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[NUC472/M453/M487/NANO130] Rework us_ticker and lp_ticker with one H/W timer
Originally, we use 2 H/W timers for us_ticker/lp_ticker, one for counting and the other for alarm. With H/W timer running in continuous mode, we could use just one H/W timer for counting/alarm simultaneously.
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8 files changed

+396
-1171
lines changed

8 files changed

+396
-1171
lines changed

‎targets/TARGET_NUVOTON/TARGET_M451/lp_ticker.c

Lines changed: 52 additions & 149 deletions
Original file line numberDiff line numberDiff line change
@@ -35,18 +35,14 @@
3535
/* Timer max counter */
3636
#define NU_TMR_MAXCNT ((1 << NU_TMR_MAXCNT_BITSIZE) - 1)
3737

38-
static void tmr2_vec(void);
39-
static void tmr3_vec(void);
40-
/* Configure scheduled alarm */
41-
static void arm_alarm(uint32_t cd_clk);
42-
43-
static int ticker_inited = 0;
44-
static uint32_t ticker_last_read_clk = 0;
38+
static void tmr1_vec(void);
4539

4640
/* NOTE: To wake the system from power down mode, timer clock source must be ether LXT or LIRC. */
47-
/* NOTE: TIMER_2 for normal counting and TIMER_3 for scheduled alarm */
48-
static const struct nu_modinit_s timer2_modinit = {TIMER_2, TMR2_MODULE, CLK_CLKSEL1_TMR2SEL_LXT, 0, TMR2_RST, TMR2_IRQn, (void *) tmr2_vec};
49-
static const struct nu_modinit_s timer3_modinit = {TIMER_3, TMR3_MODULE, CLK_CLKSEL1_TMR3SEL_LXT, 0, TMR3_RST, TMR3_IRQn, (void *) tmr3_vec};
41+
static const struct nu_modinit_s timer1_modinit = {TIMER_1, TMR1_MODULE, CLK_CLKSEL1_TMR1SEL_LXT, 0, TMR1_RST, TMR1_IRQn, (void *) tmr1_vec};
42+
43+
#define TIMER_MODINIT timer1_modinit
44+
45+
static int ticker_inited = 0;
5046

5147
#define TMR_CMP_MIN 2
5248
#define TMR_CMP_MAX 0xFFFFFFu
@@ -58,43 +54,37 @@ void lp_ticker_init(void)
5854
}
5955
ticker_inited = 1;
6056

61-
ticker_last_read_clk = 0;
62-
6357
// Reset module
64-
SYS_ResetModule(timer2_modinit.rsetidx);
65-
SYS_ResetModule(timer3_modinit.rsetidx);
58+
SYS_ResetModule(TIMER_MODINIT.rsetidx);
6659

6760
// Select IP clock source
68-
CLK_SetModuleClock(timer2_modinit.clkidx, timer2_modinit.clksrc, timer2_modinit.clkdiv);
69-
CLK_SetModuleClock(timer3_modinit.clkidx, timer3_modinit.clksrc, timer3_modinit.clkdiv);
61+
CLK_SetModuleClock(TIMER_MODINIT.clkidx, TIMER_MODINIT.clksrc, TIMER_MODINIT.clkdiv);
62+
7063
// Enable IP clock
71-
CLK_EnableModuleClock(timer2_modinit.clkidx);
72-
CLK_EnableModuleClock(timer3_modinit.clkidx);
64+
CLK_EnableModuleClock(TIMER_MODINIT.clkidx);
7365

7466
// Configure clock
75-
uint32_t clk_timer2 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
76-
uint32_t prescale_timer2 = clk_timer2 / NU_TMRCLK_PER_SEC - 1;
77-
MBED_ASSERT((prescale_timer2 != (uint32_t) -1) && prescale_timer2 <= 127);
78-
MBED_ASSERT((clk_timer2 % NU_TMRCLK_PER_SEC) == 0);
79-
uint32_t cmp_timer2 = TMR_CMP_MAX;
80-
MBED_ASSERT(cmp_timer2 >= TMR_CMP_MIN && cmp_timer2 <= TMR_CMP_MAX);
67+
uint32_t clk_timer = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
68+
uint32_t prescale_timer = clk_timer / NU_TMRCLK_PER_SEC - 1;
69+
MBED_ASSERT((prescale_timer != (uint32_t) -1) && prescale_timer <= 127);
70+
MBED_ASSERT((clk_timer % NU_TMRCLK_PER_SEC) == 0);
71+
uint32_t cmp_timer = TMR_CMP_MAX;
72+
MBED_ASSERT(cmp_timer >= TMR_CMP_MIN && cmp_timer <= TMR_CMP_MAX);
8173
// Continuous mode
8274
// NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451. In M451, TIMER_CNT is updated continuously by default.
83-
((TIMER_T *) NU_MODBASE(timer2_modinit.modname))->CTL = TIMER_PERIODIC_MODE | prescale_timer2/* | TIMER_CTL_CNTDATEN_Msk*/;
84-
((TIMER_T *) NU_MODBASE(timer2_modinit.modname))->CMP = cmp_timer2;
75+
((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname))->CTL = TIMER_CONTINUOUS_MODE | prescale_timer/* | TIMER_CTL_CNTDATEN_Msk*/;
76+
((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname))->CMP = cmp_timer;
8577

