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ARC changes for 3.14

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* IPI optimization and cleanups
 * Support for bootloader provided external Device Tree blobs
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Merge tag 'arc-v3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc

Pull ARC changes from Vineet Gupta:
 - IPI optimization and cleanups
 - Support for bootloader provided external Device Tree blobs

* tag 'arc-v3.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vgupta/arc:
  ARC: [cmdline] support External Device Trees from u-boot
  ARC: [cmdline] uboot cmdline handling rework
  ARC: [SMP] optimize IPI send and receive
  ARC: [SMP] simplify IPI code
  ARC: [SMP] cpu halt interface doesn't need "self" cpu-id
  ARC: [SMP] IPI ACK interface doesn't need "self" cpu-id
  ARC: [SMP] cpumask not needed in IPI send path
This commit is contained in:
Linus Torvalds 2014-01-25 10:50:43 -08:00
commit 7ae0e06b90
6 changed files with 120 additions and 107 deletions
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11
arch/arc/Kconfig
View file

@ -409,17 +409,6 @@ config ARC_DBG_TLB_MISS_COUNT
Counts number of I and D TLB Misses and exports them via Debugfs
The counters can be cleared via Debugfs as well
config CMDLINE_UBOOT
bool "Support U-boot kernel command line passing"
default n
help
If you are using U-boot (www.denx.de) and wish to pass the kernel
command line from the U-boot environment to the Linux kernel then
switch this option on.
ARC U-boot will setup the cmdline in RAM/flash and set r2 to point
to it. kernel startup code will append this to DeviceTree
/bootargs provided cmdline args.
config ARC_BUILTIN_DTB_NAME
string "Built in DTB"
help

8
arch/arc/include/asm/smp.h
View file

@ -46,14 +46,14 @@ extern int smp_ipi_irq_setup(int cpu, int irq);
*
* @info: SoC SMP specific info for /proc/cpuinfo etc
* @cpu_kick: For Master to kickstart a cpu (optionally at a PC)
* @ipi_send: To send IPI to a @cpumask
* @ips_clear: To clear IPI received by @cpu at @irq
* @ipi_send: To send IPI to a @cpu
* @ips_clear: To clear IPI received at @irq
*/
struct plat_smp_ops {
const char *info;
void (*cpu_kick)(int cpu, unsigned long pc);
void (*ipi_send)(void *callmap);
void (*ipi_clear)(int cpu, int irq);
void (*ipi_send)(int cpu);
void (*ipi_clear)(int irq);
};
/* TBD: stop exporting it for direct population by platform */

26
arch/arc/kernel/head.S
View file

@ -49,25 +49,13 @@ stext:
st.ab 0, [r5,4]
brlt r5, r6, 1b
#ifdef CONFIG_CMDLINE_UBOOT
; support for bootloader provided cmdline
; If cmdline passed by u-boot, then
; r0 = 1 (because ATAGS parsing, now retired, used to use 0)
; r1 = magic number (board identity)
; r2 = addr of cmdline string (somewhere in memory/flash)
brne r0, 1, .Lother_bootup_chores ; u-boot didn't pass cmdline
breq r2, 0, .Lother_bootup_chores ; or cmdline is NULL
mov r5, @command_line
1:
ldb.ab r6, [r2, 1]
breq r6, 0, .Lother_bootup_chores
b.d 1b
stb.ab r6, [r5, 1]
#endif
.Lother_bootup_chores:
; Uboot - kernel ABI
; r0 = [0] No uboot interaction, [1] cmdline in r2, [2] DTB in r2
; r1 = magic number (board identity, unused as of now
; r2 = pointer to uboot provided cmdline or external DTB in mem
; These are handled later in setup_arch()
st r0, [@uboot_tag]
st r2, [@uboot_arg]
; Identify if running on ISS vs Silicon
; IDENTITY Reg [ 3 2 1 0 ]

