[PATCH v4] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls

[PATCH v4] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls

[Komal Bajaj]

EUD_MODE_MANAGER2 register is mapped to a memory region that is marked
as read-only for HLOS, enforcing access restrictions that prohibit
direct memory-mapped writes via writel().

Attempts to write to this region from HLOS can result in silent failures
or memory access violations, particularly when toggling EUD (Embedded
USB Debugger) state. To ensure secure register access, modify the driver
to use qcom_scm_io_writel(), which routes the write operation to Qualcomm
Secure Channel Monitor (SCM). SCM has the necessary permissions to access
protected memory regions, enabling reliable control over EUD state.

SC7280, the only user of EUD is also affected, indicating that this could
never have worked on a properly fused device.

Fixes: 9a1bf58ccd44 ("usb: misc: eud: Add driver support for Embedded USB Debugger(EUD)")
Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
Signed-off-by: Komal Bajaj <komal.bajaj@oss.qualcomm.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
---
Changes in v4:
* Added error logging in disable_eud() for SCM write failures, per Konrad’s suggestion
* Link to v3: https://lore.kernel.org/all/20250708085208.19089-1-komal.bajaj@oss.qualcomm.com/

Changes in v3:
* Moved secure write before normal writes
* Added error checking in disable_eud()
* Use ENOMEM error code if platform_get_resource() fails
* Select QCOM_SCM driver if USB_QCOM_EUD is enabled
* Link to v2: https://lore.kernel.org/all/20250627125131.27606-1-komal.bajaj@oss.qualcomm.com/

Changes in v2:
* Drop separate compatible to be added for secure eud
* Use secure call to access EUD mode manager register
* Link to v1: https://lore.kernel.org/all/20240807183205.803847-1-quic_molvera@quicinc.com/

 drivers/usb/misc/Kconfig    |  1 +
 drivers/usb/misc/qcom_eud.c | 27 +++++++++++++++++++++------
 2 files changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
index 6497c4e81e95..f49d5ac0e957 100644
--- a/drivers/usb/misc/Kconfig
+++ b/drivers/usb/misc/Kconfig
@@ -148,6 +148,7 @@ config USB_QCOM_EUD
 	tristate "QCOM Embedded USB Debugger(EUD) Driver"
 	depends on ARCH_QCOM || COMPILE_TEST
 	select USB_ROLE_SWITCH
+	select QCOM_SCM
 	help
 	  This module enables support for Qualcomm Technologies, Inc.
 	  Embedded USB Debugger (EUD). The EUD is a control peripheral
diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
index 83079c414b4f..a58081f53db3 100644
--- a/drivers/usb/misc/qcom_eud.c
+++ b/drivers/usb/misc/qcom_eud.c
@@ -15,6 +15,7 @@
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/usb/role.h>
+#include <linux/firmware/qcom/qcom_scm.h>
 
 #define EUD_REG_INT1_EN_MASK	0x0024
 #define EUD_REG_INT_STATUS_1	0x0044
@@ -34,7 +35,7 @@ struct eud_chip {
 	struct device			*dev;
 	struct usb_role_switch		*role_sw;
 	void __iomem			*base;
-	void __iomem			*mode_mgr;
+	phys_addr_t			mode_mgr;
 	unsigned int			int_status;
 	int				irq;
 	bool				enabled;
@@ -43,18 +44,30 @@ struct eud_chip {
 
 static int enable_eud(struct eud_chip *priv)
 {
+	int ret;
+
+	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
+	if (ret)
+		return ret;
+
 	writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
 	writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
 			priv->base + EUD_REG_INT1_EN_MASK);
-	writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
 
 	return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
 }
 
 static void disable_eud(struct eud_chip *priv)
 {
+	int ret;
+
+	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0);
+	if (ret) {
+		dev_err(priv->dev, "failed to disable eud\n");
+		return;
+	}
+
 	writel(0, priv->base + EUD_REG_CSR_EUD_EN);
-	writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
 }
 
 static ssize_t enable_show(struct device *dev,
@@ -178,6 +191,7 @@ static void eud_role_switch_release(void *data)
 static int eud_probe(struct platform_device *pdev)
 {
 	struct eud_chip *chip;
+	struct resource *res;
 	int ret;
 
 	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
@@ -200,9 +214,10 @@ static int eud_probe(struct platform_device *pdev)
 	if (IS_ERR(chip->base))
 		return PTR_ERR(chip->base);
 
