[PATCH 2/2 RFC] of/mips: Add device tree support to MIPS
David Daney
ddaney at caviumnetworks.com
Tue Oct 19 07:50:56 EST 2010
Although I tested this patch, and it compiles, I have a few more
comments now that I have studied it.
Basically, it looks like most of the code in arch/mips/kernel/prom.c is
not generic to MIPS, but instead highly specific to some platform
(perhaps PowerTV).
On 10/12/2010 11:48 PM, Grant Likely wrote:
> From: Dezhong Diao<dediao at cisco.com>
>
> Add the ability to enable CONFIG_OF on the MIPS architecture.
>
> Signed-off-by: Dezhong Diao<dediao at cisco.com>
> [grant.likely at secretlab.ca: cleared out obsolete hooks,
> removed ARCH_HAS_DEVTREE_MEM from being manually selected,
> remove __init tags from header file]
> Signed-off-by: Grant Likely<grant.likely at secretlab.ca>
> Cc: linux-mips at linux-mips.org
> Cc: David Daney<ddaney at caviumnetworks.com>
> Cc: David VomLehn<dvomlehn at cisco.com>
> ---
>
> I've not tested this on anything, but I picked up the MIPS device tree
> patch written by Dezhong and updated it to match the changes in
> mainline. I also half-heartedly tried to rebase the powertv support
> patch, didn't get very far due to the refactoring in
> arch/mips/powertv/memory.c
>
> Anyway, please take a look and give it a spin. If it looks good, then
> I can add it into my -next branch.
>
> g.
>
> arch/mips/Kconfig | 13 ++++
> arch/mips/include/asm/prom.h | 35 +++++++++++
> arch/mips/kernel/Makefile | 2 +
> arch/mips/kernel/prom.c | 135 ++++++++++++++++++++++++++++++++++++++++++
> arch/mips/kernel/setup.c | 2 +
> 5 files changed, 187 insertions(+), 0 deletions(-)
> create mode 100644 arch/mips/include/asm/prom.h
> create mode 100644 arch/mips/kernel/prom.c
>
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index 3ad59dd..15e364d 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -2107,6 +2107,19 @@ config SECCOMP
>
> If unsure, say Y. Only embedded should say N here.
>
> +config USE_OF
> + bool "Flattened Device Tree support"
> + select OF
> + select OF_FLATTREE
> + help
> + Include support for flattened device tree machine descriptions.
> +
> +config ARCH_HAS_DEVTREE_MEM
> + bool
> + depends on OF
> + help
> + The user has a customized function to parse memory nodes.
> +
> endmenu
>
These Kconfig items should only be selectable if OF is truly supported.
Hardwiring ARCH_HAS_DEVTREE_MEM to USE_OF at this global level
doesn't seem quite right either. I think it is conceivable that we
would want USE_OF without ARCH_HAS_DEVTREE_MEM.
> config LOCKDEP_SUPPORT
> diff --git a/arch/mips/include/asm/prom.h b/arch/mips/include/asm/prom.h
> new file mode 100644
> index 0000000..23f8237
> --- /dev/null
> +++ b/arch/mips/include/asm/prom.h
> @@ -0,0 +1,35 @@
> +/*
> + * arch/mips/include/asm/prom.h
> + *
> + * Copyright (C) 2010 Cisco Systems Inc.<dediao at cisco.com>
> + *
> + * 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_PROM_H
> +#define __ASM_MIPS_PROM_H
> +
> +#ifdef CONFIG_OF
> +#include<linux/init.h>
> +
> +#include<asm/setup.h>
> +#include<asm/irq.h>
> +#include<asm/bootinfo.h>
> +
> +/* which is compatible with the flattened device tree (FDT) */
> +#define cmd_line arcs_cmdline
> +
> +extern int early_init_dt_scan_memory_arch(unsigned long node,
> + const char *uname, int depth, void *data);
> +
> +extern int reserve_mem_mach(unsigned long addr, unsigned long size);
> +extern void free_mem_mach(unsigned long addr, unsigned long size);
> +
> +extern void __init device_tree_init(void);
> +#else /* CONFIG_OF */
> +static inline void __init device_tree_init(void) { }
> +#endif /* CONFIG_OF */
> +
> +#endif /* _ASM_MIPS_PROM_H */
> diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
> index 06f8482..8088498 100644
> --- a/arch/mips/kernel/Makefile
> +++ b/arch/mips/kernel/Makefile
> @@ -96,6 +96,8 @@ 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_OF) += prom.o
> +
> CFLAGS_cpu-bugs64.o = $(shell if $(CC) $(KBUILD_CFLAGS) -Wa,-mdaddi -c -o /dev/null -xc /dev/null>/dev/null 2>&1; then echo "-DHAVE_AS_SET_DADDI"; fi)
>
> obj-$(CONFIG_HAVE_STD_PC_SERIAL_PORT) += 8250-platform.o
> diff --git a/arch/mips/kernel/prom.c b/arch/mips/kernel/prom.c
> new file mode 100644
> index 0000000..6378834
> --- /dev/null
> +++ b/arch/mips/kernel/prom.c
> @@ -0,0 +1,135 @@
> +/*
> + * linux/arch/mips/kernel/prom.c
> + *
> + * Copyright (C) 2010 Cisco Systems Inc.<dediao at cisco.com>
