MIPS: Add generic support for multiple machines within a single kernel

This patch adds a generic solution to support multiple machines based on
a given SoC within a single kernel image. It is implemented already for
several other architectures but MIPS has no generic support for that yet.

[Ralf: This competes with DT but DT is a much more complex solution and this
code has been used by OpenWRT for a long time so for now DT is a bad reason
to stop the merge but longer term this should be migrated to DT.]

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: kaloz@openwrt.org
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1814/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

6 files changed, 157 insertions, 1 deletions

diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index f489ec30e071..2106781d7473 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -883,6 +883,9 @@ config MIPS_DISABLE_OBSOLETE_IDE
 config SYNC_R4K
         bool
 
+config MIPS_MACHINE
+        def_bool n
+
 config NO_IOPORT
         def_bool n
 
diff --git a/arch/mips/include/asm/mips_machine.h b/arch/mips/include/asm/mips_machine.h
new file mode 100644
index 000000000000..363bb352c7f7
--- /dev/null
+++ b/arch/mips/include/asm/mips_machine.h
@@ -0,0 +1,54 @@
+/*
+ *  Copyright (C) 2008-2010 Gabor Juhos <juhosg@openwrt.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ */
+
+#ifndef __ASM_MIPS_MACHINE_H
+#define __ASM_MIPS_MACHINE_H
+
+#include <linux/init.h>
+#include <linux/stddef.h>
+
+#include <asm/bootinfo.h>
+
+struct mips_machine {
+        unsigned long           mach_type;
+        const char              *mach_id;
+        const char              *mach_name;
+        void                    (*mach_setup)(void);
+};
+
+#define MIPS_MACHINE(_type, _id, _name, _setup)                 \
+static const char machine_name_##_type[] __initconst            \
+                        __aligned(1) = _name;                   \
+static const char machine_id_##_type[] __initconst              \
+                        __aligned(1) = _id;                     \
+static struct mips_machine machine_##_type                      \
+                __used __section(.mips.machines.init) =         \
+{                                                               \
+        .mach_type      = _type,                                \
+        .mach_id        = machine_id_##_type,                   \
+        .mach_name      = machine_name_##_type,                 \
+        .mach_setup     = _setup,                               \
+};
+
+extern long __mips_machines_start;
+extern long __mips_machines_end;
+
+#ifdef CONFIG_MIPS_MACHINE
+int  mips_machtype_setup(char *id) __init;
+void mips_machine_setup(void) __init;
+void mips_set_machine_name(const char *name) __init;
+char *mips_get_machine_name(void);
+#else
+static inline int mips_machtype_setup(char *id) { return 1; }
+static inline void mips_machine_setup(void) { }
+static inline void mips_set_machine_name(const char *name) { }
+static inline char *mips_get_machine_name(void) { return NULL; }
+#endif /* CONFIG_MIPS_MACHINE */
+
+#endif /* __ASM_MIPS_MACHINE_H */
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 22b2e0e38617..39773979ca6d 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -95,6 +95,7 @@ obj-$(CONFIG_GPIO_TXX9)		+= gpio_txx9.o
 obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
 obj-$(CONFIG_EARLY_PRINTK)      += early_printk.o
 obj-$(CONFIG_SPINLOCK_TEST)     += spinlock_test.o
+obj-$(CONFIG_MIPS_MACHINE)      += mips_machine.o
 
