CC devicetree
On Mon, Mar 5, 2018 at 6:17 PM, Geert Uytterhoeven
<geert+renesas@xxxxxxxxx> wrote:
> On DT platforms, the sh-sci driver requires the presence of "serialN"
> aliases in DT, from which instance IDs are derived. If a DT alias is
> missing, the drivers fails to probe the corresponding serial port.
>
> This becomes cumbersome when considering DT overlays, as currently
> there is no upstream support for dynamically updating the /aliases node
> in DT. Furthermore, even in the presence of such support, hardcoded
> instance IDs in independent overlays are prone to conflicts.
>
> Hence add support for dynamic instance IDs, to be used in the absence of
> a DT alias. This makes serial ports behave similar to I2C and SPI
> buses, which already support dynamic instances.
>
> Ports in use are tracked using a simple bitmask of type unsigned long,
> which is sufficient to handle all current hardware (max. 18 ports).
> The maximum number of serial ports is still fixed, and configurable
> through Kconfig. Range validation is done through both Kconfig and a
> compile-time check.
>
> Due to the fixed maximum number of serial ports, dynamic and static
> instances share the same ID space. Static instances added later are
> rejected when conflicting with dynamic instances registered earlier.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> drivers/tty/serial/Kconfig | 2 ++
> drivers/tty/serial/sh-sci.c | 8 ++++++++
> 2 files changed, 10 insertions(+)
>
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index 3682fd3e960cbd64..76005dc5f6246593 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -762,6 +762,8 @@ config SERIAL_SH_SCI
>
> config SERIAL_SH_SCI_NR_UARTS
> int "Maximum number of SCI(F) serial ports" if EXPERT
> + range 1 64 if 64BIT
> + range 1 32 if !64BIT
> depends on SERIAL_SH_SCI
> default "3" if H8300
> default "10" if SUPERH
> diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
> index 9e1dfbb4b40bf849..3a03d391fcc72656 100644
> --- a/drivers/tty/serial/sh-sci.c
> +++ b/drivers/tty/serial/sh-sci.c
> @@ -159,6 +159,7 @@ struct sci_port {
> #define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS
>
> static struct sci_port sci_ports[SCI_NPORTS];
> +static unsigned long sci_ports_in_use;
> static struct uart_driver sci_uart_driver;
>
> static inline struct sci_port *
> @@ -3011,6 +3012,7 @@ static int sci_remove(struct platform_device *dev)
> {
> struct sci_port *port = platform_get_drvdata(dev);
>
> + sci_ports_in_use &= ~BIT(port->port.line);
> uart_remove_one_port(&sci_uart_driver, &port->port);
>
> sci_cleanup_single(port);
> @@ -3092,6 +3094,8 @@ static struct plat_sci_port *sci_parse_dt(struct platform_device *pdev,
>
> /* Get the line number from the aliases node. */
> id = of_alias_get_id(np, "serial");
> + if (id < 0 && ~sci_ports_in_use)
> + id = ffz(sci_ports_in_use);
> if (id < 0) {
> dev_err(&pdev->dev, "failed to get alias id (%d)\n", id);
> return NULL;
> @@ -3126,6 +3130,9 @@ static int sci_probe_single(struct platform_device *dev,
> dev_notice(&dev->dev, "Consider bumping CONFIG_SERIAL_SH_SCI_NR_UARTS!\n");
> return -EINVAL;
> }
> + BUILD_BUG_ON(SCI_NPORTS > sizeof(sci_ports_in_use) * 8);
> + if (sci_ports_in_use & BIT(index))
> + return -EBUSY;
>
> mutex_lock(&sci_uart_registration_lock);
> if (!sci_uart_driver.state) {
> @@ -3224,6 +3231,7 @@ static int sci_probe(struct platform_device *dev)
> sh_bios_gdb_detach();
> #endif
>
> + sci_ports_in_use |= BIT(dev_id);
> return 0;
> }
>
> --
> 2.7.4