-	chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
-	if (IS_ERR(chip->mode_mgr))
-		return PTR_ERR(chip->mode_mgr);
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res)
+		return -ENODEV;
+	chip->mode_mgr = res->start;
 
 	chip->irq = platform_get_irq(pdev, 0);
 	if (chip->irq < 0)
-- 
2.48.1

Re: [PATCH v4] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls

[Greg Kroah-Hartman]

On Wed, Jul 09, 2025 at 12:25:14PM +0530, Komal Bajaj wrote:
> EUD_MODE_MANAGER2 register is mapped to a memory region that is marked
> as read-only for HLOS, enforcing access restrictions that prohibit
> direct memory-mapped writes via writel().
> 
> Attempts to write to this region from HLOS can result in silent failures
> or memory access violations, particularly when toggling EUD (Embedded
> USB Debugger) state. To ensure secure register access, modify the driver
> to use qcom_scm_io_writel(), which routes the write operation to Qualcomm
> Secure Channel Monitor (SCM). SCM has the necessary permissions to access
> protected memory regions, enabling reliable control over EUD state.
> 
> SC7280, the only user of EUD is also affected, indicating that this could
> never have worked on a properly fused device.
> 
> Fixes: 9a1bf58ccd44 ("usb: misc: eud: Add driver support for Embedded USB Debugger(EUD)")
> Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
> Signed-off-by: Komal Bajaj <komal.bajaj@oss.qualcomm.com>
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> ---
> Changes in v4:
> * Added error logging in disable_eud() for SCM write failures, per Konrad’s suggestion
> * Link to v3: https://lore.kernel.org/all/20250708085208.19089-1-komal.bajaj@oss.qualcomm.com/
> 
> Changes in v3:
> * Moved secure write before normal writes
> * Added error checking in disable_eud()
> * Use ENOMEM error code if platform_get_resource() fails
> * Select QCOM_SCM driver if USB_QCOM_EUD is enabled
> * Link to v2: https://lore.kernel.org/all/20250627125131.27606-1-komal.bajaj@oss.qualcomm.com/
> 
> Changes in v2:
> * Drop separate compatible to be added for secure eud
> * Use secure call to access EUD mode manager register
> * Link to v1: https://lore.kernel.org/all/20240807183205.803847-1-quic_molvera@quicinc.com/
> 
>  drivers/usb/misc/Kconfig    |  1 +
>  drivers/usb/misc/qcom_eud.c | 27 +++++++++++++++++++++------
>  2 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> index 6497c4e81e95..f49d5ac0e957 100644
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -148,6 +148,7 @@ config USB_QCOM_EUD
>  	tristate "QCOM Embedded USB Debugger(EUD) Driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	select USB_ROLE_SWITCH
> +	select QCOM_SCM
>  	help
>  	  This module enables support for Qualcomm Technologies, Inc.
>  	  Embedded USB Debugger (EUD). The EUD is a control peripheral
> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
> index 83079c414b4f..a58081f53db3 100644
> --- a/drivers/usb/misc/qcom_eud.c
> +++ b/drivers/usb/misc/qcom_eud.c
> @@ -15,6 +15,7 @@
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
>  #include <linux/usb/role.h>
> +#include <linux/firmware/qcom/qcom_scm.h>
>  
>  #define EUD_REG_INT1_EN_MASK	0x0024
>  #define EUD_REG_INT_STATUS_1	0x0044
> @@ -34,7 +35,7 @@ struct eud_chip {
>  	struct device			*dev;
>  	struct usb_role_switch		*role_sw;
>  	void __iomem			*base;
> -	void __iomem			*mode_mgr;
> +	phys_addr_t			mode_mgr;
>  	unsigned int			int_status;
>  	int				irq;
>  	bool				enabled;
> @@ -43,18 +44,30 @@ struct eud_chip {
>  
>  static int enable_eud(struct eud_chip *priv)
>  {
> +	int ret;
> +
> +	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
> +	if (ret)
> +		return ret;
> +
>  	writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
>  	writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
>  			priv->base + EUD_REG_INT1_EN_MASK);
> -	writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
>  
>  	return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>  }
>  
>  static void disable_eud(struct eud_chip *priv)
>  {
> +	int ret;
> +
> +	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0);
> +	if (ret) {
> +		dev_err(priv->dev, "failed to disable eud\n");
> +		return;
> +	}
> +
>  	writel(0, priv->base + EUD_REG_CSR_EUD_EN);
> -	writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
>  }
>  
>  static ssize_t enable_show(struct device *dev,
> @@ -178,6 +191,7 @@ static void eud_role_switch_release(void *data)
>  static int eud_probe(struct platform_device *pdev)
>  {
>  	struct eud_chip *chip;
> +	struct resource *res;
>  	int ret;
>  
>  	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> @@ -200,9 +214,10 @@ static int eud_probe(struct platform_device *pdev)
>  	if (IS_ERR(chip->base))
>  		return PTR_ERR(chip->base);
>  
> -	chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
> -	if (IS_ERR(chip->mode_mgr))
> -		return PTR_ERR(chip->mode_mgr);
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	if (!res)
> +		return -ENODEV;
> +	chip->mode_mgr = res->start;
>  
>  	chip->irq = platform_get_irq(pdev, 0);
>  	if (chip->irq < 0)
> -- 
> 2.48.1
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v4] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls

