ArmPlatformPkg/Drivers/SP805WatchdogDxe/SP805Watchdog.c

   1 /** @file
   2 *
   3 *  Copyright (c) 2011-2013, ARM Limited. All rights reserved.
   4 *  Copyright (c) 2018, Linaro Limited. All rights reserved.
   5 *
   6 *  SPDX-License-Identifier: BSD-2-Clause-Patent
   7 *
   8 **/
   9
  10
  11 #include <PiDxe.h>
  12
  13 #include <Library/BaseLib.h>
  14 #include <Library/BaseMemoryLib.h>
  15 #include <Library/DebugLib.h>
  16 #include <Library/IoLib.h>
  17 #include <Library/UefiBootServicesTableLib.h>
  18 #include <Library/UefiRuntimeServicesTableLib.h>
  19
  20 #include <Protocol/HardwareInterrupt.h>
  21 #include <Protocol/WatchdogTimer.h>
  22
  23 #include "SP805Watchdog.h"
  24
  25 STATIC EFI_EVENT                        mEfiExitBootServicesEvent;
  26 STATIC EFI_HARDWARE_INTERRUPT_PROTOCOL  *mInterrupt;
  27 STATIC EFI_WATCHDOG_TIMER_NOTIFY        mWatchdogNotify;
  28 STATIC UINT32                           mTimerPeriod;
  29
  30 /**
  31   Make sure the SP805 registers are unlocked for writing.
  32
  33   Note: The SP805 Watchdog Timer supports locking of its registers,
  34   i.e. it inhibits all writes to avoid rogue software accidentally
  35   corrupting their contents.
  36 **/
  37 STATIC
  38 VOID
  39 SP805Unlock (
  40   VOID
  41   )
  42 {
  43   if (MmioRead32 (SP805_WDOG_LOCK_REG) == SP805_WDOG_LOCK_IS_LOCKED) {
  44     MmioWrite32 (SP805_WDOG_LOCK_REG, SP805_WDOG_SPECIAL_UNLOCK_CODE);
  45   }
  46 }
  47
  48 /**
  49   Make sure the SP805 registers are locked and can not be overwritten.
  50
  51   Note: The SP805 Watchdog Timer supports locking of its registers,
  52   i.e. it inhibits all writes to avoid rogue software accidentally
  53   corrupting their contents.
  54 **/
  55 STATIC
  56 VOID
  57 SP805Lock (
  58   VOID
  59   )
  60 {
  61   if (MmioRead32 (SP805_WDOG_LOCK_REG) == SP805_WDOG_LOCK_IS_UNLOCKED) {
  62     // To lock it, just write in any number (except the special unlock code).
  63     MmioWrite32 (SP805_WDOG_LOCK_REG, SP805_WDOG_LOCK_IS_LOCKED);
  64   }
  65 }
  66
  67 STATIC
  68 VOID
  69 EFIAPI
  70 SP805InterruptHandler (
  71   IN  HARDWARE_INTERRUPT_SOURCE   Source,
  72   IN  EFI_SYSTEM_CONTEXT          SystemContext
  73   )
  74 {
  75   SP805Unlock ();
  76   MmioWrite32 (SP805_WDOG_INT_CLR_REG, 0); // write of any value clears the irq
  77   SP805Lock ();
  78
  79   mInterrupt->EndOfInterrupt (mInterrupt, Source);
  80
  81   //
  82   // The notify function should be called with the elapsed number of ticks
  83   // since the watchdog was armed, which should exceed the timer period.
  84   // We don't actually know the elapsed number of ticks, so let's return
  85   // the timer period plus 1.
  86   //
  87   if (mWatchdogNotify != NULL) {
  88     mWatchdogNotify (mTimerPeriod + 1);
  89   }
  90
  91   gRT->ResetSystem (EfiResetCold, EFI_TIMEOUT, 0, NULL);
  92 }
  93
  94 /**
  95   Stop the SP805 watchdog timer from counting down by disabling interrupts.
  96 **/
  97 STATIC
  98 VOID
  99 SP805Stop (
 100   VOID
 101   )
 102 {
 103   // Disable interrupts
 104   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_INTEN) != 0) {
 105     MmioAnd32 (SP805_WDOG_CONTROL_REG, ~SP805_WDOG_CTRL_INTEN);
 106   }
 107 }
 108
 109 /**
 110   Starts the SP805 counting down by enabling interrupts.
 111   The count down will start from the value stored in the Load register,
 112   not from the value where it was previously stopped.
