android_kernel_xiaomi_sm8350/drivers/parisc/power.c
Alan Stern e041c68341 [PATCH] Notifier chain update: API changes
The kernel's implementation of notifier chains is unsafe.  There is no
protection against entries being added to or removed from a chain while the
chain is in use.  The issues were discussed in this thread:

    http://marc.theaimsgroup.com/?l=linux-kernel&m=113018709002036&w=2

We noticed that notifier chains in the kernel fall into two basic usage
classes:

	"Blocking" chains are always called from a process context
	and the callout routines are allowed to sleep;

	"Atomic" chains can be called from an atomic context and
	the callout routines are not allowed to sleep.

We decided to codify this distinction and make it part of the API.  Therefore
this set of patches introduces three new, parallel APIs: one for blocking
notifiers, one for atomic notifiers, and one for "raw" notifiers (which is
really just the old API under a new name).  New kinds of data structures are
used for the heads of the chains, and new routines are defined for
registration, unregistration, and calling a chain.  The three APIs are
explained in include/linux/notifier.h and their implementation is in
kernel/sys.c.

With atomic and blocking chains, the implementation guarantees that the chain
links will not be corrupted and that chain callers will not get messed up by
entries being added or removed.  For raw chains the implementation provides no
guarantees at all; users of this API must provide their own protections.  (The
idea was that situations may come up where the assumptions of the atomic and
blocking APIs are not appropriate, so it should be possible for users to
handle these things in their own way.)

There are some limitations, which should not be too hard to live with.  For
atomic/blocking chains, registration and unregistration must always be done in
a process context since the chain is protected by a mutex/rwsem.  Also, a
callout routine for a non-raw chain must not try to register or unregister
entries on its own chain.  (This did happen in a couple of places and the code
had to be changed to avoid it.)

Since atomic chains may be called from within an NMI handler, they cannot use
spinlocks for synchronization.  Instead we use RCU.  The overhead falls almost
entirely in the unregister routine, which is okay since unregistration is much
less frequent that calling a chain.

Here is the list of chains that we adjusted and their classifications.  None
of them use the raw API, so for the moment it is only a placeholder.

  ATOMIC CHAINS
  -------------
arch/i386/kernel/traps.c:		i386die_chain
arch/ia64/kernel/traps.c:		ia64die_chain
arch/powerpc/kernel/traps.c:		powerpc_die_chain
arch/sparc64/kernel/traps.c:		sparc64die_chain
arch/x86_64/kernel/traps.c:		die_chain
drivers/char/ipmi/ipmi_si_intf.c:	xaction_notifier_list
kernel/panic.c:				panic_notifier_list
kernel/profile.c:			task_free_notifier
net/bluetooth/hci_core.c:		hci_notifier
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_chain
net/ipv4/netfilter/ip_conntrack_core.c:	ip_conntrack_expect_chain
net/ipv6/addrconf.c:			inet6addr_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_chain
net/netfilter/nf_conntrack_core.c:	nf_conntrack_expect_chain
net/netlink/af_netlink.c:		netlink_chain

  BLOCKING CHAINS
  ---------------
arch/powerpc/platforms/pseries/reconfig.c:	pSeries_reconfig_chain
arch/s390/kernel/process.c:		idle_chain
arch/x86_64/kernel/process.c		idle_notifier
drivers/base/memory.c:			memory_chain
drivers/cpufreq/cpufreq.c		cpufreq_policy_notifier_list
drivers/cpufreq/cpufreq.c		cpufreq_transition_notifier_list
drivers/macintosh/adb.c:		adb_client_list
drivers/macintosh/via-pmu.c		sleep_notifier_list
drivers/macintosh/via-pmu68k.c		sleep_notifier_list
drivers/macintosh/windfarm_core.c	wf_client_list
drivers/usb/core/notify.c		usb_notifier_list
drivers/video/fbmem.c			fb_notifier_list
kernel/cpu.c				cpu_chain
kernel/module.c				module_notify_list
kernel/profile.c			munmap_notifier
kernel/profile.c			task_exit_notifier
kernel/sys.c				reboot_notifier_list
net/core/dev.c				netdev_chain
net/decnet/dn_dev.c:			dnaddr_chain
net/ipv4/devinet.c:			inetaddr_chain

It's possible that some of these classifications are wrong.  If they are,
please let us know or submit a patch to fix them.  Note that any chain that
gets called very frequently should be atomic, because the rwsem read-locking
used for blocking chains is very likely to incur cache misses on SMP systems.
(However, if the chain's callout routines may sleep then the chain cannot be
atomic.)

The patch set was written by Alan Stern and Chandra Seetharaman, incorporating
material written by Keith Owens and suggestions from Paul McKenney and Andrew
Morton.

[jes@sgi.com: restructure the notifier chain initialization macros]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Jes Sorensen <jes@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-27 08:44:50 -08:00

281 lines
7.2 KiB
C

/*
* linux/arch/parisc/kernel/power.c
* HP PARISC soft power switch support driver
*
* Copyright (c) 2001-2005 Helge Deller <deller@gmx.de>
* All rights reserved.
*
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions, and the following disclaimer,
* without modification.
* 2. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* Alternatively, this software may be distributed under the terms of the
* GNU General Public License ("GPL").
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
*
*
*
* HINT:
* Support of the soft power switch button may be enabled or disabled at
* runtime through the "/proc/sys/kernel/power" procfs entry.
*/
#include <linux/config.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/string.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/workqueue.h>
#include <asm/pdc.h>
#include <asm/io.h>
#include <asm/led.h>
#include <asm/uaccess.h>
#ifdef DEBUG
# define DPRINTK(x...) printk(x)
#else
# define DPRINTK(x...)
#endif
/* filename in /proc which can be used to enable/disable the power switch */
#define SYSCTL_FILENAME "sys/kernel/power"
#define DIAG_CODE(code) (0x14000000 + ((code)<<5))
/* this will go to processor.h or any other place... */
/* taken from PCXL ERS page 82 */
#define MFCPU_X(rDiagReg, t_ch, t_th, code) \
(DIAG_CODE(code) + ((rDiagReg)<<21) + ((t_ch)<<16) + ((t_th)<<0) )
#define MTCPU(dr, gr) MFCPU_X(dr, gr, 0, 0x12) /* move value of gr to dr[dr] */
#define MFCPU_C(dr, gr) MFCPU_X(dr, gr, 0, 0x30) /* for dr0 and dr8 only ! */
#define MFCPU_T(dr, gr) MFCPU_X(dr, 0, gr, 0xa0) /* all dr except dr0 and dr8 */
#define __getDIAG(dr) ( { \
register unsigned long __res asm("r28");\
__asm__ __volatile__ ( \
".word %1\n nop\n" : "=&r" (__res) : "i" (MFCPU_T(dr,28)) \
); \
__res; \
} )
static void deferred_poweroff(void *dummy)
{
extern int cad_pid; /* from kernel/sys.c */
if (kill_proc(cad_pid, SIGINT, 1)) {
/* just in case killing init process failed */
machine_power_off();
}
}
/*
* This function gets called from interrupt context.
* As it's called within an interrupt, it wouldn't sync if we don't
* use schedule_work().
*/
static DECLARE_WORK(poweroff_work, deferred_poweroff, NULL);
static void poweroff(void)
{
static int powering_off __read_mostly;
if (powering_off)
return;
powering_off++;
schedule_work(&poweroff_work);
}
/* local time-counter for shutdown */
static int shutdown_timer __read_mostly;
/* check, give feedback and start shutdown after one second */
static void process_shutdown(void)
{
if (shutdown_timer == 0)
DPRINTK(KERN_INFO "Shutdown requested...\n");
shutdown_timer++;
/* wait until the button was pressed for 1 second */
if (shutdown_timer == HZ) {
#if defined (DEBUG) || defined(CONFIG_CHASSIS_LCD_LED)
static char msg[] = "Shutting down...";
#endif
DPRINTK(KERN_INFO "%s\n", msg);
lcd_print(msg);
poweroff();
