soc/fsl/qe: fix Oops on CPM1 (and likely CPM2)

Commit 0e6e01ff694ee ("CPM/QE: use genalloc to manage CPM/QE muram")
has changed the way muram is managed.
genalloc uses kmalloc(), hence requires the SLAB to be up and running.

On powerpc 8xx, cpm_reset() is called early during startup.
cpm_reset() then calls cpm_muram_init() before SLAB is available,
hence the following Oops.

cpm_reset() cannot be called during initcalls because the CPM is
needed for console.

This patch removes the call to cpm_muram_init() from cpm_reset().
cpm_muram_init() will be called from a new function called cpm_init()
which is declared as subsys_initcall, unless cpm_muram_alloc() is
called earlier for the serial console in which case cpm_muram_init()
will be called from there.

The reason for calling it from two places is that some drivers
(e.g. i2c-cpm) need some of the initialisations done by
cpm_muram_init() but don't call cpm_muram_alloc(). The console
driver calls cpm_muram_alloc() but some platforms might not use
the CPM serial ports for console.

[    0.000000] Unable to handle kernel paging request for data at address 0x00000008
[    0.000000] Faulting instruction address: 0xc01acce0
[    0.000000] Oops: Kernel access of bad area, sig: 11 [#1]
[    0.000000] PREEMPT CMPC885
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 4.4.14-g0886ed8 #5
[    0.000000] task: c05183e0 ti: c0536000 task.ti: c0536000
[    0.000000] NIP: c01acce0 LR: c0011068 CTR: 00000000
[    0.000000] REGS: c0537e50 TRAP: 0300   Not tainted (4.4.14-s3k-dev-g0886ed8-svn)
[    0.000000] MSR: 00001032 <ME,IR,DR,RI>  CR: 28044428  XER: 00000000
[    0.000000] DAR: 00000008 DSISR: c0000000
GPR00: c0011068 c0537f00 c05183e0 00000000 00009000 ffffffff 00000bc0 ffffffff
GPR08: ff003000 ff00b000 ff003bbf 00000000 22044422 100d43a8 00000000 07ff94e8
GPR16: 00000000 07bb5d70 00000000 07ff81f4 07ff81f4 07ff81f4 00000000 00000000
GPR24: 07ffb3a0 07fe7628 c0550000 c7ffa190 c0540000 ff003bbf 00000000 00000001
[    0.000000] NIP [c01acce0] gen_pool_add_virt+0x14/0xdc
[    0.000000] LR [c0011068] cpm_muram_init+0xd4/0x18c
[    0.000000] Call Trace:
[    0.000000] [c0537f00] [00000200] 0x200 (unreliable)
[    0.000000] [c0537f20] [c0011068] cpm_muram_init+0xd4/0x18c
[    0.000000] [c0537f70] [c0494684] cpm_reset+0xb4/0xc8
[    0.000000] [c0537f90] [c0494c64] cmpc885_setup_arch+0x10/0x30
[    0.000000] [c0537fa0] [c0493cd4] setup_arch+0x130/0x168
[    0.000000] [c0537fb0] [c04906bc] start_kernel+0x88/0x380
[    0.000000] [c0537ff0] [c0002224] start_here+0x38/0x98
[    0.000000] Instruction dump:
[    0.000000] 91430010 91430014 80010014 83e1000c 7c0803a6 38210010 4e800020 7c0802a6
[    0.000000] 9421ffe0 bf61000c 90010024 7c7e1b78 <80630008> 7c9c2378 7cc31c30 3863001f
[    0.000000] ---[ end trace dc8fa200cb88537f ]---

fixes: 0e6e01ff694ee ("CPM/QE: use genalloc to manage CPM/QE muram")
Cc: stable@vger.linux.org
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[scottwood: Removed some string changes unrelated to bugfix]
Signed-off-by: Scott Wood <oss@buserror.net>

arch/powerpc/sysdev/cpm1.c

@@ -233,8 +233,6 @@ void __init cpm_reset(void)
 	else
 		out_be32(&siu_conf->sc_sdcr, 1);
 	immr_unmap(siu_conf);
-
-	cpm_muram_init();
 }
 
 static DEFINE_SPINLOCK(cmd_lock);

arch/powerpc/sysdev/cpm2.c

@@ -66,10 +66,6 @@ void __init cpm2_reset(void)
 	cpm2_immr = ioremap(get_immrbase(), CPM_MAP_SIZE);
 #endif
 
-	/* Reclaim the DP memory for our use.
-	 */
-	cpm_muram_init();
-
 	/* Tell everyone where the comm processor resides.
 	 */
 	cpmp = &cpm2_immr->im_cpm;

arch/powerpc/sysdev/cpm_common.c

@@ -37,6 +37,21 @@
 #include <linux/of_gpio.h>
 #endif
 
+static int __init cpm_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "fsl,cpm1");
+	if (!np)
+		np = of_find_compatible_node(NULL, NULL, "fsl,cpm2");
+	if (!np)
+		return -ENODEV;
+	cpm_muram_init();
+	of_node_put(np);
+	return 0;
+}
+subsys_initcall(cpm_init);
+
 #ifdef CONFIG_PPC_EARLY_DEBUG_CPM
 static u32 __iomem *cpm_udbg_txdesc;
 static u8 __iomem *cpm_udbg_txbuf;

drivers/soc/fsl/qe/qe_common.c

@@ -70,6 +70,11 @@ int cpm_muram_init(void)
 	}
 
 	muram_pool = gen_pool_create(0, -1);
+	if (!muram_pool) {
+		pr_err("Cannot allocate memory pool for CPM/QE muram");
+		ret = -ENOMEM;
+		goto out_muram;
+	}
 	muram_pbase = of_translate_address(np, zero);
 	if (muram_pbase == (phys_addr_t)OF_BAD_ADDR) {
 		pr_err("Cannot translate zero through CPM muram node");
@@ -116,6 +121,9 @@ static unsigned long cpm_muram_alloc_common(unsigned long size,
 	struct muram_block *entry;
 	unsigned long start;
 
+	if (!muram_pool && cpm_muram_init())
+		goto out2;
+
 	start = gen_pool_alloc_algo(muram_pool, size, algo, data);
 	if (!start)
 		goto out2;