m68k: Add kexec support

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

6 files changed, 268 insertions, 0 deletions

diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 75f25a8e3001..178dffa9de80 100644
--- a/arch/m68k/Kconfig
+++ b/arch/m68k/Kconfig
@@ -87,6 +87,23 @@ config MMU_SUN3
         bool
         depends on MMU && !MMU_MOTOROLA && !MMU_COLDFIRE
 
+config KEXEC
+        bool "kexec system call"
+        depends on M68KCLASSIC
+        help
+          kexec is a system call that implements the ability to shutdown your
+          current kernel, and to start another kernel.  It is like a reboot
+          but it is independent of the system firmware.   And like a reboot
+          you can start any kernel with it, not just Linux.
+
+          The name comes from the similarity to the exec system call.
+
+          It is an ongoing process to be certain the hardware in a machine
+          is properly shutdown, so do not be surprised if this code does not
+          initially work for you.  As of this writing the exact hardware
+          interface is strongly in flux, so no good recommendation can be
+          made.
+
 menu "Platform setup"
 
 source arch/m68k/Kconfig.cpu
diff --git a/arch/m68k/include/asm/kexec.h b/arch/m68k/include/asm/kexec.h
new file mode 100644
index 000000000000..3df97abac147
--- /dev/null
+++ b/arch/m68k/include/asm/kexec.h
@@ -0,0 +1,29 @@
+#ifndef _ASM_M68K_KEXEC_H
+#define _ASM_M68K_KEXEC_H
+
+#ifdef CONFIG_KEXEC
+
+/* Maximum physical address we can use pages from */
+#define KEXEC_SOURCE_MEMORY_LIMIT (-1UL)
+/* Maximum address we can reach in physical address mode */
+#define KEXEC_DESTINATION_MEMORY_LIMIT (-1UL)
+/* Maximum address we can use for the control code buffer */
+#define KEXEC_CONTROL_MEMORY_LIMIT (-1UL)
+
+#define KEXEC_CONTROL_PAGE_SIZE 4096
+
+#define KEXEC_ARCH KEXEC_ARCH_68K
+
+#ifndef __ASSEMBLY__
+
+static inline void crash_setup_regs(struct pt_regs *newregs,
+                                    struct pt_regs *oldregs)
+{
+        /* Dummy implementation for now */
+}
+
+#endif /* __ASSEMBLY__ */
+
+#endif /* CONFIG_KEXEC */
+
+#endif /* _ASM_M68K_KEXEC_H */
diff --git a/arch/m68k/kernel/Makefile b/arch/m68k/kernel/Makefile
index 655347d80780..7ee5f00a9abb 100644
--- a/arch/m68k/kernel/Makefile
+++ b/arch/m68k/kernel/Makefile
@@ -22,3 +22,5 @@ obj-$(CONFIG_PCI) += pcibios.o
 
 obj-$(CONFIG_HAS_DMA)   += dma.o
 
+obj-$(CONFIG_KEXEC)             += machine_kexec.o relocate_kernel.o
+
diff --git a/arch/m68k/kernel/asm-offsets.c b/arch/m68k/kernel/asm-offsets.c
index 8b7b22846366..3a386341aa6e 100644
--- a/arch/m68k/kernel/asm-offsets.c
+++ b/arch/m68k/kernel/asm-offsets.c
@@ -98,6 +98,9 @@ int main(void)
         DEFINE(CIABBASE, &ciab);
         DEFINE(C_PRA, offsetof(struct CIA, pra));
         DEFINE(ZTWOBASE, zTwoBase);
+
+        /* enum m68k_fixup_type */
+        DEFINE(M68K_FIXUP_MEMOFFSET, m68k_fixup_memoffset);
 #endif
 
