[PATCH v2 2/5] ARM: mstar: Add machine for MStar/Sigmastar infinity/mercury family ARMv7 SoCs

[Daniel Palmer]

Initial support for the MStar/Sigmastar infinity/mercury series of ARMv7
based IP camera and dashcam SoCs.

These chips are interesting in that they contain a Cortex A7,
peripherals and system memory in a single tiny QFN package that
can be hand soldered allowing almost anyone to embed Linux
in their projects.

Signed-off-by: Daniel Palmer <daniel@xxxxxxxx>
---
 MAINTAINERS                   |  1 +
 arch/arm/Kconfig              |  2 +
 arch/arm/Makefile             |  1 +
 arch/arm/mach-mstar/Kconfig   | 26 +++++++++++++
 arch/arm/mach-mstar/Makefile  |  1 +
 arch/arm/mach-mstar/mstarv7.c | 72 +++++++++++++++++++++++++++++++++++
 6 files changed, 103 insertions(+)
 create mode 100644 arch/arm/mach-mstar/Kconfig
 create mode 100644 arch/arm/mach-mstar/Makefile
 create mode 100644 arch/arm/mach-mstar/mstarv7.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 1ca77f97b8ee..754521938303 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2114,6 +2114,7 @@ ARM/MStar/Sigmastar ARMv7 SoC support
 M:	Daniel Palmer <daniel@xxxxxxxxx>
 L:	linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers)
 S:	Maintained
+F:	arch/arm/mach-mstar/
 F:	Documentation/devicetree/bindings/arm/mstar.yaml
 
 ARM/NEC MOBILEPRO 900/c MACHINE SUPPORT
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index fb6c85c5d344..e466694f8486 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -669,6 +669,8 @@ source "arch/arm/mach-mmp/Kconfig"
 
 source "arch/arm/mach-moxart/Kconfig"
 
+source "arch/arm/mach-mstar/Kconfig"
+
 source "arch/arm/mach-mv78xx0/Kconfig"
 
 source "arch/arm/mach-mvebu/Kconfig"
diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 59fde2d598d8..e7f4ca060c0f 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile
@@ -197,6 +197,7 @@ machine-$(CONFIG_ARCH_MXC)		+= imx
 machine-$(CONFIG_ARCH_MEDIATEK)		+= mediatek
 machine-$(CONFIG_ARCH_MILBEAUT)		+= milbeaut
 machine-$(CONFIG_ARCH_MXS)		+= mxs
+machine-$(CONFIG_ARCH_MSTARV7)		+= mstar
 machine-$(CONFIG_ARCH_NOMADIK)		+= nomadik
 machine-$(CONFIG_ARCH_NPCM)		+= npcm
 machine-$(CONFIG_ARCH_NSPIRE)		+= nspire
diff --git a/arch/arm/mach-mstar/Kconfig b/arch/arm/mach-mstar/Kconfig
new file mode 100644
index 000000000000..6235d0a7860a
--- /dev/null
+++ b/arch/arm/mach-mstar/Kconfig
@@ -0,0 +1,26 @@
+menuconfig ARCH_MSTARV7
+	bool "MStar/Sigmastar ARMv7 SoC Support"
+	depends on ARCH_MULTI_V7
+	select ARM_GIC
+	select ARM_HEAVY_MB
+	help
+	  Support for newer MStar/Sigmastar SoC families that are
+	  based on ARMv7 cores like the Cortex A7 and share the same
+	  basic hardware like the infinity and mercury series.
+
+if ARCH_MSTARV7
+
+config MACH_INFINITY
+	bool "MStar/Sigmastar infinity SoC support"
+	default ARCH_MSTARV7
+	help
+	  Support for MStar/Sigmastar infinity IP camera SoCs.
+
+config MACH_MERCURY
+	bool "MStar/Sigmastar mercury SoC support"
+	default ARCH_MSTARV7
+	help
+	  Support for MStar/Sigmastar mercury dash camera SoCs.
+	  Note that older Mercury2 SoCs are ARM9 based and not supported.
+
+endif
diff --git a/arch/arm/mach-mstar/Makefile b/arch/arm/mach-mstar/Makefile
new file mode 100644
index 000000000000..93b0391ede7e
--- /dev/null
+++ b/arch/arm/mach-mstar/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_ARCH_MSTARV7) += mstarv7.o
diff --git a/arch/arm/mach-mstar/mstarv7.c b/arch/arm/mach-mstar/mstarv7.c
new file mode 100644
index 000000000000..ee96ce46cbbc
--- /dev/null
+++ b/arch/arm/mach-mstar/mstarv7.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Device Tree support for MStar/Sigmastar ARMv7 SoCs
+ *
+ * Copyright (c) 2019 thingy.jp
+ * Author: Daniel Palmer <daniel@xxxxxxxxx>
+ */
+
+#include <linux/init.h>
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+#include <linux/of.h>
+#include <linux/io.h>
+
+/*
+ * In the u-boot code the area these registers are in is
+ * called "L3 bridge" and there are register descriptions
+ * for something in the same area called "AXI".
+ *
+ * It's not exactly known what this is but the vendor code
+ * for both u-boot and linux share calls to "flush the miu pipe".
+ * This seems to be to force pending CPU writes to memory so that
+ * the state is right before DMA capable devices try to read
+ * descriptors and data the CPU has prepared. Without doing this
+ * ethernet doesn't work reliably for example.
+ */
+
+#define MSTARV7_L3BRIDGE_FLUSH		0x1f204414
+#define MSTARV7_L3BRIDGE_STATUS		0x1f204440
+#define MSTARV7_L3BRIDGE_FLUSH_TRIGGER	BIT(0)
+#define MSTARV7_L3BRIDGE_STATUS_DONE	BIT(12)
+
+static u32 __iomem *miu_status;
+static u32 __iomem *miu_flush;
+
+static const char * const mstarv7_board_dt_compat[] __initconst = {
+	"mstar,infinity",
+	"mstar,infinity3",
+	"mstar,mercury5",
+	NULL,
+};
+
+/*
+ * This may need locking to deal with situations where an interrupt
+ * happens while we are in here and mb() gets called by the interrupt handler.
+ */
+static void mstarv7_mb(void)
+{
+	/* toggle the flush miu pipe fire bit */
+	writel_relaxed(0, miu_flush);
+	writel_relaxed(MSTARV7_L3BRIDGE_FLUSH_TRIGGER, miu_flush);
+	while (!(readl_relaxed(miu_status) & MSTARV7_L3BRIDGE_STATUS_DONE)) {
+		/* wait for flush to complete */
+	}
+}
+
+static void __init mstarv7_barriers_init(void)
+{
+	miu_flush = ioremap(MSTARV7_L3BRIDGE_FLUSH, sizeof(*miu_flush));
+	miu_status = ioremap(MSTARV7_L3BRIDGE_STATUS, sizeof(*miu_status));
+	soc_mb = mstarv7_mb;
+}
+
+static void __init mstarv7_init(void)
+{
+	mstarv7_barriers_init();
+}
+
+DT_MACHINE_START(MSTARV7_DT, "MStar/Sigmastar ARMv7 (Device Tree)")
+	.dt_compat	= mstarv7_board_dt_compat,
+	.init_machine	= mstarv7_init,
+MACHINE_END
-- 
2.27.0.rc0