[PATCH V3] soc: imx-scu: Add SoC UID(unique identifier) support

[Anson . Huang]

From: Anson Huang <anson.hu...@nxp.com>

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.hu...@nxp.com>
Reviewed-by: Daniel Baluta <daniel.bal...@nxp.com>
---
Change since V2:
        - The SCU FW API for getting UID does NOT have response, so we should 
set
          imx_scu_call_rpc()'s 3rd parameter as false and still can check the 
returned
          value, and comment is no needed any more.
---
 drivers/soc/imx/soc-imx-scu.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/soc/imx/soc-imx-scu.c b/drivers/soc/imx/soc-imx-scu.c
index 676f612..50831eb 100644
--- a/drivers/soc/imx/soc-imx-scu.c
+++ b/drivers/soc/imx/soc-imx-scu.c
@@ -27,6 +27,40 @@ 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;
+       int ret;
+
+       hdr->ver = IMX_SC_RPC_VERSION;
+       hdr->svc = IMX_SC_RPC_SVC_MISC;
+       hdr->func = IMX_SC_MISC_FUNC_UNIQUE_ID;
+       hdr->size = 1;
+
+       ret = imx_scu_call_rpc(soc_ipc_handle, &msg, false);
+       if (ret) {
+               pr_err("%s: get soc uid failed, ret %d\n", __func__, ret);
+               return ret;
+       }
+
+       soc_uid = msg.uid_high;
+       soc_uid <<= 32;
+       soc_uid |= msg.uid_low;
+
+       return sprintf(buf, "%016llX\n", soc_uid);
+}
+
+static DEVICE_ATTR_RO(soc_uid);
+
 static int imx_scu_soc_id(void)
 {
        struct imx_sc_msg_misc_get_soc_id msg;
@@ -102,6 +136,11 @@ 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