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

[Matthew Starr <mstarr@hedonline.com>]

> -----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