[Greg Kroah-Hartman]

On Wed, Jul 09, 2025 at 12:25:14PM +0530, Komal Bajaj wrote:
> EUD_MODE_MANAGER2 register is mapped to a memory region that is marked
> as read-only for HLOS, enforcing access restrictions that prohibit
> direct memory-mapped writes via writel().
> 
> Attempts to write to this region from HLOS can result in silent failures
> or memory access violations, particularly when toggling EUD (Embedded
> USB Debugger) state. To ensure secure register access, modify the driver
> to use qcom_scm_io_writel(), which routes the write operation to Qualcomm
> Secure Channel Monitor (SCM). SCM has the necessary permissions to access
> protected memory regions, enabling reliable control over EUD state.
> 
> SC7280, the only user of EUD is also affected, indicating that this could
> never have worked on a properly fused device.
> 
> Fixes: 9a1bf58ccd44 ("usb: misc: eud: Add driver support for Embedded USB Debugger(EUD)")
> Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
> Signed-off-by: Komal Bajaj <komal.bajaj@oss.qualcomm.com>
> Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> ---
> Changes in v4:
> * Added error logging in disable_eud() for SCM write failures, per Konrad’s suggestion
> * Link to v3: https://lore.kernel.org/all/20250708085208.19089-1-komal.bajaj@oss.qualcomm.com/
> 
> Changes in v3:
> * Moved secure write before normal writes
> * Added error checking in disable_eud()
> * Use ENOMEM error code if platform_get_resource() fails
> * Select QCOM_SCM driver if USB_QCOM_EUD is enabled
> * Link to v2: https://lore.kernel.org/all/20250627125131.27606-1-komal.bajaj@oss.qualcomm.com/
> 
> Changes in v2:
> * Drop separate compatible to be added for secure eud
> * Use secure call to access EUD mode manager register
> * Link to v1: https://lore.kernel.org/all/20240807183205.803847-1-quic_molvera@quicinc.com/
> 
>  drivers/usb/misc/Kconfig    |  1 +
>  drivers/usb/misc/qcom_eud.c | 27 +++++++++++++++++++++------
>  2 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> index 6497c4e81e95..f49d5ac0e957 100644
> --- a/drivers/usb/misc/Kconfig
> +++ b/drivers/usb/misc/Kconfig
> @@ -148,6 +148,7 @@ config USB_QCOM_EUD
>  	tristate "QCOM Embedded USB Debugger(EUD) Driver"
>  	depends on ARCH_QCOM || COMPILE_TEST
>  	select USB_ROLE_SWITCH
> +	select QCOM_SCM

How is this select going to work if COMPILE_TEST is enabled on
non-ARCH_QCOM configs?

Please don't use select if at all possible, use "depends" properly.


>  	help
>  	  This module enables support for Qualcomm Technologies, Inc.
>  	  Embedded USB Debugger (EUD). The EUD is a control peripheral
> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
> index 83079c414b4f..a58081f53db3 100644
> --- a/drivers/usb/misc/qcom_eud.c
> +++ b/drivers/usb/misc/qcom_eud.c
> @@ -15,6 +15,7 @@
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
>  #include <linux/usb/role.h>
> +#include <linux/firmware/qcom/qcom_scm.h>
>  
>  #define EUD_REG_INT1_EN_MASK	0x0024
>  #define EUD_REG_INT_STATUS_1	0x0044
> @@ -34,7 +35,7 @@ struct eud_chip {
>  	struct device			*dev;
>  	struct usb_role_switch		*role_sw;
>  	void __iomem			*base;
> -	void __iomem			*mode_mgr;
> +	phys_addr_t			mode_mgr;
>  	unsigned int			int_status;
>  	int				irq;
>  	bool				enabled;
> @@ -43,18 +44,30 @@ struct eud_chip {
>  
>  static int enable_eud(struct eud_chip *priv)
>  {
> +	int ret;
> +
> +	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
> +	if (ret)
> +		return ret;
> +
>  	writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);

Nit, why is your local writel() function in backwards order of
parameters from qcom_scm_io_writel()?  That's going to be a major pain
to maintain over time, don't you think?


