linux-kernel - Re: [PATCH v6 5/5] drivers/tty/serial: add LiteUART driver

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Date:   Thu, 4 Jun 2020 09:57:16 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Mateusz Holenko <mholenko@...micro.com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jiri Slaby <jslaby@...e.com>,
        devicetree <devicetree@...r.kernel.org>,
        "open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
        Stafford Horne <shorne@...il.com>,
        Karol Gugala <kgugala@...micro.com>,
        Mauro Carvalho Chehab <mchehab+samsung@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Paul E. McKenney" <paulmck@...ux.ibm.com>,
        Filip Kokosinski <fkokosinski@...micro.com>,
        Pawel Czarnecki <pczarnecki@...ernships.antmicro.com>,
        Joel Stanley <joel@....id.au>,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Maxime Ripard <mripard@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Heiko Stuebner <heiko@...ech.de>,
        Sam Ravnborg <sam@...nborg.org>,
        Icenowy Zheng <icenowy@...c.io>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "Gabriel L. Somlo" <gsomlo@...il.com>
Subject: Re: [PATCH v6 5/5] drivers/tty/serial: add LiteUART driver

On Thu, Jun 04, 2020 at 09:16:25AM +0200, Mateusz Holenko wrote:
> On Wed, May 27, 2020 at 6:27 PM Mateusz Holenko <mholenko@...micro.com> wrote:
> >
> > From: Filip Kokosinski <fkokosinski@...micro.com>
> >
> > This commit adds driver for the FPGA-based LiteUART serial controller
> > from LiteX SoC builder.
> >
> > The current implementation supports LiteUART configured
> > for 32 bit data width and 8 bit CSR bus width.
> >
> > It does not support IRQ.
> >
> > Signed-off-by: Filip Kokosinski <fkokosinski@...micro.com>
> > Signed-off-by: Mateusz Holenko <mholenko@...micro.com>
> > ---
> >
> > Notes:
> >     Changes in v6:
> >     - LiteUART ports now stored in xArray
> >     - removed PORT_LITEUART
> >     - fixed formatting
> >     - removed some unnecessary defines
> >
> >     No changes in v5.
> >
> >     Changes in v4:
> >     - fixed copyright header
> >     - removed a wrong dependency on UARTLITE from Kconfig
> >     - added a dependency on LITEX_SOC_CONTROLLER to LITEUART in Kconfig
> >
> >     Changes in v3:
> >     - aliases made optional
> >     - used litex_get_reg/litex_set_reg functions instead of macros
> >     - SERIAL_LITEUART_NR_PORTS renamed to SERIAL_LITEUART_MAX_PORTS
> >     - PORT_LITEUART changed from 122 to 123
> >     - added dependency on LITEX_SOC_CONTROLLER
> >     - patch number changed from 4 to 5
> >
> >     No changes in v2.
> >
> >  MAINTAINERS                   |   1 +
> >  drivers/tty/serial/Kconfig    |  31 +++
> >  drivers/tty/serial/Makefile   |   1 +
> >  drivers/tty/serial/liteuart.c | 404 ++++++++++++++++++++++++++++++++++
> >  4 files changed, 437 insertions(+)
> >  create mode 100644 drivers/tty/serial/liteuart.c
> >
> > diff --git a/MAINTAINERS b/MAINTAINERS
> > index 51d2d6a61fb0..d855fe807833 100644
> > --- a/MAINTAINERS
> > +++ b/MAINTAINERS
> > @@ -9846,6 +9846,7 @@ M:        Mateusz Holenko <mholenko@...micro.com>
> >  S:     Maintained
> >  F:     Documentation/devicetree/bindings/*/litex,*.yaml
> >  F:     drivers/soc/litex/litex_soc_ctrl.c
> > +F:     drivers/tty/serial/liteuart.c
> >  F:     include/linux/litex.h
> >
> >  LIVE PATCHING
> > diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> > index adf9e80e7dc9..17aaf0afb27a 100644
> > --- a/drivers/tty/serial/Kconfig
> > +++ b/drivers/tty/serial/Kconfig
> > @@ -1562,6 +1562,37 @@ config SERIAL_MILBEAUT_USIO_CONSOLE
