RefRefine soma code to make code run safely.
[mirror_edk2.git] / PcAtChipsetPkg / 8254TimerDxe / Timer.c
1 /** @file
2 Timer Architectural Protocol as defined in the DXE CIS
3
4 Copyright (c) 2005 - 2010, Intel Corporation. All rights reserved.<BR>
5 This program and the accompanying materials
6 are licensed and made available under the terms and conditions of the BSD License
7 which accompanies this distribution. The full text of the license may be found at
8 http://opensource.org/licenses/bsd-license.php
9
10 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
11 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
12
13 **/
14
15 #include "Timer.h"
16
17 //
18 // The handle onto which the Timer Architectural Protocol will be installed
19 //
20 EFI_HANDLE mTimerHandle = NULL;
21
22 //
23 // The Timer Architectural Protocol that this driver produces
24 //
25 EFI_TIMER_ARCH_PROTOCOL mTimer = {
26 TimerDriverRegisterHandler,
27 TimerDriverSetTimerPeriod,
28 TimerDriverGetTimerPeriod,
29 TimerDriverGenerateSoftInterrupt
30 };
31
32 //
33 // Pointer to the CPU Architectural Protocol instance
34 //
35 EFI_CPU_ARCH_PROTOCOL *mCpu;
36
37 //
38 // Pointer to the Legacy 8259 Protocol instance
39 //
40 EFI_LEGACY_8259_PROTOCOL *mLegacy8259;
41
42 //
43 // The notification function to call on every timer interrupt.
44 // A bug in the compiler prevents us from initializing this here.
45 //
46 EFI_TIMER_NOTIFY mTimerNotifyFunction;
47
48 //
49 // The current period of the timer interrupt
50 //
51 volatile UINT64 mTimerPeriod = 0;
52
53 //
54 // Worker Functions
55 //
56 /**
57 Sets the counter value for Timer #0 in a legacy 8254 timer.
58
59 @param Count The 16-bit counter value to program into Timer #0 of the legacy 8254 timer.
60 **/
61 VOID
62 SetPitCount (
63 IN UINT16 Count
64 )
65 {
66 IoWrite8 (TIMER_CONTROL_PORT, 0x36);
67 IoWrite8 (TIMER0_COUNT_PORT, (UINT8)(Count & 0xff));
68 IoWrite8 (TIMER0_COUNT_PORT, (UINT8)((Count >> 8) & 0xff));
69 }
70
71 /**
72 8254 Timer #0 Interrupt Handler.
73
74 @param InterruptType The type of interrupt that occured
75 @param SystemContext A pointer to the system context when the interrupt occured
76 **/
77 VOID
78 EFIAPI
79 TimerInterruptHandler (
80 IN EFI_EXCEPTION_TYPE InterruptType,
81 IN EFI_SYSTEM_CONTEXT SystemContext
82 )
83 {
84 EFI_TPL OriginalTPL;
85
86 OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
87
88 mLegacy8259->EndOfInterrupt (mLegacy8259, Efi8259Irq0);
89
90 if (mTimerNotifyFunction != NULL) {
91 //
92 // @bug : This does not handle missed timer interrupts
93 //
94 mTimerNotifyFunction (mTimerPeriod);
95 }
96
97 gBS->RestoreTPL (OriginalTPL);
98 }
99
100 /**
101
102 This function registers the handler NotifyFunction so it is called every time
103 the timer interrupt fires. It also passes the amount of time since the last
104 handler call to the NotifyFunction. If NotifyFunction is NULL, then the
105 handler is unregistered. If the handler is registered, then EFI_SUCCESS is
106 returned. If the CPU does not support registering a timer interrupt handler,
107 then EFI_UNSUPPORTED is returned. If an attempt is made to register a handler
108 when a handler is already registered, then EFI_ALREADY_STARTED is returned.
109 If an attempt is made to unregister a handler when a handler is not registered,
110 then EFI_INVALID_PARAMETER is returned. If an error occurs attempting to
111 register the NotifyFunction with the timer interrupt, then EFI_DEVICE_ERROR
112 is returned.
113
114
115 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
116 @param NotifyFunction The function to call when a timer interrupt fires. This
117 function executes at TPL_HIGH_LEVEL. The DXE Core will
118 register a handler for the timer interrupt, so it can know
119 how much time has passed. This information is used to
120 signal timer based events. NULL will unregister the handler.
121
122 @retval EFI_SUCCESS The timer handler was registered.
123 @retval EFI_UNSUPPORTED The platform does not support timer interrupts.
124 @retval EFI_ALREADY_STARTED NotifyFunction is not NULL, and a handler is already
125 registered.
126 @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
127 previously registered.
128 @retval EFI_DEVICE_ERROR The timer handler could not be registered.
