1/** @file
2
3  Copyright (c) 2008 - 2010, Apple Inc. All rights reserved.<BR>
4  Copyright (c) 2011 - 2014, ARM 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#include <Base.h>
17
18#include <Library/BaseLib.h>
19#include <Library/TimerLib.h>
20#include <Library/DebugLib.h>
21#include <Library/PcdLib.h>
22#include <Library/IoLib.h>
23#include <Drivers/SP804Timer.h>
24
25#define SP804_TIMER_METRONOME_BASE    ((UINTN)PcdGet32 (PcdSP804TimerMetronomeBase))
26#define SP804_TIMER_PERFORMANCE_BASE  ((UINTN)PcdGet32 (PcdSP804TimerPerformanceBase))
27
28// Setup SP810's Timer2 for managing delay functions. And Timer3 for Performance counter
29// Note: ArmVE's Timer0 and Timer1 are used by TimerDxe.
30RETURN_STATUS
31EFIAPI
32TimerConstructor (
33  VOID
34  )
35{
36  // Check if the Metronome Timer is already initialized
37  if ((MmioRead32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CONTROL_REG) & SP804_TIMER_CTRL_ENABLE) == 0) {
38    // Configure the Metronome Timer for free running operation, 32 bits, no prescaler, and interrupt disabled
39    MmioWrite32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CONTROL_REG, SP804_TIMER_CTRL_32BIT | SP804_PRESCALE_DIV_1);
40
41    // Start the Metronome Timer ticking
42    MmioOr32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CONTROL_REG, SP804_TIMER_CTRL_ENABLE);
43  }
44
45  // Check if the Performance Timer is already initialized
46  if ((MmioRead32 (SP804_TIMER_PERFORMANCE_BASE + SP804_TIMER_CONTROL_REG) & SP804_TIMER_CTRL_ENABLE) == 0) {
47    // Configure the Performance timer for free running operation, 32 bits, no prescaler, interrupt disabled
48    MmioWrite32 (SP804_TIMER_PERFORMANCE_BASE + SP804_TIMER_CONTROL_REG, SP804_TIMER_CTRL_32BIT | SP804_PRESCALE_DIV_1);
49
50    // Start the Performance Timer ticking
51    MmioOr32 (SP804_TIMER_PERFORMANCE_BASE + SP804_TIMER_CONTROL_REG, SP804_TIMER_CTRL_ENABLE);
52  }
53
54  return RETURN_SUCCESS;
55}
56
57/**
58  Stalls the CPU for at least the given number of microseconds.
59
60  Stalls the CPU for the number of microseconds specified by MicroSeconds.
61  The hardware timer is 32 bits.
62  The maximum possible delay is (0xFFFFFFFF / TimerFrequencyMHz), i.e. ([32bits] / FreqInMHz)
63  For example:
64  +----------------+------------+----------+----------+
65  | TimerFrequency |  MaxDelay  | MaxDelay | MaxDelay |
66  |     (MHz)      |    (us)    |   (s)    |  (min)   |
67  +----------------+------------+----------+----------+
68  |        1       | 0xFFFFFFFF |   4294   |   71.5   |
69  |        5       | 0x33333333 |    859   |   14.3   |
70  |       10       | 0x19999999 |    429   |    7.2   |
71  |       50       | 0x051EB851 |     86   |    1.4   |
72  +----------------+------------+----------+----------+
73  If it becomes necessary to support higher delays, then consider using the
74  real time clock.
75
76  During this delay, the cpu is not yielded to any other process, with one exception:
77  events that are triggered off a timer and which execute at a higher TPL than
78  this function. These events may call MicroSecondDelay (or NanoSecondDelay) to
79  fulfil their own needs.
80  Therefore, this function must be re-entrant, as it may be interrupted and re-started.
81
82  @param  MicroSeconds  The minimum number of microseconds to delay.
83
84  @return The value of MicroSeconds inputted.
85
86**/
87UINTN
88EFIAPI
89MicroSecondDelay (
90  IN  UINTN MicroSeconds
91  )
92{
93  UINT64    DelayTicks64;         // Convert from microseconds to timer ticks, more bits to detect over-range conditions.
94  UINTN     DelayTicks;           // Convert from microseconds to timer ticks, native size for general calculations.
95  UINTN     StartTicks;           // Timer value snapshot at the start of the delay
96  UINTN     TargetTicks;          // Timer value to signal the end of the delay
97  UINTN     CurrentTicks;         // Current value of the 64-bit timer value at any given moment
98
99  // If we snapshot the timer at the start of the delay function then we minimise unaccounted overheads.
100  StartTicks = MmioRead32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CURRENT_REG);
101
102  // We are operating at the limit of 32bits. For the range checking work in 64 bits to avoid overflows.
103  DelayTicks64 = MultU64x32((UINT64)MicroSeconds, PcdGet32(PcdSP804TimerFrequencyInMHz));
104
105  // We are limited to 32 bits.
106  // If the specified delay is exactly equal to the max range of the timer,
107  // then the start will be equal to the stop plus one timer overflow (wrap-around).
108  // To avoid having to check for that, reduce the maximum acceptable range by 1 tick,
109  // i.e. reject delays equal or greater than the max range of the timer.
