[PATCH 2/2] bsp/raspberrypi: Mini UART driver

Christian Mauderer list at c-mauderer.de
Tue Jan 21 21:11:32 UTC 2020


>From a first look this seems to be OK. But I didn't test it yet on
hardware. I'll try to do that in the next days.

On 17/01/2020 15:50, G S Niteesh wrote:
> This patch adds driver for Mini UART present in Raspberry Pi 3
> and above, this UART is currently used as the primary UART in
> these models.
> The Mini UART is similar to ns16550, this driver is built
> upon libchip/ns16550.
> ---
>  bsps/arm/raspberrypi/console/console-config.c | 117 ++++++++++++++++--
>  bsps/arm/raspberrypi/include/bsp/usart.h      |   1 +
>  2 files changed, 109 insertions(+), 9 deletions(-)
> 
> diff --git a/bsps/arm/raspberrypi/console/console-config.c b/bsps/arm/raspberrypi/console/console-config.c
> index 48c4c6a3ec7..720033cb295 100644
> --- a/bsps/arm/raspberrypi/console/console-config.c
> +++ b/bsps/arm/raspberrypi/console/console-config.c
> @@ -24,6 +24,7 @@
>  
>  #include <libchip/serial.h>
>  #include <libfdt.h>
> +#include <libchip/ns16550.h>
>  
>  #include <bspopts.h>
>  #include <bsp/usart.h>
> @@ -34,35 +35,103 @@
>  #include <bsp/console-termios.h>
>  #include <bsp/fdt.h>
>  #include <bsp/fatal.h>
> +#include <bsp/gpio.h>
> +#include <bsp/rpi-gpio.h>
>  
> -
> -#define UART0     "/dev/ttyS0"
> +/**
> + * UART0 - PL011
> + * UART1 - Mini UART
> + */
> +#define PL011     "/dev/ttyAMA0"
> +#define MINIUART  "/dev/ttyS0"
>  #define FBCONS    "/dev/fbcons"
>  
>  arm_pl011_context pl011_context;
> +ns16550_context mini_uart_context;
>  
>  rpi_fb_context fb_context;
>  
> -static void output_char_serial(char c)
> +static void output_char_pl011(char c)
>  {
>    arm_pl011_write_polled(&pl011_context.base, c);
>  }
>  
> +static void output_char_mini_uart(char c)
> +{
> +  ns16550_polled_putchar(&mini_uart_context.base, c);
> +}
> +
>  void output_char_fb(char c)
>  {
>    fbcons_write_polled(&fb_context.base, c);
>  }
>  
> +static uint8_t mini_uart_get_reg(uintptr_t port, uint8_t index)
> +{
> +  volatile uint32_t *val = (volatile uint32_t *)port + index;
> +  return (uint8_t) *val;
> +}
> +
> +static void mini_uart_set_reg(uintptr_t port, uint8_t index, uint8_t val)
> +{
> +  volatile uint32_t *reg = (volatile uint32_t *)port + index;
> +  *reg = val;
> +}
> +
>  static void init_ctx_arm_pl011(
>    const void *fdt,
>    int node
>  )
>  {
>    arm_pl011_context *ctx = &pl011_context;
> -  rtems_termios_device_context_initialize(&ctx->base, "UART");
> +  rtems_termios_device_context_initialize(&ctx->base, "PL011UART");
>    ctx->regs = raspberrypi_get_reg_of_node(fdt, node);
>  }
>  
> +static uint32_t calculate_baud_divisor(
> +  ns16550_context *ctx,
> +  uint32_t baud
> +)
> +{
> +  uint32_t baudDivisor = (ctx->clock / (8 * baud)) - 1;
> +  return baudDivisor;
> +}
> +
> +static void init_ctx_mini_uart(
> +  const void *fdt,
> +  int node
> +)
> +{
> +  const char *status;
> +  int len;
> +  ns16550_context *ctx;
> +
> +  memset(&mini_uart_context, 0, sizeof(mini_uart_context));
> +  ctx = &mini_uart_context;
> +
> +  rtems_termios_device_context_initialize(&ctx->base, "MiniUART");
> +
> +  status = fdt_getprop(fdt, node, "status", &len);
> +  if ( status == NULL || strcmp(status, "disabled" ) == 0){
> +    return ;
> +  }
> +
> +  ctx->port = (uintptr_t) raspberrypi_get_reg_of_node(fdt, node);
