drivers/tty/hvc/hvc_bfin_jtag.c

   1 /*
   2  * Console via Blackfin JTAG Communication
   3  *
   4  * Copyright 2008-2011 Analog Devices Inc.
   5  *
   6  * Enter bugs at http://blackfin.uclinux.org/
   7  *
   8  * Licensed under the GPL-2 or later.
   9  */
  10
  11 #include <linux/console.h>
  12 #include <linux/delay.h>
  13 #include <linux/err.h>
  14 #include <linux/init.h>
  15 #include <linux/moduleparam.h>
  16 #include <linux/types.h>
  17
  18 #include "hvc_console.h"
  19
  20 /* See the Debug/Emulation chapter in the HRM */
  21 #define EMUDOF   0x00000001     /* EMUDAT_OUT full & valid */
  22 #define EMUDIF   0x00000002     /* EMUDAT_IN full & valid */
  23 #define EMUDOOVF 0x00000004     /* EMUDAT_OUT overflow */
  24 #define EMUDIOVF 0x00000008     /* EMUDAT_IN overflow */
  25
  26 /* Helper functions to glue the register API to simple C operations */
  27 static inline uint32_t bfin_write_emudat(uint32_t emudat)
  28 {
  29         __asm__ __volatile__("emudat = %0;" : : "d"(emudat));
  30         return emudat;
  31 }
  32
  33 static inline uint32_t bfin_read_emudat(void)
  34 {
  35         uint32_t emudat;
  36         __asm__ __volatile__("%0 = emudat;" : "=d"(emudat));
  37         return emudat;
  38 }
  39
  40 /* Send data to the host */
  41 static int hvc_bfin_put_chars(uint32_t vt, const char *buf, int count)
  42 {
  43         static uint32_t outbound_len;
  44         uint32_t emudat;
  45         int ret;
  46
  47         if (bfin_read_DBGSTAT() & EMUDOF)
  48                 return 0;
  49
  50         if (!outbound_len) {
  51                 outbound_len = count;
  52                 bfin_write_emudat(outbound_len);
  53                 return 0;
  54         }
  55
  56         ret = min(outbound_len, (uint32_t)4);
  57         memcpy(&emudat, buf, ret);
  58         bfin_write_emudat(emudat);
  59         outbound_len -= ret;
  60
  61         return ret;
  62 }
  63
  64 /* Receive data from the host */
  65 static int hvc_bfin_get_chars(uint32_t vt, char *buf, int count)
  66 {
  67         static uint32_t inbound_len;
  68         uint32_t emudat;
  69         int ret;
  70
  71         if (!(bfin_read_DBGSTAT() & EMUDIF))
  72                 return 0;
  73         emudat = bfin_read_emudat();
  74
  75         if (!inbound_len) {
  76                 inbound_len = emudat;
  77                 return 0;
  78         }
  79
  80         ret = min(inbound_len, (uint32_t)4);
  81         memcpy(buf, &emudat, ret);
  82         inbound_len -= ret;
  83
  84         return ret;
  85 }
  86
  87 /* Glue the HVC layers to the Blackfin layers */
  88 static const struct hv_ops hvc_bfin_get_put_ops = {
  89         .get_chars = hvc_bfin_get_chars,
  90         .put_chars = hvc_bfin_put_chars,
  91 };
  92
  93 static int __init hvc_bfin_console_init(void)
  94 {
  95         hvc_instantiate(0, 0, &hvc_bfin_get_put_ops);
  96         return 0;
  97 }
  98 console_initcall(hvc_bfin_console_init);
  99
 100 static int __init hvc_bfin_init(void)
 101 {
 102         hvc_alloc(0, 0, &hvc_bfin_get_put_ops, 128);
 103         return 0;
 104 }
 105 device_initcall(hvc_bfin_init);