Re: [PATCH v2 05/15] x86/dtb: add early parsing of APIC and IO APIC

[Grant Likely <grant.likely@secretlab.ca>]

On Tue, Jan 04, 2011 at 02:23:02PM +0100, Sebastian Andrzej Siewior wrote:
> The apic & ioapic have to be added to system early because
> native_init_IRQ() requires it. In order to obtain the address of the
> ioapic the device tree has to be unflattened because
> of_address_to_resource() has to work.
> The device tree is relocated to ensure it is always covered by the
> kernel and the boot loader does not have to make assumptions about
> kernel's memory layout.

Hi Sebastian,

Some comments below...

> 
> Cc: devicetree-discuss@lists.ozlabs.org
> Cc: Dirk Brandewie <dirk.brandewie@gmail.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> ---
>  arch/x86/include/asm/prom.h |    7 +++
>  arch/x86/kernel/irqinit.c   |    2 +-
>  arch/x86/kernel/prom.c      |  121 +++++++++++++++++++++++++++++++++++++++++-
>  3 files changed, 126 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/x86/include/asm/prom.h b/arch/x86/include/asm/prom.h
> index 9076ae4..3bc8ed5 100644
> --- a/arch/x86/include/asm/prom.h
> +++ b/arch/x86/include/asm/prom.h
> @@ -22,10 +22,17 @@
>  #include <asm/irq_controller.h>
>  
>  #ifdef CONFIG_OF
> +extern int of_ioapic;
> +extern u64 initial_dtb;
>  extern void add_dtb(u64 data);
> +void x86_dtb_find_config(void);
> +void x86_dtb_get_config(unsigned int unused);
>  void add_interrupt_host(struct irq_domain *ih);
>  #else
>  static inline void add_dtb(u64 data) { }
> +#define x86_dtb_find_config x86_init_noop
> +#define x86_dtb_get_config x86_init_uint_noop
> +#define of_ioapic 0

Nit: Personally, I prefer static inlines over preprocessor macros, but
that isn't anything that will block this patch.

>  #endif
>  
>  extern char cmd_line[COMMAND_LINE_SIZE];
> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> index 149c87f..4cadf86 100644
> --- a/arch/x86/kernel/irqinit.c
> +++ b/arch/x86/kernel/irqinit.c
> @@ -244,7 +244,7 @@ void __init native_init_IRQ(void)
>  			set_intr_gate(i, interrupt[i-FIRST_EXTERNAL_VECTOR]);
>  	}
>  
> -	if (!acpi_ioapic)
> +	if (!acpi_ioapic && !of_ioapic)
>  		setup_irq(2, &irq2);
>  
>  #ifdef CONFIG_X86_32
> diff --git a/arch/x86/kernel/prom.c b/arch/x86/kernel/prom.c
> index 53948cb..388fdff 100644
> --- a/arch/x86/kernel/prom.c
> +++ b/arch/x86/kernel/prom.c
> @@ -6,15 +6,20 @@
>  #include <linux/interrupt.h>
>  #include <linux/list.h>
>  #include <linux/of.h>
> +#include <linux/of_address.h>
>  #include <linux/of_platform.h>
>  #include <linux/slab.h>
>  
>  #include <asm/irq_controller.h>
> +#include <asm/io_apic.h>
>  
> +__initdata u64 initial_dtb;
>  char __initdata cmd_line[COMMAND_LINE_SIZE];
>  static LIST_HEAD(irq_domains);
>  static DEFINE_RAW_SPINLOCK(big_irq_lock);
>  
> +int __initdata of_ioapic;
> +
>  void add_interrupt_host(struct irq_domain *ih)
>  {
>  	unsigned long flags;
> @@ -93,7 +98,117 @@ u64 __init early_init_dt_alloc_memory_arch(u64 size, u64 align)
>  
>  void __init add_dtb(u64 data)
>  {
> -	initial_boot_params = (struct boot_param_header *)
> -		phys_to_virt((u64) (u32) data +
> -				offsetof(struct setup_data, data));
> +	initial_dtb = data + offsetof(struct setup_data, data);
> +}
> +
> +static void __init dtb_lapic_setup(void)
> +{
> +#ifdef CONFIG_X86_LOCAL_APIC
> +	if (apic_force_enable())
> +		return;
> +
> +	smp_found_config = 1;
> +	pic_mode = 1;
> +	/* Required for ioapic registration */
> +	set_fixmap_nocache(FIX_APIC_BASE, mp_lapic_addr);
> +	if (boot_cpu_physical_apicid == -1U)
> +		boot_cpu_physical_apicid = read_apic_id();
> +
> +	generic_processor_info(boot_cpu_physical_apicid,
> +			GET_APIC_VERSION(apic_read(APIC_LVR)));
> +#endif
> +}
> +
> +#ifdef CONFIG_X86_IO_APIC
> +static void __init dtb_add_ioapic(struct device_node *dn)
> +{
> +	unsigned int ioapic_id;
> +	const __be32 *cell;
> +	int len;
> +	struct resource r;
> +	int ret;
> +
> +	cell = of_get_property(dn, "id", &len);
> +	if (!cell) {
> +		printk(KERN_ERR "Node %s is missing id property.\n",
> +				dn->full_name);
> +		return;
> +	}
> +	ioapic_id = of_read_ulong(cell, len / 4);