> +  ctx->initial_baud = MINI_UART_DEFAULT_BAUD;
> +  ctx->clock = BCM2835_CLOCK_FREQ;
> +  ctx->calculate_baud_divisor = calculate_baud_divisor;
> +  ctx->get_reg = mini_uart_get_reg;
> +  ctx->set_reg = mini_uart_set_reg;
> +
> +  rtems_gpio_bsp_select_specific_io(0, 14, RPI_ALT_FUNC_5, NULL);
> +  rtems_gpio_bsp_select_specific_io(0, 15, RPI_ALT_FUNC_5, NULL);
> +  rtems_gpio_bsp_set_resistor_mode(0, 14, NO_PULL_RESISTOR);
> +  rtems_gpio_bsp_set_resistor_mode(0, 15, NO_PULL_RESISTOR);
> +
> +  BCM2835_REG(AUX_ENABLES) |= 0x1;
> +  ns16550_probe(&ctx->base);
> +}
> +
>  static void register_fb( void )
>  {
>    if (fbcons_probe(&fb_context.base) == true) {
> @@ -87,16 +156,27 @@ static void console_select( void )
>          link(FBCONS, CONSOLE_DEVICE_NAME);
>          return ;
>        }
> +    } else if ( strncmp( opt, MINIUART, sizeof(MINIUART) - 1 ) == 0) {
> +      BSP_output_char = output_char_mini_uart;
> +      link(MINIUART, CONSOLE_DEVICE_NAME);
> +    } else if ( strncmp( opt, PL011, sizeof(PL011) - 1 ) == 0) {
> +      BSP_output_char = output_char_pl011;
> +      link(PL011, CONSOLE_DEVICE_NAME);
>      }
>    }
> -  BSP_output_char = output_char_serial;
> -  link(UART0, CONSOLE_DEVICE_NAME);
> +  /**
> +   * If no command line option was given, default to PL011.
> +   */
> +  BSP_output_char = output_char_pl011;
> +  link(PL011, CONSOLE_DEVICE_NAME);
>  }
>  
>  static void uart_probe(void)
>  {
>    static bool initialized = false;
>    const void *fdt;
> +  const char *console;
> +  int len;
>    int node;
>  
>    if ( initialized ) {
> @@ -104,17 +184,29 @@ static void uart_probe(void)
>    }
>  
>    fdt = bsp_fdt_get();
> -  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-pl011");
>  
> +  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-pl011");
>    init_ctx_arm_pl011(fdt, node);
>  
> +  node = fdt_node_offset_by_compatible(fdt, -1, "brcm,bcm2835-aux-uart");
> +  init_ctx_mini_uart(fdt, node);
> +
> +  node = fdt_path_offset(fdt, "/aliases");
> +  console = fdt_getprop(fdt, node, "serial0", &len);
> +
> +  if ( strcmp(console, "/soc/serial at 7e215040" ) == 0) {
> +    BSP_output_char = output_char_mini_uart;
> +  }else {
> +    BSP_output_char = output_char_pl011;
> +  }
> +
>    initialized = true;
>  }
>  
>  static void output_char(char c)
>  {
>    uart_probe();
> -  output_char_serial(c);
> +  (*BSP_output_char)(c);
>  }
>  
>  rtems_status_code console_initialize(
> @@ -127,12 +219,19 @@ rtems_status_code console_initialize(
>  
>    uart_probe();
>    rtems_termios_device_install(
> -    UART0,
> +    PL011,
>      &arm_pl011_fns,
>      NULL,
>      &pl011_context.base
>    );
>  
> +  rtems_termios_device_install(
> +    MINIUART,
> +    &ns16550_handler_polled,
> +    NULL,
> +    &mini_uart_context.base
> +  );
> +
>    register_fb();
>  
>    console_select();
> diff --git a/bsps/arm/raspberrypi/include/bsp/usart.h b/bsps/arm/raspberrypi/include/bsp/usart.h
> index abbf53626c9..6af1844b3ca 100644
> --- a/bsps/arm/raspberrypi/include/bsp/usart.h
> +++ b/bsps/arm/raspberrypi/include/bsp/usart.h
> @@ -33,6 +33,7 @@ extern "C" {
>  #endif /* __cplusplus */
>  
>  #define PL011_DEFAULT_BAUD 115000
> +#define MINI_UART_DEFAULT_BAUD   115200
>  #define BCM2835_PL011_BASE (RPI_PERIPHERAL_BASE + 0x201000)
>  
>  #ifdef __cplusplus
> 


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