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SubjectRE: [PATCH] tty: serial: samsung: support driver modulization
Date
To support module for Samsung serial driver,
I would like to split the file into 2 files.
Because it cannot be supported in one file both early console and
module driver
Thus some function need to change to EXPORT_SYMBOL to use in module
driver file.
I'm not pushed yet for module driver.

> -----Original Message-----
> From: Greg KH <gregkh@linuxfoundation.org>
> Sent: Friday, December 6, 2019 1:03 AM
> To: Krzysztof Kozlowski <krzk@kernel.org>
> Cc: Hyunki Koo <kkoos00@naver.com>; jslaby@suse.com; linux-
> serial@vger.kernel.org; linux-kernel@vger.kernel.org;
> kkoos00@gmail.com; Shinbeom Choi <sbeom.choi@samsung.com>; Hyunki Koo
> <hyunki00.koo@samsung.com>
> Subject: Re: [PATCH] tty: serial: samsung: support driver modulization
>
> On Thu, Dec 05, 2019 at 04:36:48PM +0100, Krzysztof Kozlowski wrote:
> > On Sun, 1 Dec 2019 at 09:05, Greg KH <gregkh@linuxfoundation.org>
> wrote:
> > >
> > > On Sun, Dec 01, 2019 at 04:59:14PM +0900, Hyunki Koo wrote:
> > > > From: Shinbeom Choi <sbeom.choi@samsung.com>
> > > >
> > > > This commit enables modulization of samsung uart driver.
> > > >
> > > > There was no way to make use of this driver in other module,
> > > > because uart functions were static.
> > > >
> > > > By exporting required functions, user can use this driver in
> other
> > > > module.
> > > >
> > > > Signed-off-by: Shinbeom Choi <sbeom.choi@samsung.com>
> > > > Signed-off-by: Hyunki Koo <hyunki00.koo@samsung.com>
> > > > ---
> > > > drivers/tty/serial/samsung.h | 32 ++++++++++++
> > > > drivers/tty/serial/samsung_tty.c | 85
> > > > +++++++++++++++-----------------
> > > > 2 files changed, 73 insertions(+), 44 deletions(-)
> > > >
> > > > diff --git a/drivers/tty/serial/samsung.h
> > > > b/drivers/tty/serial/samsung.h index f93022113f59..25be0962284d
> > > > 100644
> > > > --- a/drivers/tty/serial/samsung.h
> > > > +++ b/drivers/tty/serial/samsung.h
> > > > @@ -144,4 +144,36 @@ static inline void s3c24xx_clear_bit(struct
> uart_port *port, int idx,
> > > > local_irq_restore(flags);
> > > > }
> > > >
> > > > +#if defined(CONFIG_ARCH_EXYNOS)
> > > > +#define EXYNOS_COMMON_SERIAL_DRV_DATA
\
> > > > + .info = &(struct s3c24xx_uart_info) { \
> > > > + .name = "Samsung Exynos UART", \
> > > > + .type = PORT_S3C6400, \
> > > > + .has_divslot = 1, \
> > > > + .rx_fifomask = S5PV210_UFSTAT_RXMASK, \
> > > > + .rx_fifoshift = S5PV210_UFSTAT_RXSHIFT, \
> > > > + .rx_fifofull = S5PV210_UFSTAT_RXFULL, \
> > > > + .tx_fifofull = S5PV210_UFSTAT_TXFULL, \
> > > > + .tx_fifomask = S5PV210_UFSTAT_TXMASK, \
> > > > + .tx_fifoshift = S5PV210_UFSTAT_TXSHIFT, \
> > > > + .def_clk_sel = S3C2410_UCON_CLKSEL0, \
> > > > + .num_clks = 1, \
> > > > + .clksel_mask = 0, \
> > > > + .clksel_shift = 0, \
> > > > + }, \
> > > > + .def_cfg = &(struct s3c2410_uartcfg) { \
> > > > + .ucon = S5PV210_UCON_DEFAULT, \
> > > > + .ufcon = S5PV210_UFCON_DEFAULT, \
> > > > + .has_fracval = 1, \
> > > > + } \
> > > > +
> > > > +#endif
> > > > +
> > > > +int s3c24xx_serial_get_ports(struct s3c24xx_uart_port
**ourport,
> > > > +int index); int s3c24xx_serial_init_port(struct
> s3c24xx_uart_port *ourport,
> > > > + struct platform_device
> > > > +*platdev); int s3c24xx_serial_unregister_port(struct
> > > > +platform_device *dev); int s3c24xx_serial_suspend(struct device
> > > > +*dev); int s3c24xx_serial_resume(struct device *dev); int
> > > > +s3c24xx_serial_resume_noirq(struct device *dev);
> > > > #endif
> > > > diff --git a/drivers/tty/serial/samsung_tty.c
> > > > b/drivers/tty/serial/samsung_tty.c
> > > > index 83fd51607741..15414ecd9008 100644
> > > > --- a/drivers/tty/serial/samsung_tty.c
> > > > +++ b/drivers/tty/serial/samsung_tty.c
> > > > @@ -1735,7 +1735,7 @@ static int
> s3c24xx_serial_enable_baudclk(struct s3c24xx_uart_port *ourport)
> > > > * initialise a single serial port from the platform device
> given
> > > > */
> > > >
> > > > -static int s3c24xx_serial_init_port(struct s3c24xx_uart_port
> > > > *ourport,
> > > > +int s3c24xx_serial_init_port(struct s3c24xx_uart_port *ourport,
> > > > struct platform_device
*platdev)
> > > > {
> > > > struct uart_port *port = &ourport->port; @@ -1842,12
> > > > +1842,24 @@ static int s3c24xx_serial_init_port(struct
> s3c24xx_uart_port *ourport,
> > > > /* reset the fifos (and setup the uart) */
> > > > s3c24xx_serial_resetport(port, cfg);
> > > >
> > > > + if (!s3c24xx_uart_drv.state) {
> > > > + ret = uart_register_driver(&s3c24xx_uart_drv);
> > > > + if (ret < 0) {
> > > > + dev_err(port->dev, "Failed to register
Samsung
> UART driver\n");
> > > > + return ret;
> > > > + }
> > > > + }
> > > > +
> > > > + dbg("%s: adding port\n", __func__);
> > > > + uart_add_one_port(&s3c24xx_uart_drv, &ourport->port);
> > > > +
> > > > return 0;
> > > >
> > > > err:
> > > > port->mapbase = 0;
> > > > return ret;
> > > > }
> > > > +EXPORT_SYMBOL_GPL(s3c24xx_serial_init_port);
> > >
> > > Why are you exporting all of these functions? What other code
> uses
> > > them? Why are you converting them all to global functions I don't
> > > see any other in-kernel callers, so why are those changes needed
> here?
> > >
> > > totally confused,
> >
> > I cannot find the original email from Hyunki on mailing lists
> (neither
> > LKML nor serial) so this was not even public till Greg replied.
>
> I think it might have been sent in html format.
>
> > Anyway, probably this is for new Android and some out-of-tree
> usage...
> > but it is wrong.
>
> Making the driver be able to be built as a module is a good thing, no
> matter what project is causing the work to have happen.
>
> And yes, it's Android :)
>
> thanks,
>
> greg k-h

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