46
arch/arc/kernel/setup.c
View file

@ -29,7 +29,10 @@
int running_on_hw = 1; /* vs. on ISS */
char __initdata command_line[COMMAND_LINE_SIZE];
/* Part of U-boot ABI: see head.S */
int __initdata uboot_tag;
char __initdata *uboot_arg;
const struct machine_desc *machine_desc;
struct task_struct *_current_task[NR_CPUS]; /* For stack switching */
@ -311,19 +314,40 @@ void setup_processor(void)
arc_chk_fpu();
}
static inline int is_kernel(unsigned long addr)
{
if (addr >= (unsigned long)_stext && addr <= (unsigned long)_end)
return 1;
return 0;
}
void __init setup_arch(char **cmdline_p)
{
/* This also populates @boot_command_line from /bootargs */
machine_desc = setup_machine_fdt(__dtb_start);
if (!machine_desc)
panic("Embedded DT invalid\n");
/* make sure that uboot passed pointer to cmdline/dtb is valid */
if (uboot_tag && is_kernel((unsigned long)uboot_arg))
panic("Invalid uboot arg\n");
/* Append any u-boot provided cmdline */
#ifdef CONFIG_CMDLINE_UBOOT
/* Add a whitespace seperator between the 2 cmdlines */
strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
strlcat(boot_command_line, command_line, COMMAND_LINE_SIZE);
#endif
/* See if u-boot passed an external Device Tree blob */
machine_desc = setup_machine_fdt(uboot_arg); /* uboot_tag == 2 */
if (!machine_desc) {
/* No, so try the embedded one */
machine_desc = setup_machine_fdt(__dtb_start);
if (!machine_desc)
panic("Embedded DT invalid\n");
/*
* If we are here, it is established that @uboot_arg didn't
* point to DT blob. Instead if u-boot says it is cmdline,
* Appent to embedded DT cmdline.
* setup_machine_fdt() would have populated @boot_command_line
*/
if (uboot_tag == 1) {
/* Ensure a whitespace between the 2 cmdlines */
strlcat(boot_command_line, " ", COMMAND_LINE_SIZE);
strlcat(boot_command_line, uboot_arg,
COMMAND_LINE_SIZE);
}
}
/* Save unparsed command line copy for /proc/cmdline */
*cmdline_p = boot_command_line;

