[PATCH] lib: utils/serial: Add PXA UARTs support

[Anup Patel]

On Sun, Feb 23, 2025 at 8:59 PM Junhui Liu <junhui.liu at pigmoral.tech> wrote:
>
> The PXA variant of the uart8250 adds the UART Unit Enable bit (UUE) that
> needs to be set to enable the XScale PXA UART. And it is required for
> some RISC-V SoCs like the Spacemit K1 that implement the PXA UART.
>
> This introduces the "intel,xscale-uart" compatible to handle setting the
> UUE bit.
>
> Signed-off-by: Junhui Liu <junhui.liu at pigmoral.tech>
> ---
>  include/sbi_utils/serial/uart8250.h    |  4 +++-
>  lib/utils/serial/fdt_serial_uart8250.c |  7 +++++--
>  lib/utils/serial/uart8250.c            | 11 +++++++++--
>  3 files changed, 17 insertions(+), 5 deletions(-)
>
> diff --git a/include/sbi_utils/serial/uart8250.h b/include/sbi_utils/serial/uart8250.h
> index d4a8c136a4552c8045a3c83820a35ae2ae86e810..39f4b316ff631159cc81284460fcaf92490be310 100644
> --- a/include/sbi_utils/serial/uart8250.h
> +++ b/include/sbi_utils/serial/uart8250.h
> @@ -12,7 +12,9 @@
>
>  #include <sbi/sbi_types.h>
>
> +#define UART_CAP_UUE   BIT(0)  /* Check UUE capability for XScale PXA UARTs */
> +
>  int uart8250_init(unsigned long base, u32 in_freq, u32 baudrate, u32 reg_shift,
> -                 u32 reg_width, u32 reg_offset);
> +                 u32 reg_width, u32 reg_offset, u32 capabilities);

This patch does not update all uses of uart8250_init(). Please update.

>
>  #endif
> diff --git a/lib/utils/serial/fdt_serial_uart8250.c b/lib/utils/serial/fdt_serial_uart8250.c
> index af5ceac924873216a85374b6c937af1b067841d0..02ca92e1ae4659f712559efed4f4399c80f9871e 100644
> --- a/lib/utils/serial/fdt_serial_uart8250.c
> +++ b/lib/utils/serial/fdt_serial_uart8250.c
> @@ -14,8 +14,9 @@
>  static int serial_uart8250_init(const void *fdt, int nodeoff,
>                                 const struct fdt_match *match)
>  {
> -       int rc;
>         struct platform_uart_data uart = { 0 };
> +       ulong capabilities = (ulong)match->data;
> +       int rc;
>
>         rc = fdt_parse_uart_node(fdt, nodeoff, &uart);
>         if (rc)
> @@ -23,13 +24,15 @@ static int serial_uart8250_init(const void *fdt, int nodeoff,
>
>         return uart8250_init(uart.addr, uart.freq, uart.baud,
>                              uart.reg_shift, uart.reg_io_width,
> -                            uart.reg_offset);
> +                            uart.reg_offset, capabilities);
>  }
>
>  static const struct fdt_match serial_uart8250_match[] = {
>         { .compatible = "ns16550" },
>         { .compatible = "ns16550a" },
>         { .compatible = "snps,dw-apb-uart" },
> +       { .compatible = "intel,xscale-uart",
> +         .data = (void *)UART_CAP_UUE },
>         { },
>  };
>
> diff --git a/lib/utils/serial/uart8250.c b/lib/utils/serial/uart8250.c
> index 1fe053f860e56e7a447259dadb649734ff5016b0..4932fe9f1cc6f5ae196cefa08393eb2f21c8244c 100644
> --- a/lib/utils/serial/uart8250.c
> +++ b/lib/utils/serial/uart8250.c
> @@ -39,6 +39,12 @@
>  #define UART_LSR_DR            0x01    /* Receiver data ready */
>  #define UART_LSR_BRK_ERROR_BITS        0x1E    /* BI, FE, PE, OE bits */
>
> +/* The XScale PXA UARTs define these bits */
> +#define UART_IER_DMAE          0x80    /* DMA Requests Enable */
> +#define UART_IER_UUE           0x40    /* UART Unit Enable */
> +#define UART_IER_NRZE          0x20    /* NRZ coding Enable */
> +#define UART_IER_RTOIE         0x10    /* Receiver Time Out Interrupt Enable */
> +
>  /* clang-format on */
>
>  static volatile char *uart8250_base;
> @@ -93,7 +99,7 @@ static struct sbi_console_device uart8250_console = {
>  };
>
>  int uart8250_init(unsigned long base, u32 in_freq, u32 baudrate, u32 reg_shift,
> -                 u32 reg_width, u32 reg_offset)
> +                 u32 reg_width, u32 reg_offset, u32 capabilities)
>  {
>         u16 bdiv = 0;
>
> @@ -109,7 +115,8 @@ int uart8250_init(unsigned long base, u32 in_freq, u32 baudrate, u32 reg_shift,
>         }
>
>         /* Disable all interrupts */
> -       set_reg(UART_IER_OFFSET, 0x00);
> +       set_reg(UART_IER_OFFSET, (capabilities & UART_CAP_UUE) ?
> +                                UART_IER_UUE : 0x00);
>         /* Enable DLAB */
>         set_reg(UART_LCR_OFFSET, 0x80);
>
>
> ---
> base-commit: 1ad199124479b9944d5dddc2119e6da9f088f7a7
> change-id: 20250223-pxa-uart-support-b9482a6b7297
>
> Best regards,
> --
> Junhui Liu <junhui.liu at pigmoral.tech>
>
>
> --
> opensbi mailing list
> opensbi at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/opensbi

Regards,
Anup