[MIPS] APM emu support

Signed-off-by: Rodolfo Giometti <[e-mail]>
Signed-off-by: Ralf Baechle <[e-mail]>

arch/mips/Kconfig

···
 	bool "Power Management support (EXPERIMENTAL)"
 	depends on EXPERIMENTAL && SOC_AU1X00
 
+config APM
+        tristate "Advanced Power Management Emulation"
+	depends on PM
+        ---help---
+	  APM is a BIOS specification for saving power using several different
+	  techniques. This is mostly useful for battery powered systems with
+	  APM compliant BIOSes. If you say Y here, the system time will be
+	  reset after a RESUME operation, the /proc/apm device will provide
+	  battery status information, and user-space programs will receive
+	  notification of APM "events" (e.g. battery status change).
+
+	  In order to use APM, you will need supporting software. For location
+	  and more information, read <file:Documentation/pm.txt> and the
+	  Battery Powered Linux mini-HOWTO, available from
+	  <http://www.tldp.org/docs.html#howto>.
+
+	  This driver does not spin down disk drives (see the hdparm(8)
+	  manpage ("man 8 hdparm") for that), and it doesn't turn off
+	  VESA-compliant "green" monitors.
+
+	  Generally, if you don't have a battery in your machine, there isn't
+	  much point in using this driver and you should say N. If you get
+	  random kernel OOPSes or reboots that don't seem to be related to
+	  anything, try disabling/enabling this option (or disabling/enabling
+	  APM in your BIOS).
+
 endmenu
 
 source "net/Kconfig"

arch/mips/kernel/Makefile

···
 
 obj-$(CONFIG_MODULES)		+= mips_ksyms.o module.o
 
+obj-$(CONFIG_APM)		+= apm.o
+
 obj-$(CONFIG_CPU_R3000)		+= r2300_fpu.o r2300_switch.o
 obj-$(CONFIG_CPU_TX39XX)	+= r2300_fpu.o r2300_switch.o
 obj-$(CONFIG_CPU_TX49XX)	+= r4k_fpu.o r4k_switch.o

