kernel/arch/earm/bsp/ti/omap_serial.c

   1 #include <assert.h>
   2 #include <sys/types.h>
   3 #include <machine/cpu.h>
   4 #include <minix/type.h>
   5 #include <minix/board.h>
   6 #include <io.h>
   7
   8 #include "kernel/kernel.h"
   9 #include "kernel/proc.h"
  10 #include "kernel/vm.h"
  11 #include "kernel/proto.h"
  12 #include "arch_proto.h"
  13
  14 #include "omap_serial.h"
  15
  16 struct omap_serial
  17 {
  18         vir_bytes base;
  19         vir_bytes size;
  20 };
  21
  22 static struct omap_serial omap_serial = {
  23         .base = 0,
  24 };
  25
  26 static kern_phys_map serial_phys_map;
  27
  28 /*
  29  * In kernel serial for the omap. The serial driver like most other
  30  * drivers needs to be started early and even before the MMU is turned on.
  31  * We start by directly accessing the hardware memory address. Later on
  32  * a when the MMU is turned on we still use a 1:1 mapping for these addresses.
  33  *
  34  * Pretty soon we are going to remap these addresses at later stage. And this
  35  * requires us to use a dynamic base address. The idea is to receive a callback
  36  * from VM with the new address to use.
  37  *
  38  * We also anticipate on the beaglebone port an try to keep the differences between
  39  * the drivers to a minimum by initializing a struct here and not using (to much)
  40  * constants in the code.
  41  *
  42  * The serial driver also gets used in the "pre_init" stage before the kernel is loaded
  43  * in high memory so keep in mind there are two copies of this code in the kernel.
  44  */
  45 void
  46 bsp_ser_init()
  47 {
  48         if (BOARD_IS_BBXM(machine.board_id)) {
  49                 omap_serial.base = OMAP3_DM37XX_DEBUG_UART_BASE;
  50         } else if (BOARD_IS_BB(machine.board_id)) {
  51                 omap_serial.base = OMAP3_AM335X_DEBUG_UART_BASE;
  52         }
  53         omap_serial.size = 0x1000;      /* 4k */
  54
  55         kern_phys_map_ptr(omap_serial.base, omap_serial.size,
  56             VMMF_UNCACHED | VMMF_WRITE, &serial_phys_map,
  57             (vir_bytes) & omap_serial.base);
  58         assert(omap_serial.base);
  59 }
  60
  61 void
  62 bsp_ser_putc(char c)
  63 {
  64         int i;
  65         assert(omap_serial.base);
  66
  67         /* Wait until FIFO's empty */
  68         for (i = 0; i < 100000; i++) {
  69                 if (mmio_read(omap_serial.base + OMAP3_LSR) & OMAP3_LSR_THRE) {
  70                         break;
  71                 }
  72         }
  73
  74         /* Write character */
  75         mmio_write(omap_serial.base + OMAP3_THR, c);
  76
  77         /* And wait again until FIFO's empty to prevent TTY from overwriting */
  78         for (i = 0; i < 100000; i++) {
  79                 if (mmio_read(omap_serial.base +
  80                         OMAP3_LSR) & (OMAP3_LSR_THRE | OMAP3_LSR_TEMT)) {
  81                         break;
  82                 }
  83         }
  84 }