>  	writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
>  			priv->base + EUD_REG_INT1_EN_MASK);
> -	writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
>  
>  	return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
>  }
>  
>  static void disable_eud(struct eud_chip *priv)
>  {
> +	int ret;
> +
> +	ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0);
> +	if (ret) {
> +		dev_err(priv->dev, "failed to disable eud\n");
> +		return;
> +	}
> +
>  	writel(0, priv->base + EUD_REG_CSR_EUD_EN);
> -	writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
>  }
>  
>  static ssize_t enable_show(struct device *dev,
> @@ -178,6 +191,7 @@ static void eud_role_switch_release(void *data)
>  static int eud_probe(struct platform_device *pdev)
>  {
>  	struct eud_chip *chip;
> +	struct resource *res;
>  	int ret;
>  
>  	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> @@ -200,9 +214,10 @@ static int eud_probe(struct platform_device *pdev)
>  	if (IS_ERR(chip->base))
>  		return PTR_ERR(chip->base);
>  
> -	chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
> -	if (IS_ERR(chip->mode_mgr))
> -		return PTR_ERR(chip->mode_mgr);
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +	if (!res)
> +		return -ENODEV;
> +	chip->mode_mgr = res->start;

No ioremap() call needed anymore?   Why not?

thanks,

greg k-h

Re: [PATCH v4] usb: misc: qcom_eud: Access EUD_MODE_MANAGER2 through secure calls

[Komal Bajaj]

On Wed, Jul 9, 2025 at 2:14 PM Greg Kroah-Hartman
<gregkh@linuxfoundation.org> wrote:
>
> On Wed, Jul 09, 2025 at 12:25:14PM +0530, Komal Bajaj wrote:
> > EUD_MODE_MANAGER2 register is mapped to a memory region that is marked
> > as read-only for HLOS, enforcing access restrictions that prohibit
> > direct memory-mapped writes via writel().
> >
> > Attempts to write to this region from HLOS can result in silent failures
> > or memory access violations, particularly when toggling EUD (Embedded
> > USB Debugger) state. To ensure secure register access, modify the driver
> > to use qcom_scm_io_writel(), which routes the write operation to Qualcomm
> > Secure Channel Monitor (SCM). SCM has the necessary permissions to access
> > protected memory regions, enabling reliable control over EUD state.
> >
> > SC7280, the only user of EUD is also affected, indicating that this could
> > never have worked on a properly fused device.
> >
> > Fixes: 9a1bf58ccd44 ("usb: misc: eud: Add driver support for Embedded USB Debugger(EUD)")
> > Signed-off-by: Melody Olvera <quic_molvera@quicinc.com>
> > Signed-off-by: Komal Bajaj <komal.bajaj@oss.qualcomm.com>
> > Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
> > ---
> > Changes in v4:
> > * Added error logging in disable_eud() for SCM write failures, per Konrad’s suggestion
> > * Link to v3: https://lore.kernel.org/all/20250708085208.19089-1-komal.bajaj@oss.qualcomm.com/
> >
> > Changes in v3:
> > * Moved secure write before normal writes
> > * Added error checking in disable_eud()
> > * Use ENOMEM error code if platform_get_resource() fails
> > * Select QCOM_SCM driver if USB_QCOM_EUD is enabled
> > * Link to v2: https://lore.kernel.org/all/20250627125131.27606-1-komal.bajaj@oss.qualcomm.com/
> >
> > Changes in v2:
> > * Drop separate compatible to be added for secure eud
> > * Use secure call to access EUD mode manager register
> > * Link to v1: https://lore.kernel.org/all/20240807183205.803847-1-quic_molvera@quicinc.com/
> >
> >  drivers/usb/misc/Kconfig    |  1 +
> >  drivers/usb/misc/qcom_eud.c | 27 +++++++++++++++++++++------
> >  2 files changed, 22 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/misc/Kconfig b/drivers/usb/misc/Kconfig
> > index 6497c4e81e95..f49d5ac0e957 100644
> > --- a/drivers/usb/misc/Kconfig
> > +++ b/drivers/usb/misc/Kconfig
> > @@ -148,6 +148,7 @@ config USB_QCOM_EUD
> >       tristate "QCOM Embedded USB Debugger(EUD) Driver"
> >       depends on ARCH_QCOM || COMPILE_TEST
> >       select USB_ROLE_SWITCH
> > +     select QCOM_SCM
>
> How is this select going to work if COMPILE_TEST is enabled on
> non-ARCH_QCOM configs?
>
> Please don't use select if at all possible, use "depends" properly.

