On Thu, Jun 30, 2022 at 02:40:34PM +0200, Ahmad Fatoum wrote:
> For OF-enabled platforms with aliases, device file naming is pretty much
> solved: If there is mmc2 = &something, then we have a mmc2 device and
> a /dev/mmc2 device file. For other platforms like x86, EFI-provided
> devices are harder to get ahold of. Add a command to make this
> straight-forward to do in scripts. The main use of this is probably to
> access parameters like nt_signature or guid:
>
> devloop /dev/disk0 guid
>
> This would print to console, but we have no output capture yet, so add
> an optional -v VARIABLE parameter as well to allow easy use from
> scripts.
>
> Signed-off-by: Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx>
> ---
> commands/Kconfig | 13 ++++++++
> commands/Makefile | 1 +
> commands/devlookup.c | 73 ++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 87 insertions(+)
> create mode 100644 commands/devlookup.c
>
> diff --git a/commands/Kconfig b/commands/Kconfig
> index fb4dcefed8bf..5bab78fd1ce7 100644
> --- a/commands/Kconfig
> +++ b/commands/Kconfig
> @@ -75,6 +75,19 @@ config CMD_DEVINFO
> If called with a device path being the argument, devinfo shows more
> default information about this device and its parameters.
>
> +config CMD_DEVLOOKUP
> + tristate
> + prompt "devlookup"
> + help
> + Look up device behind device file and its parameters
> +
> + devlookup [-v VAR] /dev/DEVICE [parameter]
> +
> + Detects the device behind a device file and outputs it,
> + unless a second argument is given. In that case the device
> + parameter with that name is looked up. Specifying -v VARIABLE
> + will write output to VARIABLE instead of printing it.
> +
> config CMD_DEVUNBIND
> tristate
> prompt "devunbind"
> diff --git a/commands/Makefile b/commands/Makefile
> index 6c3a7a1dabcd..b43da1a80173 100644
> --- a/commands/Makefile
> +++ b/commands/Makefile
> @@ -110,6 +110,7 @@ obj-$(CONFIG_CMD_DETECT) += detect.o
> obj-$(CONFIG_CMD_BOOT) += boot.o
> obj-$(CONFIG_CMD_DEVINFO) += devinfo.o
> obj-$(CONFIG_CMD_DEVUNBIND) += devunbind.o
> +obj-$(CONFIG_CMD_DEVLOOKUP) += devlookup.o
> obj-$(CONFIG_CMD_DRVINFO) += drvinfo.o
> obj-$(CONFIG_CMD_READF) += readf.o
> obj-$(CONFIG_CMD_MENUTREE) += menutree.o
> diff --git a/commands/devlookup.c b/commands/devlookup.c
> new file mode 100644
> index 000000000000..9599df7b10bc
> --- /dev/null
> +++ b/commands/devlookup.c
> @@ -0,0 +1,73 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +#include <common.h>
> +#include <command.h>
> +#include <fs.h>
> +#include <getopt.h>
> +#include <malloc.h>
> +#include <linux/stat.h>
> +#include <linux/ctype.h>
> +#include <environment.h>
> +
> +static int report(const char *variable, const char *val)
> +{
> + if (variable)
> + return setenv(variable, val);
> +
> + if (!val)
> + return -errno;
> +
> + printf("%s\n", val);
> + return 0;
> +}
> +
> +static int do_devlookup(int argc, char *argv[])
> +{
> + const char *variable = NULL, *devicefile, *paramname;
> + struct cdev *cdev;
> + int opt;
> +
> + while ((opt = getopt(argc, argv, "v:")) > 0) {
> + switch(opt) {
> + case 'v':
> + variable = optarg;
> + break;
> + }
> + }
> +
> + if (argc - optind == 0 || argc - optind > 2)
> + return COMMAND_ERROR_USAGE;
> +
> + devicefile = argv[optind];
> + paramname = argv[optind+1];
> +
> + if (!strstarts(devicefile, "/dev/"))
> + return COMMAND_ERROR_USAGE;
Should we skip the /dev/ part so that we can allow cdev names directly?
Something like:
if (strstarts(devicefile, "/dev/"))
devicefile += sizeof "/dev/" - 1;
Sascha
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