arch/mips/kernel/apm.c

···
+/*
+ * bios-less APM driver for MIPS Linux
+ *  Jamey Hicks <[e-mail]>
+ *  adapted from the APM BIOS driver for Linux by Stephen Rothwell ([e-mail])
+ *
+ * APM 1.2 Reference:
+ *   Intel Corporation, Microsoft Corporation. Advanced Power Management
+ *   (APM) BIOS Interface Specification, Revision 1.2, February 1996.
+ *
+ * [This document is available from Microsoft at:
+ *    http://www.microsoft.com/hwdev/busbios/amp_12.htm]
+ */
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/poll.h>
+#include <linux/timer.h>
+#include <linux/slab.h>
+#include <linux/proc_fs.h>
+#include <linux/miscdevice.h>
+#include <linux/apm_bios.h>
+#include <linux/capability.h>
+#include <linux/sched.h>
+#include <linux/pm.h>
+#include <linux/device.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/init.h>
+#include <linux/completion.h>
+
+#include <asm/apm.h> /* apm_power_info */
+#include <asm/system.h>
+
+/*
+ * The apm_bios device is one of the misc char devices.
+ * This is its minor number.
+ */
+#define APM_MINOR_DEV	134
+
+/*
+ * See Documentation/Config.help for the configuration options.
+ *
+ * Various options can be changed at boot time as follows:
+ * (We allow underscores for compatibility with the modules code)
+ *	apm=on/off			enable/disable APM
+ */
+
+/*
+ * Maximum number of events stored
+ */
+#define APM_MAX_EVENTS		16
+
+struct apm_queue {
+	unsigned int		event_head;
+	unsigned int		event_tail;
+	apm_event_t		events[APM_MAX_EVENTS];
+};
+
+/*
+ * The per-file APM data
+ */
+struct apm_user {
+	struct list_head	list;
+
+	unsigned int		suser: 1;
+	unsigned int		writer: 1;
+	unsigned int		reader: 1;
+
+	int			suspend_result;
+	unsigned int		suspend_state;
+#define SUSPEND_NONE	0		/* no suspend pending */
+#define SUSPEND_PENDING	1		/* suspend pending read */
+#define SUSPEND_READ	2		/* suspend read, pending ack */
+#define SUSPEND_ACKED	3		/* suspend acked */
+#define SUSPEND_DONE	4		/* suspend completed */
+
+	struct apm_queue	queue;
+};
+
+/*
+ * Local variables
+ */
+static int suspends_pending;
+static int apm_disabled;
+static int mips_apm_active;
+
+static DECLARE_WAIT_QUEUE_HEAD(apm_waitqueue);
+static DECLARE_WAIT_QUEUE_HEAD(apm_suspend_waitqueue);
+
+/*
+ * This is a list of everyone who has opened /dev/apm_bios
+ */
+static DECLARE_RWSEM(user_list_lock);
+static LIST_HEAD(apm_user_list);
+
+/*
+ * kapmd info.  kapmd provides us a process context to handle
+ * "APM" events within - specifically necessary if we're going
+ * to be suspending the system.
+ */
+static DECLARE_WAIT_QUEUE_HEAD(kapmd_wait);
+static DECLARE_COMPLETION(kapmd_exit);
+static DEFINE_SPINLOCK(kapmd_queue_lock);
+static struct apm_queue kapmd_queue;
+
+
+static const char driver_version[] = "1.13";	/* no spaces */
+
+
+
+/*
+ * Compatibility cruft until the IPAQ people move over to the new
+ * interface.
+ */
+static void __apm_get_power_status(struct apm_power_info *info)
+{
+}
+
+/*
+ * This allows machines to provide their own "apm get power status" function.
+ */
+void (*apm_get_power_status)(struct apm_power_info *) = __apm_get_power_status;
+EXPORT_SYMBOL(apm_get_power_status);
+
+
+/*
+ * APM event queue management.
+ */
+static inline int queue_empty(struct apm_queue *q)
+{
+	return q->event_head == q->event_tail;
+}
+
+static inline apm_event_t queue_get_event(struct apm_queue *q)
+{
+	q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+	return q->events[q->event_tail];
+}
+
+static void queue_add_event(struct apm_queue *q, apm_event_t event)
+{
+	q->event_head = (q->event_head + 1) % APM_MAX_EVENTS;
+	if (q->event_head == q->event_tail) {
+		static int notified;
+
