ARM: BCM5301X: initial support for the BCM5301X/BCM470X SoCs with ARM CPU

I am working on mainlining this SoC again which I started in Summer 2013.

This adds initial support for Broadcom network SoC from the BCM5301X and BCM470X line.

The vendor BSP also uses BCM5301X for this SoC, so I just toke that.

I haven't found a better solution than the abort handler for the memory fault.

I do not have any documentation, only the vendor source code published by Asus and Netgear to conform with the GPL, it would be nice to get some documentation for this Soc like this
https://www.broadcom.com/collateral/pg/440X-PG02-R.pdf
for the Broadcom BCM440X Ethernet controller.

With some additional patches I got Ethernet working with ~250 MBit/s.

A bootlog can be found here:
http://hauke-m.de/files/openwrt/devices/R6250/openwrt-boot-2014-01-05.txt

Changes since v3:
* rebase on Linus 3.13-rc7
* split the workaround into an own patch
* add L2 cache controller to Device tree
* rename config option
* add local-timer and SCU entry to device tree

Changes since v2:
* use vendor prefix brcm
* move code to arch/arm/mach-bcm/
* cleanup arch/arm/mach-bcm/bcm5301x.c
* rename to bcm5301x
* split into more patches

Changes since v1:
* add file Documentation/devicetree/bindings/arm/bcm4708.txt
* rename bcm5301x to bcm4708 in dts files
* use preprocessor includes in dts file
* add CONFIG_ARCH_BCM53XX to multi_v7_defconfig
* remove init_machine callback
* rename vendor prefix from brcm to bcm
* split into two patches

Hauke Mehrtens (4):
ARM: BCM5301X: initial support for the BCM5301X/BCM470X SoCs with ARM
CPU
ARM: BCM5301X: add early debugging support
ARM: BCM5301X: add dts files for BCM4708 SoC
ARM: BCM5301X: workaround suppress fault

 Documentation/devicetree/bindings/arm/bcm4708.txt |    8 ++
 MAINTAINERS                                       |    7 ++
 arch/arm/Kconfig.debug                            |    7 ++
 arch/arm/boot/dts/Makefile                        |    1 +
 arch/arm/boot/dts/bcm4708-netgear-r6250.dts       |   20 ++++
 arch/arm/boot/dts/bcm4708.dtsi                    |  102 +++++++++++++++++++++
 arch/arm/configs/multi_v7_defconfig               |    1 +
 arch/arm/mach-bcm/Kconfig                         |   27 ++++++
 arch/arm/mach-bcm/Makefile                        |    1 +
 arch/arm/mach-bcm/bcm_5301x.c                     |   60 ++++++++++++
 10 files changed, 234 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/bcm4708.txt
 create mode 100644 arch/arm/boot/dts/bcm4708-netgear-r6250.dts
 create mode 100644 arch/arm/boot/dts/bcm4708.dtsi
 create mode 100644 arch/arm/mach-bcm/bcm_5301x.c

1.7.10.4

This patch adds support for the BCM5301X/BCM470X SoCs with an ARM CPUs. Currently just booting to a shell is working and nothing else, no Ethernet, wifi, flash, ...
I have some pending patches to make Ethernet work for this device. Mostly device tree support for bcma is missing.

This SoC is used in small office and home router with Broadcom SoCs. This code should support the BCM4707, BCM4708, BCM4709, BCM53010, BCM53011 and BCM53012 SoC. It uses one or two ARM Cortex A9 Cores, some highlights are 2 PCIe 2.0 controllers, 4 Gigabit Ethernet MACs and a USB 3.0 host controller.