124
arch/arc/kernel/smp.c
View file

@ -197,51 +197,65 @@ int __init setup_profiling_timer(unsigned int multiplier)
/* Inter Processor Interrupt Handling */
/*****************************************************************************/
/*
* structures for inter-processor calls
* A Collection of single bit ipi messages
*
*/
/*
* TODO_rajesh investigate tlb message types.
* IPI Timer not needed because each ARC has an individual Interrupting Timer
*/
enum ipi_msg_type {
IPI_NOP = 0,
IPI_EMPTY = 0,
IPI_RESCHEDULE = 1,
IPI_CALL_FUNC,
IPI_CPU_STOP
IPI_CPU_STOP,
};
struct ipi_data {
unsigned long bits;
};
/*
* In arches with IRQ for each msg type (above), receiver can use IRQ-id to
* figure out what msg was sent. For those which don't (ARC has dedicated IPI
* IRQ), the msg-type needs to be conveyed via per-cpu data
*/
static DEFINE_PER_CPU(struct ipi_data, ipi_data);
static DEFINE_PER_CPU(unsigned long, ipi_data);
static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
static void ipi_send_msg_one(int cpu, enum ipi_msg_type msg)
{
unsigned long __percpu *ipi_data_ptr = per_cpu_ptr(&ipi_data, cpu);
unsigned long old, new;
unsigned long flags;
unsigned int cpu;
pr_debug("%d Sending msg [%d] to %d\n", smp_processor_id(), msg, cpu);
local_irq_save(flags);
for_each_cpu(cpu, callmap) {
struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
set_bit(msg, &ipi->bits);
}
/*
* Atomically write new msg bit (in case others are writing too),
* and read back old value
*/
do {
new = old = *ipi_data_ptr;
new |= 1U << msg;
} while (cmpxchg(ipi_data_ptr, old, new) != old);
/* Call the platform specific cross-CPU call function */
if (plat_smp_ops.ipi_send)
plat_smp_ops.ipi_send((void *)callmap);
/*
* Call the platform specific IPI kick function, but avoid if possible:
* Only do so if there's no pending msg from other concurrent sender(s).
* Otherwise, recevier will see this msg as well when it takes the
* IPI corresponding to that msg. This is true, even if it is already in
* IPI handler, because !@old means it has not yet dequeued the msg(s)
* so @new msg can be a free-loader
*/
if (plat_smp_ops.ipi_send && !old)
plat_smp_ops.ipi_send(cpu);
local_irq_restore(flags);
}
static void ipi_send_msg(const struct cpumask *callmap, enum ipi_msg_type msg)
{
unsigned int cpu;
for_each_cpu(cpu, callmap)
ipi_send_msg_one(cpu, msg);
}
void smp_send_reschedule(int cpu)
{
ipi_send_msg(cpumask_of(cpu), IPI_RESCHEDULE);
ipi_send_msg_one(cpu, IPI_RESCHEDULE);
}
void smp_send_stop(void)
@ -254,7 +268,7 @@ void smp_send_stop(void)
void arch_send_call_function_single_ipi(int cpu)
{
ipi_send_msg(cpumask_of(cpu), IPI_CALL_FUNC);
ipi_send_msg_one(cpu, IPI_CALL_FUNC);
}
void arch_send_call_function_ipi_mask(const struct cpumask *mask)
@ -265,33 +279,29 @@ void arch_send_call_function_ipi_mask(const struct cpumask *mask)
/*
* ipi_cpu_stop - handle IPI from smp_send_stop()
*/
static void ipi_cpu_stop(unsigned int cpu)
static void ipi_cpu_stop(void)
{
machine_halt();
}
static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
static inline void __do_IPI(unsigned long msg)
{
unsigned long msg = 0;
switch (msg) {
case IPI_RESCHEDULE:
scheduler_ipi();
break;
do {
msg = find_next_bit(ops, BITS_PER_LONG, msg+1);
case IPI_CALL_FUNC:
generic_smp_call_function_interrupt();
break;
switch (msg) {
case IPI_RESCHEDULE:
scheduler_ipi();
break;
case IPI_CALL_FUNC:
generic_smp_call_function_interrupt();
break;
case IPI_CPU_STOP:
ipi_cpu_stop(cpu);
break;
}
} while (msg < BITS_PER_LONG);
case IPI_CPU_STOP:
ipi_cpu_stop();
break;
default:
pr_warn("IPI with unexpected msg %ld\n", msg);
}
}
/*
@ -300,19 +310,25 @@ static inline void __do_IPI(unsigned long *ops, struct ipi_data *ipi, int cpu)
*/
irqreturn_t do_IPI(int irq, void *dev_id)
{
int cpu = smp_processor_id();
struct ipi_data *ipi = &per_cpu(ipi_data, cpu);
unsigned long ops;
unsigned long pending;
pr_debug("IPI [%ld] received on cpu %d\n",
*this_cpu_ptr(&ipi_data), smp_processor_id());
if (plat_smp_ops.ipi_clear)
plat_smp_ops.ipi_clear(cpu, irq);
plat_smp_ops.ipi_clear(irq);
/*
* XXX: is this loop really needed
* And do we need to move ipi_clean inside
* "dequeue" the msg corresponding to this IPI (and possibly other
* piggybacked msg from elided IPIs: see ipi_send_msg_one() above)
*/
while ((ops = xchg(&ipi->bits, 0)) != 0)
__do_IPI(&ops, ipi, cpu);
pending = xchg(this_cpu_ptr(&ipi_data), 0);
do {
unsigned long msg = __ffs(pending);
__do_IPI(msg);
pending &= ~(1U << msg);
} while (pending);
return IRQ_HANDLED;
}

12
arch/arc/plat-arcfpga/smp.c
View file

@ -88,18 +88,14 @@ void iss_model_init_smp(unsigned int cpu)
smp_ipi_irq_setup(cpu, IDU_INTERRUPT_0 + cpu);
}
static void iss_model_ipi_send(void *arg)
static void iss_model_ipi_send(int cpu)
{
struct cpumask *callmap = arg;
unsigned int cpu;
for_each_cpu(cpu, callmap)
idu_irq_assert(cpu);
idu_irq_assert(cpu);
}
static void iss_model_ipi_clear(int cpu, int irq)
static void iss_model_ipi_clear(int irq)
{
idu_irq_clear(IDU_INTERRUPT_0 + cpu);
idu_irq_clear(IDU_INTERRUPT_0 + smp_processor_id());
}
void iss_model_init_early_smp(void)