+		if (notified++ == 0)
+		    printk(KERN_ERR "apm: an event queue overflowed\n");
+		q->event_tail = (q->event_tail + 1) % APM_MAX_EVENTS;
+	}
+	q->events[q->event_head] = event;
+}
+
+static void queue_event_one_user(struct apm_user *as, apm_event_t event)
+{
+	if (as->suser && as->writer) {
+		switch (event) {
+		case APM_SYS_SUSPEND:
+		case APM_USER_SUSPEND:
+			/*
+			 * If this user already has a suspend pending,
+			 * don't queue another one.
+			 */
+			if (as->suspend_state != SUSPEND_NONE)
+				return;
+
+			as->suspend_state = SUSPEND_PENDING;
+			suspends_pending++;
+			break;
+		}
+	}
+	queue_add_event(&as->queue, event);
+}
+
+static void queue_event(apm_event_t event, struct apm_user *sender)
+{
+	struct apm_user *as;
+
+	down_read(&user_list_lock);
+	list_for_each_entry(as, &apm_user_list, list) {
+		if (as != sender && as->reader)
+			queue_event_one_user(as, event);
+	}
+	up_read(&user_list_lock);
+	wake_up_interruptible(&apm_waitqueue);
+}
+
+static void apm_suspend(void)
+{
+	struct apm_user *as;
+	int err = pm_suspend(PM_SUSPEND_MEM);
+
+	/*
+	 * Anyone on the APM queues will think we're still suspended.
+	 * Send a message so everyone knows we're now awake again.
+	 */
+	queue_event(APM_NORMAL_RESUME, NULL);
+
+	/*
+	 * Finally, wake up anyone who is sleeping on the suspend.
+	 */
+	down_read(&user_list_lock);
+	list_for_each_entry(as, &apm_user_list, list) {
+		as->suspend_result = err;
+		as->suspend_state = SUSPEND_DONE;
+	}
+	up_read(&user_list_lock);
+
+	wake_up(&apm_suspend_waitqueue);
+}
+
+static ssize_t apm_read(struct file *fp, char __user *buf, size_t count, loff_t *ppos)
+{
+	struct apm_user *as = fp->private_data;
+	apm_event_t event;
+	int i = count, ret = 0;
+
+	if (count < sizeof(apm_event_t))
+		return -EINVAL;
+
+	if (queue_empty(&as->queue) && fp->f_flags & O_NONBLOCK)
+		return -EAGAIN;
+
+	wait_event_interruptible(apm_waitqueue, !queue_empty(&as->queue));
+
+	while ((i >= sizeof(event)) && !queue_empty(&as->queue)) {
+		event = queue_get_event(&as->queue);
+
+		ret = -EFAULT;
+		if (copy_to_user(buf, &event, sizeof(event)))
+			break;
+
+		if (event == APM_SYS_SUSPEND || event == APM_USER_SUSPEND)
+			as->suspend_state = SUSPEND_READ;
+
+		buf += sizeof(event);
+		i -= sizeof(event);
+	}
+
+	if (i < count)
+		ret = count - i;
+
+	return ret;
+}
+
+static unsigned int apm_poll(struct file *fp, poll_table * wait)
+{
+	struct apm_user *as = fp->private_data;
+
+	poll_wait(fp, &apm_waitqueue, wait);
+	return queue_empty(&as->queue) ? 0 : POLLIN | POLLRDNORM;
+}
+
+/*
+ * apm_ioctl - handle APM ioctl
+ *
+ * APM_IOC_SUSPEND
+ *   This IOCTL is overloaded, and performs two functions.  It is used to:
+ *     - initiate a suspend
+ *     - acknowledge a suspend read from /dev/apm_bios.
+ *   Only when everyone who has opened /dev/apm_bios with write permission
+ *   has acknowledge does the actual suspend happen.
+ */
+static int
+apm_ioctl(struct inode * inode, struct file *filp, u_int cmd, u_long arg)
+{
+	struct apm_user *as = filp->private_data;
+	unsigned long flags;
+	int err = -EINVAL;
+
+	if (!as->suser || !as->writer)
+		return -EPERM;
+
+	switch (cmd) {
+	case APM_IOC_SUSPEND:
+		as->suspend_result = -EINTR;
+
+		if (as->suspend_state == SUSPEND_READ) {
+			/*
+			 * If we read a suspend command from /dev/apm_bios,
+			 * then the corresponding APM_IOC_SUSPEND ioctl is
+			 * interpreted as an acknowledge.
+			 */
+			as->suspend_state = SUSPEND_ACKED;
+			suspends_pending--;
+		} else {
+			/*
+			 * Otherwise it is a request to suspend the system.
+			 * Queue an event for all readers, and expect an
+			 * acknowledge from all writers who haven't already
