powerpc/ioremap: warn on early use of ioremap()

Powerpc now has EARLY_IOREMAP.

Next step is to convert all early users of ioremap() to
early_ioremap().

Add a warning to help locate those users.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/b4f03a68ee8e68773c8973d74ec35f9c82c72871.1568295907.git.christophe.leroy@c-s.fr

arch/powerpc/mm/ioremap_32.c

@@ -68,6 +68,7 @@ __ioremap_caller(phys_addr_t addr, unsigned long size, pgprot_t prot, void *call
 	/*
 	 * Should check if it is a candidate for a BAT mapping
 	 */
+	pr_warn("ioremap() called early from %pS. Use early_ioremap() instead\n", caller);
 
 	err = early_ioremap_range(ioremap_bot - size, p, size, prot);
 	if (err)

arch/powerpc/mm/ioremap_64.c

@@ -81,6 +81,8 @@ void __iomem *__ioremap_caller(phys_addr_t addr, unsigned long size,
 	if (slab_is_available())
 		return do_ioremap(paligned, offset, size, prot, caller);
 
+	pr_warn("ioremap() called early from %pS. Use early_ioremap() instead\n", caller);
+
 	err = early_ioremap_range(ioremap_bot, paligned, size, prot);
 	if (err)
 		return NULL;