129
130 **/
131 EFI_STATUS
132 EFIAPI
133 TimerDriverRegisterHandler (
134 IN EFI_TIMER_ARCH_PROTOCOL *This,
135 IN EFI_TIMER_NOTIFY NotifyFunction
136 )
137 {
138 //
139 // Check for invalid parameters
140 //
141 if (NotifyFunction == NULL && mTimerNotifyFunction == NULL) {
142 return EFI_INVALID_PARAMETER;
143 }
144
145 if (NotifyFunction != NULL && mTimerNotifyFunction != NULL) {
146 return EFI_ALREADY_STARTED;
147 }
148
149 mTimerNotifyFunction = NotifyFunction;
150
151 return EFI_SUCCESS;
152 }
153
154 /**
155
156 This function adjusts the period of timer interrupts to the value specified
157 by TimerPeriod. If the timer period is updated, then the selected timer
158 period is stored in EFI_TIMER.TimerPeriod, and EFI_SUCCESS is returned. If
159 the timer hardware is not programmable, then EFI_UNSUPPORTED is returned.
160 If an error occurs while attempting to update the timer period, then the
161 timer hardware will be put back in its state prior to this call, and
162 EFI_DEVICE_ERROR is returned. If TimerPeriod is 0, then the timer interrupt
163 is disabled. This is not the same as disabling the CPU's interrupts.
164 Instead, it must either turn off the timer hardware, or it must adjust the
165 interrupt controller so that a CPU interrupt is not generated when the timer
166 interrupt fires.
167
168
169 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
170 @param TimerPeriod The rate to program the timer interrupt in 100 nS units. If
171 the timer hardware is not programmable, then EFI_UNSUPPORTED is
172 returned. If the timer is programmable, then the timer period
173 will be rounded up to the nearest timer period that is supported
174 by the timer hardware. If TimerPeriod is set to 0, then the
175 timer interrupts will be disabled.
176
177 @retval EFI_SUCCESS The timer period was changed.
178 @retval EFI_UNSUPPORTED The platform cannot change the period of the timer interrupt.
179 @retval EFI_DEVICE_ERROR The timer period could not be changed due to a device error.
180
181 **/
182 EFI_STATUS
183 EFIAPI
184 TimerDriverSetTimerPeriod (
185 IN EFI_TIMER_ARCH_PROTOCOL *This,
186 IN UINT64 TimerPeriod
187 )
188 {
189 UINT64 TimerCount;
190
191 //
192 // The basic clock is 1.19318 MHz or 0.119318 ticks per 100 ns.
193 // TimerPeriod * 0.119318 = 8254 timer divisor. Using integer arithmetic
194 // TimerCount = (TimerPeriod * 119318)/1000000.
195 //
196 // Round up to next highest integer. This guarantees that the timer is
197 // equal to or slightly longer than the requested time.
198 // TimerCount = ((TimerPeriod * 119318) + 500000)/1000000
199 //
200 // Note that a TimerCount of 0 is equivalent to a count of 65,536
201 //
202 // Since TimerCount is limited to 16 bits for IA32, TimerPeriod is limited
203 // to 20 bits.
204 //
205 if (TimerPeriod == 0) {
206 //
207 // Disable timer interrupt for a TimerPeriod of 0
208 //
209 mLegacy8259->DisableIrq (mLegacy8259, Efi8259Irq0);
210 } else {
211
212 //
213 // Convert TimerPeriod into 8254 counts
214 //
215 TimerCount = DivU64x32 (MultU64x32 (119318, (UINT32) TimerPeriod) + 500000, 1000000);
216
217 //
218 // Check for overflow
219 //
220 if (TimerCount >= 65536) {
221 TimerCount = 0;
222 if (TimerPeriod >= DEFAULT_TIMER_TICK_DURATION) {
223 TimerPeriod = DEFAULT_TIMER_TICK_DURATION;
224 }
225 }
226 //
227 // Program the 8254 timer with the new count value
228 //
229 SetPitCount ((UINT16) TimerCount);
230
231 //
232 // Enable timer interrupt
233 //
234 mLegacy8259->EnableIrq (mLegacy8259, Efi8259Irq0, FALSE);
235 }
236 //
237 // Save the new timer period
238 //
239 mTimerPeriod = TimerPeriod;
240
241 return EFI_SUCCESS;
242 }
243
244 /**
245
246 This function retrieves the period of timer interrupts in 100 ns units,
247 returns that value in TimerPeriod, and returns EFI_SUCCESS. If TimerPeriod
248 is NULL, then EFI_INVALID_PARAMETER is returned. If a TimerPeriod of 0 is
249 returned, then the timer is currently disabled.
250
251
252 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
253 @param TimerPeriod A pointer to the timer period to retrieve in 100 ns units. If
254 0 is returned, then the timer is currently disabled.
255
256 @retval EFI_SUCCESS The timer period was returned in TimerPeriod.
257 @retval EFI_INVALID_PARAMETER TimerPeriod is NULL.
258
259 **/
260 EFI_STATUS
261 EFIAPI
262 TimerDriverGetTimerPeriod (
263 IN EFI_TIMER_ARCH_PROTOCOL *This,
264 OUT UINT64 *TimerPeriod
265 )
266 {
267 if (TimerPeriod == NULL) {
268 return EFI_INVALID_PARAMETER;
269 }
270
271 *TimerPeriod = mTimerPeriod;
272
273 return EFI_SUCCESS;
274 }
275
276 /**
277
278 This function generates a soft timer interrupt. If the platform does not support soft
279 timer interrupts, then EFI_UNSUPPORTED is returned. Otherwise, EFI_SUCCESS is returned.
