Add documentation for the HAL Ticker API

c1728p9 · 0xc0170 · commit 67dfdde5628d · 2017-12-21T15:05:16.000Z
Add documentation and test header for the HAL Ticker API.
diff --git a/TESTS/mbed_hal/lp_ticker_api_tests.h b/TESTS/mbed_hal/lp_ticker_api_tests.h
@@ -0,0 +1,51 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017-2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** \addtogroup hal_lp_ticker_tests
+ *  @{
+ */
+
+#ifndef LP_TICKER_API_TESTS_H
+#define LP_TICKER_API_TESTS_H
+
+#include "device.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/** Test that the ticker has the right frequency and number of bits
+ *
+ */
+void lp_ticker_info_test(void);
+
+/** Test that the ticker operates in deep sleep mode
+ *
+ */
+void lp_ticker_deepsleep_test(void);
+
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/**@}*/
diff --git a/TESTS/mbed_hal/ticker_api_tests.h b/TESTS/mbed_hal/ticker_api_tests.h
@@ -0,0 +1,103 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017-2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** \addtogroup hal_ticker_tests */
+/** @{*/
+
+#ifndef TICKER_API_TESTS_H
+#define TICKER_API_TESTS_H
+
+#include "device.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** Test that ticker_init can be called multiple times
+ *
+ */
+void ticker_init_test(void);
+
+/** Test that ticker has a valid frequency and bitwidth
+ *
+ */
+void ticker_info_test(void);
+
+/** Test that the ticker increments by one on each tick
+ *
+ */
+void ticker_increment_test(void);
+
+/** Test that the interrupt fires at the right time
+ *
+ */
+void ticker_interrupt_test(void);
+
+/** Test that an interrupt is not triggered when ticker_set_interrupt is called with a time from the past
+ *
+ */
+void ticker_past_test(void);
+
+/** Test that a ticker can be rescheduled repeatedly before the handler has been called
+ *
+ */
+void ticker_repeat_reschedule_test(void);
+
+/** Test that ticker_fire_interrupt causes and interrupt to get fired immediately
+ *
+ */
+void ticker_fire_now_test(void);
+
+/** Test that common ticker functions complete with the required amount of time
+ *
+ * Ensure that ticker_read, ticker_clear_interrupt, ticker_set_interrupt
+ * and ticker_fire_interrupt take less than 20us to complete.
+ *
+ */
+void ticker_speed_test(void);
+
+/** Test that the ticker correctly handles overflows
+ *
+ * This test verifies that rollover is properly handled and
+ * that scheduling for a time after overflow works.
+ *
+ */
+void ticker_overflow_test(void);
+
+/** Test that rescheduling does not cause drift
+ *
+ * This test verifies that repeated rescheduling does not cause a
+ * drift.
+ *
+ */
+void ticker_reschedule_test(void);
+
+/** Test that the ticker is operating at the frequency it specifies
+ *
+ */
+void ticker_frequency_test(void);
+
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/**@}*/
diff --git a/TESTS/mbed_hal/us_ticker_api_tests.h b/TESTS/mbed_hal/us_ticker_api_tests.h
@@ -0,0 +1,45 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2017-2017 ARM Limited
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/** \addtogroup hal_us_ticker_tests */
+/** @{*/
+
+#ifndef US_TICKER_API_TESTS_H
+#define US_TICKER_API_TESTS_H
+
+#include "device.h"
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/** Test that the ticker has the right frequency and number of bits
+ *
+ */
+void us_ticker_info_test(void);
+
+
+/**@}*/
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+
+/**@}*/
diff --git a/hal/lp_ticker_api.h b/hal/lp_ticker_api.h
@@ -30,10 +30,33 @@ extern "C" {
 #endif
 
 /**
- * \defgroup hal_LpTicker Low Power Ticker Functions
+ * \defgroup hal_lp_ticker Low Power Ticker
+ * Low level interface to the low power ticker of a target
+ *
+ * # Defined behavior
+ * * Has a reported frequency between 8KHz and 64KHz - verified by lp_ticker_info_test
+ * * Has a counter that is at least 12 bits wide - verified by lp_ticker_info_test
+ * * Continues operating in deep sleep mode - verified by lp_ticker_sleep_test
+ * * All behavior defined by the @ref hal_ticker_shared "ticker specification"
+ *
+ * # Undefined behavior
+ * * See the @ref hal_ticker_shared "ticker specification"
+ *
+ * @see hal_lp_ticker_tests
+ *
  * @{
  */
 
+/**
+ * \defgroup hal_lp_ticker_tests Low Power Ticker tests
+ * Tests to validate the proper implementation of the low power ticker
+ *
+ * To run the low power ticker hal tests use the command:
+ *
+ *     mbed test -t <toolchain> -m <target> -n tests-mbed_hal-us_lp_ticker*,tests-mbed_hal-lp_ticker*
+ *
+ */
+
 typedef void (*ticker_irq_handler_type)(const ticker_data_t *const);
 