 obj-$(CONFIG_OF)                += prom.o
 
diff --git a/arch/mips/kernel/mips_machine.c b/arch/mips/kernel/mips_machine.c
new file mode 100644
index 000000000000..411a058d2c53
--- /dev/null
+++ b/arch/mips/kernel/mips_machine.c
@@ -0,0 +1,86 @@
+/*
+ *  Copyright (C) 2008-2010 Gabor Juhos <juhosg@openwrt.org>
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms of the GNU General Public License version 2 as published
+ *  by the Free Software Foundation.
+ *
+ */
+#include <linux/mm.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+
+#include <asm/mips_machine.h>
+
+static struct mips_machine *mips_machine __initdata;
+static char *mips_machine_name = "Unknown";
+
+#define for_each_machine(mach) \
+        for ((mach) = (struct mips_machine *)&__mips_machines_start; \
+             (mach) && \
+             (unsigned long)(mach) < (unsigned long)&__mips_machines_end; \
+             (mach)++)
+
+__init void mips_set_machine_name(const char *name)
+{
+        char *p;
+
+        if (name == NULL)
+                return;
+
+        p = kstrdup(name, GFP_KERNEL);
+        if (!p)
+                pr_err("MIPS: no memory for machine_name\n");
+
+        mips_machine_name = p;
+}
+
+char *mips_get_machine_name(void)
+{
+        return mips_machine_name;
+}
+
+__init int mips_machtype_setup(char *id)
+{
+        struct mips_machine *mach;
+
+        for_each_machine(mach) {
+                if (mach->mach_id == NULL)
+                        continue;
+
+                if (strcmp(mach->mach_id, id) == 0) {
+                        mips_machtype = mach->mach_type;
+                        return 0;
+                }
+        }
+
+        pr_err("MIPS: no machine found for id '%s', supported machines:\n", id);
+        pr_err("%-24s %s\n", "id", "name");
+        for_each_machine(mach)
+                pr_err("%-24s %s\n", mach->mach_id, mach->mach_name);
+
+        return 1;
+}
+
+__setup("machtype=", mips_machtype_setup);
+
+__init void mips_machine_setup(void)
+{
+        struct mips_machine *mach;
+
+        for_each_machine(mach) {
+                if (mips_machtype == mach->mach_type) {
+                        mips_machine = mach;
+                        break;
+                }
+        }
+
+        if (!mips_machine)
+                return;
+
+        mips_set_machine_name(mips_machine->mach_name);
+        pr_info("MIPS: machine is %s\n", mips_machine_name);
+
+        if (mips_machine->mach_setup)
+                mips_machine->mach_setup();
+}
diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c
index 26109c4d5170..4195abb55e59 100644
--- a/arch/mips/kernel/proc.c
+++ b/arch/mips/kernel/proc.c
@@ -12,6 +12,7 @@
 #include <asm/cpu-features.h>
 #include <asm/mipsregs.h>
 #include <asm/processor.h>
+#include <asm/mips_machine.h>
 
 unsigned int vced_count, vcei_count;
 
@@ -31,8 +32,12 @@ static int show_cpuinfo(struct seq_file *m, void *v)
         /*
          * For the first processor also print the system type
          */
-        if (n == 0)
+        if (n == 0) {
                 seq_printf(m, "system type\t\t: %s\n", get_system_type());
+                if (mips_get_machine_name())
+                        seq_printf(m, "machine\t\t\t: %s\n",
+                                   mips_get_machine_name());
+        }
 
         seq_printf(m, "processor\t\t: %ld\n", n);
         sprintf(fmt, "cpu model\t\t: %%s V%%d.%%d%s\n",
diff --git a/arch/mips/kernel/vmlinux.lds.S b/arch/mips/kernel/vmlinux.lds.S
index f25df73db923..570607b376b5 100644
--- a/arch/mips/kernel/vmlinux.lds.S
+++ b/arch/mips/kernel/vmlinux.lds.S
@@ -98,6 +98,13 @@ SECTIONS
         INIT_TEXT_SECTION(PAGE_SIZE)
         INIT_DATA_SECTION(16)
 
+        . = ALIGN(4);
+        .mips.machines.init : AT(ADDR(.mips.machines.init) - LOAD_OFFSET) {
+                __mips_machines_start = .;
+                *(.mips.machines.init)
+                __mips_machines_end = .;
+        }
+
         /* .exit.text is discarded at runtime, not link time, to deal with
          * references from .rodata
          */