Device number 204 has a range of minors on major number. uart_register_driver is failing due to lack of minor numbers when more number of uart ports used. So, to avoid minor number limitation on 204 major number use dynamic major allocation when more than 4 uart ports used otherwise use static major allocation. https://docs.kernel.org/arch/arm/sa1100/serial_uart.html Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli@xxxxxxx> --- Changes for V2: Update logic to use either static or dynamic major allocation. Update commit description. Update description of SERIAL_UARTLITE_NR_UARTS in Kconfig. Changes for V3: Fix typo. Remove parentheses. Changes for V4: Fix typo. --- drivers/tty/serial/Kconfig | 3 +++ drivers/tty/serial/uartlite.c | 5 +++++ 2 files changed, 8 insertions(+) diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig index 732c893c8d16..8b1f5756002f 100644 --- a/drivers/tty/serial/Kconfig +++ b/drivers/tty/serial/Kconfig @@ -532,6 +532,9 @@ config SERIAL_UARTLITE_NR_UARTS help Set this to the number of uartlites in your system, or the number you think you might implement. + If maximum number of uartlite serial ports is more than 4, then the + driver uses dynamic allocation instead of static allocation for major + number. config SERIAL_SUNCORE bool diff --git a/drivers/tty/serial/uartlite.c b/drivers/tty/serial/uartlite.c index 404c14acafa5..66d751edcf45 100644 --- a/drivers/tty/serial/uartlite.c +++ b/drivers/tty/serial/uartlite.c @@ -24,8 +24,13 @@ #include <linux/pm_runtime.h> #define ULITE_NAME "ttyUL" +#if CONFIG_SERIAL_UARTLITE_NR_UARTS > 4 +#define ULITE_MAJOR 0 /* use dynamic node allocation */ +#define ULITE_MINOR 0 +#else #define ULITE_MAJOR 204 #define ULITE_MINOR 187 +#endif #define ULITE_NR_UARTS CONFIG_SERIAL_UARTLITE_NR_UARTS /* --------------------------------------------------------------------- -- 2.25.1