 113 **/
 114 STATIC
 115 VOID
 116 SP805Start (
 117   VOID
 118   )
 119 {
 120   // Enable interrupts
 121   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_INTEN) == 0) {
 122     MmioOr32 (SP805_WDOG_CONTROL_REG, SP805_WDOG_CTRL_INTEN);
 123   }
 124 }
 125
 126 /**
 127     On exiting boot services we must make sure the SP805 Watchdog Timer
 128     is stopped.
 129 **/
 130 STATIC
 131 VOID
 132 EFIAPI
 133 ExitBootServicesEvent (
 134   IN EFI_EVENT  Event,
 135   IN VOID       *Context
 136   )
 137 {
 138   SP805Unlock ();
 139   SP805Stop ();
 140   SP805Lock ();
 141 }
 142
 143 /**
 144   This function registers the handler NotifyFunction so it is called every time
 145   the watchdog timer expires.  It also passes the amount of time since the last
 146   handler call to the NotifyFunction.
 147   If NotifyFunction is not NULL and a handler is not already registered,
 148   then the new handler is registered and EFI_SUCCESS is returned.
 149   If NotifyFunction is NULL, and a handler is already registered,
 150   then that handler is unregistered.
 151   If an attempt is made to register a handler when a handler is already registered,
 152   then EFI_ALREADY_STARTED is returned.
 153   If an attempt is made to unregister a handler when a handler is not registered,
 154   then EFI_INVALID_PARAMETER is returned.
 155
 156   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 157   @param  NotifyFunction   The function to call when a timer interrupt fires. This
 158                            function executes at TPL_HIGH_LEVEL. The DXE Core will
 159                            register a handler for the timer interrupt, so it can know
 160                            how much time has passed. This information is used to
 161                            signal timer based events. NULL will unregister the handler.
 162
 163   @retval EFI_SUCCESS           The watchdog timer handler was registered.
 164   @retval EFI_ALREADY_STARTED   NotifyFunction is not NULL, and a handler is already
 165                                 registered.
 166   @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
 167                                 previously registered.
 168
 169 **/
 170 STATIC
 171 EFI_STATUS
 172 EFIAPI
 173 SP805RegisterHandler (
 174   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 175   IN EFI_WATCHDOG_TIMER_NOTIFY                NotifyFunction
 176   )
 177 {
 178   if (mWatchdogNotify == NULL && NotifyFunction == NULL) {
 179     return EFI_INVALID_PARAMETER;
 180   }
 181
 182   if (mWatchdogNotify != NULL && NotifyFunction != NULL) {
 183     return EFI_ALREADY_STARTED;
 184   }
 185
 186   mWatchdogNotify = NotifyFunction;
 187   return EFI_SUCCESS;
 188 }
 189
 190 /**
 191
 192   This function adjusts the period of timer interrupts to the value specified
 193   by TimerPeriod.  If the timer period is updated, then the selected timer
 194   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 195   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 196   If an error occurs while attempting to update the timer period, then the
 197   timer hardware will be put back in its state prior to this call, and
 198   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 199   is disabled.  This is not the same as disabling the CPU's interrupts.
 200   Instead, it must either turn off the timer hardware, or it must adjust the
 201   interrupt controller so that a CPU interrupt is not generated when the timer
 202   interrupt fires.
 203
 204   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 205   @param  TimerPeriod      The rate to program the timer interrupt in 100 nS units. If
 206                            the timer hardware is not programmable, then EFI_UNSUPPORTED is
 207                            returned. If the timer is programmable, then the timer period
 208                            will be rounded up to the nearest timer period that is supported
 209                            by the timer hardware. If TimerPeriod is set to 0, then the
 210                            timer interrupts will be disabled.
 211
 212
 213   @retval EFI_SUCCESS           The timer period was changed.
 214   @retval EFI_UNSUPPORTED       The platform cannot change the period of the timer interrupt.
 215   @retval EFI_DEVICE_ERROR      The timer period could not be changed due to a device error.