8678
// Set vector
87-
NVIC_SetVector(timer2_modinit.irq_n, (uint32_t) timer2_modinit.var);
88-
NVIC_SetVector(timer3_modinit.irq_n, (uint32_t) timer3_modinit.var);
79+
NVIC_SetVector(TIMER_MODINIT.irq_n, (uint32_t) TIMER_MODINIT.var);
8980

90-
NVIC_EnableIRQ(timer2_modinit.irq_n);
91-
NVIC_EnableIRQ(timer3_modinit.irq_n);
81+
NVIC_EnableIRQ(TIMER_MODINIT.irq_n);
9282

93-
TIMER_EnableInt((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
94-
TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
83+
TIMER_EnableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
84+
TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
9585
/* NOTE: When engine is clocked by low power clock source (LXT/LIRC), we need to wait for 3 engine clocks. */
9686
wait_us((NU_US_PER_SEC / NU_TMRCLK_PER_SEC) * 3);
97-
TIMER_Start((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
87+
TIMER_Start((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
9888
}
9989

10090
timestamp_t lp_ticker_read()
@@ -103,145 +93,49 @@ timestamp_t lp_ticker_read()
10393
lp_ticker_init();
10494
}
10595

106-
TIMER_T * timer2_base = (TIMER_T *) NU_MODBASE(timer2_modinit.modname);
96+
TIMER_T * timer_base = (TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname);
10797

108-
ticker_last_read_clk = TIMER_GetCounter(timer2_base);
109-
return (ticker_last_read_clk / NU_TMRCLK_PER_TICK);
98+
return (TIMER_GetCounter(timer_base) / NU_TMRCLK_PER_TICK);
11099
}
111100

112101
void lp_ticker_set_interrupt(timestamp_t timestamp)
113102
{
114-
TIMER_Stop((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
115-
116-
/* We need to get alarm interval from alarm timestamp `timestamp` to configure H/W timer.
117-
*
118-
* Because both `timestamp` and xx_ticker_read() would wrap around, we have difficulties in distinguishing
119-
* long future event and past event. To distinguish them, we need `tick_last_read` against which
120-
* `timestamp` is calculated out. In timeline, we would always have below after fixing wrap-around:
121-
* (1) tick_last_read <= present_clk
122-
* (2) tick_last_read <= alarm_ts_clk
123-
*
124-
*
125-
* 1. Future event case:
126-
*
127-
* tick_last_read present_clk alarm_ts_clk
128-
* | | |
129-
* --------------------------------------------------------
130-
* |-alarm_intvl1_clk-|
131-
* |-------------------alarm_intvl2_clk-------------------|
132-
*
133-
* 2. Past event case:
134-
*
135-
* tick_last_read alarm_ts_clk present_clk
136-
* | | |
137-
* --------------------------------------------------------
138-
* |-------------------alarm_intvl1_clk-------------------|
139-
* |-alarm_intvl2_clk-|
103+
/* In continuous mode, counter will be reset to zero with the following sequence:
104+
* 1. Stop counting
105+
* 2. Configure new CMP value
106+
* 3. Restart counting
140107
*
141-
* Unfortunately, `tick_last_read` is not passed along the xx_ticker_set_interrupt() call. To solve it, we
142-
* assume that `tick_last_read` tick is exactly the one returned by the last xx_ticker_read() call before
143-
* xx_ticker_set_interrupt() is invoked. With this assumption, we can hold it via `xx_ticker_last_read_clk`
144-
* in xx_ticker_read().
108+
* This behavior is not what we want. To fix it, we could configure new CMP value
109+
* without stopping counting first.
145110
*/
146-
147-
/* ticker_last_read_clk will update in lp_ticker_read(). Keep it beforehand. */
148-
uint32_t last_read_clk = ticker_last_read_clk;
149-
uint32_t present_clk = lp_ticker_read() * NU_TMRCLK_PER_TICK;
150-
uint32_t alarm_ts_clk = timestamp * NU_TMRCLK_PER_TICK;
151-
uint32_t alarm_intvl1_clk, alarm_intvl2_clk;
152-
153-
/* alarm_intvl1_clk = present_clk - last_read_clk
154-
*
155-
* NOTE: Don't miss the `=` sign here. Otherwise, we would get the wrong result.
156-
*/
157-
if (present_clk >= last_read_clk) {
158-
alarm_intvl1_clk = present_clk - last_read_clk;
159-
} else {
160-
alarm_intvl1_clk = (uint32_t) (((uint64_t) NU_TMR_MAXCNT) + 1 + present_clk - last_read_clk);
161-
}
111+
TIMER_T * timer_base = (TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname);
162112

