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

[Daniel Thompson]

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.


> 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@xxxxxxxxxx>
> ---
>  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(... )

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

> +}
> +
> +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
>