| Message ID | 20220408122636.505737-4-valentin.caron@foss.st.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | serial: stm32: add earlycon and polling mode | expand |
Hi Valentin, On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron <valentin.caron@foss.st.com> wrote: > Add early console support in stm32 uart driver. > > Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com> > Signed-off-by: Valentin Caron <valentin.caron@foss.st.com> Thanks for your patch! > --- a/Documentation/admin-guide/kernel-parameters.txt > +++ b/Documentation/admin-guide/kernel-parameters.txt > @@ -1264,6 +1264,12 @@ > address must be provided, and the serial port must > already be setup and configured. > > + stm32,<addr> > + Use early console provided by ST Microelectronics > + serial driver for STM32 SoCs. A valid base address > + must be provided, and the serial port must already > + be setup and configured. Why do you need this parameter? Given this driver uses DT, can't it figure out the serial port address from chosen/stdout-path? +OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup); Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
On 4/11/22 16:59, Geert Uytterhoeven wrote: > Hi Valentin, > > On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron > <valentin.caron@foss.st.com> wrote: >> Add early console support in stm32 uart driver. >> >> Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com> >> Signed-off-by: Valentin Caron <valentin.caron@foss.st.com> > Thanks for your patch! > >> --- a/Documentation/admin-guide/kernel-parameters.txt >> +++ b/Documentation/admin-guide/kernel-parameters.txt >> @@ -1264,6 +1264,12 @@ >> address must be provided, and the serial port must >> already be setup and configured. >> >> + stm32,<addr> >> + Use early console provided by ST Microelectronics >> + serial driver for STM32 SoCs. A valid base address >> + must be provided, and the serial port must already >> + be setup and configured. > Why do you need this parameter? > > Given this driver uses DT, can't it figure out the serial port address > from chosen/stdout-path? > > +OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup); > +OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup); > +OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup); > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds Hi Geert, I took the example of other serial drivers. Both methods work (with earlycon/stdout-path and with earlycon=stm32,0xXXXXXXX) but your right, the second will probably never used on this driver. Should I remove it ? Thanks, Valentin
Hi Valentin, On Thu, Apr 14, 2022 at 2:17 PM Valentin CARON <valentin.caron@foss.st.com> wrote: > On 4/11/22 16:59, Geert Uytterhoeven wrote: > > On Fri, Apr 8, 2022 at 3:14 PM Valentin Caron > > <valentin.caron@foss.st.com> wrote: > >> Add early console support in stm32 uart driver. > >> > >> Signed-off-by: Alexandre Torgue <alexandre.torgue@foss.st.com> > >> Signed-off-by: Valentin Caron <valentin.caron@foss.st.com> > > Thanks for your patch! > > > >> --- a/Documentation/admin-guide/kernel-parameters.txt > >> +++ b/Documentation/admin-guide/kernel-parameters.txt > >> @@ -1264,6 +1264,12 @@ > >> address must be provided, and the serial port must > >> already be setup and configured. > >> > >> + stm32,<addr> > >> + Use early console provided by ST Microelectronics > >> + serial driver for STM32 SoCs. A valid base address > >> + must be provided, and the serial port must already > >> + be setup and configured. > > Why do you need this parameter? > > > > Given this driver uses DT, can't it figure out the serial port address > > from chosen/stdout-path? > > I took the example of other serial drivers. > Both methods work (with earlycon/stdout-path and with > earlycon=stm32,0xXXXXXXX) > but your right, the second will probably never used on this driver. > > Should I remove it ? I think you should. The less platform-specific kernel parameters, the better. And the less bad examples to copy from. Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index 3f1cc5e317ed..e941c3351c7a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -1264,6 +1264,12 @@ address must be provided, and the serial port must already be setup and configured. + stm32,<addr> + Use early console provided by ST Microelectronics + serial driver for STM32 SoCs. A valid base address + must be provided, and the serial port must already + be setup and configured. + earlyprintk= [X86,SH,ARM,M68k,S390] earlyprintk=vga earlyprintk=sclp diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 6949e883ffab..ed59de8d2e11 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -1443,6 +1443,7 @@ config SERIAL_STM32_CONSOLE bool "Support for console on STM32" depends on SERIAL_STM32=y select SERIAL_CORE_CONSOLE + select SERIAL_EARLYCON config SERIAL_MVEBU_UART bool "Marvell EBU serial port support" diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 4307c822afe4..65988e6efaa2 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -1766,6 +1766,57 @@ static struct console stm32_console = { #define STM32_SERIAL_CONSOLE NULL #endif /* CONFIG_SERIAL_STM32_CONSOLE */ +#ifdef CONFIG_SERIAL_EARLYCON +static void early_stm32_usart_console_putchar(struct uart_port *port, unsigned char ch) +{ + struct stm32_usart_info *info = port->private_data; + + while (!(readl_relaxed(port->membase + info->ofs.isr) & USART_SR_TXE)) + cpu_relax(); + + writel_relaxed(ch, port->membase + info->ofs.tdr); +} + +static void early_stm32_serial_write(struct console *console, const char *s, unsigned int count) +{ + struct earlycon_device *device = console->data; + struct uart_port *port = &device->port; + + uart_console_write(port, s, count, early_stm32_usart_console_putchar); +} + +static int __init early_stm32_h7_serial_setup(struct earlycon_device *device, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data = &stm32h7_info; + device->con->write = early_stm32_serial_write; + return 0; +} + +static int __init early_stm32_f7_serial_setup(struct earlycon_device *device, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data = &stm32f7_info; + device->con->write = early_stm32_serial_write; + return 0; +} + +static int __init early_stm32_f4_serial_setup(struct earlycon_device *device, const char *options) +{ + if (!(device->port.membase || device->port.iobase)) + return -ENODEV; + device->port.private_data = &stm32f4_info; + device->con->write = early_stm32_serial_write; + return 0; +} + +OF_EARLYCON_DECLARE(stm32, "st,stm32h7-uart", early_stm32_h7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32f7-uart", early_stm32_f7_serial_setup); +OF_EARLYCON_DECLARE(stm32, "st,stm32-uart", early_stm32_f4_serial_setup); +#endif /* CONFIG_SERIAL_EARLYCON */ + static struct uart_driver stm32_usart_driver = { .driver_name = DRIVER_NAME, .dev_name = STM32_SERIAL_NAME,