Ack, will switch to depends on QCOM_SCM to avoid build issues with COMPILE_TEST

>
>
> >       help
> >         This module enables support for Qualcomm Technologies, Inc.
> >         Embedded USB Debugger (EUD). The EUD is a control peripheral
> > diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
> > index 83079c414b4f..a58081f53db3 100644
> > --- a/drivers/usb/misc/qcom_eud.c
> > +++ b/drivers/usb/misc/qcom_eud.c
> > @@ -15,6 +15,7 @@
> >  #include <linux/slab.h>
> >  #include <linux/sysfs.h>
> >  #include <linux/usb/role.h>
> > +#include <linux/firmware/qcom/qcom_scm.h>
> >
> >  #define EUD_REG_INT1_EN_MASK 0x0024
> >  #define EUD_REG_INT_STATUS_1 0x0044
> > @@ -34,7 +35,7 @@ struct eud_chip {
> >       struct device                   *dev;
> >       struct usb_role_switch          *role_sw;
> >       void __iomem                    *base;
> > -     void __iomem                    *mode_mgr;
> > +     phys_addr_t                     mode_mgr;
> >       unsigned int                    int_status;
> >       int                             irq;
> >       bool                            enabled;
> > @@ -43,18 +44,30 @@ struct eud_chip {
> >
> >  static int enable_eud(struct eud_chip *priv)
> >  {
> > +     int ret;
> > +
> > +     ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 1);
> > +     if (ret)
> > +             return ret;
> > +
> >       writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
>
> Nit, why is your local writel() function in backwards order of
> parameters from qcom_scm_io_writel()?  That's going to be a major pain
> to maintain over time, don't you think?

The current ordering of parameters in qcom_scm_io_writel  is the same as in
qcom_scm_io_readl, possibly to keep them consistent. However, if you believe
it's more appropriate to align the parameter order with the standard writel
convention, I’m open to updating it accordingly.

>
>
> >       writel(EUD_INT_VBUS | EUD_INT_SAFE_MODE,
> >                       priv->base + EUD_REG_INT1_EN_MASK);
> > -     writel(1, priv->mode_mgr + EUD_REG_EUD_EN2);
> >
> >       return usb_role_switch_set_role(priv->role_sw, USB_ROLE_DEVICE);
> >  }
> >
> >  static void disable_eud(struct eud_chip *priv)
> >  {
> > +     int ret;
> > +
> > +     ret = qcom_scm_io_writel(priv->mode_mgr + EUD_REG_EUD_EN2, 0);
> > +     if (ret) {
> > +             dev_err(priv->dev, "failed to disable eud\n");
> > +             return;
> > +     }
> > +
> >       writel(0, priv->base + EUD_REG_CSR_EUD_EN);
> > -     writel(0, priv->mode_mgr + EUD_REG_EUD_EN2);
> >  }
> >
> >  static ssize_t enable_show(struct device *dev,
> > @@ -178,6 +191,7 @@ static void eud_role_switch_release(void *data)
> >  static int eud_probe(struct platform_device *pdev)
> >  {
> >       struct eud_chip *chip;
> > +     struct resource *res;
> >       int ret;
> >
> >       chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
> > @@ -200,9 +214,10 @@ static int eud_probe(struct platform_device *pdev)
> >       if (IS_ERR(chip->base))
> >               return PTR_ERR(chip->base);
> >
> > -     chip->mode_mgr = devm_platform_ioremap_resource(pdev, 1);
> > -     if (IS_ERR(chip->mode_mgr))
> > -             return PTR_ERR(chip->mode_mgr);
> > +     res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> > +     if (!res)
> > +             return -ENODEV;
> > +     chip->mode_mgr = res->start;
>
> No ioremap() call needed anymore?   Why not?

We’re only using the address for qcom_scm_io_writel(), which operates on
physical addresses and doesn’t require an ioremap’d virtual address.
That’s why devm_ioremap_resource() isn’t needed here.

>
> thanks,
>
> greg k-h