[v2,1/3] usb: chipidea: imx: support configuring for active low oc signal

Message ID 20181202213325.26017-1-u.kleine-koenig@pengutronix.de
State New
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Series
  • [v2,1/3] usb: chipidea: imx: support configuring for active low oc signal
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Commit Message

Uwe Kleine-König Dec. 2, 2018, 9:33 p.m.
The status quo on i.MX6 is that if "over-current-active-high" is
specified in the device tree this is configured as expected. If
the property is missing polarity isn't changed and so the
polarity is kept as setup by the bootloader. Reset default is
active high, so active low can only be used with help by the
bootloader. On i.MX7 it is similar, but there disabling of
over current detection has a similar inconsistency.

This patch introduces a new property that allows to explicitly
configure for active low over current detection and consistently
sets this up. In the absence of an explicit configuration the
bit is kept as is. On i.MX7 over current detection is used unless
disabled in the device tree.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
---
 .../devicetree/bindings/usb/ci-hdrc-usb2.txt  |  5 ++--
 drivers/usb/chipidea/ci_hdrc_imx.c            |  9 ++++--
 drivers/usb/chipidea/ci_hdrc_imx.h            |  8 +++++-
 drivers/usb/chipidea/usbmisc_imx.c            | 28 ++++++++++++++-----
 4 files changed, 38 insertions(+), 12 deletions(-)

Comments

Matthew Starr Dec. 3, 2018, 4:10 p.m. | #1
> -----Original Message-----
> From: Uwe Kleine-König [mailto:u.kleine-koenig@pengutronix.de]
> Sent: Sunday, December 02, 2018 3:33 PM
> 
> The status quo on i.MX6 is that if "over-current-active-high" is
> specified in the device tree this is configured as expected. If
> the property is missing polarity isn't changed and so the
> polarity is kept as setup by the bootloader. Reset default is
> active high, so active low can only be used with help by the
> bootloader. On i.MX7 it is similar, but there disabling of
> over current detection has a similar inconsistency.
> 
> This patch introduces a new property that allows to explicitly
> configure for active low over current detection and consistently
> sets this up. In the absence of an explicit configuration the
> bit is kept as is. On i.MX7 over current detection is used unless
> disabled in the device tree.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> ---
>  .../devicetree/bindings/usb/ci-hdrc-usb2.txt  |  5 ++--
>  drivers/usb/chipidea/ci_hdrc_imx.c            |  9 ++++--
>  drivers/usb/chipidea/ci_hdrc_imx.h            |  8 +++++-
>  drivers/usb/chipidea/usbmisc_imx.c            | 28 ++++++++++++++-----
>  4 files changed, 38 insertions(+), 12 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> index 529e51879fb2..c32f6e983cf6 100644
> --- a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> +++ b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> @@ -87,8 +87,9 @@ i.mx specific properties
>  - fsl,usbmisc: phandler of non-core register device, with one
>    argument that indicate usb controller index
>  - disable-over-current: disable over current detect
> -- over-current-active-high: over current signal polarity is high active,
> -  typically over current signal polarity is low active.
> +- over-current-active-low: over current signal polarity is active low.
> +- over-current-active-high: over current signal polarity is active high.
> +  It's recommended to specify the over current polarity.
>  - external-vbus-divider: enables off-chip resistor divider for Vbus
> 
>  Example:
> diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
> index 09b37c0d075d..80b4e4ef9b68 100644
> --- a/drivers/usb/chipidea/ci_hdrc_imx.c
> +++ b/drivers/usb/chipidea/ci_hdrc_imx.c
> @@ -135,8 +135,13 @@ static struct imx_usbmisc_data *usbmisc_get_init_data(struct device *dev)
>  	if (of_find_property(np, "disable-over-current", NULL))
>  		data->disable_oc = 1;
> 
> -	if (of_find_property(np, "over-current-active-high", NULL))
> -		data->oc_polarity = 1;
> +	if (of_find_property(np, "over-current-active-high", NULL)) {
> +		data->oc_pol_active_low = 0;
> +		data->oc_pol_configured = 1;
> +	} else if (of_find_property(np, "over-current-active-low", NULL)) {
> +		data->oc_pol_active_low = 1;
> +		data->oc_pol_configured = 1;
> +	}

Since both over-current-active-high and over-current-active-low can be enabled, the error case of when both are in the device tree is not covered here.  An error or warning should be given.  Also in this case the safest thing to do would be to leave the OC polarity bit alone and leave it the way it was set by the bootloader.

