device with allocating one of the (scarce) timers (aka comparators). This
is a limitation in that the main counter may be valuable to applications
seeking a high-resolution timer who have no use for the interrupt
generating functionality of the comparators.
This patch alters the open semantics so that when the device is opened, no
timer is allocated. Operations that depend on a timer being in context
implicitly attempt allocating a timer, to maintain backward compatibility.
There is also an IOCTL (HPET_ALLOC_TIMER _IO) added so that the
allocation may be done explicitly. (I prefer the explicit open then
allocate pattern but don't know how practical it would be to require all
existing code to be changed.)
/dev/hpet is accessed via mmap(). This is the only interface of /dev/hpet
that is actually used in practice.
[akpm@linux-foundation.org: coding-style tweaks]
[arnd@arndb.de: fix build]
Signed-off-by: Magnus Lynch <maglyx@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
static int hpet_open(struct inode *inode, struct file *file)
{
static int hpet_open(struct inode *inode, struct file *file)
{
if (file->f_mode & FMODE_WRITE)
return -EINVAL;
if (file->f_mode & FMODE_WRITE)
return -EINVAL;
+ hpetp = hpets;
+ /* starting with timer-neutral instance */
+ file->private_data = &hpetp->hp_dev[hpetp->hp_ntimer];
+
+ return 0;
+}
+
+static int hpet_alloc_timer(struct file *file)
+{
+ struct hpet_dev *devp;
+ struct hpets *hpetp;
+ int i;
+
+ /* once acquired, will remain */
+ devp = file->private_data;
+ if (devp->hd_timer)
+ return 0;
+
mutex_lock(&hpet_mutex);
spin_lock_irq(&hpet_lock);
mutex_lock(&hpet_mutex);
spin_lock_irq(&hpet_lock);
+ /* check for race acquiring */
+ devp = file->private_data;
+ if (devp->hd_timer) {
+ spin_unlock_irq(&hpet_lock);
+ mutex_unlock(&hpet_mutex);
+ return 0;
+ }
+
for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
for (i = 0; i < hpetp->hp_ntimer; i++)
if (hpetp->hp_dev[i].hd_flags & HPET_OPEN)
for (devp = NULL, hpetp = hpets; hpetp && !devp; hpetp = hpetp->hp_next)
for (i = 0; i < hpetp->hp_ntimer; i++)
if (hpetp->hp_dev[i].hd_flags & HPET_OPEN)
static int hpet_fasync(int fd, struct file *file, int on)
{
struct hpet_dev *devp;
static int hpet_fasync(int fd, struct file *file, int on)
{
struct hpet_dev *devp;
+ int r;
+
+ r = hpet_alloc_timer(file);
+ if (r < 0)
+ return r;
devp = file->private_data;
devp = file->private_data;
devp = file->private_data;
timer = devp->hd_timer;
devp = file->private_data;
timer = devp->hd_timer;
+ if (!timer)
+ goto out;
+
spin_lock_irq(&hpet_lock);
writeq((readq(&timer->hpet_config) & ~Tn_INT_ENB_CNF_MASK),
spin_lock_irq(&hpet_lock);
writeq((readq(&timer->hpet_config) & ~Tn_INT_ENB_CNF_MASK),
if (irq)
free_irq(irq, devp);
if (irq)
free_irq(irq, devp);
file->private_data = NULL;
return 0;
}
file->private_data = NULL;
return 0;
}
break;
case HPET_IE_ON:
return hpet_ioctl_ieon(devp);
break;
case HPET_IE_ON:
return hpet_ioctl_ieon(devp);
+ case HPET_ALLOC_TIMER:
+ /* nothing to do */
+ return 0;
default:
return -EINVAL;
}
default:
return -EINVAL;
}
- siz = sizeof(struct hpets) + ((hdp->hd_nirqs - 1) *
+ /*
+ * last hpet_dev will have null timer pointer, gives timer-neutral
+ * representation of block
+ */
+ siz = sizeof(struct hpets) + ((hdp->hd_nirqs) *
sizeof(struct hpet_dev));
hpetp = kzalloc(siz, GFP_KERNEL);
sizeof(struct hpet_dev));
hpetp = kzalloc(siz, GFP_KERNEL);
writeq(mcfg, &hpet->hpet_config);
}
writeq(mcfg, &hpet->hpet_config);
}
- for (i = 0, devp = hpetp->hp_dev; i < hpetp->hp_ntimer; i++, devp++) {
+ for (i = 0, devp = hpetp->hp_dev; i < hpetp->hp_ntimer + 1;
+ i++, devp++) {
struct hpet_timer __iomem *timer;
struct hpet_timer __iomem *timer;
- timer = &hpet->hpet_timers[devp - hpetp->hp_dev];
-
devp->hd_hpets = hpetp;
devp->hd_hpet = hpet;
devp->hd_hpets = hpetp;
devp->hd_hpet = hpet;
+ if (i == hpetp->hp_ntimer)
+ continue;
+
+ timer = &hpet->hpet_timers[devp - hpetp->hp_dev];
devp->hd_timer = timer;
/*
devp->hd_timer = timer;
/*
#define HPET_EPI _IO('h', 0x04) /* enable periodic */
#define HPET_DPI _IO('h', 0x05) /* disable periodic */
#define HPET_IRQFREQ _IOW('h', 0x6, unsigned long) /* IRQFREQ usec */
#define HPET_EPI _IO('h', 0x04) /* enable periodic */
#define HPET_DPI _IO('h', 0x05) /* disable periodic */
#define HPET_IRQFREQ _IOW('h', 0x6, unsigned long) /* IRQFREQ usec */
+#define HPET_ALLOC_TIMER _IO('h', 0x7)
#define MAX_HPET_TBS 8 /* maximum hpet timer blocks */
#define MAX_HPET_TBS 8 /* maximum hpet timer blocks */