powerpc/powernv: delay rng platform device creation until later in boot

The platform device for the rng must be created much later in boot.
Otherwise it tries to connect to a parent that doesn't yet exist,
resulting in this splat:

  [    0.000478] kobject: '(null)' ((____ptrval____)): is not initialized, yet kobject_get() is being called.
  [    0.002925] [c000000002a0fb30] [c00000000073b0bc] kobject_get+0x8c/0x100 (unreliable)
  [    0.003071] [c000000002a0fba0] [c00000000087e464] device_add+0xf4/0xb00
  [    0.003194] [c000000002a0fc80] [c000000000a7f6e4] of_device_add+0x64/0x80
  [    0.003321] [c000000002a0fcb0] [c000000000a800d0] of_platform_device_create_pdata+0xd0/0x1b0
  [    0.003476] [c000000002a0fd00] [c00000000201fa44] pnv_get_random_long_early+0x240/0x2e4
  [    0.003623] [c000000002a0fe20] [c000000002060c38] random_init+0xc0/0x214

This patch fixes the issue by doing the platform device creation inside
of machine_subsys_initcall.

Fixes: f3eac426657d ("powerpc/powernv: wire up rng during setup_arch")
Cc: stable@vger.kernel.org
Reported-by: Sachin Sant <sachinp@linux.ibm.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Tested-by: Sachin Sant <sachinp@linux.ibm.com>
[mpe: Change "of node" to "platform device" in change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220630121654.1939181-1-Jason@zx2c4.com

diff --git a/arch/powerpc/platforms/powernv/rng.c b/arch/powerpc/platforms/powernv/rng.c
index 463c78c..3805ad1 100644 (file)
--- a/arch/powerpc/platforms/powernv/rng.c
+++ b/arch/powerpc/platforms/powernv/rng.c
@@ -176,12 +176,8 @@ static int __init pnv_get_random_long_early(unsigned long *v)
                    NULL) != pnv_get_random_long_early)
                return 0;
 
-       for_each_compatible_node(dn, NULL, "ibm,power-rng") {
-               if (rng_create(dn))
-                       continue;
-               /* Create devices for hwrng driver */
-               of_platform_device_create(dn, NULL, NULL);
-       }
+       for_each_compatible_node(dn, NULL, "ibm,power-rng")
+               rng_create(dn);
 
        if (!ppc_md.get_random_seed)
                return 0;
@@ -205,10 +201,18 @@ void __init pnv_rng_init(void)
 
 static int __init pnv_rng_late_init(void)
 {
+       struct device_node *dn;
        unsigned long v;
+
        /* In case it wasn't called during init for some other reason. */
        if (ppc_md.get_random_seed == pnv_get_random_long_early)
                pnv_get_random_long_early(&v);
+
+       if (ppc_md.get_random_seed == powernv_get_random_long) {
+               for_each_compatible_node(dn, NULL, "ibm,power-rng")
+                       of_platform_device_create(dn, NULL, NULL);
+       }
+
        return 0;
 }
 machine_subsys_initcall(powernv, pnv_rng_late_init);