Matt Starr

> 
>  	if (of_find_property(np, "external-vbus-divider", NULL))
>  		data->evdo = 1;
> diff --git a/drivers/usb/chipidea/ci_hdrc_imx.h b/drivers/usb/chipidea/ci_hdrc_imx.h
> index 204275f47573..640721fef0d7 100644
> --- a/drivers/usb/chipidea/ci_hdrc_imx.h
> +++ b/drivers/usb/chipidea/ci_hdrc_imx.h
> @@ -11,7 +11,13 @@ struct imx_usbmisc_data {
>  	int index;
> 
>  	unsigned int disable_oc:1; /* over current detect disabled */
> -	unsigned int oc_polarity:1; /* over current polarity if oc enabled */
> +
> +	/* true if over-current polarity is active low */
> +	unsigned int oc_pol_active_low:1;
> +
> +	/* true if dt specifies polarity */
> +	unsigned int oc_pol_configured:1;
> +
>  	unsigned int evdo:1; /* set external vbus divider option */
>  	unsigned int ulpi:1; /* connected to an ULPI phy */
>  };
> diff --git a/drivers/usb/chipidea/usbmisc_imx.c b/drivers/usb/chipidea/usbmisc_imx.c
> index def80ff547e4..4a8de1b37f67 100644
> --- a/drivers/usb/chipidea/usbmisc_imx.c
> +++ b/drivers/usb/chipidea/usbmisc_imx.c
> @@ -340,11 +340,17 @@ static int usbmisc_imx6q_init(struct imx_usbmisc_data *data)
>  	reg = readl(usbmisc->base + data->index * 4);
>  	if (data->disable_oc) {
>  		reg |= MX6_BM_OVER_CUR_DIS;
> -	} else if (data->oc_polarity == 1) {
> -		/* High active */
> -		reg &= ~(MX6_BM_OVER_CUR_DIS | MX6_BM_OVER_CUR_POLARITY);
>  	} else {
> -		reg &= ~(MX6_BM_OVER_CUR_DIS);
> +		reg &= ~MX6_BM_OVER_CUR_DIS;
> +
> +		/*
> +		 * If the polarity is not configured keep it as setup by the
> +		 * bootloader.
> +		 */
> +		if (data->oc_pol_configured && data->oc_pol_active_low)
> +			reg |= MX6_BM_OVER_CUR_POLARITY;
> +		else if (data->oc_pol_configured)
> +			reg &= ~MX6_BM_OVER_CUR_POLARITY;
>  	}
>  	writel(reg, usbmisc->base + data->index * 4);
> 
> @@ -444,9 +450,17 @@ static int usbmisc_imx7d_init(struct imx_usbmisc_data *data)
>  	reg = readl(usbmisc->base);
>  	if (data->disable_oc) {
>  		reg |= MX6_BM_OVER_CUR_DIS;
> -	} else if (data->oc_polarity == 1) {
> -		/* High active */
> -		reg &= ~(MX6_BM_OVER_CUR_DIS | MX6_BM_OVER_CUR_POLARITY);
> +	} else {
> +		reg &= ~MX6_BM_OVER_CUR_DIS;
> +
> +		/*
> +		 * If the polarity is not configured keep it as setup by the
> +		 * bootloader.
> +		 */
> +		if (data->oc_pol_configured && data->oc_pol_active_low)
> +			reg |= MX6_BM_OVER_CUR_POLARITY;
> +		else if (data->oc_pol_configured)
> +			reg &= ~MX6_BM_OVER_CUR_POLARITY;
>  	}
>  	writel(reg, usbmisc->base);
> 
> --
> 2.19.2
Uwe Kleine-König Dec. 3, 2018, 5:22 p.m. | #2
On Mon, Dec 03, 2018 at 04:10:37PM +0000, Matthew Starr wrote:
> > -----Original Message-----
> > From: Uwe Kleine-König [mailto:u.kleine-koenig@pengutronix.de]
> > Sent: Sunday, December 02, 2018 3:33 PM
> > 
> > The status quo on i.MX6 is that if "over-current-active-high" is
> > specified in the device tree this is configured as expected. If
> > the property is missing polarity isn't changed and so the
