Re: [PATCH v5 1/4] tee: add bus driver framework for TEE based devices

[Sumit Garg <sumit.garg@linaro.org>]

On Thu, 24 Jan 2019 at 15:15, Daniel Thompson
<daniel.thompson@linaro.org> wrote:
>
> On Thu, Jan 24, 2019 at 11:24:36AM +0530, Sumit Garg wrote:
> > Introduce a generic TEE bus driver concept for TEE based kernel drivers
> > which would like to communicate with TEE based devices/services. Also
> > add support in module device table for these new TEE based devices.
> >
> > 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 following apis:
> > - match(): 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.
> > - uevent(): Notifies user-space (udev) whenever a new device is registered
> >   on this bus for auto-loading of out-of-tree drivers.
>
> out-of-tree? Surely it can be used to auto-load any modulized driver.
>

Agree, will correct.

>
> > 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            | 57 ++++++++++++++++++++++++++++++++++++---
> >  include/linux/mod_devicetable.h   |  9 +++++++
> >  include/linux/tee_drv.h           | 32 +++++++++++++++++++++-
> >  scripts/mod/devicetable-offsets.c |  3 +++
> >  scripts/mod/file2alias.c          | 19 +++++++++++++
> >  5 files changed, 115 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/tee/tee_core.c b/drivers/tee/tee_core.c
> > index 7b2bb4c..9f4c8bc 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 +1026,42 @@ 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 struct 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->uuid)) {
> > +             if (uuid_equal(&tee_device->id.uuid, &id_table->uuid))
> > +                     return 1;
> > +             id_table++;
> > +     }
> > +
> > +     return 0;
> > +}
> > +
> > +static int tee_client_device_uevent(struct device *dev,
> > +                                 struct kobj_uevent_env *env)
> > +{
> > +     uuid_t *dev_id = &to_tee_client_device(dev)->id.uuid;
> > +
> > +     if (add_uevent_var(env, "MODALIAS=tee:%pUb", dev_id))
> > +             return -ENOMEM;
> > +
> > +     return 0;
>
> Can just return directly here:
>
>         return add_uevent_var(... )

Okay will use this instead.

>
> Other than these nitpicks then FWIW:
> Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
>

Thanks.
-Sumit

> > +}
> > +
> > +struct bus_type tee_bus_type = {
> > +     .name           = "tee",
> > +     .match          = tee_client_device_match,
> > +     .uevent         = tee_client_device_uevent,
> > +};
> > +EXPORT_SYMBOL_GPL(tee_bus_type);
> > +
> >  static int __init tee_init(void)
> >  {
> >       int rc;
> > @@ -1040,18 +1075,32 @@ 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/mod_devicetable.h b/include/linux/mod_devicetable.h
> > index f9bd2f3..14eaeeb 100644
> > --- a/include/linux/mod_devicetable.h
> > +++ b/include/linux/mod_devicetable.h
> > @@ -779,4 +779,13 @@ struct typec_device_id {
> >       kernel_ulong_t driver_data;
> >  };
> >
> > +/**
> > + * struct tee_client_device_id - tee based device identifier
> > + * @uuid: For TEE based client devices we use the device uuid as
> > + *        the identifier.
> > + */
> > +struct tee_client_device_id {
> > +     uuid_t uuid;
> > +};
> > +
> >  #endif /* LINUX_MOD_DEVICETABLE_H */
> > diff --git a/include/linux/tee_drv.h b/include/linux/tee_drv.h
> > index 6cfe058..ce957ce 100644
> > --- a/include/linux/tee_drv.h
> > +++ b/include/linux/tee_drv.h
> > @@ -15,11 +15,14 @@
> >  #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/mod_devicetable.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 +541,31 @@ static inline bool tee_param_is_memref(struct tee_param *param)
> >       }
> >  }
> >
> > +extern struct bus_type tee_bus_type;
> > +
> > +/**
> > + * struct tee_client_device - tee based device
> > + * @id:                      device identifier
> > + * @dev:             device structure
> > + */
> > +struct tee_client_device {
> > +     struct 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 struct 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*/
> > diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
> > index 2930044..1607183 100644
> > --- a/scripts/mod/devicetable-offsets.c
> > +++ b/scripts/mod/devicetable-offsets.c
> > @@ -225,5 +225,8 @@ int main(void)
> >       DEVID_FIELD(typec_device_id, svid);
> >       DEVID_FIELD(typec_device_id, mode);
> >
> > +     DEVID(tee_client_device_id);
> > +     DEVID_FIELD(tee_client_device_id, uuid);
> > +
> >       return 0;
> >  }
> > diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> > index a37af7d..d0e4172 100644
> > --- a/scripts/mod/file2alias.c
> > +++ b/scripts/mod/file2alias.c
> > @@ -37,6 +37,9 @@ typedef unsigned char       __u8;
> >  typedef struct {
> >       __u8 b[16];
> >  } uuid_le;
> > +typedef struct {
> > +     __u8 b[16];
> > +} uuid_t;
> >
> >  /* Big exception to the "don't include kernel headers into userspace, which
> >   * even potentially has different endianness and word sizes, since
> > @@ -1287,6 +1290,21 @@ static int do_typec_entry(const char *filename, void *symval, char *alias)
> >       return 1;
> >  }
> >
> > +/* Looks like: tee:uuid */
> > +static int do_tee_entry(const char *filename, void *symval, char *alias)
> > +{
> > +     DEF_FIELD(symval, tee_client_device_id, uuid);
> > +
> > +     sprintf(alias, "tee:%02x%02x%02x%02x-%02x%02x-%02x%02x-%02x%02x-%02x%02x%02x%02x%02x%02x",
> > +             uuid.b[0], uuid.b[1], uuid.b[2], uuid.b[3], uuid.b[4],
> > +             uuid.b[5], uuid.b[6], uuid.b[7], uuid.b[8], uuid.b[9],
> > +             uuid.b[10], uuid.b[11], uuid.b[12], uuid.b[13], uuid.b[14],
> > +             uuid.b[15]);
> > +
> > +     add_wildcard(alias);
> > +     return 1;
> > +}
> > +
> >  /* Does namelen bytes of name exactly match the symbol? */
> >  static bool sym_is(const char *name, unsigned namelen, const char *symbol)
> >  {
> > @@ -1357,6 +1375,7 @@ static const struct devtable devtable[] = {
> >       {"fslmc", SIZE_fsl_mc_device_id, do_fsl_mc_entry},
> >       {"tbsvc", SIZE_tb_service_id, do_tbsvc_entry},
> >       {"typec", SIZE_typec_device_id, do_typec_entry},
> > +     {"tee", SIZE_tee_client_device_id, do_tee_entry},
> >  };
> >
> >  /* Create MODULE_ALIAS() statements.
> > --
> > 2.7.4
> >