[PATCH] ARM: 9220/1: amba: Add sanity check for dev->periphid in amba_probe()

[Zhen Lei]

Commit f2d3b9a46e0e ("ARM: 9220/1: amba: Remove deferred device addition")
forcibly invokes device_add() even if dev->periphid is not ready. Although
it will be remedied in amba_match(): dev->periphid will be initialized
if everything is in place; Otherwise, return -EPROBE_DEFER to block
__driver_attach() from further execution. But not all drivers have .match
hook, such as pl031, the dev->bus->probe will be called directly in
__driver_attach(). Unfortunately, if dev->periphid is still not
initialized, the following exception will be triggered.

8<--- cut here ---
Unable to handle kernel NULL pointer dereference at virtual address 00000008
[00000008] *pgd=00000000
Internal error: Oops: 5 [#1] SMP ARM
Modules linked in:
CPU: 1 PID: 1 Comm: swapper/0 Not tainted 6.0.0-rc2+ #7
Hardware name: ARM-Versatile Express
PC is at pl031_probe+0x8/0x208
LR is at amba_probe+0xf0/0x160
pc : 80698df8  lr : 8050eb54  psr: 80000013
sp : c0825df8  ip : 00000000  fp : 811fda38
r10: 00000000  r9 : 80d72470  r8 : fffffdfb
r7 : 811fd800  r6 : be7eb330  r5 : 00000000  r4 : 811fd900
r3 : 80698df0  r2 : 37000000  r1 : 00000000  r0 : 811fd800
Flags: Nzcv  IRQs on  FIQs on  Mode SVC_32  ISA ARM  Segment none
Control: 10c5387d  Table: 6000406a  DAC: 00000051
... ...
 pl031_probe from amba_probe+0xf0/0x160
 amba_probe from really_probe+0x118/0x290
 really_probe from __driver_probe_device+0x84/0xe4
 __driver_probe_device from driver_probe_device+0x30/0xd0
 driver_probe_device from __driver_attach+0x8c/0xfc
 __driver_attach from bus_for_each_dev+0x70/0xb0
 bus_for_each_dev from bus_add_driver+0x168/0x1f4
 bus_add_driver from driver_register+0x7c/0x118
 driver_register from do_one_initcall+0x44/0x1ec
 do_one_initcall from kernel_init_freeable+0x238/0x288
 kernel_init_freeable from kernel_init+0x18/0x12c
 kernel_init from ret_from_fork+0x14/0x2c
... ...
---[ end trace 0000000000000000 ]---

Therefore, take the same action as in amba_match(): return -EPROBE_DEFER
if dev->periphid is not ready in amba_probe().

Fixes: f2d3b9a46e0e ("ARM: 9220/1: amba: Remove deferred device addition")
Signed-off-by: Zhen Lei <thunder.leizhen at huawei.com>
---
KernelVersion: v6.0-rc2
 drivers/amba/bus.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
index 32b0e0b930c1068..2e5572f60692a33 100644
--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -274,9 +274,17 @@ static int amba_probe(struct device *dev)
 {
 	struct amba_device *pcdev = to_amba_device(dev);
 	struct amba_driver *pcdrv = to_amba_driver(dev->driver);
-	const struct amba_id *id = amba_lookup(pcdrv->id_table, pcdev);
+	const struct amba_id *id;
 	int ret;
 
+	if (!pcdev->periphid) {
+		ret = amba_read_periphid(pcdev);
+		if (ret)
+			return -EPROBE_DEFER;
+	}
+
+	id = amba_lookup(pcdrv->id_table, pcdev);
+
 	do {
 		ret = of_amba_device_decode_irq(pcdev);
 		if (ret)
-- 
2.25.1