This SoC uses a dual core CPU, but this is currently not implemented. More information about this SoC can be found here:
http://www.anandtech.com/show/5925/broadcom-announces-bcm4708x-and-bcm5301x-socs-for-80211ac-routers

---
 Documentation/devicetree/bindings/arm/bcm4708.txt |    8 +++++
 MAINTAINERS                                       |    7 ++++
 arch/arm/configs/multi_v7_defconfig               |    1 +
 arch/arm/mach-bcm/Kconfig                         |   27 +++++++++++++++
 arch/arm/mach-bcm/Makefile                        |    1 +
 arch/arm/mach-bcm/bcm_5301x.c                     |   37 +++++++++++++++++++++
 6 files changed, 81 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/arm/bcm4708.txt
 create mode 100644 arch/arm/mach-bcm/bcm_5301x.c

new file mode 100644
index 0000000..6527fad
@@ -0,0 +1,8 @@
+Broadcom BCM4708 device tree bindings
+-------------------------------------------
+
+Boards with the BCM4708 SoC shall have the following properties:
+
+Required root node property:
+
+compatible = "broadcom,bcm4708";

index 6c20792..2d98736 100644
@@ -1862,6 +1862,13 @@ F:	arch/arm/boot/dts/bcm2835*
 F:	arch/arm/configs/bcm2835_defconfig
 F:	drivers/*/*bcm2835*
 
+BROADCOM BCM5301X ARM ARCHICTURE
+M:	Hauke Mehrtens <[email protected]>
+L:	linux-arm-kernel at lists.infradead.org
+S:	Maintained
+F:	arch/arm/mach-bcm/bcm_5301x.c
+F:	arch/arm/boot/dts/bcm470*
+
 BROADCOM TG3 GIGABIT ETHERNET DRIVER
 M:	Nithin Nayak Sujir <[email protected]>
 M:	Michael Chan <[email protected]>

index c1df4e9..e7909ce 100644
@@ -6,6 +6,7 @@ CONFIG_ARCH_MVEBU=y
 CONFIG_MACH_ARMADA_370=y
 CONFIG_MACH_ARMADA_XP=y
 CONFIG_ARCH_BCM=y
+CONFIG_ARCH_BCM_5301X=y
 CONFIG_ARCH_BCM_MOBILE=y
 CONFIG_GPIO_PCA953X=y
 CONFIG_ARCH_HIGHBANK=y

index 9fe6d88..e47f9de 100644
@@ -31,6 +31,33 @@ config ARCH_BCM_MOBILE
 	  BCM11130, BCM11140, BCM11351, BCM28145 and
 	  BCM28155 variants.
 
+config ARCH_BCM_5301X
+	bool "Broadcom BCM470X / BCM5301X ARM SoC" if ARCH_MULTI_V7
+	depends on MMU
+	select ARM_GIC
+	select CACHE_L2X0
+	select HAVE_ARM_SCU if SMP
+	select HAVE_ARM_TWD if SMP
+	select HAVE_SMP
+	select COMMON_CLK
+	select GENERIC_CLOCKEVENTS
+	select GENERIC_TIME
+	select ARM_GLOBAL_TIMER
+	select CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
+	select MIGHT_HAVE_PCI
+	help
+	  Support for Broadcom BCM470X and BCM5301X SoCs with ARM CPU cores.
+
+	  This is a network SoC line mostly used in home routers and
+	  wifi access points.
+	  This inclused the following SoC: BCM53010, BCM53011, BCM53012,
+	  BCM53014, BCM53015, BCM53016, BCM53017, BCM53018, BCM4707,
+	  BCM4708 and BCM4709.
+
+	  Do not confuse this with the BCM4760 which is a totally
+	  different SoC or with the older BCM47XX and BCM53XX based
+	  network SoC using a MIPS CPU, they are supported by arch/mips/bcm47xx
+
 endmenu
 
 endif

index c2ccd5a..0164913 100644
@@ -13,3 +13,4 @@
 obj-$(CONFIG_ARCH_BCM_MOBILE)	:= board_bcm281xx.o bcm_kona_smc.o bcm_kona_smc_asm.o kona.o
 plus_sec := $(call as-instr,.arch_extension sec,+sec)
 AFLAGS_bcm_kona_smc_asm.o	:=-Wa,-march=armv7-a$(plus_sec)
+obj-$(CONFIG_ARCH_BCM_5301X)	+= bcm_5301x.o