+			 * acknowledged.
+			 */
+			queue_event(APM_USER_SUSPEND, as);
+		}
+
+		/*
+		 * If there are no further acknowledges required, suspend
+		 * the system.
+		 */
+		if (suspends_pending == 0)
+			apm_suspend();
+
+		/*
+		 * Wait for the suspend/resume to complete.  If there are
+		 * pending acknowledges, we wait here for them.
+		 *
+		 * Note that we need to ensure that the PM subsystem does
+		 * not kick us out of the wait when it suspends the threads.
+		 */
+		flags = current->flags;
+		current->flags |= PF_NOFREEZE;
+
+		/*
+		 * Note: do not allow a thread which is acking the suspend
+		 * to escape until the resume is complete.
+		 */
+		if (as->suspend_state == SUSPEND_ACKED)
+			wait_event(apm_suspend_waitqueue,
+					 as->suspend_state == SUSPEND_DONE);
+		else
+			wait_event_interruptible(apm_suspend_waitqueue,
+					 as->suspend_state == SUSPEND_DONE);
+
+		current->flags = flags;
+		err = as->suspend_result;
+		as->suspend_state = SUSPEND_NONE;
+		break;
+	}
+
+	return err;
+}
+
+static int apm_release(struct inode * inode, struct file * filp)
+{
+	struct apm_user *as = filp->private_data;
+	filp->private_data = NULL;
+
+	down_write(&user_list_lock);
+	list_del(&as->list);
+	up_write(&user_list_lock);
+
+	/*
+	 * We are now unhooked from the chain.  As far as new
+	 * events are concerned, we no longer exist.  However, we
+	 * need to balance suspends_pending, which means the
+	 * possibility of sleeping.
+	 */
+	if (as->suspend_state != SUSPEND_NONE) {
+		suspends_pending -= 1;
+		if (suspends_pending == 0)
+			apm_suspend();
+	}
+
+	kfree(as);
+	return 0;
+}
+
+static int apm_open(struct inode * inode, struct file * filp)
+{
+	struct apm_user *as;
+
+	as = (struct apm_user *)kzalloc(sizeof(*as), GFP_KERNEL);
+	if (as) {
+		/*
+		 * XXX - this is a tiny bit broken, when we consider BSD
+		 * process accounting. If the device is opened by root, we
+		 * instantly flag that we used superuser privs. Who knows,
+		 * we might close the device immediately without doing a
+		 * privileged operation -- cevans
+		 */
+		as->suser = capable(CAP_SYS_ADMIN);
+		as->writer = (filp->f_mode & FMODE_WRITE) == FMODE_WRITE;
+		as->reader = (filp->f_mode & FMODE_READ) == FMODE_READ;
+
+		down_write(&user_list_lock);
+		list_add(&as->list, &apm_user_list);
+		up_write(&user_list_lock);
+
+		filp->private_data = as;
+	}
+
+	return as ? 0 : -ENOMEM;
+}
+
+static struct file_operations apm_bios_fops = {
+	.owner		= THIS_MODULE,
+	.read		= apm_read,
+	.poll		= apm_poll,
+	.ioctl		= apm_ioctl,
+	.open		= apm_open,
+	.release	= apm_release,
+};
+
+static struct miscdevice apm_device = {
+	.minor		= APM_MINOR_DEV,
+	.name		= "apm_bios",
+	.fops		= &apm_bios_fops
+};
+
+
+#ifdef CONFIG_PROC_FS
+/*
+ * Arguments, with symbols from linux/apm_bios.h.
+ *
+ *   0) Linux driver version (this will change if format changes)
+ *   1) APM BIOS Version.  Usually 1.0, 1.1 or 1.2.
+ *   2) APM flags from APM Installation Check (0x00):
+ *	bit 0: APM_16_BIT_SUPPORT
+ *	bit 1: APM_32_BIT_SUPPORT
+ *	bit 2: APM_IDLE_SLOWS_CLOCK
+ *	bit 3: APM_BIOS_DISABLED
+ *	bit 4: APM_BIOS_DISENGAGED
+ *   3) AC line status
+ *	0x00: Off-line
+ *	0x01: On-line
+ *	0x02: On backup power (BIOS >= 1.1 only)
+ *	0xff: Unknown
+ *   4) Battery status
+ *	0x00: High
+ *	0x01: Low
+ *	0x02: Critical
+ *	0x03: Charging
+ *	0x04: Selected battery not present (BIOS >= 1.2 only)
+ *	0xff: Unknown
+ *   5) Battery flag
+ *	bit 0: High
+ *	bit 1: Low
+ *	bit 2: Critical
+ *	bit 3: Charging
+ *	bit 7: No system battery
+ *	0xff: Unknown
+ *   6) Remaining battery life (percentage of charge):
+ *	0-100: valid
+ *	-1: Unknown