 216
 217 **/
 218 STATIC
 219 EFI_STATUS
 220 EFIAPI
 221 SP805SetTimerPeriod (
 222   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 223   IN UINT64                                   TimerPeriod   // In 100ns units
 224   )
 225 {
 226   EFI_STATUS  Status;
 227   UINT64      Ticks64bit;
 228
 229   SP805Unlock ();
 230
 231   Status = EFI_SUCCESS;
 232
 233   if (TimerPeriod == 0) {
 234     // This is a watchdog stop request
 235     SP805Stop ();
 236   } else {
 237     // Calculate the Watchdog ticks required for a delay of (TimerTicks * 100) nanoseconds
 238     // The SP805 will count down to zero and generate an interrupt.
 239     //
 240     // WatchdogTicks = ((TimerPeriod * 100 * SP805_CLOCK_FREQUENCY) / 1GHz);
 241     //
 242     // i.e.:
 243     //
 244     // WatchdogTicks = (TimerPeriod * SP805_CLOCK_FREQUENCY) / 10 MHz ;
 245
 246     Ticks64bit = MultU64x32 (TimerPeriod, PcdGet32 (PcdSP805WatchdogClockFrequencyInHz));
 247     Ticks64bit = DivU64x32 (Ticks64bit, 10 * 1000 * 1000);
 248
 249     // The registers in the SP805 are only 32 bits
 250     if (Ticks64bit > MAX_UINT32) {
 251       // We could load the watchdog with the maximum supported value but
 252       // if a smaller value was requested, this could have the watchdog
 253       // triggering before it was intended.
 254       // Better generate an error to let the caller know.
 255       Status = EFI_DEVICE_ERROR;
 256       goto EXIT;
 257     }
 258
 259     // Update the watchdog with a 32-bit value.
 260     MmioWrite32 (SP805_WDOG_LOAD_REG, (UINT32)Ticks64bit);
 261
 262     // Start the watchdog
 263     SP805Start ();
 264   }
 265
 266   mTimerPeriod = TimerPeriod;
 267
 268 EXIT:
 269   // Ensure the watchdog is locked before exiting.
 270   SP805Lock ();
 271   ASSERT_EFI_ERROR (Status);
 272   return Status;
 273 }
 274
 275 /**
 276   This function retrieves the period of timer interrupts in 100 ns units,
 277   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 278   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 279   returned, then the timer is currently disabled.
 280
 281   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 282   @param  TimerPeriod      A pointer to the timer period to retrieve in 100 ns units. If
 283                            0 is returned, then the timer is currently disabled.
 284
 285
 286   @retval EFI_SUCCESS           The timer period was returned in TimerPeriod.
 287   @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
 288
 289 **/
 290 STATIC
 291 EFI_STATUS
 292 EFIAPI
 293 SP805GetTimerPeriod (
 294   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 295   OUT UINT64                                  *TimerPeriod
 296   )
 297 {
 298   if (TimerPeriod == NULL) {
 299     return EFI_INVALID_PARAMETER;
 300   }
 301
 302   *TimerPeriod = mTimerPeriod;
 303   return EFI_SUCCESS;
 304 }
 305
 306 /**
 307   Interface structure for the Watchdog Architectural Protocol.
 308
 309   @par Protocol Description:
 310   This protocol provides a service to set the amount of time to wait
 311   before firing the watchdog timer, and it also provides a service to
 312   register a handler that is invoked when the watchdog timer fires.
 313
 314   @par When the watchdog timer fires, control will be passed to a handler
 315   if one has been registered.  If no handler has been registered,
 316   or the registered handler returns, then the system will be
 317   reset by calling the Runtime Service ResetSystem().
 318
 319   @param RegisterHandler
 320   Registers a handler that will be called each time the
 321   watchdogtimer interrupt fires.  TimerPeriod defines the minimum
 322   time between timer interrupts, so TimerPeriod will also
 323   be the minimum time between calls to the registered
 324   handler.
 325   NOTE: If the watchdog resets the system in hardware, then
 326         this function will not have any chance of executing.
 327
 328   @param SetTimerPeriod
 329   Sets the period of the timer interrupt in 100 nS units.
 330   This function is optional, and may return EFI_UNSUPPORTED.
 331   If this function is supported, then the timer period will
 332   be rounded up to the nearest supported timer period.
