Re: [PATCH 4/4] drivers/mailbox: Add ASpeed mailbox driver

[Cyril Bur <cyrilbur-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Tue, 2017-02-07 at 16:10 +1030, Joel Stanley wrote:
> On Thu, Jan 12, 2017 at 10:59 AM, Cyril Bur <cyrilbur-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> > This provides access to the mbox registers on the ast2400 and ast2500
> > boards.
> 

Hey Joel,

Thanks for review, just one thing, I'll fixup the rest.

Cyril

> s/boards/SoCs/
> 
> > 
> > This driver allows arbitrary reads and writes to the 16 data registers as
> > the other end may have configured the mbox hardware to provide an
> > interrupt when a specific register gets written to.
> > 
> > Signed-off-by: Cyril Bur <cyrilbur-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> 
> Send this to lkml as well next time you submit.
> 
> > ---
> >  drivers/mailbox/Kconfig       |   9 ++
> >  drivers/mailbox/Makefile      |   2 +
> >  drivers/mailbox/aspeed-mbox.c | 334 ++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 345 insertions(+)
> >  create mode 100644 drivers/mailbox/aspeed-mbox.c
> > 
> > diff --git a/drivers/mailbox/Kconfig b/drivers/mailbox/Kconfig
> > index ceff415f201c..10a7f3f2765c 100644
> > --- a/drivers/mailbox/Kconfig
> > +++ b/drivers/mailbox/Kconfig
> > @@ -152,4 +152,13 @@ config BCM_PDC_MBOX
> >           Mailbox implementation for the Broadcom PDC ring manager,
> >           which provides access to various offload engines on Broadcom
> >           SoCs. Say Y here if you want to use the Broadcom PDC.
> > +
> > +config ASPEED_MBOX
> 
> Call this ASPEED_LPC_MAILBOX, as it's a in the LPC IP block.
> 

I think I'll stick with ASPEED_LPC_MBOX, the rest of the file uses MBOX
more widely when talking about controllers.

> > +       depends on (ARCH_ASPEED || COMPILE_TEST) && REGMAP && MFD_SYSCON
> > +       bool "Aspeed ast2400/2500 Mailbox Controller"
> 
> Call this Aspeed LPC Mailbox Controller, as the layout is shared by
> SoCs other than the 2500 and 2400.
> 
> > +       default "y"
> > +       ---help---
> > +         Provides a driver for the MBOX registers found on Aspeed SOCs
> > +         (AST2400 and AST2500). This driver provides a device for aspeed
> > +         mbox registers
> >  endif
> > diff --git a/drivers/mailbox/Makefile b/drivers/mailbox/Makefile
> > index 7dde4f609ae8..db5b4f3f29e0 100644
> > --- a/drivers/mailbox/Makefile
> > +++ b/drivers/mailbox/Makefile
> > @@ -31,3 +31,5 @@ obj-$(CONFIG_HI6220_MBOX)     += hi6220-mailbox.o
> >  obj-$(CONFIG_BCM_PDC_MBOX)     += bcm-pdc-mailbox.o
> > 
> >  obj-$(CONFIG_TEGRA_HSP_MBOX)   += tegra-hsp.o
> > +
> > +obj-$(CONFIG_ASPEED_MBOX)      += aspeed-mbox.o
> > diff --git a/drivers/mailbox/aspeed-mbox.c b/drivers/mailbox/aspeed-mbox.c
> > new file mode 100644
> > index 000000000000..c4ee6ba228ea
> > --- /dev/null
> > +++ b/drivers/mailbox/aspeed-mbox.c
> > +
> > +static ssize_t aspeed_mbox_read(struct file *file, char __user *buf,
> > +                               size_t count, loff_t *ppos)
> > +{
> > +       struct aspeed_mbox *mbox = file_mbox(file);
> > +       char __user *p = buf;
> > +       ssize_t ret;
> > +       int i;
> > +
> > +       if (!access_ok(VERIFY_WRITE, buf, count))
> > +               return -EFAULT;
> 
> As discussed in the LPC driver review:
> 
>  "And don't call access_ok(), it's racy and no driver should ever do that."
> 
> Make sure all of the things you fixed in that driver are fixed in this one.
> 
> > +
> > +       if (count + *ppos > ASPEED_MBOX_NUM_REGS)
> > +               return -EINVAL;
> > +
> > +       if (file->f_flags & O_NONBLOCK) {
> > +               if (!(aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
> > +                               ASPEED_MBOX_CTRL_RECV))
> > +                       return -EAGAIN;
> > +       } else if (wait_event_interruptible(mbox->queue,
> > +                               aspeed_mbox_inb(mbox, ASPEED_MBOX_BMC_CTRL) &
> > +                               ASPEED_MBOX_CTRL_RECV)) {
> > +               return -ERESTARTSYS;
> > +       }
> > +
> > +       mutex_lock(&mbox->mutex);
> > +
> > +       for (i = *ppos; count > 0 && i < ASPEED_MBOX_NUM_REGS; i++) {
> > +               uint8_t reg = aspeed_mbox_inb(mbox, ASPEED_MBOX_DATA_0 + (i * 4));
> > +
> > +               ret = __put_user(reg, p);
> > +               if (ret)
> > +                       goto out_unlock;
> > +
> > +               p++;
> > +               count--;
> > +       }
> > +
> > +       /* ASPEED_MBOX_CTRL_RECV bit is W1C, this also unmasks in 1 step */
> 
> W1C? Write to clear?
> 
> > +       aspeed_mbox_outb(mbox, ASPEED_MBOX_CTRL_RECV, ASPEED_MBOX_BMC_CTRL);
> > +       ret = p - buf;
> > +
> > +out_unlock:
> > +       mutex_unlock(&mbox->mutex);
> > +       return ret;
> > +}
> > +
> > +module_platform_driver(aspeed_mbox_driver);
> > +
> > +MODULE_DEVICE_TABLE(of, aspeed_mbox_match);
> > +MODULE_LICENSE("GPL");
> > +MODULE_AUTHOR("Cyril Bur <cyrilbur-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
> > +MODULE_DESCRIPTION("ASpeed mailbox device driver");
> 
> ASPEED or Aspeed.
> 
> > --
> > 2.11.0
> > 
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