110  if (DelayTicks64 >= (UINT64)SP804_MAX_TICKS) {
111    DEBUG((EFI_D_ERROR,"MicroSecondDelay: ERROR: MicroSeconds=%d exceed SP804 count range. Max MicroSeconds=%d\n",
112      MicroSeconds,
113      ((UINTN)SP804_MAX_TICKS/PcdGet32(PcdSP804TimerFrequencyInMHz))));
114  }
115  ASSERT(DelayTicks64 < (UINT64)SP804_MAX_TICKS);
116
117  // From now on do calculations only in native bit size.
118  DelayTicks = (UINTN)DelayTicks64;
119
120  // Calculate the target value of the timer.
121
122  //Note: SP804 timer is counting down
123  if (StartTicks >= DelayTicks) {
124    // In this case we do not expect a wrap-around of the timer to occur.
125    // CurrentTicks must be less than StartTicks and higher than TargetTicks.
126    // If this is not the case, then the delay has been reached and may even have been exceeded if this
127    // function was suspended by a higher priority interrupt.
128
129    TargetTicks = StartTicks - DelayTicks;
130
131    do {
132      CurrentTicks = MmioRead32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CURRENT_REG);
133    } while ((CurrentTicks > TargetTicks) && (CurrentTicks <= StartTicks));
134
135  } else {
136    // In this case TargetTicks is larger than StartTicks.
137    // This means we expect a wrap-around of the timer to occur and we must wait for it.
138    // Before the wrap-around, CurrentTicks must be less than StartTicks and less than TargetTicks.
139    // After the wrap-around, CurrentTicks must be larger than StartTicks and larger than TargetTicks.
140    // If this is not the case, then the delay has been reached and may even have been exceeded if this
141    // function was suspended by a higher priority interrupt.
142
143    // The order of operations is essential to avoid arithmetic overflow problems
144    TargetTicks = ((UINTN)SP804_MAX_TICKS - DelayTicks) + StartTicks;
145
146    // First wait for the wrap-around to occur
147    do {
148      CurrentTicks = MmioRead32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CURRENT_REG);
149    } while (CurrentTicks <= StartTicks);
150
151    // Then wait for the target
152    do {
153      CurrentTicks = MmioRead32 (SP804_TIMER_METRONOME_BASE + SP804_TIMER_CURRENT_REG);
154    } while (CurrentTicks > TargetTicks);
155  }
156
157  return MicroSeconds;
158}
159
160/**
161  Stalls the CPU for at least the given number of nanoseconds.
162
163  Stalls the CPU for the number of nanoseconds specified by NanoSeconds.
164
165  When the timer frequency is 1MHz, each tick corresponds to 1 microsecond.
166  Therefore, the nanosecond delay will be rounded up to the nearest 1 microsecond.
167
168  @param  NanoSeconds The minimum number of nanoseconds to delay.
169
170  @return The value of NanoSeconds inputted.
171
172**/
173UINTN
174EFIAPI
175NanoSecondDelay (
176  IN  UINTN NanoSeconds
177  )
178{
179  UINTN  MicroSeconds;
180
181  // Round up to 1us Tick Number
182  MicroSeconds = NanoSeconds / 1000;
183  MicroSeconds += ((NanoSeconds % 1000) == 0) ? 0 : 1;
184
185  MicroSecondDelay (MicroSeconds);
186
187  return NanoSeconds;
188}
189
190/**
191  Retrieves the current value of a 64-bit free running performance counter.
192
193  The counter can either count up by 1 or count down by 1. If the physical
194  performance counter counts by a larger increment, then the counter values
195  must be translated. The properties of the counter can be retrieved from
196  GetPerformanceCounterProperties().
197
198  @return The current value of the free running performance counter.
199
200**/
201UINT64
202EFIAPI
203GetPerformanceCounter (
204  VOID
205  )
206{
207  // Free running 64-bit/32-bit counter is needed here.
208  // Don't think we need this to boot, just to do performance profile
209  UINT64 Value;
210  Value = MmioRead32 (SP804_TIMER_PERFORMANCE_BASE + SP804_TIMER_CURRENT_REG);
211  return Value;
212}
213
214
215/**
216  Retrieves the 64-bit frequency in Hz and the range of performance counter
217  values.
218
219  If StartValue is not NULL, then the value that the performance counter starts
220  with immediately after is it rolls over is returned in StartValue. If
221  EndValue is not NULL, then the value that the performance counter end with
222  immediately before it rolls over is returned in EndValue. The 64-bit
223  frequency of the performance counter in Hz is always returned. If StartValue
224  is less than EndValue, then the performance counter counts up. If StartValue
225  is greater than EndValue, then the performance counter counts down. For
226  example, a 64-bit free running counter that counts up would have a StartValue
227  of 0 and an EndValue of 0xFFFFFFFFFFFFFFFF. A 24-bit free running counter
228  that counts down would have a StartValue of 0xFFFFFF and an EndValue of 0.
229
230  @param  StartValue  The value the performance counter starts with when it
231                      rolls over.
232  @param  EndValue    The value that the performance counter ends with before
233                      it rolls over.
234
235  @return The frequency in Hz.
236
237**/
238UINT64
239EFIAPI
240GetPerformanceCounterProperties (
241  OUT UINT64  *StartValue,  OPTIONAL
242  OUT UINT64  *EndValue     OPTIONAL
243  )
244{
245  if (StartValue != NULL) {
246    // Timer starts with the reload value
247    *StartValue = 0xFFFFFFFF;
248  }
249
250  if (EndValue != NULL) {
251    // Timer counts down to 0x0
252    *EndValue = (UINT64)0ULL;
253  }
254
255  return PcdGet64 (PcdEmbeddedPerformanceCounterFrequencyInHz);
256}
257