ns16550.c 2.1 KB

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  1. // SPDX-License-Identifier: GPL-2.0
  2. /*
  3. * 16550 serial console support.
  4. *
  5. * Original copied from <file:arch/ppc/boot/common/ns16550.c>
  6. * (which had no copyright)
  7. * Modifications: 2006 (c) MontaVista Software, Inc.
  8. *
  9. * Modified by: Mark A. Greer <mgreer@mvista.com>
  10. */
  11. #include <stdarg.h>
  12. #include <stddef.h>
  13. #include "types.h"
  14. #include "string.h"
  15. #include "stdio.h"
  16. #include "io.h"
  17. #include "ops.h"
  18. #include "of.h"
  19. #define UART_DLL 0 /* Out: Divisor Latch Low */
  20. #define UART_DLM 1 /* Out: Divisor Latch High */
  21. #define UART_FCR 2 /* Out: FIFO Control Register */
  22. #define UART_LCR 3 /* Out: Line Control Register */
  23. #define UART_MCR 4 /* Out: Modem Control Register */
  24. #define UART_LSR 5 /* In: Line Status Register */
  25. #define UART_LSR_THRE 0x20 /* Transmit-hold-register empty */
  26. #define UART_LSR_DR 0x01 /* Receiver data ready */
  27. #define UART_MSR 6 /* In: Modem Status Register */
  28. #define UART_SCR 7 /* I/O: Scratch Register */
  29. static unsigned char *reg_base;
  30. static u32 reg_shift;
  31. static int ns16550_open(void)
  32. {
  33. out_8(reg_base + (UART_FCR << reg_shift), 0x06);
  34. return 0;
  35. }
  36. static void ns16550_putc(unsigned char c)
  37. {
  38. while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_THRE) == 0);
  39. out_8(reg_base, c);
  40. }
  41. static unsigned char ns16550_getc(void)
  42. {
  43. while ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) == 0);
  44. return in_8(reg_base);
  45. }
  46. static u8 ns16550_tstc(void)
  47. {
  48. return ((in_8(reg_base + (UART_LSR << reg_shift)) & UART_LSR_DR) != 0);
  49. }
  50. int ns16550_console_init(void *devp, struct serial_console_data *scdp)
  51. {
  52. int n;
  53. u32 reg_offset;
  54. if (dt_get_virtual_reg(devp, (void **)&reg_base, 1) < 1) {
  55. printf("virt reg parse fail...\r\n");
  56. return -1;
  57. }
  58. n = getprop(devp, "reg-offset", &reg_offset, sizeof(reg_offset));
  59. if (n == sizeof(reg_offset))
  60. reg_base += be32_to_cpu(reg_offset);
  61. n = getprop(devp, "reg-shift", &reg_shift, sizeof(reg_shift));
  62. if (n != sizeof(reg_shift))
  63. reg_shift = 0;
  64. else
  65. reg_shift = be32_to_cpu(reg_shift);
  66. scdp->open = ns16550_open;
  67. scdp->putc = ns16550_putc;
  68. scdp->getc = ns16550_getc;
  69. scdp->tstc = ns16550_tstc;
  70. scdp->close = NULL;
  71. return 0;
  72. }