> > polarity is kept as setup by the bootloader. Reset default is
> > active high, so active low can only be used with help by the
> > bootloader. On i.MX7 it is similar, but there disabling of
> > over current detection has a similar inconsistency.
> > 
> > This patch introduces a new property that allows to explicitly
> > configure for active low over current detection and consistently
> > sets this up. In the absence of an explicit configuration the
> > bit is kept as is. On i.MX7 over current detection is used unless
> > disabled in the device tree.
> > 
> > Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
> > ---
> >  .../devicetree/bindings/usb/ci-hdrc-usb2.txt  |  5 ++--
> >  drivers/usb/chipidea/ci_hdrc_imx.c            |  9 ++++--
> >  drivers/usb/chipidea/ci_hdrc_imx.h            |  8 +++++-
> >  drivers/usb/chipidea/usbmisc_imx.c            | 28 ++++++++++++++-----
> >  4 files changed, 38 insertions(+), 12 deletions(-)
> > 
> > diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> > index 529e51879fb2..c32f6e983cf6 100644
> > --- a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> > +++ b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
> > @@ -87,8 +87,9 @@ i.mx specific properties
> >  - fsl,usbmisc: phandler of non-core register device, with one
> >    argument that indicate usb controller index
> >  - disable-over-current: disable over current detect
> > -- over-current-active-high: over current signal polarity is high active,
> > -  typically over current signal polarity is low active.
> > +- over-current-active-low: over current signal polarity is active low.
> > +- over-current-active-high: over current signal polarity is active high.
> > +  It's recommended to specify the over current polarity.
> >  - external-vbus-divider: enables off-chip resistor divider for Vbus
> > 
> >  Example:
> > diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
> > index 09b37c0d075d..80b4e4ef9b68 100644
> > --- a/drivers/usb/chipidea/ci_hdrc_imx.c
> > +++ b/drivers/usb/chipidea/ci_hdrc_imx.c
> > @@ -135,8 +135,13 @@ static struct imx_usbmisc_data *usbmisc_get_init_data(struct device *dev)
> >  	if (of_find_property(np, "disable-over-current", NULL))
> >  		data->disable_oc = 1;
> > 
> > -	if (of_find_property(np, "over-current-active-high", NULL))
> > -		data->oc_polarity = 1;
> > +	if (of_find_property(np, "over-current-active-high", NULL)) {
> > +		data->oc_pol_active_low = 0;
> > +		data->oc_pol_configured = 1;
> > +	} else if (of_find_property(np, "over-current-active-low", NULL)) {
> > +		data->oc_pol_active_low = 1;
> > +		data->oc_pol_configured = 1;
> > +	}
> 
> Since both over-current-active-high and over-current-active-low can be
> enabled, the error case of when both are in the device tree is not
> covered here.  An error or warning should be given.  Also in this case
> the safest thing to do would be to leave the OC polarity bit alone and
> leave it the way it was set by the bootloader.

