[PATCH v2] serial: pl011: Fix earlycon register LUT breakage

[Huang Shijie]

On Tue, Sep 08, 2015 at 03:53:28PM +0800, Jun Nie wrote:
> 2015-09-08 15:52 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
> > 2015-09-08 10:23 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
> >> 2015-09-05 23:57 GMT+08:00 Jun Nie <jun.nie at linaro.org>:
> >>> Commit 7b753f318d14 ("uart: pl011: Introduce register accessor")
> >>> mistakenly used the register LUT i/o accessors for the pl011
> >>> earlycon. Since the port has not been probed at earlycon time,
> >>> the struct uart_amba_port (and register LUTs) are uninitialized.
> >>>
> >>> Use direct register addressing for pl011 earlycon; other h/w supported
> >>> by the amba-pl011 driver should declare an alternate earlycon.
> >>>
> >>> Signed-off-by: Peter Hurley <peter at hurleysoftware.com>
> >>> Signed-off-by: Jun Nie <jun.nie at linaro.org>
> >>> ---
> >>>  drivers/tty/serial/amba-pl011.c | 15 +++------------
> >>>  1 file changed, 3 insertions(+), 12 deletions(-)
> >>>
> >>> diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
> >>> index 2af09ab..cce41e0 100644
> >>> --- a/drivers/tty/serial/amba-pl011.c
> >>> +++ b/drivers/tty/serial/amba-pl011.c
> >>> @@ -326,12 +326,6 @@ static void pl011_writew(struct uart_amba_port *uap, int val, int index)
> >>>         writew_relaxed(val, uap->port.membase + uap->reg_lut[index]);
> >>>  }
> >>>
> >>> -static void pl011_writeb(struct uart_amba_port *uap, u8 val, int index)
> >>> -{
> >>> -       WARN_ON(index > REG_NR);
> >>> -       writeb_relaxed(val, uap->port.membase + uap->reg_lut[index]);
> >>> -}
> >>> -
> >>>  /*
> >>>   * Reads up to 256 characters from the FIFO or until it's empty and
> >>>   * inserts them into the TTY layer. Returns the number of characters
> >>> @@ -2348,13 +2342,10 @@ static struct console amba_console = {
> >>>
> >>>  static void pl011_putc(struct uart_port *port, int c)
> >>>  {
> >>> -       struct uart_amba_port *uap =
> >>> -           container_of(port, struct uart_amba_port, port);
> >>> -
> >>> -       while (pl011_readw(uap, REG_FR) & UART01x_FR_TXFF)
> >>> +       while (readw_relaxed(port->membase + UART01x_FR) & UART01x_FR_TXFF)
> >>>                 ;
> >>> -       pl011_writeb(uap, c, REG_DR);
> >>> -       while (pl011_readw(uap, REG_FR) & uap->fr_busy)
> >>> +       writeb_relaxed(c, port->membase + UART01x_DR);
> >>> +       while (readw_relaxed(port->membase + UART01x_FR) & UART01x_FR_BUSY)
> >>>                 ;
> >>>  }
> >>>
> >>> --
> >>> 1.9.1
> >>>
> >>
> >> Could anybody help test this earlycon patch on hardware with standard
> >> pl011 serial? Your help is appreciated and valuable no matter the
> >> previous patch set is carried on or reverted.
> >> Thank you very much!
> >>
> >> Jun
> 
> cc linux-arm-kernel at lists.infradead.org in case someone may have
> resource to help have a test. Thank you!
I tested this patch with the ARM Juno-r1 board, it works.

Tested-by: Huang Shijie <shijie.huang at arm.com>