> >           receives all kernel messages and warnings and which allows logins in
> >           single user mode).
> >
> > +config SERIAL_LITEUART
> > +       tristate "LiteUART serial port support"
> > +       depends on HAS_IOMEM
> > +       depends on OF || COMPILE_TEST
> > +       depends on LITEX_SOC_CONTROLLER
> > +       select SERIAL_CORE
> > +       help
> > +         This driver is for the FPGA-based LiteUART serial controller from LiteX
> > +         SoC builder.
> > +
> > +         Say 'Y' here if you wish to use the LiteUART serial controller.
> > +         Otherwise, say 'N'.
> > +
> > +config SERIAL_LITEUART_MAX_PORTS
> > +       int "Maximum number of LiteUART ports"
> > +       depends on SERIAL_LITEUART
> > +       default "1"
> > +       help
> > +         Set this to the maximum number of serial ports you want the driver
> > +         to support.
> > +
> > +config SERIAL_LITEUART_CONSOLE
> > +       bool "LiteUART serial port console support"
> > +       depends on SERIAL_LITEUART=y
> > +       select SERIAL_CORE_CONSOLE
> > +       help
> > +         Say 'Y' here if you wish to use the FPGA-based LiteUART serial controller
> > +         from LiteX SoC builder as the system console (the system console is the
> > +         device which receives all kernel messages and warnings and which allows
> > +         logins in single user mode). Otherwise, say 'N'.
> > +
> >  endmenu
> >
> >  config SERIAL_MCTRL_GPIO
> > diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> > index d056ee6cca33..9f8ba419ff3b 100644
> > --- a/drivers/tty/serial/Makefile
> > +++ b/drivers/tty/serial/Makefile
> > @@ -89,6 +89,7 @@ obj-$(CONFIG_SERIAL_OWL)      += owl-uart.o
> >  obj-$(CONFIG_SERIAL_RDA)       += rda-uart.o
> >  obj-$(CONFIG_SERIAL_MILBEAUT_USIO) += milbeaut_usio.o
> >  obj-$(CONFIG_SERIAL_SIFIVE)    += sifive.o
> > +obj-$(CONFIG_SERIAL_LITEUART) += liteuart.o
> >
> >  # GPIOLIB helpers for modem control lines
> >  obj-$(CONFIG_SERIAL_MCTRL_GPIO)        += serial_mctrl_gpio.o
> > diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
> > new file mode 100644
> > index 000000000000..22b7612c13ca
> > --- /dev/null
> > +++ b/drivers/tty/serial/liteuart.c
> > @@ -0,0 +1,404 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * LiteUART serial controller (LiteX) Driver
> > + *
> > + * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
> > + */
> > +
> > +#include <linux/console.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_address.h>
> > +#include <linux/of_platform.h>
> > +#include <linux/serial.h>
> > +#include <linux/serial_core.h>
> > +#include <linux/timer.h>
> > +#include <linux/tty_flip.h>
> > +#include <linux/litex.h>
> > +#include <linux/xarray.h>
> 
> kbuild test robot reported problems with this patch, namely: implicit
> declaration of function 'kzalloc'
> This is caused by the missing include directive. When I was testing it
> I must have missed the warning, but the compilation succeeded and the
> resulting binary worked fine on HW (LiteX/mor1kx platform).
> The fix is a simple one-liner, adding a new include:
> 
> +#include <linux/slab.h>
> 
> Since this is a very small fix and does not modify the actual code of
> the driver I want to wait for more feedback on all patches in the
> series before resubmitting, in order to limit traffic on the list.
> Or should I generate the next version and resend the whole patchset
> with this single fix, as otherwise it won't be reviewed at all?

Please fix up and resend.  We can't do anything until after 5.8-rc1 is
out anyway...

thanks,

greg k-h