 333
 334   @param GetTimerPeriod
 335   Retrieves the period of the timer interrupt in 100 nS units.
 336
 337 **/
 338 STATIC EFI_WATCHDOG_TIMER_ARCH_PROTOCOL mWatchdogTimer = {
 339   SP805RegisterHandler,
 340   SP805SetTimerPeriod,
 341   SP805GetTimerPeriod
 342 };
 343
 344 /**
 345   Initialize the state information for the Watchdog Timer Architectural Protocol.
 346
 347   @param  ImageHandle   of the loaded driver
 348   @param  SystemTable   Pointer to the System Table
 349
 350   @retval EFI_SUCCESS           Protocol registered
 351   @retval EFI_OUT_OF_RESOURCES  Cannot allocate protocol data structure
 352   @retval EFI_DEVICE_ERROR      Hardware problems
 353
 354 **/
 355 EFI_STATUS
 356 EFIAPI
 357 SP805Initialize (
 358   IN EFI_HANDLE         ImageHandle,
 359   IN EFI_SYSTEM_TABLE   *SystemTable
 360   )
 361 {
 362   EFI_STATUS  Status;
 363   EFI_HANDLE  Handle;
 364
 365   // Find the interrupt controller protocol.  ASSERT if not found.
 366   Status = gBS->LocateProtocol (&gHardwareInterruptProtocolGuid, NULL,
 367                   (VOID **)&mInterrupt);
 368   ASSERT_EFI_ERROR (Status);
 369
 370   // Unlock access to the SP805 registers
 371   SP805Unlock ();
 372
 373   // Stop the watchdog from triggering unexpectedly
 374   SP805Stop ();
 375
 376   // Set the watchdog to reset the board when triggered
 377   // This is a last resort in case the interrupt handler fails
 378   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_RESEN) == 0) {
 379     MmioOr32 (SP805_WDOG_CONTROL_REG, SP805_WDOG_CTRL_RESEN);
 380   }
 381
 382   // Clear any pending interrupts
 383   MmioWrite32 (SP805_WDOG_INT_CLR_REG, 0); // write of any value clears the irq
 384
 385   // Prohibit any rogue access to SP805 registers
 386   SP805Lock ();
 387
 388   if (PcdGet32 (PcdSP805WatchdogInterrupt) > 0) {
 389     Status = mInterrupt->RegisterInterruptSource (mInterrupt,
 390                            PcdGet32 (PcdSP805WatchdogInterrupt),
 391                            SP805InterruptHandler);
 392     if (EFI_ERROR (Status)) {
 393       DEBUG ((DEBUG_ERROR, "%a: failed to register watchdog interrupt - %r\n",
 394         __FUNCTION__, Status));
 395       return Status;
 396     }
 397   } else {
 398     DEBUG ((DEBUG_WARN, "%a: no interrupt specified, running in RESET mode only\n",
 399       __FUNCTION__));
 400   }
 401
 402   //
 403   // Make sure the Watchdog Timer Architectural Protocol has not been installed in the system yet.
 404   // This will avoid conflicts with the universal watchdog
 405   //
 406   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiWatchdogTimerArchProtocolGuid);
 407
 408   // Register for an ExitBootServicesEvent
 409   Status = gBS->CreateEvent (EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_NOTIFY,
 410                   ExitBootServicesEvent, NULL, &mEfiExitBootServicesEvent);
 411   if (EFI_ERROR (Status)) {
 412     Status = EFI_OUT_OF_RESOURCES;
 413     goto EXIT;
 414   }
 415
 416   // Install the Timer Architectural Protocol onto a new handle
 417   Handle = NULL;
 418   Status = gBS->InstallMultipleProtocolInterfaces (
 419                   &Handle,
 420                   &gEfiWatchdogTimerArchProtocolGuid, &mWatchdogTimer,
 421                   NULL
 422                   );
 423   if (EFI_ERROR (Status)) {
 424     Status = EFI_OUT_OF_RESOURCES;
 425     goto EXIT;
 426   }
 427
 428 EXIT:
 429   ASSERT_EFI_ERROR (Status);
 430   return Status;
 431 }