}
}
/* main power switch tasklet struct (scheduled from time.c) */
DECLARE_TASKLET_DISABLED(power_tasklet, NULL, 0);
/* soft power switch enabled/disabled */
int pwrsw_enabled __read_mostly = 1;
/*
* On gecko style machines (e.g. 712/xx and 715/xx)
* the power switch status is stored in Bit 0 ("the highest bit")
* of CPU diagnose register 25.
*
*/
static void gecko_tasklet_func(unsigned long unused)
{
if (unlikely(!pwrsw_enabled))
return;
if (__getDIAG(25) & 0x80000000) {
/* power switch button not pressed or released again */
/* Warning: Some machines do never reset this DIAG flag! */
shutdown_timer = 0;
} else {
process_shutdown();
}
}
/*
* Check the power switch status which is read from the
* real I/O location at soft_power_reg.
* Bit 31 ("the lowest bit) is the status of the power switch.
*/
static void polling_tasklet_func(unsigned long soft_power_reg)
{
unsigned long current_status;
if (unlikely(!pwrsw_enabled))
return;
current_status = gsc_readl(soft_power_reg);
if (current_status & 0x1) {
/* power switch button not pressed */
shutdown_timer = 0;
} else {
process_shutdown();
}
}
/*
* powerfail interruption handler (irq IRQ_FROM_REGION(CPU_IRQ_REGION)+2)
*/
#if 0
static void powerfail_interrupt(int code, void *x, struct pt_regs *regs)
{
printk(KERN_CRIT "POWERFAIL INTERRUPTION !\n");
poweroff();
}
#endif
/* parisc_panic_event() is called by the panic handler.
* As soon as a panic occurs, our tasklets above will not be
* executed any longer. This function then re-enables the
* soft-power switch and allows the user to switch off the system
*/
static int parisc_panic_event(struct notifier_block *this,
unsigned long event, void *ptr)
{
/* re-enable the soft-power switch */
pdc_soft_power_button(0);
return NOTIFY_DONE;
}
static struct notifier_block parisc_panic_block = {
.notifier_call = parisc_panic_event,
.priority = INT_MAX,
};
static int __init power_init(void)
{
unsigned long ret;
unsigned long soft_power_reg = 0;
#if 0
request_irq( IRQ_FROM_REGION(CPU_IRQ_REGION)+2, &powerfail_interrupt,
0, "powerfail", NULL);
#endif
/* enable the soft power switch if possible */
ret = pdc_soft_power_info(&soft_power_reg);
if (ret == PDC_OK)
ret = pdc_soft_power_button(1);
if (ret != PDC_OK)
soft_power_reg = -1UL;
switch (soft_power_reg) {
case 0: printk(KERN_INFO "Gecko-style soft power switch enabled.\n");
power_tasklet.func = gecko_tasklet_func;
break;
case -1UL: printk(KERN_INFO "Soft power switch support not available.\n");
return -ENODEV;
default: printk(KERN_INFO "Soft power switch enabled, polling @ 0x%08lx.\n",
soft_power_reg);
power_tasklet.data = soft_power_reg;
power_tasklet.func = polling_tasklet_func;
}
/* Register a call for panic conditions. */
atomic_notifier_chain_register(&panic_notifier_list,
&parisc_panic_block);
tasklet_enable(&power_tasklet);
return 0;
}
static void __exit power_exit(void)
{
if (!power_tasklet.func)
return;
tasklet_disable(&power_tasklet);
atomic_notifier_chain_unregister(&panic_notifier_list,
&parisc_panic_block);
power_tasklet.func = NULL;
pdc_soft_power_button(0);
}
module_init(power_init);
module_exit(power_exit);
MODULE_AUTHOR("Helge Deller");
MODULE_DESCRIPTION("Soft power switch driver");
MODULE_LICENSE("Dual BSD/GPL");