RE: [PATCH] soc: imx-scu: Add SoC UID(unique identifier) support

[Anson Huang]

Hi, Daniel

> -----Original Message-----
> From: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> Sent: Wednesday, June 26, 2019 8:42 PM
> To: Anson Huang <anson.huang@xxxxxxx>
> Cc: Shawn Guo <shawnguo@xxxxxxxxxx>; Sascha Hauer
> <s.hauer@xxxxxxxxxxxxxx>; Pengutronix Kernel Team
> <kernel@xxxxxxxxxxxxxx>; Fabio Estevam <festevam@xxxxxxxxx>; Aisheng
> Dong <aisheng.dong@xxxxxxx>; Abel Vesa <abel.vesa@xxxxxxx>; linux-
> arm-kernel <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; Linux Kernel Mailing List
> <linux-kernel@xxxxxxxxxxxxxxx>; dl-linux-imx <linux-imx@xxxxxxx>; Daniel
> Baluta <daniel.baluta@xxxxxxx>
> Subject: Re: [PATCH] soc: imx-scu: Add SoC UID(unique identifier) support
> 
> On Wed, Jun 26, 2019 at 10:06 AM <Anson.Huang@xxxxxxx> wrote:
> >
> > From: Anson Huang <Anson.Huang@xxxxxxx>
> >
> > Add i.MX SCU SoC's UID(unique identifier) support, user can read it
> > from sysfs:
> >
> > root@imx8qxpmek:~# cat /sys/devices/soc0/soc_uid
> > 7B64280B57AC1898
> >
> > Signed-off-by: Anson Huang <Anson.Huang@xxxxxxx>
> > ---
> >  drivers/soc/imx/soc-imx-scu.c | 35
> > +++++++++++++++++++++++++++++++++++
> >  1 file changed, 35 insertions(+)
> >
> > diff --git a/drivers/soc/imx/soc-imx-scu.c
> > b/drivers/soc/imx/soc-imx-scu.c index 676f612..8d322a1 100644
> > --- a/drivers/soc/imx/soc-imx-scu.c
> > +++ b/drivers/soc/imx/soc-imx-scu.c
> > @@ -27,6 +27,36 @@ struct imx_sc_msg_misc_get_soc_id {
> >         } data;
> >  } __packed;
> >
> > +struct imx_sc_msg_misc_get_soc_uid {
> > +       struct imx_sc_rpc_msg hdr;
> > +       u32 uid_low;
> > +       u32 uid_high;
> > +} __packed;
> > +
> > +static ssize_t soc_uid_show(struct device *dev,
> > +                           struct device_attribute *attr, char *buf)
> > +{
> > +       struct imx_sc_msg_misc_get_soc_uid msg;
> > +       struct imx_sc_rpc_msg *hdr = &msg.hdr;
> > +       u64 soc_uid;
> > +
> > +       hdr->ver = IMX_SC_RPC_VERSION;
> > +       hdr->svc = IMX_SC_RPC_SVC_MISC;
> > +       hdr->func = IMX_SC_MISC_FUNC_UNIQUE_ID;
> > +       hdr->size = 1;
> > +
> > +       /* the return value of SCU FW is in correct, skip return value
> > + check */
> 
> Why do you mean by "in correct"?

I made a mistake, it should be "incorrect", the existing SCFW of this API returns
an error value even this API is successfully called, to make it work with current
SCFW, I have to skip the return value check for this API for now. Will send V2 patch
to fix this typo.

> > +       imx_scu_call_rpc(soc_ipc_handle, &msg, true);
> > +
> > +       soc_uid = msg.uid_high;
> > +       soc_uid <<= 32;
> > +       soc_uid |= msg.uid_low;
> > +
> > +       return sprintf(buf, "%016llX\n", soc_uid);
> 
> snprintf?

The snprintf is to avoid buffer overflow, which in this case, I don't know the size
of "buf", and the value(u64) to be printed is with fixed length of 64, so I think
sprint is just OK.

Anson.
> 
> > +}
> > +
> > +static DEVICE_ATTR_RO(soc_uid);
> > +
> >  static int imx_scu_soc_id(void)
> >  {
> >         struct imx_sc_msg_misc_get_soc_id msg; @@ -102,6 +132,11 @@
> > static int imx_scu_soc_probe(struct platform_device *pdev)
> >                 goto free_revision;
> >         }
> >
> > +       ret = device_create_file(soc_device_to_device(soc_dev),
> > +                                &dev_attr_soc_uid);
> > +       if (ret)
> > +               goto free_revision;
> > +
> >         return 0;
> >
> >  free_revision:
> > --
> > 2.7.4
> >