new file mode 100644
index 0000000..4b83b52
@@ -0,0 +1,37 @@
+/*
+ * Broadcom BCM470X / BCM5301X ARM platform code.
+ *
+ * Copyright 2013 Hauke Mehrtens <[email protected]>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/clocksource.h>
+#include <linux/clk-provider.h>
+#include <asm/hardware/cache-l2x0.h>
+
+#include <asm/mach/arch.h>
+
+static void __init bcm5301x_timer_init(void)
+{
+	of_clk_init(NULL);
+	clocksource_of_init();
+}
+
+static void __init bcm5301x_dt_init(void)
+{
+	l2x0_of_init(0, ~0UL);
+	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+}
+
+static const char __initconst *bcm5301x_dt_compat[] = {
+	"brcm,bcm4708",
+	NULL,
+};
+
+DT_MACHINE_START(BCM5301X, "BCM5301X")
+	.init_time	= bcm5301x_timer_init,
+	.init_machine	= bcm5301x_dt_init,
+	.dt_compat	= bcm5301x_dt_compat,
+MACHINE_END

1.7.10.4

Yes I will remove bcm5301x_timer_init(), but calling l2x0_of_init() is still needed with kernel 3.13-rc7.

Hauke

...

This adds support for early debugging of BCM5301X SoC.

---
 arch/arm/Kconfig.debug |    7 +++++++
 1 file changed, 7 insertions(+)

index 5765abf..16bd36e 100644
@@ -94,6 +94,11 @@ choice
 		depends on ARCH_BCM2835
 		select DEBUG_UART_PL01X
 
+	config DEBUG_BCM_5301X
+		bool "Kernel low-level debugging on BCM5301X UART1"
+		depends on ARCH_BCM_5301X
+		select DEBUG_UART_PL01X
+
 	config DEBUG_CLPS711X_UART1
 		bool "Kernel low-level debugging messages via UART1"
 		depends on ARCH_CLPS711X

@@ -988,6 +993,7 @@ config DEBUG_UART_PHYS
 	default 0x20064000 if DEBUG_RK29_UART1 || DEBUG_RK3X_UART2
 	default 0x20068000 if DEBUG_RK29_UART2 || DEBUG_RK3X_UART3
 	default 0x20201000 if DEBUG_BCM2835
+	default 0x18000300 if DEBUG_BCM_5301X
 	default 0x4000e400 if DEBUG_LL_UART_EFM32
 	default 0x40090000 if ARCH_LPC32XX
 	default 0x40100000 if DEBUG_PXA_UART1

@@ -1029,6 +1035,7 @@ config DEBUG_UART_VIRT
 	default 0xf0009000 if DEBUG_CNS3XXX
 	default 0xf01fb000 if DEBUG_NOMADIK_UART
 	default 0xf0201000 if DEBUG_BCM2835
+	default 0xf1000300 if DEBUG_BCM_5301X
 	default 0xf11f1000 if ARCH_VERSATILE
 	default 0xf1600000 if ARCH_INTEGRATOR
 	default 0xf1c28000 if DEBUG_SUNXI_UART0

1.7.10.4

This uses the newly added BCM5301X SoC code.

---
 arch/arm/boot/dts/Makefile                  |    1 +
 arch/arm/boot/dts/bcm4708-netgear-r6250.dts |   20 ++++++
 arch/arm/boot/dts/bcm4708.dtsi              |  102 +++++++++++++++++++++++++++
 3 files changed, 123 insertions(+)
 create mode 100644 arch/arm/boot/dts/bcm4708-netgear-r6250.dts
 create mode 100644 arch/arm/boot/dts/bcm4708.dtsi

index d57c1a6..9c385bb 100644
@@ -45,6 +45,7 @@ dtb-$(CONFIG_ARCH_BCM2835) += bcm2835-rpi-b.dtb
 dtb-$(CONFIG_ARCH_BCM_MOBILE) += bcm11351-brt.dtb \
 	bcm28155-ap.dtb
 dtb-$(CONFIG_ARCH_BCM2835) += bcm2835-rpi-b.dtb
+dtb-$(CONFIG_ARCH_BCM_5301X) += bcm4708-netgear-r6250.dtb
 dtb-$(CONFIG_ARCH_DAVINCI) += da850-enbw-cmc.dtb \
 	da850-evm.dtb
 dtb-$(CONFIG_ARCH_DOVE) += dove-cm-a510.dtb \

new file mode 100644
index 0000000..34875f6
@@ -0,0 +1,20 @@
+/*
+ * Broadcom BCM470X / BCM5301X arm platform code.
+ *
+ * Copyright 2013 Hauke Mehrtens <[email protected]>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+/dts-v1/;
+
+#include "bcm4708.dtsi"
+
+/ {
+	compatible = "netgear,r6250v1", "brcm,bcm4708";
+	model = "Netgear R6250 V1 (BCM4708)";
+
+	memory {
+		reg = <0x00000000 0x08000000>;
+	};
+};

