MIPS: CPS: Read CM GCR base from cop0

Rather than patching the start of mips_cps_core_entry to provide the
base address of the CM GCRs, simply read that base address from the cop0
CMGCRBase register, converting from the physical address to an uncached
virtual address.
Signed-off-by: Paul Burton <paul.burton@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andrew Bresticker <abrestic@chromium.org>
Cc: linux-kernel@vger.kernel.org
Cc: Niklas Cassel <niklas.cassel@axis.com>
Cc: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Cc: Markos Chandras <markos.chandras@imgtec.com>
Patchwork: https://patchwork.linux-mips.org/patch/11203/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/kernel/cps-vec.S

@@ -67,11 +67,9 @@
 
 LEAF(mips_cps_core_entry)
 	/*
-	 * These first 12 bytes will be patched by cps_smp_setup to load the
-	 * base address of the CM GCRs into register v1 and the CCA to use into
-	 * register s0.
+	 * These first 4 bytes will be patched by cps_smp_setup to load the
+	 * CCA to use into register s0.
 	 */
-	.quad	0
 	.word	0
 
 	/* Check whether we're here due to an NMI */
@@ -171,6 +169,12 @@ dcache_done:
 	mtc0	t0, CP0_CONFIG
 	ehb
 
+	/* Calculate an uncached address for the CM GCRs */
+	MFC0	v1, CP0_CMGCRBASE
+	PTR_SLL	v1, v1, 4
+	PTR_LI	t0, UNCAC_BASE
+	PTR_ADDU v1, v1, t0
+
 	/* Enter the coherent domain */
 	li	t0, 0xff
 	sw	t0, GCR_CL_COHERENCE_OFS(v1)

arch/mips/kernel/smp-cps.c

@@ -133,11 +133,9 @@ static void __init cps_prepare_cpus(unsigned int max_cpus)
 	/*
 	 * Patch the start of mips_cps_core_entry to provide:
 	 *
-	 * v1 = CM base address
 	 * s0 = kseg0 CCA
 	 */
 	entry_code = (u32 *)&mips_cps_core_entry;
-	UASM_i_LA(&entry_code, 3, (long)mips_cm_base);
 	uasm_i_addiu(&entry_code, 16, 0, cca);
 	blast_dcache_range((unsigned long)&mips_cps_core_entry,
 			   (unsigned long)entry_code);