         return 0;
diff --git a/arch/m68k/kernel/machine_kexec.c b/arch/m68k/kernel/machine_kexec.c
new file mode 100644
index 000000000000..d4affc917d9d
--- /dev/null
+++ b/arch/m68k/kernel/machine_kexec.c
@@ -0,0 +1,58 @@
+/*
+ * machine_kexec.c - handle transition of Linux booting another kernel
+ */
+#include <linux/compiler.h>
+#include <linux/kexec.h>
+#include <linux/mm.h>
+#include <linux/delay.h>
+
+#include <asm/cacheflush.h>
+#include <asm/page.h>
+#include <asm/setup.h>
+
+extern const unsigned char relocate_new_kernel[];
+extern const size_t relocate_new_kernel_size;
+
+int machine_kexec_prepare(struct kimage *kimage)
+{
+        return 0;
+}
+
+void machine_kexec_cleanup(struct kimage *kimage)
+{
+}
+
+void machine_shutdown(void)
+{
+}
+
+void machine_crash_shutdown(struct pt_regs *regs)
+{
+}
+
+typedef void (*relocate_kernel_t)(unsigned long ptr,
+                                  unsigned long start,
+                                  unsigned long cpu_mmu_flags) __noreturn;
+
+void machine_kexec(struct kimage *image)
+{
+        void *reboot_code_buffer;
+        unsigned long cpu_mmu_flags;
+
+        reboot_code_buffer = page_address(image->control_code_page);
+
+        memcpy(reboot_code_buffer, relocate_new_kernel,
+               relocate_new_kernel_size);
+
+        /*
+         * we do not want to be bothered.
+         */
+        local_irq_disable();
+
+        pr_info("Will call new kernel at 0x%08lx. Bye...\n", image->start);
+        __flush_cache_all();
+        cpu_mmu_flags = m68k_cputype | m68k_mmutype << 8;
+        ((relocate_kernel_t) reboot_code_buffer)(image->head & PAGE_MASK,
+                                                 image->start,
+                                                 cpu_mmu_flags);
+}
diff --git a/arch/m68k/kernel/relocate_kernel.S b/arch/m68k/kernel/relocate_kernel.S
new file mode 100644
index 000000000000..3e09a89067ad
--- /dev/null
+++ b/arch/m68k/kernel/relocate_kernel.S
@@ -0,0 +1,159 @@
+#include <linux/linkage.h>
+
+#include <asm/asm-offsets.h>
+#include <asm/page.h>
+#include <asm/setup.h>
+
+
+#define MMU_BASE        8               /* MMU flags base in cpu_mmu_flags */
+
+.text
+
+ENTRY(relocate_new_kernel)
+        movel %sp@(4),%a0               /* a0 = ptr */
+        movel %sp@(8),%a1               /* a1 = start */
+        movel %sp@(12),%d1              /* d1 = cpu_mmu_flags */
+        movew #PAGE_MASK,%d2            /* d2 = PAGE_MASK */
+
+        /* Disable MMU */
+
+        btst #MMU_BASE + MMUB_68851,%d1
+        jeq 3f
+
+1:      /* 68851 or 68030 */
+
+        lea %pc@(.Lcopy),%a4
+2:      addl #0x00000000,%a4            /* virt_to_phys() */
+
+        .section ".m68k_fixup","aw"
+        .long M68K_FIXUP_MEMOFFSET, 2b+2
+        .previous
+
+        .chip 68030
+        pmove %tc,%d0                   /* Disable MMU */
+        bclr #7,%d0
+        pmove %d0,%tc
+        jmp %a4@                        /* Jump to physical .Lcopy */
+        .chip 68k
+
+3:
+        btst #MMU_BASE + MMUB_68030,%d1
+        jne 1b
+
+        btst #MMU_BASE + MMUB_68040,%d1
+        jeq 6f
+
+4:      /* 68040 or 68060 */
+
+        lea %pc@(.Lcont040),%a4
+5:      addl #0x00000000,%a4            /* virt_to_phys() */
+
+        .section ".m68k_fixup","aw"
+        .long M68K_FIXUP_MEMOFFSET, 5b+2
+        .previous
+
+        movel %a4,%d0
+        andl #0xff000000,%d0
+        orw #0xe020,%d0                 /* Map 16 MiB, enable, cacheable */
+        .chip 68040
+        movec %d0,%itt0
+        movec %d0,%dtt0
+        .chip 68k
+        jmp %a4@                        /* Jump to physical .Lcont040 */
+
+.Lcont040:
+        moveq #0,%d0
+        .chip 68040
+        movec %d0,%tc                   /* Disable MMU */
+        movec %d0,%itt0
+        movec %d0,%itt1
+        movec %d0,%dtt0
+        movec %d0,%dtt1
+        .chip 68k
+        jra .Lcopy
+
+6:
+        btst #MMU_BASE + MMUB_68060,%d1
+        jne 4b
+
+.Lcopy:
+        movel %a0@+,%d0                 /* d0 = entry = *ptr */
+        jeq .Lflush
+
+        btst #2,%d0                     /* entry & IND_DONE? */
+        jne .Lflush
+
+        btst #1,%d0                     /* entry & IND_INDIRECTION? */
+        jeq 1f
+        andw %d2,%d0
+        movel %d0,%a0                   /* ptr = entry & PAGE_MASK */
+        jra .Lcopy
+
+1:
+        btst #0,%d0                     /* entry & IND_DESTINATION? */
+        jeq 2f
+        andw %d2,%d0
+        movel %d0,%a2                   /* a2 = dst = entry & PAGE_MASK */
+        jra .Lcopy
+
+2:
+        btst #3,%d0                     /* entry & IND_SOURCE? */
+        jeq .Lcopy
+
+        andw %d2,%d0
+        movel %d0,%a3                   /* a3 = src = entry & PAGE_MASK */
+        movew #PAGE_SIZE/32 - 1,%d0     /* d0 = PAGE_SIZE/32 - 1 */
+3:
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        movel %a3@+,%a2@+               /* *dst++ = *src++ */
+        dbf %d0, 3b
+        jra .Lcopy
+
+.Lflush:
+        /* Flush all caches */
+
+        btst #CPUB_68020,%d1
+        jeq 2f
+
+1:      /* 68020 or 68030 */
+        .chip 68030
+        movec %cacr,%d0
+        orw #0x808,%d0
+        movec %d0,%cacr
+        .chip 68k
+        jra .Lreincarnate
+
+2:
+        btst #CPUB_68030,%d1
+        jne 1b
+
+        btst #CPUB_68040,%d1
+        jeq 4f
+
+3:      /* 68040 or 68060 */
+        .chip 68040
+        nop
+        cpusha %bc
+        nop
+        cinva %bc
+        nop
+        .chip 68k
+        jra .Lreincarnate
+
+4:
+        btst #CPUB_68060,%d1
+        jne 3b
+
+.Lreincarnate:
+        jmp %a1@
+
+relocate_new_kernel_end:
+
+ENTRY(relocate_new_kernel_size)
+        .long relocate_new_kernel_end - relocate_new_kernel