arch/powerpc/platforms/wsp/h8.c

   1 /*
   2  * Copyright 2008-2011, IBM Corporation
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version
   7  * 2 of the License, or (at your option) any later version.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/of.h>
  12 #include <linux/io.h>
  13
  14 #include "wsp.h"
  15
  16 /*
  17  * The UART connection to the H8 is over ttyS1 which is just a 16550.
  18  * We assume that FW has it setup right and no one messes with it.
  19  */
  20
  21
  22 static u8 __iomem *h8;
  23
  24 #define RBR 0           /* Receiver Buffer Register */
  25 #define THR 0           /* Transmitter Holding Register */
  26 #define LSR 5           /* Line Status Register */
  27 #define LSR_DR 0x01     /* LSR value for Data-Ready */
  28 #define LSR_THRE 0x20   /* LSR value for Transmitter-Holding-Register-Empty */
  29 static void wsp_h8_putc(int c)
  30 {
  31         u8 lsr;
  32
  33         do {
  34                 lsr = readb(h8 + LSR);
  35         } while ((lsr & LSR_THRE) != LSR_THRE);
  36         writeb(c, h8 + THR);
  37 }
  38
  39 static int wsp_h8_getc(void)
  40 {
  41         u8 lsr;
  42
  43         do {
  44                 lsr = readb(h8 + LSR);
  45         } while ((lsr & LSR_DR) != LSR_DR);
  46
  47         return readb(h8 + RBR);
  48 }
  49
  50 static void wsp_h8_puts(const char *s, int sz)
  51 {
  52         int i;
  53
  54         for (i = 0; i < sz; i++) {
  55                 wsp_h8_putc(s[i]);
  56
  57                 /* no flow control so wait for echo */
  58                 wsp_h8_getc();
  59         }
  60         wsp_h8_putc('\r');
  61         wsp_h8_putc('\n');
  62 }
  63
  64 static void wsp_h8_terminal_cmd(const char *cmd, int sz)
  65 {
  66         hard_irq_disable();
  67         wsp_h8_puts(cmd, sz);
  68         /* should never return, but just in case */
  69         for (;;)
  70                 continue;
  71 }
  72
  73
  74 void wsp_h8_restart(char *cmd)
  75 {
  76         static const char restart[] = "warm-reset";
  77
  78         (void)cmd;
  79         wsp_h8_terminal_cmd(restart, sizeof(restart) - 1);
  80 }
  81
  82 void wsp_h8_power_off(void)
  83 {
  84         static const char off[] = "power-off";
  85
  86         wsp_h8_terminal_cmd(off, sizeof(off) - 1);
  87 }
  88
  89 static void __iomem *wsp_h8_getaddr(void)
  90 {
  91         struct device_node *aliases;
  92         struct device_node *uart;
  93         struct property *path;
  94         void __iomem *va = NULL;
  95
  96         /*
  97          * there is nothing in the devtree to tell us which is mapped
  98          * to the H8, but se know it is the second serial port.
  99          */
 100
 101         aliases = of_find_node_by_path("/aliases");
 102         if (aliases == NULL)
 103                 return NULL;
 104
 105         path = of_find_property(aliases, "serial1", NULL);
 106         if (path == NULL)
 107                 goto out;
 108
 109         uart = of_find_node_by_path(path->value);
 110         if (uart == NULL)
 111                 goto out;
 112
 113         va = of_iomap(uart, 0);
 114
 115         /* remove it so no one messes with it */
 116         of_detach_node(uart);
 117         of_node_put(uart);
 118
 119 out:
 120         of_node_put(aliases);
 121
 122         return va;
 123 }
 124
 125 void __init wsp_setup_h8(void)
 126 {
 127         h8 = wsp_h8_getaddr();
 128
 129         /* Devtree change? lets hard map it anyway */
 130         if (h8 == NULL) {
 131                 pr_warn("UART to H8 could not be found");
 132                 h8 = ioremap(0xffc0008000ULL, 0x100);
 133         }
 134 }