This looks like poor usage practise for the device tree.  'id' or any
kind of enumeration property in a device tree node is strongly
discouraged.  As much as possible, let Linux dynamically enumerate
devices rather than trying to explicitly specify the numbering.  Since
you can explicitly describe the relationship between device nodes in
the tree, you should find that explicitly specifying numbers is almost
never required.

If you *really* need to enumerate devices in the device tree, then use
properties in the /aliases node to assign globally unique numbers.

> +
> +	ret = of_address_to_resource(dn, 0, &r);
> +	if (ret) {
> +		printk(KERN_ERR "Can't obtain address from node %s.\n",
> +				dn->full_name);
> +		return;
> +	}
> +	mp_register_ioapic(ioapic_id, r.start, gsi_top);
> +}
> +
> +static void __init dtb_ioapic_setup(void)
> +{
> +	struct device_node *dn;
> +
> +	if (!smp_found_config)
> +		return;
> +
> +	for_each_compatible_node(dn, NULL, "intel,ioapic")
> +		dtb_add_ioapic(dn);
> +
> +	if (nr_ioapics) {
> +		of_ioapic = 1;
> +		return;
> +	}
> +	printk(KERN_ERR "Error: No information about IO-APIC in OF.\n");
> +	smp_found_config = 0;
> +}
> +#else
> +static void __init dtb_ioapic_setup(void) {}
> +#endif
> +
> +static void __init dtb_apic_setup(void)
> +{
> +	dtb_lapic_setup();
> +	dtb_ioapic_setup();
> +}
> +
> +void __init x86_dtb_find_config(void)
> +{
> +	if (initial_dtb)
> +		smp_found_config = 1;
> +	else
> +		printk(KERN_ERR "Missing device tree!.\n");
> +}
> +
> +void __init x86_dtb_get_config(unsigned int unused)
> +{
> +	u32 size;
> +	u32 map_len;
> +	void *new_dtb;
> +
> +	if (!initial_dtb)
> +		return;
> +
> +	map_len = max(PAGE_SIZE - (initial_dtb & ~PAGE_MASK),
> +			(u64)sizeof(struct boot_param_header));
> +
> +	initial_boot_params = early_memremap(initial_dtb, map_len);
> +	size = be32_to_cpu(initial_boot_params->totalsize);
> +	if (map_len < size) {
> +		early_iounmap(initial_boot_params, map_len);
> +		initial_boot_params = early_memremap(initial_dtb, size);
> +		map_len = size;
> +	}
> +
> +	new_dtb = alloc_bootmem(size);
> +	memcpy(new_dtb, initial_boot_params, size);
> +	early_iounmap(initial_boot_params, map_len);
> +
> +	initial_boot_params = new_dtb;
> +
> +	/* root level address cells */
> +	of_scan_flat_dt(early_init_dt_scan_root, NULL);
> +
> +	unflatten_device_tree();
> +	dtb_apic_setup();
>  }
> -- 
> 1.7.3.2
>