arch/parisc/kernel/pdc_cons.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *    PDC Console support - ie use firmware to dump text via boot console
   4  *
   5  *    Copyright (C) 1999-2003 Matthew Wilcox <willy at parisc-linux.org>
   6  *    Copyright (C) 2000 Martin K Petersen <mkp at mkp.net>
   7  *    Copyright (C) 2000 John Marvin <jsm at parisc-linux.org>
   8  *    Copyright (C) 2000-2003 Paul Bame <bame at parisc-linux.org>
   9  *    Copyright (C) 2000 Philipp Rumpf <prumpf with tux.org>
  10  *    Copyright (C) 2000 Michael Ang <mang with subcarrier.org>
  11  *    Copyright (C) 2000 Grant Grundler <grundler with parisc-linux.org>
  12  *    Copyright (C) 2001-2002 Ryan Bradetich <rbrad at parisc-linux.org>
  13  *    Copyright (C) 2001 Helge Deller <deller at parisc-linux.org>
  14  *    Copyright (C) 2001 Thomas Bogendoerfer <tsbogend at parisc-linux.org>
  15  *    Copyright (C) 2002 Randolph Chung <tausq with parisc-linux.org>
  16  *    Copyright (C) 2010 Guy Martin <gmsoft at tuxicoman.be>
  17  */
  18
  19 /*
  20  *  The PDC console is a simple console, which can be used for debugging
  21  *  boot related problems on HP PA-RISC machines. It is also useful when no
  22  *  other console works.
  23  *
  24  *  This code uses the ROM (=PDC) based functions to read and write characters
  25  *  from and to PDC's boot path.
  26  */
  27
  28 /* Define EARLY_BOOTUP_DEBUG to debug kernel related boot problems.
  29  * On production kernels EARLY_BOOTUP_DEBUG should be undefined. */
  30 #define EARLY_BOOTUP_DEBUG
  31
  32
  33 #include <linux/kernel.h>
  34 #include <linux/console.h>
  35 #include <linux/string.h>
  36 #include <linux/init.h>
  37 #include <linux/major.h>
  38 #include <linux/tty.h>
  39 #include <asm/page.h>           /* for PAGE0 */
  40 #include <asm/pdc.h>            /* for iodc_call() proto and friends */
  41
  42 static DEFINE_SPINLOCK(pdc_console_lock);
  43 static struct console pdc_cons;
  44
  45 static void pdc_console_write(struct console *co, const char *s, unsigned count)
  46 {
  47         int i = 0;
  48         unsigned long flags;
  49
  50         spin_lock_irqsave(&pdc_console_lock, flags);
  51         do {
  52                 i += pdc_iodc_print(s + i, count - i);
  53         } while (i < count);
  54         spin_unlock_irqrestore(&pdc_console_lock, flags);
  55 }
  56
  57 int pdc_console_poll_key(struct console *co)
  58 {
  59         int c;
  60         unsigned long flags;
  61
  62         spin_lock_irqsave(&pdc_console_lock, flags);
  63         c = pdc_iodc_getc();
  64         spin_unlock_irqrestore(&pdc_console_lock, flags);
  65
  66         return c;
  67 }
  68
  69 static int pdc_console_setup(struct console *co, char *options)
  70 {
  71         return 0;
  72 }
  73
  74 #if defined(CONFIG_PDC_CONSOLE)
  75 #include <linux/vt_kern.h>
  76 #include <linux/tty_flip.h>
  77
  78 #define PDC_CONS_POLL_DELAY (30 * HZ / 1000)
  79
  80 static void pdc_console_poll(struct timer_list *unused);
  81 static DEFINE_TIMER(pdc_console_timer, pdc_console_poll);
  82 static struct tty_port tty_port;
  83
  84 static int pdc_console_tty_open(struct tty_struct *tty, struct file *filp)
  85 {
  86         tty_port_tty_set(&tty_port, tty);
  87         mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
  88
  89         return 0;
  90 }
  91
  92 static void pdc_console_tty_close(struct tty_struct *tty, struct file *filp)
  93 {
  94         if (tty->count == 1) {
  95                 del_timer_sync(&pdc_console_timer);
  96                 tty_port_tty_set(&tty_port, NULL);
  97         }
  98 }
  99
 100 static int pdc_console_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
 101 {
 102         pdc_console_write(NULL, buf, count);
 103         return count;
 104 }
 105
 106 static int pdc_console_tty_write_room(struct tty_struct *tty)
 107 {
 108         return 32768; /* no limit, no buffer used */
 109 }
 110
 111 static int pdc_console_tty_chars_in_buffer(struct tty_struct *tty)
 112 {
 113         return 0; /* no buffer */
 114 }
 115
 116 static const struct tty_operations pdc_console_tty_ops = {
 117         .open = pdc_console_tty_open,
 118         .close = pdc_console_tty_close,
 119         .write = pdc_console_tty_write,
 120         .write_room = pdc_console_tty_write_room,
 121         .chars_in_buffer = pdc_console_tty_chars_in_buffer,
 122 };
 123
 124 static void pdc_console_poll(struct timer_list *unused)
 125 {
 126         int data, count = 0;
 127
 128         while (1) {
 129                 data = pdc_console_poll_key(NULL);
 130                 if (data == -1)
 131                         break;
 132                 tty_insert_flip_char(&tty_port, data & 0xFF, TTY_NORMAL);
 133                 count ++;
 134         }
 135
 136         if (count)
 137                 tty_flip_buffer_push(&tty_port);
 138
 139         if (pdc_cons.flags & CON_ENABLED)
 140                 mod_timer(&pdc_console_timer, jiffies + PDC_CONS_POLL_DELAY);
 141 }
 142
 143 static struct tty_driver *pdc_console_tty_driver;
 144
 145 static int __init pdc_console_tty_driver_init(void)
 146 {
 147         int err;
 148
 149         /* Check if the console driver is still registered.
