MIPS: BMIPS: Add quirks for several Broadcom platforms

A couple of chips require special handling in order to make SMP secondary
boot and/or exception vectors work correctly.  Take care of these in
setup.c.

Signed-off-by: Kevin Cernekee <cernekee@gmail.com>
Cc: f.fainelli@gmail.com
Cc: jaedon.shin@gmail.com
Cc: abrestic@chromium.org
Cc: tglx@linutronix.de
Cc: jason@lakedaemon.net
Cc: jogo@openwrt.org
Cc: arnd@arndb.de
Cc: computersforpeace@gmail.com
Cc: linux-mips@linux-mips.org
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/8852/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/bmips/setup.c

@@ -8,9 +8,12 @@
  */
 
 #include <linux/init.h>
+#include <linux/bitops.h>
 #include <linux/bootmem.h>
 #include <linux/clk-provider.h>
 #include <linux/ioport.h>
+#include <linux/kernel.h>
+#include <linux/io.h>
 #include <linux/of.h>
 #include <linux/of_fdt.h>
 #include <linux/of_platform.h>
@@ -18,9 +21,92 @@
 #include <asm/addrspace.h>
 #include <asm/bmips.h>
 #include <asm/bootinfo.h>
+#include <asm/cpu-type.h>
+#include <asm/mipsregs.h>
 #include <asm/prom.h>
 #include <asm/smp-ops.h>
 #include <asm/time.h>
+#include <asm/traps.h>
+
+#define RELO_NORMAL_VEC		BIT(18)
+
+#define REG_BCM6328_OTP		((void __iomem *)CKSEG1ADDR(0x1000062c))
+#define BCM6328_TP1_DISABLED	BIT(9)
+
+static const unsigned long kbase = VMLINUX_LOAD_ADDRESS & 0xfff00000;
+
+struct bmips_quirk {
+	const char		*compatible;
+	void			(*quirk_fn)(void);
+};
+
+static void kbase_setup(void)
+{
+	__raw_writel(kbase | RELO_NORMAL_VEC,
+		     BMIPS_GET_CBR() + BMIPS_RELO_VECTOR_CONTROL_1);
+	ebase = kbase;
+}
+
+static void bcm3384_viper_quirks(void)
+{
+	/*
+	 * Some experimental CM boxes are set up to let CM own the Viper TP0
+	 * and let Linux own TP1.  This requires moving the kernel
+	 * load address to a non-conflicting region (e.g. via
+	 * CONFIG_PHYSICAL_START) and supplying an alternate DTB.
+	 * If we detect this condition, we need to move the MIPS exception
+	 * vectors up to an area that we own.
+	 *
+	 * This is distinct from the OTHER special case mentioned in
+	 * smp-bmips.c (boot on TP1, but enable SMP, then TP0 becomes our
+	 * logical CPU#1).  For the Viper TP1 case, SMP is off limits.
+	 *
+	 * Also note that many BMIPS435x CPUs do not have a
+	 * BMIPS_RELO_VECTOR_CONTROL_1 register, so it isn't safe to just
+	 * write VMLINUX_LOAD_ADDRESS into that register on every SoC.
+	 */
+	board_ebase_setup = &kbase_setup;
+	bmips_smp_enabled = 0;
+}
+
+static void bcm63xx_fixup_cpu1(void)
+{
+	/*
+	 * The bootloader has set up the CPU1 reset vector at
+	 * 0xa000_0200.
+	 * This conflicts with the special interrupt vector (IV).
+	 * The bootloader has also set up CPU1 to respond to the wrong
+	 * IPI interrupt.
+	 * Here we will start up CPU1 in the background and ask it to
+	 * reconfigure itself then go back to sleep.
+	 */
+	memcpy((void *)0xa0000200, &bmips_smp_movevec, 0x20);
+	__sync();
+	set_c0_cause(C_SW0);
+	cpumask_set_cpu(1, &bmips_booted_mask);
+}
+
+static void bcm6328_quirks(void)
+{
+	/* Check CPU1 status in OTP (it is usually disabled) */
+	if (__raw_readl(REG_BCM6328_OTP) & BCM6328_TP1_DISABLED)
+		bmips_smp_enabled = 0;
+	else
+		bcm63xx_fixup_cpu1();
+}
+
+static void bcm6368_quirks(void)
+{
+	bcm63xx_fixup_cpu1();
+}
+
+static const struct bmips_quirk bmips_quirk_list[] = {
+	{ "brcm,bcm3384-viper",		&bcm3384_viper_quirks		},
+	{ "brcm,bcm33843-viper",	&bcm3384_viper_quirks		},
+	{ "brcm,bcm6328",		&bcm6328_quirks			},
+	{ "brcm,bcm6368",		&bcm6368_quirks			},
+	{ },
+};
 
 void __init prom_init(void)
 {
@@ -53,7 +139,8 @@ void __init plat_time_init(void)
 
 void __init plat_mem_setup(void)
 {
-	void *dtb = __dtb_start;
+	void *dtb;
+	const struct bmips_quirk *q;
 
 	set_io_port_base(0);
 	ioport_resource.start = 0;
@@ -62,10 +149,20 @@ void __init plat_mem_setup(void)
 	/* intended to somewhat resemble ARM; see Documentation/arm/Booting */
 	if (fw_arg0 == 0 && fw_arg1 == 0xffffffff)
 		dtb = phys_to_virt(fw_arg2);
+	else if (__dtb_start != __dtb_end)
+		dtb = (void *)__dtb_start;
+	else
+		panic("no dtb found");
 
 	__dt_setup_arch(dtb);
-
 	strlcpy(arcs_cmdline, boot_command_line, COMMAND_LINE_SIZE);
+
+	for (q = bmips_quirk_list; q->quirk_fn; q++) {
+		if (of_flat_dt_is_compatible(of_get_flat_dt_root(),
+					     q->compatible)) {
+			q->quirk_fn();
+		}
+	}
 }
 
 void __init device_tree_init(void)