+ *   7) Remaining battery life (time units):
+ *	Number of remaining minutes or seconds
+ *	-1: Unknown
+ *   8) min = minutes; sec = seconds
+ */
+static int apm_get_info(char *buf, char **start, off_t fpos, int length)
+{
+	struct apm_power_info info;
+	char *units;
+	int ret;
+
+	info.ac_line_status = 0xff;
+	info.battery_status = 0xff;
+	info.battery_flag   = 0xff;
+	info.battery_life   = -1;
+	info.time	    = -1;
+	info.units	    = -1;
+
+	if (apm_get_power_status)
+		apm_get_power_status(&info);
+
+	switch (info.units) {
+	default:	units = "?";	break;
+	case 0: 	units = "min";	break;
+	case 1: 	units = "sec";	break;
+	}
+
+	ret = sprintf(buf, "%s 1.2 0x%02x 0x%02x 0x%02x 0x%02x %d%% %d %s\n",
+		     driver_version, APM_32_BIT_SUPPORT,
+		     info.ac_line_status, info.battery_status,
+		     info.battery_flag, info.battery_life,
+		     info.time, units);
+
+ 	return ret;
+}
+#endif
+
+static int kapmd(void *arg)
+{
+	daemonize("kapmd");
+	current->flags |= PF_NOFREEZE;
+
+	do {
+		apm_event_t event;
+
+		wait_event_interruptible(kapmd_wait,
+				!queue_empty(&kapmd_queue) || !mips_apm_active);
+
+		if (!mips_apm_active)
+			break;
+
+		spin_lock_irq(&kapmd_queue_lock);
+		event = 0;
+		if (!queue_empty(&kapmd_queue))
+			event = queue_get_event(&kapmd_queue);
+		spin_unlock_irq(&kapmd_queue_lock);
+
+		switch (event) {
+		case 0:
+			break;
+
+		case APM_LOW_BATTERY:
+		case APM_POWER_STATUS_CHANGE:
+			queue_event(event, NULL);
+			break;
+
+		case APM_USER_SUSPEND:
+		case APM_SYS_SUSPEND:
+			queue_event(event, NULL);
+			if (suspends_pending == 0)
+				apm_suspend();
+			break;
+
+		case APM_CRITICAL_SUSPEND:
+			apm_suspend();
+			break;
+		}
+	} while (1);
+
+	complete_and_exit(&kapmd_exit, 0);
+}
+
+static int __init apm_init(void)
+{
+	int ret;
+
+	if (apm_disabled) {
+		printk(KERN_NOTICE "apm: disabled on user request.\n");
+		return -ENODEV;
+	}
+
+	mips_apm_active = 1;
+
+	ret = kernel_thread(kapmd, NULL, CLONE_KERNEL);
+	if (ret < 0) {
+		mips_apm_active = 0;
+		return ret;
+	}
+
+#ifdef CONFIG_PROC_FS
+	create_proc_info_entry("apm", 0, NULL, apm_get_info);
+#endif
+
+	ret = misc_register(&apm_device);
+	if (ret != 0) {
+		remove_proc_entry("apm", NULL);
+
+		mips_apm_active = 0;
+		wake_up(&kapmd_wait);
+		wait_for_completion(&kapmd_exit);
+	}
+
+	return ret;
+}
+
+static void __exit apm_exit(void)
+{
+	misc_deregister(&apm_device);
+	remove_proc_entry("apm", NULL);
+
+	mips_apm_active = 0;
+	wake_up(&kapmd_wait);
+	wait_for_completion(&kapmd_exit);
+}
+
+module_init(apm_init);
+module_exit(apm_exit);
+
+MODULE_AUTHOR("Stephen Rothwell");
+MODULE_DESCRIPTION("Advanced Power Management");
+MODULE_LICENSE("GPL");
+
+#ifndef MODULE
+static int __init apm_setup(char *str)
+{
+	while ((str != NULL) && (*str != '\0')) {
+		if (strncmp(str, "off", 3) == 0)
+			apm_disabled = 1;
+		if (strncmp(str, "on", 2) == 0)
+			apm_disabled = 0;
+		str = strchr(str, ',');
+		if (str != NULL)
+			str += strspn(str, ", \t");
+	}
+	return 1;
+}
+
+__setup("apm=", apm_setup);
+#endif
+
+/**
+ * apm_queue_event - queue an APM event for kapmd
+ * @event: APM event
+ *
+ * Queue an APM event for kapmd to process and ultimately take the
+ * appropriate action.  Only a subset of events are handled:
+ *   %APM_LOW_BATTERY
+ *   %APM_POWER_STATUS_CHANGE
+ *   %APM_USER_SUSPEND
+ *   %APM_SYS_SUSPEND
+ *   %APM_CRITICAL_SUSPEND
+ */
+void apm_queue_event(apm_event_t event)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&kapmd_queue_lock, flags);
+	queue_add_event(&kapmd_queue, event);
+	spin_unlock_irqrestore(&kapmd_queue_lock, flags);
+
+	wake_up_interruptible(&kapmd_wait);
+}
+EXPORT_SYMBOL(apm_queue_event);

