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From:   Bhupesh Sharma <bhsharma@redhat.com>
Date:   Mon, 21 Jan 2019 20:58:36 +0530
Message-ID: <CACi5LpMN2N1joWxmwDy=DtH+stenUs64oJ2_T4T-7sSoS=NAgw@mail.gmail.com>
Subject: Re: [PATCH v4 1/4] tee: add bus driver framework for TEE based devices
To:     Sumit Garg <sumit.garg@linaro.org>
Cc:     Jens Wiklander <jens.wiklander@linaro.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" 
        <linux-crypto@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        mpm@selenic.com, Rob Herring <robh+dt@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Daniel Thompson <daniel.thompson@linaro.org>,
        Ard Biesheuvel <ard.biesheuvel@linaro.org>,
        tee-dev@lists.linaro.org
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Sumit,

On Mon, Jan 21, 2019 at 3:00 PM Sumit Garg <sumit.garg@linaro.org> wrote:
>
> Introduce a generic TEE bus driver concept for TEE based kernel drivers
> which would like to communicate with TEE based devices/services.
>
> In this TEE bus concept, devices/services are identified via Universally
> Unique Identifier (UUID) and drivers register a table of device UUIDs
> which they can support.
>
> So this TEE bus framework registers a match() callback function which
> iterates over the driver UUID table to find a corresponding match for
> device UUID. If a match is found, then this particular device is probed
> via corresponding probe api registered by the driver. This process
> happens whenever a device or a driver is registered with TEE bus.
>
> Also this framework allows for device enumeration to be specific to
> corresponding TEE implementation like OP-TEE etc.
>
> Signed-off-by: Sumit Garg <sumit.garg@linaro.org>
> ---
>  drivers/tee/tee_core.c  | 45 +++++++++++++++++++++++++++++++++++++++++----
>  include/linux/tee_drv.h | 37 ++++++++++++++++++++++++++++++++++++-
>  2 files changed, 77 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> index 7b2bb4c..55370d5 100644
> --- a/drivers/tee/tee_core.c
> +++ b/drivers/tee/tee_core.c
> @@ -15,7 +15,6 @@
>  #define pr_fmt(fmt) "%s: " fmt, __func__
>
>  #include <linux/cdev.h>
> -#include <linux/device.h>
>  #include <linux/fs.h>
>  #include <linux/idr.h>
>  #include <linux/module.h>
> @@ -1027,6 +1026,30 @@ int tee_client_invoke_func(struct tee_context *ctx,
>  }
>  EXPORT_SYMBOL_GPL(tee_client_invoke_func);
>
> +static int tee_client_device_match(struct device *dev,
> +                                  struct device_driver *drv)
> +{
> +       const tee_client_device_id *id_table;
> +       struct tee_client_device *tee_device;
> +
> +       id_table = to_tee_client_driver(drv)->id_table;
> +       tee_device = to_tee_client_device(dev);
> +
> +       while (!uuid_is_null(id_table)) {
> +               if (uuid_equal(&tee_device->id, id_table))
> +                       return 1;
> +               id_table++;
> +       }
> +
> +       return 0;
> +}
> +
> +struct bus_type tee_bus_type = {
> +       .name           = "tee",
> +       .match          = tee_client_device_match,
> +};
> +EXPORT_SYMBOL_GPL(tee_bus_type);
> +
>  static int __init tee_init(void)
>  {
>         int rc;
> @@ -1040,18 +1063,32 @@ static int __init tee_init(void)
>         rc = alloc_chrdev_region(&tee_devt, 0, TEE_NUM_DEVICES, "tee");
>         if (rc) {
>                 pr_err("failed to allocate char dev region\n");
> -               class_destroy(tee_class);
> -               tee_class = NULL;
> +               goto out_unreg_class;
>         }
>
> +       rc = bus_register(&tee_bus_type);
> +       if (rc) {
> +               pr_err("failed to register tee bus\n");
> +               goto out_unreg_chrdev;
> +       }
> +
> +       return 0;
> +
> +out_unreg_chrdev:
> +       unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
> +out_unreg_class:
> +       class_destroy(tee_class);
> +       tee_class = NULL;
> +
>         return rc;
>  }
>
>  static void __exit tee_exit(void)
>  {
> +       bus_unregister(&tee_bus_type);
> +       unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
>         class_destroy(tee_class);
>         tee_class = NULL;
> -       unregister_chrdev_region(tee_devt, TEE_NUM_DEVICES);
>  }
>
>  subsys_initcall(tee_init);
> diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> index 6cfe058..ba985d8 100644
> --- a/include/linux/tee_drv.h
> +++ b/include/linux/tee_drv.h
> @@ -15,11 +15,13 @@
>  #ifndef __TEE_DRV_H
>  #define __TEE_DRV_H
>
> -#include <linux/types.h>
> +#include <linux/device.h>
>  #include <linux/idr.h>
>  #include <linux/kref.h>
>  #include <linux/list.h>
>  #include <linux/tee.h>
> +#include <linux/types.h>
> +#include <linux/uuid.h>
>
>  /*
>   * The file describes the API provided by the generic TEE driver to the
> @@ -538,4 +540,37 @@ static inline bool tee_param_is_memref(struct tee_param *param)
>         }
>  }
>
> +extern struct bus_type tee_bus_type;
> +
> +/*
> + * For TEE based client devices we use the device uuid as the
> + * identifier.
> + */
> +typedef uuid_t tee_client_device_id;
> +
> +/**
> + * struct tee_client_device - tee based device
> + * @id:                        device identifier
> + * @dev:               device structure
> + */
> +struct tee_client_device {
> +       tee_client_device_id id;
> +       struct device dev;
> +};
> +
> +#define to_tee_client_device(d) container_of(d, struct tee_client_device, dev)
> +
> +/**
> + * struct tee_client_driver - tee client driver
> + * @id_table:          device id table supported by this driver
> + * @driver:            driver structure
> + */
> +struct tee_client_driver {
> +       const tee_client_device_id *id_table;
> +       struct device_driver driver;
> +};
> +
> +#define to_tee_client_driver(d) \
> +               container_of(d, struct tee_client_driver, driver)
> +
>  #endif /*__TEE_DRV_H*/
> --
> 2.7.4
>

LGTM, if there are no further comments on this patch please free to add:
Reviewed-by: Bhupesh Sharma <bhsharma@redhat.com>

Thanks.