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author | Christian Borntraeger <borntraeger@de.ibm.com> | 2008-06-20 13:24:08 (GMT) |
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committer | Rusty Russell <rusty@rustcorp.com.au> | 2008-07-25 02:06:06 (GMT) |
commit | 611e097d7707741a336a0677d9d69bec40f29f3d (patch) | |
tree | 0b0059544914bf027ada51a1ba90f694c54df835 /drivers/char/hvc_irq.c | |
parent | 066f4d82a67f621ddd547bfa4b9c94631d8457b0 (diff) | |
download | linux-611e097d7707741a336a0677d9d69bec40f29f3d.tar.xz |
hvc_console: rework setup to replace irq functions with callbacks
This patch tries to change hvc_console to not use request_irq/free_irq if
the backend does not use irqs. This allows virtio_console to use hvc_console
without having a linker reference to request_irq/free_irq.
In addition, together with patch 2/3 it improves the performance for virtio
console input. (an earlier version of this patch was tested by Yajin on lguest)
The irq specific code is moved to hvc_irq.c and selected by the drivers that
use irqs (System p, System i, XEN).
I replaced "int irq" with the opaque "int data". The request_irq and
free_irq calls are replaced with notifier_add and notifier_del. I have also
changed the code a bit to call the notifier_add and notifier_del inside the
spinlock area as the callbacks are found via hp->ops.
Changes since last version:
o remove ifdef
o reintroduce "irq_requested" as "notified"
o cleanups, sparse..
I did not move the timer based polling into a separate polling scheme. I
played with several variants, but it seems we need to sleep/schedule in
a thread even for irq based consoles, as there are throttleing and buffer
size constraints.
I also kept hvc_struct defined in hvc_console.h so that hvc_irq.c can access
the irq_requested element.
Feedback is appreciated. virtio_console is currently the only available console
for kvm on s390. I plan to push this change as soon as all affected parties
agree on it. I would love to get test results from System p, Xen etc.
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'drivers/char/hvc_irq.c')
-rw-r--r-- | drivers/char/hvc_irq.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/drivers/char/hvc_irq.c b/drivers/char/hvc_irq.c new file mode 100644 index 0000000..73a59cd --- /dev/null +++ b/drivers/char/hvc_irq.c @@ -0,0 +1,44 @@ +/* + * Copyright IBM Corp. 2001,2008 + * + * This file contains the IRQ specific code for hvc_console + * + */ + +#include <linux/interrupt.h> + +#include "hvc_console.h" + +static irqreturn_t hvc_handle_interrupt(int irq, void *dev_instance) +{ + /* if hvc_poll request a repoll, then kick the hvcd thread */ + if (hvc_poll(dev_instance)) + hvc_kick(); + return IRQ_HANDLED; +} + +/* + * For IRQ based systems these callbacks can be used + */ +int notifier_add_irq(struct hvc_struct *hp, int irq) +{ + int rc; + + if (!irq) { + hp->irq_requested = 0; + return 0; + } + rc = request_irq(irq, hvc_handle_interrupt, IRQF_DISABLED, + "hvc_console", hp); + if (!rc) + hp->irq_requested = 1; + return rc; +} + +void notifier_del_irq(struct hvc_struct *hp, int irq) +{ + if (!irq) + return; + free_irq(irq, hp); + hp->irq_requested = 0; +} |