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SubjectRe: [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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