[bug report] firmware: thead: Add AON firmware protocol driver

[Dan Carpenter]

Hello Michal Wilczynski,

Commit e4b3cbd840e5 ("firmware: thead: Add AON firmware protocol
driver") from Mar 11, 2025 (linux-next), leads to the following
Smatch static checker warning:

	drivers/firmware/thead,th1520-aon.c:174 th1520_aon_power_update()
	error: buffer overflow 'data' 2 <= 3

drivers/firmware/thead,th1520-aon.c
    164 {
    165         struct th1520_aon_msg_req_set_resource_power_mode msg = {};
    166         struct th1520_aon_rpc_msg_hdr *hdr = &msg.hdr;
    167         int ret;
    168 
    169         hdr->svc = TH1520_AON_RPC_SVC_PM;
    170         hdr->func = TH1520_AON_PM_FUNC_SET_RESOURCE_POWER_MODE;
    171         hdr->size = TH1520_AON_RPC_MSG_NUM;
    172 
    173         RPC_SET_BE16(&msg.resource, 0, rsrc);
--> 174         RPC_SET_BE16(&msg.resource, 2,
                                            ^
&msg.resource is a 2 byte array.  This sets the 3rd and 4th bytes.
It's intentional but ugly.  Use &msg.mode instead.
Also use proper endian conversion macros which don't assume that
we're on a little endian system.  (Although Intel drivers assume they
are on little endian systems.  So there is precedence.  I supposed.)

    175                      (power_on ? TH1520_AON_PM_PW_MODE_ON :
    176                                  TH1520_AON_PM_PW_MODE_OFF));
    177 
    178         ret = th1520_aon_call_rpc(aon_chan, &msg);
    179         if (ret)
    180                 dev_err(aon_chan->cl.dev, "failed to power %s resource %d ret %d\n",
    181                         power_on ? "up" : "off", rsrc, ret);
    182 
    183         return ret;
    184 }

regards,
dan carpenter