses i2c
>  * drivers/mfd/ntxec.c uses i2c
>  * drivers/mfd/rk808.c uses regmap and i2c
> Given that we proceeded with accepting the use of i2c and regmap inside
> pm_power_off hooks, I think we can proceed with this patch as well.
> 
> Helmut

I still have concerns, but maybe it's up to the integrator of a platform to
determine if this approach for poweroff is valid and usable, although I still
think it would be good to have checks somewhere as to whether a platform can
actually perform atmoic I2C access when IRQs are disabled. However, without
further insight right now:

Reviewed-by: Adam Thomson <DLG-Adam.Thomson.Opensource@dm.renesas.com>

Re: [PATCH v2 1/2] mfd: da9062: enable being a system-power-controller

[Lee Jones]

On Fri, 22 Apr 2022, Helmut Grohne wrote:

> The DA9062 can be the device used to power the CPU. In that case, it can
> be used to power off the system. In the CONTROL_A register, the M_*_EN
> bits must be zero for the corresponding *_EN bits to have an effect. We
> zero them all to turn off the system.
> 
> Signed-off-by: Helmut Grohne <helmut.grohne@intenta.de>
> ---
>  drivers/mfd/da9062-core.c | 31 +++++++++++++++++++++++++++++++
>  1 file changed, 31 insertions(+)
> 
> This series effectively is a rebased resend. The earlier posting was
> https://lore.kernel.org/all/20200107120559.GA700@laureti-dev/. At that time,
> Adam Thomson critisized the use of regmap and i2c inside a pm_power_off hook
> since irqs are disabled. He reached out to Lee Jones, who asked Mark Brown and
> Wolfram Sang, but never got any reply. I noted that a fair number of other
> drivers do use regmap and i2c despite this issue. In the mean time, more
> instances were added:
>  * drivers/mfd/acer-ec-a500.c uses i2c
>  * drivers/mfd/ntxec.c uses i2c
>  * drivers/mfd/rk808.c uses regmap and i2c
> Given that we proceeded with accepting the use of i2c and regmap inside
> pm_power_off hooks, I think we can proceed with this patch as well.
> 
> Helmut
> 
> diff --git a/drivers/mfd/da9062-core.c b/drivers/mfd/da9062-core.c
> index 2774b2cbaea6..e7af5b5f16e0 100644
> --- a/drivers/mfd/da9062-core.c
> +++ b/drivers/mfd/da9062-core.c
> @@ -620,6 +620,23 @@ static const struct of_device_id da9062_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, da9062_dt_ids);
>  
> +/* Hold client since pm_power_off is global. */

Please drop this comment.

> +static struct i2c_client *da9062_i2c_client;
> +
> +static void da9062_power_off(void)
> +{
> +	struct da9062 *chip = i2c_get_clientdata(da9062_i2c_client);
> +	const unsigned int mask = DA9062AA_SYSTEM_EN_MASK |
> +		DA9062AA_POWER_EN_MASK | DA9062AA_POWER1_EN_MASK |
> +		DA9062AA_M_SYSTEM_EN_MASK | DA9062AA_M_POWER_EN_MASK |
> +		DA9062AA_M_POWER1_EN_MASK;
> +	int ret = regmap_update_bits(chip->regmap, DA9062AA_CONTROL_A, mask, 0);

This is messy.  Please separate declarations and assignments here.

The top one is passable.

> +	if (ret < 0)
> +		dev_err(&da9062_i2c_client->dev,
> +			"DA9062AA_CONTROL_A update failed, %d\n", ret);

You're talking to the user here.

Please use language that is more user-friendly.

> +}
> +
>  static int da9062_i2c_probe(struct i2c_client *i2c,
>  	const struct i2c_device_id *id)
>  {
> @@ -720,6 +737,15 @@ static int da9062_i2c_probe(struct i2c_client *i2c,
>  		return ret;
>  	}
>  
> +	if (of_device_is_system_power_controller(i2c->dev.of_node)) {
> +		if (!pm_power_off) {
> +			da9062_i2c_client = i2c;
> +			pm_power_off = da9062_power_off;
> +		} else {
> +			dev_warn(&i2c->dev, "Poweroff callback already assigned\n");

Do we really mind/care?

Is there anything we can do about it?

Thus, do we really need to warn() about it?

> +		}
> +	}
> +
>  	return ret;
>  }
>  
> @@ -727,6 +753,11 @@ static int da9062_i2c_remove(struct i2c_client *i2c)
>  {
>  	struct da9062 *chip = i2c_get_clientdata(i2c);
>  
> +	if (pm_power_off == da9062_power_off)
> +		pm_power_off = NULL;
> +	if (da9062_i2c_client)
> +		da9062_i2c_client = NULL;
> +
>  	mfd_remove_devices(chip->dev);
>  	regmap_del_irq_chip(i2c->irq, chip->regmap_irq);
>  

-- 
Lee Jones [李琼斯]
Principal Technical Lead - Developer Services
Linaro.org │ Open source software for Arm SoCs
Follow Linaro: Facebook | Twitter | Blog