2012-04-20 00:53:13 +08:00
|
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/*
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* arch/arm/mach-spear13xx/platsmp.c
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*
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* based upon linux/arch/arm/mach-realview/platsmp.c
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*
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* Copyright (C) 2012 ST Microelectronics Ltd.
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2014-04-19 06:07:16 +08:00
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* Shiraz Hashim <shiraz.linux.kernel@gmail.com>
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2012-04-20 00:53:13 +08:00
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/delay.h>
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#include <linux/jiffies.h>
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#include <linux/io.h>
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#include <linux/smp.h>
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#include <asm/cacheflush.h>
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#include <asm/smp_scu.h>
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#include <mach/spear.h>
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2012-12-02 22:49:04 +08:00
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#include "generic.h"
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2012-04-20 00:53:13 +08:00
|
|
|
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
/* XXX spear_pen_release is cargo culted code - DO NOT COPY XXX */
|
|
|
|
|
volatile int spear_pen_release = -1;
|
|
|
|
|
|
2014-03-16 00:47:47 +08:00
|
|
|
/*
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
* XXX CARGO CULTED CODE - DO NOT COPY XXX
|
|
|
|
|
*
|
|
|
|
|
* Write spear_pen_release in a way that is guaranteed to be visible to
|
|
|
|
|
* all observers, irrespective of whether they're taking part in coherency
|
2014-03-16 00:47:47 +08:00
|
|
|
* or not. This is necessary for the hotplug code to work reliably.
|
|
|
|
|
*/
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
static void spear_write_pen_release(int val)
|
2014-03-16 00:47:47 +08:00
|
|
|
{
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
spear_pen_release = val;
|
2014-03-16 00:47:47 +08:00
|
|
|
smp_wmb();
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
sync_cache_w(&spear_pen_release);
|
2014-03-16 00:47:47 +08:00
|
|
|
}
|
|
|
|
|
|
2012-04-20 00:53:13 +08:00
|
|
|
static DEFINE_SPINLOCK(boot_lock);
|
|
|
|
|
|
|
|
|
|
static void __iomem *scu_base = IOMEM(VA_SCU_BASE);
|
|
|
|
|
|
2013-06-18 03:43:14 +08:00
|
|
|
static void spear13xx_secondary_init(unsigned int cpu)
|
2012-04-20 00:53:13 +08:00
|
|
|
{
|
|
|
|
|
/*
|
|
|
|
|
* let the primary processor know we're out of the
|
|
|
|
|
* pen, then head off into the C entry point
|
|
|
|
|
*/
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
spear_write_pen_release(-1);
|
2012-04-20 00:53:13 +08:00
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Synchronise with the boot thread.
|
|
|
|
|
*/
|
|
|
|
|
spin_lock(&boot_lock);
|
|
|
|
|
spin_unlock(&boot_lock);
|
|
|
|
|
}
|
|
|
|
|
|
2013-06-18 03:43:14 +08:00
|
|
|
static int spear13xx_boot_secondary(unsigned int cpu, struct task_struct *idle)
|
2012-04-20 00:53:13 +08:00
|
|
|
{
|
|
|
|
|
unsigned long timeout;
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* set synchronisation state between this boot processor
|
|
|
|
|
* and the secondary one
|
|
|
|
|
*/
|
|
|
|
|
spin_lock(&boot_lock);
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* The secondary processor is waiting to be released from
|
|
|
|
|
* the holding pen - release it, then wait for it to flag
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
* that it has been released by resetting spear_pen_release.
|
2012-04-20 00:53:13 +08:00
|
|
|
*
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
* Note that "spear_pen_release" is the hardware CPU ID, whereas
|
2012-04-20 00:53:13 +08:00
|
|
|
* "cpu" is Linux's internal ID.
|
|
|
|
|
*/
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
spear_write_pen_release(cpu);
|
2012-04-20 00:53:13 +08:00
|
|
|
|
|
|
|
|
timeout = jiffies + (1 * HZ);
|
|
|
|
|
while (time_before(jiffies, timeout)) {
|
|
|
|
|
smp_rmb();
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
if (spear_pen_release == -1)
|
2012-04-20 00:53:13 +08:00
|
|
|
break;
|
|
|
|
|
|
|
|
|
|
udelay(10);
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* now the secondary core is starting up let it run its
|
|
|
|
|
* calibrations, then wait for it to finish
|
|
|
|
|
*/
|
|
|
|
|
spin_unlock(&boot_lock);
|
|
|
|
|
|
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs. However, this is far from the truth.
Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs. Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug. Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.
It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.
While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking. However, I want to remove pen_release from
arch code to remove the credence that having it gives.
This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further. Rename write_pen_release() in a similar fashion
as well.
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
2018-12-13 22:02:48 +08:00
|
|
|
return spear_pen_release != -1 ? -ENOSYS : 0;
|
2012-04-20 00:53:13 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
|
|
/*
|
|
|
|
|
* Initialise the CPU possible map early - this describes the CPUs
|
|
|
|
|
* which may be present or become present in the system.
|
|
|
|
|
*/
|
2011-09-08 20:15:22 +08:00
|
|
|
static void __init spear13xx_smp_init_cpus(void)
|
2012-04-20 00:53:13 +08:00
|
|
|
{
|
|
|
|
|
unsigned int i, ncores = scu_get_core_count(scu_base);
|
|
|
|
|
|
|
|
|
|
if (ncores > nr_cpu_ids) {
|
|
|
|
|
pr_warn("SMP: %u cores greater than maximum (%u), clipping\n",
|
|
|
|
|
ncores, nr_cpu_ids);
|
|
|
|
|
ncores = nr_cpu_ids;
|
|
|
|
|
}
|
|
|
|
|
|
|
|
|
|
for (i = 0; i < ncores; i++)
|
|
|
|
|
set_cpu_possible(i, true);
|
|
|
|
|
}
|
|
|
|
|
|
2011-09-08 20:15:22 +08:00
|
|
|
static void __init spear13xx_smp_prepare_cpus(unsigned int max_cpus)
|
2012-04-20 00:53:13 +08:00
|
|
|
{
|
|
|
|
|
|
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scu_enable(scu_base);
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/*
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* Write the address of secondary startup into the system-wide location
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* (presently it is in SRAM). The BootMonitor waits until it receives a
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* soft interrupt, and then the secondary CPU branches to this address.
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*/
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2017-01-15 10:59:29 +08:00
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__raw_writel(__pa_symbol(spear13xx_secondary_startup), SYS_LOCATION);
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2012-04-20 00:53:13 +08:00
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}
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2011-09-08 20:15:22 +08:00
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2015-11-15 09:39:53 +08:00
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const struct smp_operations spear13xx_smp_ops __initconst = {
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2011-09-08 20:15:22 +08:00
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.smp_init_cpus = spear13xx_smp_init_cpus,
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.smp_prepare_cpus = spear13xx_smp_prepare_cpus,
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.smp_secondary_init = spear13xx_secondary_init,
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.smp_boot_secondary = spear13xx_boot_secondary,
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#ifdef CONFIG_HOTPLUG_CPU
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.cpu_die = spear13xx_cpu_die,
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#endif
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};
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