> + *
> + * 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/init.h>
> +#include<linux/module.h>
> +#include<linux/errno.h>
> +#include<linux/types.h>
> +#include<linux/bootmem.h>
> +#include<linux/initrd.h>
> +#include<linux/debugfs.h>
> +#include<linux/of.h>
> +#include<linux/of_fdt.h>
> +#include<linux/of_irq.h>
> +#include<linux/of_platform.h>
> +
> +#include<asm/page.h>
> +#include<asm/prom.h>
> +
> +#ifndef CONFIG_ARCH_HAS_DEVTREE_MEM
> +int __init early_init_dt_scan_memory_arch(unsigned long node,
> + const char *uname, int depth,
> + void *data)
> +{
> + return early_init_dt_scan_memory(node, uname, depth, data);
> +}
> +
> +void __init early_init_dt_add_memory_arch(u64 base, u64 size)
> +{
> + return add_memory_region(base, size, BOOT_MEM_RAM);
> +}
> +
> +int __init reserve_mem_mach(unsigned long addr, unsigned long size)
> +{
> + return reserve_bootmem(addr, size, BOOTMEM_DEFAULT);
> +}
> +
> +void __init free_mem_mach(unsigned long addr, unsigned long size)
> +{
> + return free_bootmem(addr, size);
> +}
> +#endif
> +
> +u64 __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
> +{
> + return virt_to_phys(
> + __alloc_bootmem(size, align, __pa(MAX_DMA_ADDRESS))
> + );
> +}
> +
> +#ifdef CONFIG_BLK_DEV_INITRD
> +void __init early_init_dt_setup_initrd_arch(unsigned long start,
> + unsigned long end)
> +{
> + initrd_start = (unsigned long)__va(start);
> + initrd_end = (unsigned long)__va(end);
> + initrd_below_start_ok = 1;
> +}
> +#endif
> +
> +/*
> + * irq_create_of_mapping - Hook to resolve OF irq specifier into a Linux irq#
> + *
> + * Currently the mapping mechanism is trivial; simple flat hwirq numbers are
> + * mapped 1:1 onto Linux irq numbers. Cascaded irq controllers are not
> + * supported.
> + */
> +unsigned int irq_create_of_mapping(struct device_node *controller,
> + const u32 *intspec, unsigned int intsize)
> +{
> + return intspec[0];
> +}
> +EXPORT_SYMBOL_GPL(irq_create_of_mapping);
> +
This mapping function depends on the interrupt controller architecture.
It is not at all a good fit for what I want to do on Octeon. We have
a hierarchy of interrupt mapping that is best described by a two level
tree, so has '#interrupt-cells = <2>;'. We definitely need a different
implementation than this.
> +void __init early_init_devtree(void *params)
> +{
> + /* Setup flat device-tree pointer */
> + initial_boot_params = params;
> +
> + /* Retrieve various informations from the /chosen node of the
> + * device-tree, including the platform type, initrd location and
> + * size, and more ...
> + */
> + of_scan_flat_dt(early_init_dt_scan_chosen, NULL);
> +
> + /* Scan memory nodes */
> + of_scan_flat_dt(early_init_dt_scan_root, NULL);
> + of_scan_flat_dt(early_init_dt_scan_memory_arch, NULL);
> +}
> +
> +void __init device_tree_init(void)
> +{
> + unsigned long base, size;
> +
> + if (!initial_boot_params)
> + return;
> +
> + base = virt_to_phys((void *)initial_boot_params);
> + size = initial_boot_params->totalsize;
> +
> + /* Before we do anything, lets reserve the dt blob */
> + reserve_mem_mach(base, size);
> +
> + unflatten_device_tree();
> +
> + /* free the space reserved for the dt blob */
> + free_mem_mach(base, size);
> +}
> +
> +#if defined(CONFIG_DEBUG_FS)&& defined(DEBUG)
> +static struct dentry *of_debugfs_root;
> +static struct debugfs_blob_wrapper flat_dt_blob;
> +
> +static int __init export_flat_device_tree(void)
> +{
> + struct dentry *d;
> +
> + flat_dt_blob.data = initial_boot_params;
> + flat_dt_blob.size = initial_boot_params->totalsize;
> +
> + d = debugfs_create_blob("flat-device-tree", S_IFREG | S_IRUSR,
> + of_debugfs_root,&flat_dt_blob);
> + if (!d)
> + return 1;
> +
> + return 0;
> +}
> +device_initcall(export_flat_device_tree);
This debugfs bit will fail. of_debugfs_root is never initialized that I
can see.
> +#endif
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 85aef3f..a6b900f 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -31,6 +31,7 @@
> #include<asm/setup.h>
> #include<asm/smp-ops.h>
> #include<asm/system.h>
> +#include<asm/prom.h>
>
> struct cpuinfo_mips cpu_data[NR_CPUS] __read_mostly;
>
> @@ -487,6 +488,7 @@ static void __init arch_mem_init(char **cmdline_p)
> }
>
> bootmem_init();
> + device_tree_init();
> sparse_init();
> paging_init();
> }
>
>
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