1.7.10.4

Without this patch I am getting a unhandled fault exception like this one after "Freeing unused kernel memory":

Freeing unused kernel memory: 1260K (c02c1000 - c03fc000) Unhandled fault: imprecise external abort (0x1c06) at 0xb6f89005

Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000007

The address which is here 0xb6f89005 changes from boot to boot, with a new build the changes are bigger. With kernel 3.10 I have also seen this fault at different places in the boot process, but starting with 3.11 they are always occurring after the "Freeing unused kernel memory" message. I never was able to completely boot to userspace without this handler. The abort code is constant 0x1c06. This fault just happens once in the boot process I have never seen it happing twice or more.

I also tried changing the CPSR.A bit to 0 in init_early, with this code like Afzal suggested, but that did not change anything:
asm volatile("mrs r12, cpsr\n"

	"bic r12, r12, #0x00000100\n"
	"msr cpsr_c, r12" ::: "r12", "cc", "memory");

Disabling the L2 cache by building with CONFIG_CACHE_L2X0 unset did not help.

This workaround was copied from the vendor code including most of the comments. It says it they think this is caused by the CFE boot loader used on this device. I do not have any access to any datasheet or errata document to check this.

---
 arch/arm/mach-bcm/bcm_5301x.c |   23 +++++++++++++++++++++++
 1 file changed, 23 insertions(+)

index 4b83b52..30dcfea 100644
@@ -12,6 +12,28 @@
 #include <asm/hardware/cache-l2x0.h>
 
 #include <asm/mach/arch.h>
+#include <asm/signal.h>
+
+static int bcm5301x_abort_handler(unsigned long addr, unsigned int fsr,
+				 struct pt_regs *regs)
+{
+	/*
+	 * These happen for no good reason, possibly left over from the CFE
+	 * boot loader.
+	 */
+	pr_warn("External imprecise Data abort at addr=%#lx, fsr=%#x ignored.\n",
+		addr, fsr);
+
+	/* Returning non-zero causes fault display and panic */
+	return 0;
+}
+
+static void __init bcm5301x_init_early(void)
+{
+	/* Install our hook */
+	hook_fault_code(16 + 6, bcm5301x_abort_handler, SIGBUS, 0,
+			"imprecise external abort");
+}
 
 static void __init bcm5301x_timer_init(void)
 {

@@ -31,6 +53,7 @@ static const char __initconst *bcm5301x_dt_compat[] = {
 };
 
 DT_MACHINE_START(BCM5301X, "BCM5301X")
+	.init_early	= bcm5301x_init_early,
 	.init_time	= bcm5301x_timer_init,
 	.init_machine	= bcm5301x_dt_init,
 	.dt_compat	= bcm5301x_dt_compat,

1.7.10.4

How about narrowing down the abort handler to only ignore a single fault after boot, and only with the abort code 0x1c06? That way you don't risk silent data corruption in case something else goes wrong after booting.

Does the SoC by chance have a PCI host controller? The only other platforms with this kind of handler have it to catch things going wrong with PCI. Maybe another thing to try is to turn off the PCI core at early boot.

Arnd

Ok I extended the bcm5301x_abort_handler() to only ignore the fault when the code is 0x1c06 and it is the first fault.

Yes it has two PCIe host controller. I haven't tried to initialized the PCIe core. It could be that the boot loader did something with the PCIe controller, but I do not think so.

Hauke

First three patches Acked-by: Arnd Bergmann <[email protected]>, with my one comment addressed by removing the timer_init function.

About the fourth patch, I'd still hope we can find a less invasive workaround than to trap all external imprecise data aborts.

Arnd