 /** Set low power ticker IRQ handler
@@ -63,39 +86,135 @@ void lp_ticker_irq_handler(void);
 
 /** Initialize the low power ticker
  *
+ * Initialize or re-initialize the ticker. This resets all the
+ * clocking and prescaler registers, along with disabling
+ * the compare interrupt.
+ *
+ * Pseudo Code:
+ * @code
+ * void lp_ticker_init()
+ * {
+ *     // Enable clock gate so processor can read LPTMR registers
+ *     POWER_CTRL |= POWER_CTRL_LPTMR_Msk;
+ *
+ *     // Disable the timer and ensure it is powered down
+ *     LPTMR_CTRL &= ~(LPTMR_CTRL_ENABLE_Msk | LPTMR_CTRL_COMPARE_ENABLE_Msk);
+ *
+ *     // Configure divisors - no division necessary
+ *     LPTMR_PRESCALE = 0;
+ *     LPTMR_CTRL |= LPTMR_CTRL_ENABLE_Msk;
+ *
+ *     // Install the interrupt handler
+ *     NVIC_SetVector(LPTMR_IRQn, (uint32_t)lp_ticker_irq_handler);
+ *     NVIC_EnableIRQ(LPTMR_IRQn);
+ * }
+ * @endcode
  */
 void lp_ticker_init(void);
 
-/** Read the current counter
+/** Read the current tick
+ *
+ * If no rollover has occurred, the seconds passed since ::lp_ticker_init
+ * was called can be found by dividing the ticks returned by this function
+ * by the frequency returned by ::lp_ticker_get_info.
+ *
+ * @return The current timer's counter value in ticks
  *
- * @return The current timer's counter value in microseconds
+ * Pseudo Code:
+ * @code
+ * uint32_t lp_ticker_read()
+ * {
+ *     uint16_t count;
+ *     uint16_t last_count;
+ *
+ *     // Loop until the same tick is read twice since this
+ *     // is ripple counter on a different clock domain.
+ *     count = LPTMR_COUNT;
+ *     do {
+ *         last_count = count;
+ *         count = LPTMR_COUNT;
+ *     } while (last_count != count);
+ *
+ *     return count;
+ * }
+ * @endcode
  */
 uint32_t lp_ticker_read(void);
 
 /** Set interrupt for specified timestamp
  *
- * @param timestamp The time in microseconds to be set
+ * @param timestamp The time in ticks to be set
+ *
+ * @note no special handling needs to be done for times in the past
+ * as the common timer code will detect this and call
+ * ::lp_ticker_fire_interrupt if this is the case
+ *
+ * @note calling this function with timestamp of more than the supported
+ * number of bits returned by ::lp_ticker_get_info results in undefined
+ * behavior.
+ *
+ * Pseudo Code:
+ * @code
+ * void lp_ticker_set_interrupt(timestamp_t timestamp)
+ * {
+ *     LPTMR_COMPARE = timestamp;
+ *     LPTMR_CTRL |= LPTMR_CTRL_COMPARE_ENABLE_Msk;
+ * }
+ * @endcode
  */
 void lp_ticker_set_interrupt(timestamp_t timestamp);
 
 /** Disable low power ticker interrupt
  *
+ * Pseudo Code:
+ * @code
+ * void lp_ticker_disable_interrupt(void)
+ * {
+ *     // Disable the compare interrupt
+ *     LPTMR_CTRL &= ~LPTMR_CTRL_COMPARE_ENABLE_Msk;
+ * }
+ * @endcode
  */
 void lp_ticker_disable_interrupt(void);
 
 /** Clear the low power ticker interrupt
  *
+ * Pseudo Code:
+ * @code
+ * void lp_ticker_clear_interrupt(void)
+ * {
+ *     // Write to the ICR (interrupt clear register) of the LPTMR
+ *     LPTMR_ICR = LPTMR_ICR_COMPARE_Msk;
+ * }
+ * @endcode
  */
 void lp_ticker_clear_interrupt(void);
 
 /** Set pending interrupt that should be fired right away.
  * 
- * The ticker should be initialized prior calling this function.
+ * Pseudo Code:
+ * @code
+ * void lp_ticker_fire_interrupt(void)
+ * {
+ *     NVIC_SetPendingIRQ(LPTMR_IRQn);
+ * }
+ * @endcode
  */
 void lp_ticker_fire_interrupt(void);
 
 /** Get frequency and counter bits of this ticker.
  *
+ * Pseudo Code:
+ * @code
+ * const ticker_info_t* lp_ticker_get_info()
+ * {
+ *     static const ticker_info_t info = {
+ *         32768,      // 32KHz
+ *         16          // 16 bit counter
+ *     };
+ *     return &info;
+ * }
+ * @endcode
  */
 const ticker_info_t* lp_ticker_get_info(void);
 
diff --git a/hal/us_ticker_api.h b/hal/us_ticker_api.h
