From 611e097d7707741a336a0677d9d69bec40f29f3d Mon Sep 17 00:00:00 2001 From: Christian Borntraeger Date: Fri, 20 Jun 2008 15:24:08 +0200 Subject: 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 Signed-off-by: Rusty Russell --- drivers/char/hvc_irq.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) create mode 100644 drivers/char/hvc_irq.c (limited to 'drivers/char/hvc_irq.c') diff --git a/drivers/char/hvc_irq.c b/drivers/char/hvc_irq.c new file mode 100644 index 00000000000..73a59cdb894 --- /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 + +#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; +} -- cgit v1.2.3-18-g5258