[PATCH V1 2/3] usb: misc: Add notifier call chain to Embedded USB Debug(EUD) driver

[Bhupesh Sharma]

Hi Souradeep,

On Wed, 12 Jul 2023 at 13:58, Souradeep Chowdhury
<quic_schowdhu at quicinc.com> wrote:
>
> Add the notifier call chain to EUD driver. The notifier call chain
> is added to check the role-switch status of EUD. When multiple
> modules are switching roles on the same port, they need to call this
> notifier to check the role-switch status of EUD. If EUD is disabled,
> then the modules can go for the role-switch, otherwise it needs to
> be blocked. The notifier chain can be used to link multiple modules
> switching roles on the same port and create a ordering, priority and
> conflict resolution among them. The wrapper functions are defined here
> which can be used to register a notifier block to the chain, deregister
> it and also call the chain.
>
> Signed-off-by: Souradeep Chowdhury <quic_schowdhu at quicinc.com>
> ---
>  drivers/usb/misc/qcom_eud.c | 52 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 50 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/misc/qcom_eud.c b/drivers/usb/misc/qcom_eud.c
> index 7f371ea1248c..e6c97a2cf2df 100644
> --- a/drivers/usb/misc/qcom_eud.c
> +++ b/drivers/usb/misc/qcom_eud.c
> @@ -11,10 +11,13 @@
>  #include <linux/kernel.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
>  #include <linux/platform_device.h>
>  #include <linux/slab.h>
>  #include <linux/sysfs.h>
>  #include <linux/usb/role.h>
> +#include "qcom_eud_notifier.h"
>
>  #define EUD_REG_INT1_EN_MASK   0x0024
>  #define EUD_REG_INT_STATUS_1   0x0044
> @@ -22,14 +25,16 @@
>  #define EUD_REG_VBUS_INT_CLR   0x0080
>  #define EUD_REG_CSR_EUD_EN     0x1014
>  #define EUD_REG_SW_ATTACH_DET  0x1018
> -#define EUD_REG_EUD_EN2                0x0000
> +#define EUD_REG_EUD_EN2        0x0000
>
>  #define EUD_ENABLE             BIT(0)
> -#define EUD_INT_PET_EUD                BIT(0)

These indentation issues are already addressed in my EUD patches.
Please rebase your patches on the same to reuse those.

> +#define EUD_INT_PET_EUD        BIT(0)
>  #define EUD_INT_VBUS           BIT(2)
>  #define EUD_INT_SAFE_MODE      BIT(4)
>  #define EUD_INT_ALL            (EUD_INT_VBUS | EUD_INT_SAFE_MODE)
>
> +static RAW_NOTIFIER_HEAD(eud_nh);
> +
>  struct eud_chip {
>         struct device                   *dev;
>         struct usb_role_switch          *role_sw;
> @@ -41,6 +46,42 @@ struct eud_chip {
>         bool                            usb_attached;
>  };
>
> +int eud_register_notify(struct notifier_block *nb)
> +{
> +       return raw_notifier_chain_register(&eud_nh, nb);
> +}
> +EXPORT_SYMBOL_GPL(eud_register_notify);
> +
> +void eud_unregister_notify(struct notifier_block *nb)
> +{
> +       raw_notifier_chain_unregister(&eud_nh, nb);
> +}
> +EXPORT_SYMBOL_GPL(eud_unregister_notify);
> +
> +void eud_notifier_call_chain(unsigned long role_switch_state)
> +{
> +       raw_notifier_call_chain(&eud_nh, role_switch_state, NULL);
> +}
> +EXPORT_SYMBOL_GPL(eud_notifier_call_chain);

Probably I missed it, but you have not provided any example users of
these APIs in the patchset or reference to another one which shows how
these APIs are used.

> +static int eud_vbus_spoof_attach_detach(struct notifier_block *nb, unsigned long event,
> +                                       void *data)
> +{
> +       struct device_node *eud = of_find_compatible_node(NULL, NULL, "qcom,eud");
> +       struct device *eud_device = bus_find_device_by_of_node(&platform_bus_type, eud);
> +       struct eud_chip  *eud_data = dev_get_drvdata(eud_device);
> +
> +       if (eud_data->enabled  && event != USB_ROLE_DEVICE)
> +               return NOTIFY_BAD;
> +       else
> +               return NOTIFY_OK;
> +}
> +
> +static struct notifier_block eud_notifier = {
> +       .notifier_call = eud_vbus_spoof_attach_detach,
> +       .priority = 1,

Why do you need a 'priority = 1' here, it can be 0 or even lower?

Thanks,
Bhupesh

> +};
> +
>  static int enable_eud(struct eud_chip *priv)
>  {
>         writel(EUD_ENABLE, priv->base + EUD_REG_CSR_EUD_EN);
> @@ -196,6 +237,10 @@ static int eud_probe(struct platform_device *pdev)
>                 return dev_err_probe(chip->dev, ret,
>                                 "failed to add role switch release action\n");
>
> +       ret = eud_register_notify(&eud_notifier);
> +       if (ret)
> +               return dev_err_probe(chip->dev, ret, "failed to register notifier\n");
> +
>         chip->base = devm_platform_ioremap_resource(pdev, 0);
>         if (IS_ERR(chip->base))
>                 return PTR_ERR(chip->base);
> @@ -226,6 +271,9 @@ static void eud_remove(struct platform_device *pdev)
>
>         device_init_wakeup(&pdev->dev, false);
>         disable_irq_wake(chip->irq);
> +       eud_unregister_notify(&eud_notifier);
> +
> +       return 0;
>  }
>
>  static const struct of_device_id eud_dt_match[] = {
> --
> 2.17.1
>