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Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support

To: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH] sb1250-duart.c: SB1250 DUART serial support
From: Andrew Sharp <andy.sharp@onstor.com>
Date: Thu, 12 Jul 2007 13:14:48 -0700
Cc: Mark Mason <mason@broadcom.com>, Andy Whitcroft <apw@shadowen.org>, Randy Dunlap <rdunlap@xenotime.net>, Joel Schopp <jschopp@austin.ibm.com>, linux-mips@linux-mips.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org
In-reply-to: <20070712114712.de5d6c9d.akpm@linux-foundation.org>
Organization: Onstor
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <Pine.LNX.4.64N.0707121745010.3029@blysk.ds.pg.gda.pl> <20070712114712.de5d6c9d.akpm@linux-foundation.org>
Sender: linux-mips-bounce@linux-mips.org
On Thu, 12 Jul 2007 11:47:12 -0700 Andrew Morton
<akpm@linux-foundation.org> wrote:

> On Thu, 12 Jul 2007 18:39:00 +0100 (BST)
> "Maciej W. Rozycki" <macro@linux-mips.org> wrote:
> 
> >  This is a driver for the SB1250 DUART, a dual serial port
> > implementation included in the Broadcom family of SOCs descending
> > from the SiByte SB1250 MIPS64 chip multiprocessor.  It is a new
> > implementation replacing the old-fashioned driver currently present
> > in the linux-mips.org tree.  It supports all the usual features one
> > would expect from a(n asynchronous) serial driver, including modem
> > line control (as far as hardware supports it -- there is edge
> > detection logic missing from the DCD and RI lines and the driver
> > does not implement polling of these lines at the moment), the
> > serial console, BREAK transmission and reception, including the
> > magic SysRq.  The receive FIFO threshold is not maintained though.
> > 
> > ...
> >
> > +
> > +#if defined(CONFIG_SIBYTE_BCM1x55) ||
> > defined(CONFIG_SIBYTE_BCM1x80) +#include <asm/sibyte/bcm1480_regs.h>
> > +#include <asm/sibyte/bcm1480_int.h>
> > +
> > +#define SBD_CHANREGS(line) A_BCM1480_DUART_CHANREG((line),
> > 0) +#define SBD_CTRLREGS(line)
> > A_BCM1480_DUART_CTRLREG((line), 0) +#define
> > SBD_INT(line)               (K_BCM1480_INT_UART_0 + (line)) +
> > +#elif defined(CONFIG_SIBYTE_SB1250) ||
> > defined(CONFIG_SIBYTE_BCM112X) +#include <asm/sibyte/sb1250_regs.h>
> > +#include <asm/sibyte/sb1250_int.h>
> > +
> > +#define SBD_CHANREGS(line) A_DUART_CHANREG((line), 0)
> > +#define SBD_CTRLREGS(line) A_DUART_CTRLREG(0)
> > +#define SBD_INT(line)              (K_INT_UART_0 + (line))
> > +
> > +#else
> > +#error invalid SB1250 UART configuration
> > +
> > +#endif
> 
> If the #error can trigger, the Kconfig is broken, yes?  (No action is
> required though - it's always good to have checks)
> 
> > +#define to_sport(uport) container_of(uport, struct sbd_port, port)
> 
> That didn't need to be implemented as a macro.
> 
> > +#define __unused __attribute__((__unused__))
> 
> Please use the generic implementations here.  `grep unused
> include/linux/compiler*.h'.
> 
> > +/*
> > + * In bug 1956, we get glitches that can mess up uart registers.
> > This
> > + * "read-mode-reg after any register access" is an accepted
> > workaround.
> > + */
> 
> <looks in bugzilla.kernel.org>
> 
> <wonders how a uart driver can fix an smbfs bug>
> 
> Perhaps a reference to where that bug number came from?

It's a Sibyte errata/WAR number as I recall.

> > +static void __war_sbd1956(struct sbd_port *sport)
> > +{
> > +   __read_sbdchn(sport, R_DUART_MODE_REG_1);
> > +   __read_sbdchn(sport, R_DUART_MODE_REG_2);
> > +}
> >
> > ...
> >
> > +static struct uart_ops sbd_ops = {
> 
> I suppose if we made this const, something would blow up.
> 
> 
> 
> 
> There is no power management support in this driver.
> 

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