linux-kernel - Re: [PATCH 3/3] mic: cosm: module autoprobing support for cosm driver

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Date:   Sun, 27 Sep 2020 12:29:49 +0200
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Sherry Sun <sherry.sun@....com>
Cc:     sudeep.dutt@...el.com, ashutosh.dixit@...el.com, arnd@...db.de,
        masahiroy@...nel.org, michal.lkml@...kovi.net,
        lee.jones@...aro.org, rikard.falkeborn@...il.com, mst@...hat.co,
        bp@...e.de, jhugo@...eaurora.org, tglx@...utronix.de,
        manivannan.sadhasivam@...aro.org, mgross@...ux.intel.com,
        pierre-louis.bossart@...ux.intel.com, linux-kernel@...r.kernel.org,
        linux-kbuild@...r.kernel.org, linux-imx@....com
Subject: Re: [PATCH 3/3] mic: cosm: module autoprobing support for cosm driver

On Fri, Sep 25, 2020 at 03:31:58PM +0800, Sherry Sun wrote:
> Add uevent callback for cosm_bus and add cosm_device_id for cosm driver
> which is needed for MODULE_DEVICE_TABLE. Also adding struct
> cosm_device_id in devicetable-offsets.c and the cosm entry point in
> file2alias.c.
> 
> Cosm driver will be autoloaded when cosm device appears.
> 
> Signed-off-by: Sherry Sun <sherry.sun@....com>
> ---
>  drivers/misc/mic/bus/cosm_bus.c   |  8 ++++++++
>  drivers/misc/mic/cosm/cosm_main.c |  7 +++++++
>  include/linux/mod_devicetable.h   |  8 ++++++++
>  scripts/mod/devicetable-offsets.c |  3 +++
>  scripts/mod/file2alias.c          | 11 +++++++++++
>  5 files changed, 37 insertions(+)
> 
> diff --git a/drivers/misc/mic/bus/cosm_bus.c b/drivers/misc/mic/bus/cosm_bus.c
> index 5f2141c71738..736e27bbc9f9 100644
> --- a/drivers/misc/mic/bus/cosm_bus.c
> +++ b/drivers/misc/mic/bus/cosm_bus.c
> @@ -14,6 +14,13 @@
>  /* Unique numbering for cosm devices. */
>  static DEFINE_IDA(cosm_index_ida);
>  
> +static int cosm_uevent(struct device *d, struct kobj_uevent_env *env)
> +{
> +	struct cosm_device *dev = dev_to_cosm(d);
> +
> +	return add_uevent_var(env, "MODALIAS=cosm:cosm-dev%u", dev->index);
> +}
> +
>  static int cosm_dev_probe(struct device *d)
>  {
>  	struct cosm_device *dev = dev_to_cosm(d);
> @@ -33,6 +40,7 @@ static int cosm_dev_remove(struct device *d)
>  
>  static struct bus_type cosm_bus = {
>  	.name  = "cosm_bus",
> +	.uevent = cosm_uevent,
>  	.probe = cosm_dev_probe,
>  	.remove = cosm_dev_remove,
>  };
> diff --git a/drivers/misc/mic/cosm/cosm_main.c b/drivers/misc/mic/cosm/cosm_main.c
> index ebb0eac43754..627e7d5f3a83 100644
> --- a/drivers/misc/mic/cosm/cosm_main.c
> +++ b/drivers/misc/mic/cosm/cosm_main.c
> @@ -12,6 +12,7 @@
>  #include <linux/idr.h>
>  #include <linux/slab.h>
>  #include <linux/cred.h>
> +#include <linux/mod_devicetable.h>
>  #include "cosm_main.h"
>  
>  static const char cosm_driver_name[] = "mic";
> @@ -323,6 +324,12 @@ static int cosm_suspend(struct device *dev)
>  	return 0;
>  }
>  
> +static struct cosm_device_id __maybe_unused cosm_driver_id_table[] = {
> +	{ .name	= "cosm-dev*" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(cosm, cosm_driver_id_table);
> +
>  static const struct dev_pm_ops cosm_pm_ops = {
>  	.suspend = cosm_suspend,
>  	.freeze = cosm_suspend
> diff --git a/include/linux/mod_devicetable.h b/include/linux/mod_devicetable.h
> index 736cdc236cf9..ea6cdfe1a3a3 100644
> --- a/include/linux/mod_devicetable.h
> +++ b/include/linux/mod_devicetable.h
> @@ -845,4 +845,12 @@ struct vop_device_id {
>  };
>  #define VOP_DEV_ANY_ID	0xffffffff
>  
> +/* cosm */
> +#define COSM_NAME_SIZE			32
> +#define COSM_MODULE_PREFIX	"cosm:"
> +
> +struct cosm_device_id {
> +	char name[COSM_NAME_SIZE];
> +};
> +
>  #endif /* LINUX_MOD_DEVICETABLE_H */
> diff --git a/scripts/mod/devicetable-offsets.c b/scripts/mod/devicetable-offsets.c
> index 393acaa5302a..499a2832878d 100644
> --- a/scripts/mod/devicetable-offsets.c
> +++ b/scripts/mod/devicetable-offsets.c
> @@ -247,5 +247,8 @@ int main(void)
>  	DEVID_FIELD(vop_device_id, device);
>  	DEVID_FIELD(vop_device_id, vendor);
>  
> +	DEVID(cosm_device_id);
> +	DEVID_FIELD(cosm_device_id, name);
> +
>  	return 0;
>  }
> diff --git a/scripts/mod/file2alias.c b/scripts/mod/file2alias.c
> index 8063b778eedf..f7c80e4da137 100644
> --- a/scripts/mod/file2alias.c
> +++ b/scripts/mod/file2alias.c
> @@ -1383,6 +1383,16 @@ static int do_vop_entry(const char *filename, void *symval,
>  	return 1;
>  }
>  
> +/* Looks like: cosm:S */
> +static int do_cosm_entry(const char *filename, void *symval,
> +			  char *alias)
> +{
> +	DEF_FIELD_ADDR(symval, cosm_device_id, name);
> +	sprintf(alias, COSM_MODULE_PREFIX "%s", *name);
> +
> +	return 1;
> +}
> +
>  /* Does namelen bytes of name exactly match the symbol? */
>  static bool sym_is(const char *name, unsigned namelen, const char *symbol)
>  {
> @@ -1458,6 +1468,7 @@ static const struct devtable devtable[] = {
>  	{"wmi", SIZE_wmi_device_id, do_wmi_entry},
>  	{"mhi", SIZE_mhi_device_id, do_mhi_entry},
>  	{"vop", SIZE_vop_device_id, do_vop_entry},
> +	{"cosm", SIZE_cosm_device_id, do_cosm_entry},
>  };
>  
>  /* Create MODULE_ALIAS() statements.
> -- 
> 2.17.1
> 

You are adding MODULE_DEVICE_TABLE() support for a class of drivers, but
then never adding that support to those drivers?  Why add this at all
then?  Shouldn't you also be modifying a bunch of drivers to get this to
work properly?

thanks,

greg k-h