280 If a handler has been registered through the EFI_TIMER_ARCH_PROTOCOL.RegisterHandler()
281 service, then a soft timer interrupt will be generated. If the timer interrupt is
282 enabled when this service is called, then the registered handler will be invoked. The
283 registered handler should not be able to distinguish a hardware-generated timer
284 interrupt from a software-generated timer interrupt.
285
286
287 @param This The EFI_TIMER_ARCH_PROTOCOL instance.
288
289 @retval EFI_SUCCESS The soft timer interrupt was generated.
290 @retval EFI_UNSUPPORTEDT The platform does not support the generation of soft timer interrupts.
291
292 **/
293 EFI_STATUS
294 EFIAPI
295 TimerDriverGenerateSoftInterrupt (
296 IN EFI_TIMER_ARCH_PROTOCOL *This
297 )
298 {
299 EFI_STATUS Status;
300 UINT16 IRQMask;
301 EFI_TPL OriginalTPL;
302
303 //
304 // If the timer interrupt is enabled, then the registered handler will be invoked.
305 //
306 Status = mLegacy8259->GetMask (mLegacy8259, NULL, NULL, &IRQMask, NULL);
307 ASSERT_EFI_ERROR (Status);
308 if ((IRQMask & 0x1) == 0) {
309 //
310 // Invoke the registered handler
311 //
312 OriginalTPL = gBS->RaiseTPL (TPL_HIGH_LEVEL);
313
314 if (mTimerNotifyFunction != NULL) {
315 //
316 // @bug : This does not handle missed timer interrupts
317 //
318 mTimerNotifyFunction (mTimerPeriod);
319 }
320
321 gBS->RestoreTPL (OriginalTPL);
322 } else {
323 return EFI_UNSUPPORTED;
324 }
325
326 return EFI_SUCCESS;
327 }
328
329 /**
330 Initialize the Timer Architectural Protocol driver
331
332 @param ImageHandle ImageHandle of the loaded driver
333 @param SystemTable Pointer to the System Table
334
335 @retval EFI_SUCCESS Timer Architectural Protocol created
336 @retval EFI_OUT_OF_RESOURCES Not enough resources available to initialize driver.
337 @retval EFI_DEVICE_ERROR A device error occured attempting to initialize the driver.
338
339 **/
340 EFI_STATUS
341 EFIAPI
342 TimerDriverInitialize (
343 IN EFI_HANDLE ImageHandle,
344 IN EFI_SYSTEM_TABLE *SystemTable
345 )
346 {
347 EFI_STATUS Status;
348 UINT32 TimerVector;
349
350 //
351 // Initialize the pointer to our notify function.
352 //
353 mTimerNotifyFunction = NULL;
354
355 //
356 // Make sure the Timer Architectural Protocol is not already installed in the system
357 //
358 ASSERT_PROTOCOL_ALREADY_INSTALLED (NULL, &gEfiTimerArchProtocolGuid);
359
360 //
361 // Find the CPU architectural protocol.
362 //
363 Status = gBS->LocateProtocol (&gEfiCpuArchProtocolGuid, NULL, (VOID **) &mCpu);
364 ASSERT_EFI_ERROR (Status);
365
366 //
367 // Find the Legacy8259 protocol.
368 //
369 Status = gBS->LocateProtocol (&gEfiLegacy8259ProtocolGuid, NULL, (VOID **) &mLegacy8259);
370 ASSERT_EFI_ERROR (Status);
371
372 //
373 // Force the timer to be disabled
374 //
375 Status = TimerDriverSetTimerPeriod (&mTimer, 0);
376 ASSERT_EFI_ERROR (Status);
377
378 //
379 // Get the interrupt vector number corresponding to IRQ0 from the 8259 driver
380 //
381 TimerVector = 0;
382 Status = mLegacy8259->GetVector (mLegacy8259, Efi8259Irq0, (UINT8 *) &TimerVector);
383 ASSERT_EFI_ERROR (Status);
384
385 //
386 // Install interrupt handler for 8254 Timer #0 (ISA IRQ0)
387 //
388 Status = mCpu->RegisterInterruptHandler (mCpu, TimerVector, TimerInterruptHandler);
389 ASSERT_EFI_ERROR (Status);
390
391 //
392 // Force the timer to be enabled at its default period
393 //
394 Status = TimerDriverSetTimerPeriod (&mTimer, DEFAULT_TIMER_TICK_DURATION);
395 ASSERT_EFI_ERROR (Status);
396
397 //
398 // Install the Timer Architectural Protocol onto a new handle
399 //
400 Status = gBS->InstallMultipleProtocolInterfaces (
401 &mTimerHandle,
402 &gEfiTimerArchProtocolGuid, &mTimer,
403 NULL
404 );
405 ASSERT_EFI_ERROR (Status);
406
407 return Status;
408 }
409