On Wed, 2013-10-09 at 14:23 +1100, Michael Ellerman wrote:
> On Tue, Oct 08, 2013 at 06:46:40PM +1100, Benjamin Herrenschmidt wrote:
> > With OPALv3, the firmware can provide the address of it's internal console
> > to Linux, which we can then display using debugfs. This is handy for
> > diagnostics and debugging.
> >
> > Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
> > ---
> >
> > diff --git a/arch/powerpc/platforms/powernv/opal.c
> > b/arch/powerpc/platforms/powernv/opal.c
> > index 2911abe..10d7894 100644
> > --- a/arch/powerpc/platforms/powernv/opal.c
> > +++ b/arch/powerpc/platforms/powernv/opal.c
> > @@ -17,6 +17,8 @@
> > #include <linux/interrupt.h>
> > #include <linux/notifier.h>
> > #include <linux/slab.h>
> > +#include <linux/debugfs.h>
> > +#include <linux/uaccess.h>
> > #include <asm/opal.h>
> > #include <asm/firmware.h>
> >
> > @@ -27,6 +29,21 @@ struct opal {
> > u64 entry;
> > } opal;
> >
> > +/* OPAL in-memory console */
>
> It might be nice to point out that the format of the struct is defined
> by OPAL and must be in sync with what OPAL is using.
Yes, we could move the structure definition to opal.h...
> > +struct memcons {
> > + uint64_t magic;
>
> u64 ?
Who cares ? Especially if it goes into opal.h it should stick to the
types used in that file.
> > +#define MEMCONS_MAGIC 0x6630696567726173
> > + uint64_t obuf_phys;
> > + uint64_t ibuf_phys;
> > + uint32_t obuf_size;
> > + uint32_t ibuf_size;
> > + uint32_t out_pos;
> > +#define MEMCONS_OUT_POS_WRAP 0x80000000u
> > +#define MEMCONS_OUT_POS_MASK 0x00ffffffu
>
> Where does this come from?
My a** :-) I made it up as I wrote the OPAL side one, why ?
> > + uint32_t in_prod;
> > + uint32_t in_cons;
> > +};
>
> Should it be packed?
Nope, no need. It's all nice and naturally aligned.
> > @@ -369,6 +386,90 @@ static irqreturn_t opal_interrupt(int irq, void *data)
> > return IRQ_HANDLED;
> > }
> >
> > +#ifdef CONFIG_DEBUG_FS
> > +static ssize_t opal_memcons_read(struct file *file, char __user *to,
> > + size_t count, loff_t *ppos)
> > +{
> > + struct memcons *mc = file->private_data;
> > + size_t available, ret, chunk0, chunk1, lcount;
> > + const char *start, *conbuf = __va(mc->obuf_phys);
> > + loff_t opos, pos;
> > +
> > + /*
> > + * Find out how much is in the buffer. If it has wrapped
> > + * the whole buffer, else just the beginning. It has wrapped
> > + * if the next character is not \0
> > + */
> > + if (mc->out_pos & MEMCONS_OUT_POS_WRAP) {
> > + available = mc->obuf_size;
> > + chunk1 = mc->out_pos & MEMCONS_OUT_POS_MASK;
> > + start = conbuf + chunk1;
> > + chunk0 = mc->obuf_size - chunk1;
> > + } else {
> > + available = mc->out_pos;
> > + start = conbuf;
> > + chunk0 = available;
> > + chunk1 = 0;
> > + }
>
> Surely simple_read_from_buffer() could make some of this simpler?
If you can find a way to make it deal with a ring buffer...
Cheers,
Ben.
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