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. > +struct memcons { > + uint64_t magic; u64 ? > +#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? > + uint32_t in_prod; > + uint32_t in_cons; > +}; Should it be packed? > @@ -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? cheers _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev