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 *  This program and the accompanying materials
   7 *  are licensed and made available under the terms and conditions of the BSD License
   8 *  which accompanies this distribution.  The full text of the license may be found at
   9 *  http://opensource.org/licenses/bsd-license.php
  10 *
  11 *  THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
  12 *  WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
  13 *
  14 **/
  15
  16
  17 #include <PiDxe.h>
  18
  19 #include <Library/BaseLib.h>
  20 #include <Library/BaseMemoryLib.h>
  21 #include <Library/DebugLib.h>
  22 #include <Library/IoLib.h>
  23 #include <Library/UefiBootServicesTableLib.h>
  24 #include <Library/UefiRuntimeServicesTableLib.h>
  25
  26 #include <Protocol/HardwareInterrupt.h>
  27 #include <Protocol/WatchdogTimer.h>
  28
  29 #include "SP805Watchdog.h"
  30
  31 STATIC EFI_EVENT                        mEfiExitBootServicesEvent;
  32 STATIC EFI_HARDWARE_INTERRUPT_PROTOCOL  *mInterrupt;
  33 STATIC EFI_WATCHDOG_TIMER_NOTIFY        mWatchdogNotify;
  34 STATIC UINT32                           mTimerPeriod;
  35
  36 /**
  37   Make sure the SP805 registers are unlocked for writing.
  38
  39   Note: The SP805 Watchdog Timer supports locking of its registers,
  40   i.e. it inhibits all writes to avoid rogue software accidentally
  41   corrupting their contents.
  42 **/
  43 STATIC
  44 VOID
  45 SP805Unlock (
  46   VOID
  47   )
  48 {
  49   if (MmioRead32 (SP805_WDOG_LOCK_REG) == SP805_WDOG_LOCK_IS_LOCKED) {
  50     MmioWrite32 (SP805_WDOG_LOCK_REG, SP805_WDOG_SPECIAL_UNLOCK_CODE);
  51   }
  52 }
  53
  54 /**
  55   Make sure the SP805 registers are locked and can not be overwritten.
  56
  57   Note: The SP805 Watchdog Timer supports locking of its registers,
  58   i.e. it inhibits all writes to avoid rogue software accidentally
  59   corrupting their contents.
  60 **/
  61 STATIC
  62 VOID
  63 SP805Lock (
  64   VOID
  65   )
  66 {
  67   if (MmioRead32 (SP805_WDOG_LOCK_REG) == SP805_WDOG_LOCK_IS_UNLOCKED) {
  68     // To lock it, just write in any number (except the special unlock code).
  69     MmioWrite32 (SP805_WDOG_LOCK_REG, SP805_WDOG_LOCK_IS_LOCKED);
  70   }
  71 }
  72
  73 STATIC
  74 VOID
  75 EFIAPI
  76 SP805InterruptHandler (
  77   IN  HARDWARE_INTERRUPT_SOURCE   Source,
  78   IN  EFI_SYSTEM_CONTEXT          SystemContext
  79   )
  80 {
  81   SP805Unlock ();
  82   MmioWrite32 (SP805_WDOG_INT_CLR_REG, 0); // write of any value clears the irq
  83   SP805Lock ();
  84
  85   mInterrupt->EndOfInterrupt (mInterrupt, Source);
  86
  87   //
  88   // The notify function should be called with the elapsed number of ticks
  89   // since the watchdog was armed, which should exceed the timer period.
  90   // We don't actually know the elapsed number of ticks, so let's return
  91   // the timer period plus 1.
  92   //
  93   if (mWatchdogNotify != NULL) {
  94     mWatchdogNotify (mTimerPeriod + 1);
  95   }
  96
  97   gRT->ResetSystem (EfiResetCold, EFI_TIMEOUT, 0, NULL);
  98 }
  99
 100 /**
 101   Stop the SP805 watchdog timer from counting down by disabling interrupts.
 102 **/
 103 STATIC
 104 VOID
 105 SP805Stop (
 106   VOID
 107   )
 108 {
 109   // Disable interrupts
 110   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_INTEN) != 0) {
 111     MmioAnd32 (SP805_WDOG_CONTROL_REG, ~SP805_WDOG_CTRL_INTEN);
 112   }
 113 }
 114
 115 /**
 116   Starts the SP805 counting down by enabling interrupts.
 117   The count down will start from the value stored in the Load register,
 118   not from the value where it was previously stopped.
 119 **/
 120 STATIC
 121 VOID
 122 SP805Start (
 123   VOID
 124   )
 125 {
 126   // Enable interrupts
 127   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_INTEN) == 0) {
 128     MmioOr32 (SP805_WDOG_CONTROL_REG, SP805_WDOG_CTRL_INTEN);
 129   }
 130 }
 131
 132 /**
 133     On exiting boot services we must make sure the SP805 Watchdog Timer
 134     is stopped.
 135 **/
 136 STATIC
 137 VOID
 138 EFIAPI
 139 ExitBootServicesEvent (
 140   IN EFI_EVENT  Event,
 141   IN VOID       *Context
 142   )
 143 {
 144   SP805Unlock ();
 145   SP805Stop ();
 146   SP805Lock ();
 147 }
 148
 149 /**
 150   This function registers the handler NotifyFunction so it is called every time
 151   the watchdog timer expires.  It also passes the amount of time since the last
 152   handler call to the NotifyFunction.
 153   If NotifyFunction is not NULL and a handler is not already registered,
 154   then the new handler is registered and EFI_SUCCESS is returned.
 155   If NotifyFunction is NULL, and a handler is already registered,
 156   then that handler is unregistered.
 157   If an attempt is made to register a handler when a handler is already registered,
 158   then EFI_ALREADY_STARTED is returned.
 159   If an attempt is made to unregister a handler when a handler is not registered,
 160   then EFI_INVALID_PARAMETER is returned.
 161
 162   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 163   @param  NotifyFunction   The function to call when a timer interrupt fires. This
 164                            function executes at TPL_HIGH_LEVEL. The DXE Core will
 165                            register a handler for the timer interrupt, so it can know
 166                            how much time has passed. This information is used to
 167                            signal timer based events. NULL will unregister the handler.
 168
 169   @retval EFI_SUCCESS           The watchdog timer handler was registered.
 170   @retval EFI_ALREADY_STARTED   NotifyFunction is not NULL, and a handler is already
 171                                 registered.
 172   @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
 173                                 previously registered.
 174
 175 **/
 176 STATIC
 177 EFI_STATUS
 178 EFIAPI
 179 SP805RegisterHandler (
 180   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 181   IN EFI_WATCHDOG_TIMER_NOTIFY                NotifyFunction
 182   )
 183 {
 184   if (mWatchdogNotify == NULL && NotifyFunction == NULL) {
 185     return EFI_INVALID_PARAMETER;
 186   }
 187
 188   if (mWatchdogNotify != NULL && NotifyFunction != NULL) {
 189     return EFI_ALREADY_STARTED;
 190   }
 191
 192   mWatchdogNotify = NotifyFunction;
 193   return EFI_SUCCESS;
 194 }
 195
 196 /**
 197
 198   This function adjusts the period of timer interrupts to the value specified
 199   by TimerPeriod.  If the timer period is updated, then the selected timer
 200   period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned.  If
 201   the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
 202   If an error occurs while attempting to update the timer period, then the
 203   timer hardware will be put back in its state prior to this call, and
 204   EFI_DEVICE_ERROR is returned.  If TimerPeriod is 0, then the timer interrupt
 205   is disabled.  This is not the same as disabling the CPU's interrupts.
 206   Instead, it must either turn off the timer hardware, or it must adjust the
 207   interrupt controller so that a CPU interrupt is not generated when the timer
 208   interrupt fires.
 209
 210   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 211   @param  TimerPeriod      The rate to program the timer interrupt in 100 nS units. If
 212                            the timer hardware is not programmable, then EFI_UNSUPPORTED is
 213                            returned. If the timer is programmable, then the timer period
 214                            will be rounded up to the nearest timer period that is supported
 215                            by the timer hardware. If TimerPeriod is set to 0, then the
 216                            timer interrupts will be disabled.
 217
 218
 219   @retval EFI_SUCCESS           The timer period was changed.
 220   @retval EFI_UNSUPPORTED       The platform cannot change the period of the timer interrupt.
 221   @retval EFI_DEVICE_ERROR      The timer period could not be changed due to a device error.
 222
 223 **/
 224 STATIC
 225 EFI_STATUS
 226 EFIAPI
 227 SP805SetTimerPeriod (
 228   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 229   IN UINT64                                   TimerPeriod   // In 100ns units
 230   )
 231 {
 232   EFI_STATUS  Status;
 233   UINT64      Ticks64bit;
 234
 235   SP805Unlock ();
 236
 237   Status = EFI_SUCCESS;
 238
 239   if (TimerPeriod == 0) {
 240     // This is a watchdog stop request
 241     SP805Stop ();
 242   } else {
 243     // Calculate the Watchdog ticks required for a delay of (TimerTicks * 100) nanoseconds
 244     // The SP805 will count down to zero and generate an interrupt.
 245     //
 246     // WatchdogTicks = ((TimerPeriod * 100 * SP805_CLOCK_FREQUENCY) / 1GHz);
 247     //
 248     // i.e.:
 249     //
 250     // WatchdogTicks = (TimerPeriod * SP805_CLOCK_FREQUENCY) / 10 MHz ;
 251
 252     Ticks64bit = MultU64x32 (TimerPeriod, PcdGet32 (PcdSP805WatchdogClockFrequencyInHz));
 253     Ticks64bit = DivU64x32 (Ticks64bit, 10 * 1000 * 1000);
 254
 255     // The registers in the SP805 are only 32 bits
 256     if (Ticks64bit > MAX_UINT32) {
 257       // We could load the watchdog with the maximum supported value but
 258       // if a smaller value was requested, this could have the watchdog
 259       // triggering before it was intended.
 260       // Better generate an error to let the caller know.
 261       Status = EFI_DEVICE_ERROR;
 262       goto EXIT;
 263     }
 264
 265     // Update the watchdog with a 32-bit value.
 266     MmioWrite32 (SP805_WDOG_LOAD_REG, (UINT32)Ticks64bit);
 267
 268     // Start the watchdog
 269     SP805Start ();
 270   }
 271
 272   mTimerPeriod = TimerPeriod;
 273
 274 EXIT:
 275   // Ensure the watchdog is locked before exiting.
 276   SP805Lock ();
 277   ASSERT_EFI_ERROR (Status);
 278   return Status;
 279 }
 280
 281 /**
 282   This function retrieves the period of timer interrupts in 100 ns units,
 283   returns that value in TimerPeriod, and returns EFI_SUCCESS.  If TimerPeriod
 284   is NULL, then EFI_INVALID_PARAMETER is returned.  If a TimerPeriod of 0 is
 285   returned, then the timer is currently disabled.
 286
 287   @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
 288   @param  TimerPeriod      A pointer to the timer period to retrieve in 100 ns units. If
 289                            0 is returned, then the timer is currently disabled.
 290
 291
 292   @retval EFI_SUCCESS           The timer period was returned in TimerPeriod.
 293   @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
 294
 295 **/
 296 STATIC
 297 EFI_STATUS
 298 EFIAPI
 299 SP805GetTimerPeriod (
 300   IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL         *This,
 301   OUT UINT64                                  *TimerPeriod
 302   )
 303 {
 304   if (TimerPeriod == NULL) {
 305     return EFI_INVALID_PARAMETER;
 306   }
 307
 308   *TimerPeriod = mTimerPeriod;
 309   return EFI_SUCCESS;
 310 }
 311
 312 /**
 313   Interface structure for the Watchdog Architectural Protocol.
 314
 315   @par Protocol Description:
 316   This protocol provides a service to set the amount of time to wait
 317   before firing the watchdog timer, and it also provides a service to
 318   register a handler that is invoked when the watchdog timer fires.
 319
 320   @par When the watchdog timer fires, control will be passed to a handler
 321   if one has been registered.  If no handler has been registered,
 322   or the registered handler returns, then the system will be
 323   reset by calling the Runtime Service ResetSystem().
 324
 325   @param RegisterHandler
 326   Registers a handler that will be called each time the
 327   watchdogtimer interrupt fires.  TimerPeriod defines the minimum
 328   time between timer interrupts, so TimerPeriod will also
 329   be the minimum time between calls to the registered
 330   handler.
 331   NOTE: If the watchdog resets the system in hardware, then
 332         this function will not have any chance of executing.
 333
 334   @param SetTimerPeriod
 335   Sets the period of the timer interrupt in 100 nS units.
 336   This function is optional, and may return EFI_UNSUPPORTED.
 337   If this function is supported, then the timer period will
 338   be rounded up to the nearest supported timer period.
 339
 340   @param GetTimerPeriod
 341   Retrieves the period of the timer interrupt in 100 nS units.
 342
 343 **/
 344 STATIC EFI_WATCHDOG_TIMER_ARCH_PROTOCOL mWatchdogTimer = {
 345   SP805RegisterHandler,
 346   SP805SetTimerPeriod,
 347   SP805GetTimerPeriod
 348 };
 349
 350 /**
 351   Initialize the state information for the Watchdog Timer Architectural Protocol.
 352
 353   @param  ImageHandle   of the loaded driver
 354   @param  SystemTable   Pointer to the System Table
 355
 356   @retval EFI_SUCCESS           Protocol registered
 357   @retval EFI_OUT_OF_RESOURCES  Cannot allocate protocol data structure
 358   @retval EFI_DEVICE_ERROR      Hardware problems
 359
 360 **/
 361 EFI_STATUS
 362 EFIAPI
 363 SP805Initialize (
 364   IN EFI_HANDLE         ImageHandle,
 365   IN EFI_SYSTEM_TABLE   *SystemTable
 366   )
 367 {
 368   EFI_STATUS  Status;
 369   EFI_HANDLE  Handle;
 370
 371   // Find the interrupt controller protocol.  ASSERT if not found.
 372   Status = gBS->LocateProtocol (&gHardwareInterruptProtocolGuid, NULL,
 373                   (VOID **)&mInterrupt);
 374   ASSERT_EFI_ERROR (Status);
 375
 376   // Unlock access to the SP805 registers
 377   SP805Unlock ();
 378
 379   // Stop the watchdog from triggering unexpectedly
 380   SP805Stop ();
 381
 382   // Set the watchdog to reset the board when triggered
 383   // This is a last resort in case the interrupt handler fails
 384   if ((MmioRead32 (SP805_WDOG_CONTROL_REG) & SP805_WDOG_CTRL_RESEN) == 0) {
 385     MmioOr32 (SP805_WDOG_CONTROL_REG, SP805_WDOG_CTRL_RESEN);
 386   }
 387
 388   // Clear any pending interrupts
 389   MmioWrite32 (SP805_WDOG_INT_CLR_REG, 0); // write of any value clears the irq
 390
 391   // Prohibit any rogue access to SP805 registers
 392   SP805Lock ();
 393
 394   if (PcdGet32 (PcdSP805WatchdogInterrupt) > 0) {
 395     Status = mInterrupt->RegisterInterruptSource (mInterrupt,
 396                            PcdGet32 (PcdSP805WatchdogInterrupt),
 397                            SP805InterruptHandler);
 398     if (EFI_ERROR (Status)) {
 399       DEBUG ((DEBUG_ERROR, "%a: failed to register watchdog interrupt - %r\n",
 400         __FUNCTION__, Status));
 401       return Status;
 402     }
 403   } else {
 404     DEBUG ((DEBUG_WARN, "%a: no interrupt specified, running in RESET mode only\n",
 405       __FUNCTION__));
 406   }
 407
 408   //
 409   // Make sure the Watchdog Timer Architectural Protocol has not been installed in the system yet.
 410   // This will avoid conflicts with the universal watchdog
 411   //
 412   ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiWatchdogTimerArchProtocolGuid);
 413
 414   // Register for an ExitBootServicesEvent
 415   Status = gBS->CreateEvent (EVT_SIGNAL_EXIT_BOOT_SERVICES, TPL_NOTIFY,
 416                   ExitBootServicesEvent, NULL, &mEfiExitBootServicesEvent);
 417   if (EFI_ERROR (Status)) {
 418     Status = EFI_OUT_OF_RESOURCES;
 419     goto EXIT;
 420   }
 421
 422   // Install the Timer Architectural Protocol onto a new handle
 423   Handle = NULL;
 424   Status = gBS->InstallMultipleProtocolInterfaces (
 425                   &Handle,
 426                   &gEfiWatchdogTimerArchProtocolGuid, &mWatchdogTimer,
 427                   NULL
 428                   );
 429   if (EFI_ERROR (Status)) {
 430     Status = EFI_OUT_OF_RESOURCES;
 431     goto EXIT;
 432   }
 433
 434 EXIT:
 435   ASSERT_EFI_ERROR (Status);
 436   return Status;
 437 }