 150          * It is unregistered if the pdc console was not selected as the
 151          * primary console. */
 152
 153         struct console *tmp;
 154
 155         console_lock();
 156         for_each_console(tmp)
 157                 if (tmp == &pdc_cons)
 158                         break;
 159         console_unlock();
 160
 161         if (!tmp) {
 162                 printk(KERN_INFO "PDC console driver not registered anymore, not creating %s\n", pdc_cons.name);
 163                 return -ENODEV;
 164         }
 165
 166         printk(KERN_INFO "The PDC console driver is still registered, removing CON_BOOT flag\n");
 167         pdc_cons.flags &= ~CON_BOOT;
 168
 169         pdc_console_tty_driver = alloc_tty_driver(1);
 170
 171         if (!pdc_console_tty_driver)
 172                 return -ENOMEM;
 173
 174         tty_port_init(&tty_port);
 175
 176         pdc_console_tty_driver->driver_name = "pdc_cons";
 177         pdc_console_tty_driver->name = "ttyB";
 178         pdc_console_tty_driver->major = MUX_MAJOR;
 179         pdc_console_tty_driver->minor_start = 0;
 180         pdc_console_tty_driver->type = TTY_DRIVER_TYPE_SYSTEM;
 181         pdc_console_tty_driver->init_termios = tty_std_termios;
 182         pdc_console_tty_driver->flags = TTY_DRIVER_REAL_RAW |
 183                 TTY_DRIVER_RESET_TERMIOS;
 184         tty_set_operations(pdc_console_tty_driver, &pdc_console_tty_ops);
 185         tty_port_link_device(&tty_port, pdc_console_tty_driver, 0);
 186
 187         err = tty_register_driver(pdc_console_tty_driver);
 188         if (err) {
 189                 printk(KERN_ERR "Unable to register the PDC console TTY driver\n");
 190                 tty_port_destroy(&tty_port);
 191                 return err;
 192         }
 193
 194         return 0;
 195 }
 196 device_initcall(pdc_console_tty_driver_init);
 197
 198 static struct tty_driver * pdc_console_device (struct console *c, int *index)
 199 {
 200         *index = c->index;
 201         return pdc_console_tty_driver;
 202 }
 203 #else
 204 #define pdc_console_device NULL
 205 #endif
 206
 207 static struct console pdc_cons = {
 208         .name =         "ttyB",
 209         .write =        pdc_console_write,
 210         .device =       pdc_console_device,
 211         .setup =        pdc_console_setup,
 212         .flags =        CON_BOOT | CON_PRINTBUFFER,
 213         .index =        -1,
 214 };
 215
 216 static int pdc_console_initialized;
 217
 218 static void pdc_console_init_force(void)
 219 {
 220         if (pdc_console_initialized)
 221                 return;
 222         ++pdc_console_initialized;
 223
 224         /* If the console is duplex then copy the COUT parameters to CIN. */
 225         if (PAGE0->mem_cons.cl_class == CL_DUPLEX)
 226                 memcpy(&PAGE0->mem_kbd, &PAGE0->mem_cons, sizeof(PAGE0->mem_cons));
 227
 228         /* register the pdc console */
 229         register_console(&pdc_cons);
 230 }
 231
 232 void __init pdc_console_init(void)
 233 {
 234 #if defined(EARLY_BOOTUP_DEBUG) || defined(CONFIG_PDC_CONSOLE)
 235         pdc_console_init_force();
 236 #endif
 237 #ifdef EARLY_BOOTUP_DEBUG
 238         printk(KERN_INFO "Initialized PDC Console for debugging.\n");
 239 #endif
 240 }
 241
 242
 243 /*
 244  * Used for emergencies. Currently only used if an HPMC occurs. If an
 245  * HPMC occurs, it is possible that the current console may not be
 246  * properly initialised after the PDC IO reset. This routine unregisters
 247  * all of the current consoles, reinitializes the pdc console and
 248  * registers it.
 249  */
 250
 251 void pdc_console_restart(void)
 252 {
 253         struct console *console;
 254
 255         if (pdc_console_initialized)
 256                 return;
 257
 258         /* If we've already seen the output, don't bother to print it again */
 259         if (console_drivers != NULL)
 260                 pdc_cons.flags &= ~CON_PRINTBUFFER;
 261
 262         while ((console = console_drivers) != NULL)
 263                 unregister_console(console_drivers);
 264
 265         /* force registering the pdc console */
 266         pdc_console_init_force();
 267 }