Given that it obviously cannot describe the hardware correctly when both
(over-current-active-high and over-current-active-low) are given it is
IMHO ok to do anything in this case. In my eyes that's similar to the C
language where the compiler is free to do whatever it seems fit when the
programmer does something unspecified.

Added Rob to Cc, maybe he can comment.

Best regards
Uwe

Patch

diff --git a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
index 529e51879fb2..c32f6e983cf6 100644
--- a/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
+++ b/Documentation/devicetree/bindings/usb/ci-hdrc-usb2.txt
@@ -87,8 +87,9 @@  i.mx specific properties
 - fsl,usbmisc: phandler of non-core register device, with one
   argument that indicate usb controller index
 - disable-over-current: disable over current detect
-- over-current-active-high: over current signal polarity is high active,
-  typically over current signal polarity is low active.
+- over-current-active-low: over current signal polarity is active low.
+- over-current-active-high: over current signal polarity is active high.
+  It's recommended to specify the over current polarity.
 - external-vbus-divider: enables off-chip resistor divider for Vbus
 
 Example:
diff --git a/drivers/usb/chipidea/ci_hdrc_imx.c b/drivers/usb/chipidea/ci_hdrc_imx.c
index 09b37c0d075d..80b4e4ef9b68 100644
--- a/drivers/usb/chipidea/ci_hdrc_imx.c
+++ b/drivers/usb/chipidea/ci_hdrc_imx.c
@@ -135,8 +135,13 @@  static struct imx_usbmisc_data *usbmisc_get_init_data(struct device *dev)
 	if (of_find_property(np, "disable-over-current", NULL))
 		data->disable_oc = 1;
 
-	if (of_find_property(np, "over-current-active-high", NULL))
-		data->oc_polarity = 1;
+	if (of_find_property(np, "over-current-active-high", NULL)) {
+		data->oc_pol_active_low = 0;
+		data->oc_pol_configured = 1;
+	} else if (of_find_property(np, "over-current-active-low", NULL)) {
+		data->oc_pol_active_low = 1;
+		data->oc_pol_configured = 1;
+	}
 
 	if (of_find_property(np, "external-vbus-divider", NULL))
 		data->evdo = 1;
diff --git a/drivers/usb/chipidea/ci_hdrc_imx.h b/drivers/usb/chipidea/ci_hdrc_imx.h
index 204275f47573..640721fef0d7 100644
--- a/drivers/usb/chipidea/ci_hdrc_imx.h
+++ b/drivers/usb/chipidea/ci_hdrc_imx.h
@@ -11,7 +11,13 @@  struct imx_usbmisc_data {
 	int index;
 
 	unsigned int disable_oc:1; /* over current detect disabled */
-	unsigned int oc_polarity:1; /* over current polarity if oc enabled */
+
+	/* true if over-current polarity is active low */
+	unsigned int oc_pol_active_low:1;
+
+	/* true if dt specifies polarity */
+	unsigned int oc_pol_configured:1;
+
 	unsigned int evdo:1; /* set external vbus divider option */
 	unsigned int ulpi:1; /* connected to an ULPI phy */
 };
diff --git a/drivers/usb/chipidea/usbmisc_imx.c b/drivers/usb/chipidea/usbmisc_imx.c
index def80ff547e4..4a8de1b37f67 100644
--- a/drivers/usb/chipidea/usbmisc_imx.c
+++ b/drivers/usb/chipidea/usbmisc_imx.c
@@ -340,11 +340,17 @@  static int usbmisc_imx6q_init(struct imx_usbmisc_data *data)
 	reg = readl(usbmisc->base + data->index * 4);
 	if (data->disable_oc) {
 		reg |= MX6_BM_OVER_CUR_DIS;
-	} else if (data->oc_polarity == 1) {
-		/* High active */
-		reg &= ~(MX6_BM_OVER_CUR_DIS | MX6_BM_OVER_CUR_POLARITY);
 	} else {
-		reg &= ~(MX6_BM_OVER_CUR_DIS);
+		reg &= ~MX6_BM_OVER_CUR_DIS;
+
+		/*
+		 * If the polarity is not configured keep it as setup by the
+		 * bootloader.
+		 */
+		if (data->oc_pol_configured && data->oc_pol_active_low)
+			reg |= MX6_BM_OVER_CUR_POLARITY;
+		else if (data->oc_pol_configured)
+			reg &= ~MX6_BM_OVER_CUR_POLARITY;
 	}
 	writel(reg, usbmisc->base + data->index * 4);
 
@@ -444,9 +450,17 @@  static int usbmisc_imx7d_init(struct imx_usbmisc_data *data)
 	reg = readl(usbmisc->base);
 	if (data->disable_oc) {
 		reg |= MX6_BM_OVER_CUR_DIS;
-	} else if (data->oc_polarity == 1) {
-		/* High active */
-		reg &= ~(MX6_BM_OVER_CUR_DIS | MX6_BM_OVER_CUR_POLARITY);
+	} else {
+		reg &= ~MX6_BM_OVER_CUR_DIS;
+
+		/*
+		 * If the polarity is not configured keep it as setup by the
+		 * bootloader.
+		 */
+		if (data->oc_pol_configured && data->oc_pol_active_low)
+			reg |= MX6_BM_OVER_CUR_POLARITY;
+		else if (data->oc_pol_configured)
+			reg &= ~MX6_BM_OVER_CUR_POLARITY;
 	}
 	writel(reg, usbmisc->base);