net: eth: xgene: fix booting with devicetree

Commit de7b5b3d79 ("net: eth: xgene: change APM X-Gene SoC platform
ethernet to support ACPI") breaks booting with devicetree with UEFI
firmware. In that case, I get:

Unhandled fault: synchronous external abort (0x96000010) at 0xfffffc0000620010
 Internal error: : 96000010 [#1] SMP
 Modules linked in: vfat fat xfs libcrc32c ahci_xgene libahci_platform libahci
 CPU: 7 PID: 634 Comm: NetworkManager Not tainted 4.0.0-rc1+ #4
 Hardware name: AppliedMicro Mustang/Mustang, BIOS 1.1.0-rh-0.14 Mar  1 2015
 task: fffffe03d4c7e100 ti: fffffe03d4e24000 task.ti: fffffe03d4e24000
 PC is at xgene_enet_rd_mcx_mac.isra.11+0x58/0xd4
 LR is at xgene_gmac_tx_enable+0x2c/0x50
 pc : [<fffffe000069d6fc>] lr : [<fffffe000069dcc4>] pstate: 80000145
 sp : fffffe03d4e27590
 x29: fffffe03d4e27590 x28: 0000000000000000
 x27: fffffe03d4e277c0 x26: fffffe03da8fda10
 x25: fffffe03d4e2760c x24: fffffe03d49e28c0
 x23: fffffc0000620004 x22: 0000000000000000
 x21: fffffc0000620000 x20: fffffc0000620010
 x19: 000000000000000b x18: 000003ffd4a96020
 x17: 000003ff7fc1f7a0 x16: fffffe000079b9cc
 x15: 0000000000000000 x14: 0000000000000000
 x13: 0000000000000000 x12: fffffe03d4e24000
 x11: fffffe03d4e27da0 x10: 0000000000000001
 x9 : 0000000000000000 x8 : fffffe03d4e27a20
 x7 : 0000000000000000 x6 : 00000000ffffffef
 x5 : fffffe000105f7d0 x4 : fffffe00007ca8c8
 x3 : fffffe03d4e2760c x2 : 0000000000000000
 x1 : fffffc0000620000 x0 : 0000000040000000

 Process NetworkManager (pid: 634, stack limit = 0xfffffe03d4e24028)
 Stack: (0xfffffe03d4e27590 to 0xfffffe03d4e28000)
 ...
 Call trace:
 [<fffffe000069d6fc>] xgene_enet_rd_mcx_mac.isra.11+0x58/0xd4
 [<fffffe000069dcc0>] xgene_gmac_tx_enable+0x28/0x50
 [<fffffe00006a112c>] xgene_enet_open+0x2c/0x130
 [<fffffe00007b9254>] __dev_open+0xc8/0x148
 [<fffffe00007b956c>] __dev_change_flags+0x90/0x158
 [<fffffe00007b9664>] dev_change_flags+0x30/0x70
 [<fffffe00007c8ab8>] do_setlink+0x278/0x870
 [<fffffe00007c95bc>] rtnl_newlink+0x404/0x6a8
 [<fffffe00007c8040>] rtnetlink_rcv_msg+0x98/0x218
 [<fffffe00007e78e4>] netlink_rcv_skb+0xe0/0xf8
 [<fffffe00007c7f94>] rtnetlink_rcv+0x30/0x44
 [<fffffe00007e6f2c>] netlink_unicast+0xfc/0x210
 [<fffffe00007e75b8>] netlink_sendmsg+0x498/0x5ac
 [<fffffe00007990b8>] do_sock_sendmsg+0xa4/0xcc
 [<fffffe000079a958>] ___sys_sendmsg+0x1fc/0x208
 [<fffffe000079b984>] __sys_sendmsg+0x4c/0x94
 [<fffffe000079b9f8>] SyS_sendmsg+0x2c/0x3c

The problem here is that the enet hw clocks are not getting
initialized because of a test to avoid the initialization if
UEFI is used to boot. This is an incorrect test. When booting
with UEFI and devicetree, the kernel must still initialize
the enet hw clocks. If booting with ACPI, the clock hw is
not exposed to the kernel and it is that case where we want
to avoid initializing clocks.

Signed-off-by: Mark Salter <msalter@redhat.com>
Acked-by: Feng Kan <fkan@apm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/apm/xgene/xgene_enet_hw.c

@@ -593,7 +593,7 @@ static int xgene_enet_reset(struct xgene_enet_pdata *pdata)
 	if (!xgene_ring_mgr_init(pdata))
 		return -ENODEV;
 
-	if (!efi_enabled(EFI_BOOT)) {
+	if (pdata->clk) {
 		clk_prepare_enable(pdata->clk);
 		clk_disable_unprepare(pdata->clk);
 		clk_prepare_enable(pdata->clk);