include/asm-mips/apm.h

···
+/* -*- linux-c -*-
+ *
+ * (C) 2003 [e-mail]
+ *
+ * GPL version 2
+ *
+ * based on arch/arm/kernel/apm.c
+ * factor out the information needed by architectures to provide
+ * apm status
+ *
+ *
+ */
+#ifndef MIPS_ASM_SA1100_APM_H
+#define MIPS_ASM_SA1100_APM_H
+
+#include <linux/config.h>
+#include <linux/apm_bios.h>
+
+/*
+ * This structure gets filled in by the machine specific 'get_power_status'
+ * implementation.  Any fields which are not set default to a safe value.
+ */
+struct apm_power_info {
+	unsigned char	ac_line_status;
+#define APM_AC_OFFLINE			0
+#define APM_AC_ONLINE			1
+#define APM_AC_BACKUP			2
+#define APM_AC_UNKNOWN			0xff
+
+	unsigned char	battery_status;
+#define APM_BATTERY_STATUS_HIGH		0
+#define APM_BATTERY_STATUS_LOW		1
+#define APM_BATTERY_STATUS_CRITICAL	2
+#define APM_BATTERY_STATUS_CHARGING	3
+#define APM_BATTERY_STATUS_NOT_PRESENT	4
+#define APM_BATTERY_STATUS_UNKNOWN	0xff
+
+	unsigned char	battery_flag;
+#define APM_BATTERY_FLAG_HIGH		(1 << 0)
+#define APM_BATTERY_FLAG_LOW		(1 << 1)
+#define APM_BATTERY_FLAG_CRITICAL	(1 << 2)
+#define APM_BATTERY_FLAG_CHARGING	(1 << 3)
+#define APM_BATTERY_FLAG_NOT_PRESENT	(1 << 7)
+#define APM_BATTERY_FLAG_UNKNOWN	0xff
+
+	int		battery_life;
+	int		time;
+	int		units;
+#define APM_UNITS_MINS			0
+#define APM_UNITS_SECS			1
+#define APM_UNITS_UNKNOWN		-1
+
+};
+
+/*
+ * This allows machines to provide their own "apm get power status" function.
+ */
+extern void (*apm_get_power_status)(struct apm_power_info *);
+
+/*
+ * Queue an event (APM_SYS_SUSPEND or APM_CRITICAL_SUSPEND)
+ */
+void apm_queue_event(apm_event_t event);
+
+#endif