163-
/* alarm_intvl2_clk = alarm_ts_clk - last_read_clk
164-
*
165-
* NOTE: Don't miss the `=` sign here. Otherwise, we would get the wrong result.
166-
*/
167-
if (alarm_ts_clk >= last_read_clk) {
168-
alarm_intvl2_clk = alarm_ts_clk - last_read_clk;
169-
} else {
170-
alarm_intvl2_clk = (uint32_t) (((uint64_t) NU_TMR_MAXCNT) + 1 + alarm_ts_clk - last_read_clk);
171-
}
113+
/* NOTE: Because H/W timer requests min compare value, our implementation would have alarm delay of
114+
* (TMR_CMP_MIN - interval_clk) clocks when interval_clk is between [1, TMR_CMP_MIN). */
115+
uint32_t cmp_timer = timestamp * NU_TMRCLK_PER_TICK;
116+
cmp_timer = NU_CLAMP(cmp_timer, TMR_CMP_MIN, TMR_CMP_MAX);
117+
timer_base->CMP = cmp_timer;
172118

173-
/* Distinguish (long) future event and past event
174-
*
175-
* NOTE: No '=' sign here. Alarm should go off immediately in equal case.
176-
*/
177-
if (alarm_intvl2_clk > alarm_intvl1_clk) {
178-
/* Schedule for future event */
179-
arm_alarm(alarm_intvl2_clk - alarm_intvl1_clk);
180-
} else {
181-
/* Go off immediately for past event, including equal case */
182-
lp_ticker_fire_interrupt();
183-
}
119+
/* NOTE: When engine is clocked by low power clock source (LXT/LIRC), we need to wait for 3 engine clocks. */
120+
wait_us((NU_US_PER_SEC / NU_TMRCLK_PER_SEC) * 3);
121+
TIMER_Start(timer_base);
184122
}
185123

186124
void lp_ticker_disable_interrupt(void)
187125
{
188-
TIMER_DisableInt((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
126+
TIMER_DisableInt((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
189127
}
190128

191129
void lp_ticker_clear_interrupt(void)
192130
{
193-
TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
131+
TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
194132
}
195133

196134
void lp_ticker_fire_interrupt(void)
197135
{
198136
// NOTE: This event was in the past. Set the interrupt as pending, but don't process it here.
199137
// This prevents a recursive loop under heavy load which can lead to a stack overflow.
200-
NVIC_SetPendingIRQ(timer3_modinit.irq_n);
201-
}
202-
203-
static void tmr2_vec(void)
204-
{
205-
TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
206-
TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(timer2_modinit.modname));
207-
}
208-
209-
static void tmr3_vec(void)
210-
{
211-
TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
212-
TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
213-
214-
// NOTE: lp_ticker_set_interrupt() may get called in lp_ticker_irq_handler();
215-
lp_ticker_irq_handler();
216-
217-
}
218-
219-
static void arm_alarm(uint32_t cd_clk)
220-
{
221-
TIMER_T * timer3_base = (TIMER_T *) NU_MODBASE(timer3_modinit.modname);
222-
223-
// Reset 8-bit PSC counter, 24-bit up counter value and CNTEN bit
224-
timer3_base->CTL |= TIMER_CTL_RSTCNT_Msk;
225-
// One-shot mode, Clock = 1 KHz
226-
uint32_t clk_timer3 = TIMER_GetModuleClock((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
227-
uint32_t prescale_timer3 = clk_timer3 / NU_TMRCLK_PER_SEC - 1;
228-
MBED_ASSERT((prescale_timer3 != (uint32_t) -1) && prescale_timer3 <= 127);
229-
MBED_ASSERT((clk_timer3 % NU_TMRCLK_PER_SEC) == 0);
230-
// NOTE: TIMER_CTL_CNTDATEN_Msk exists in NUC472, but not in M451. In M451, TIMER_CNT is updated continuously by default.
231-
timer3_base->CTL &= ~(TIMER_CTL_OPMODE_Msk | TIMER_CTL_PSC_Msk/* | TIMER_CTL_CNTDATEN_Msk*/);
232-
timer3_base->CTL |= TIMER_ONESHOT_MODE | prescale_timer3/* | TIMER_CTL_CNTDATEN_Msk*/;
233-
234-
/* NOTE: Because H/W timer requests min compare value, our implementation would have alarm delay of
235-
* (TMR_CMP_MIN - interval_clk) clocks when interval_clk is between [1, TMR_CMP_MIN). */
236-
uint32_t cmp_timer3 = cd_clk;
237-
cmp_timer3 = NU_CLAMP(cmp_timer3, TMR_CMP_MIN, TMR_CMP_MAX);
238-
timer3_base->CMP = cmp_timer3;
239-
240-
TIMER_EnableInt(timer3_base);
241-
TIMER_EnableWakeup((TIMER_T *) NU_MODBASE(timer3_modinit.modname));
242-
/* NOTE: When engine is clocked by low power clock source (LXT/LIRC), we need to wait for 3 engine clocks. */
243-
wait_us((NU_US_PER_SEC / NU_TMRCLK_PER_SEC) * 3);
244-
TIMER_Start(timer3_base);
138+
NVIC_SetPendingIRQ(TIMER_MODINIT.irq_n);
245139
}
246140

247141
const ticker_info_t* lp_ticker_get_info()
@@ -253,4 +147,13 @@ const ticker_info_t* lp_ticker_get_info()
253147
return &info;
254148
}
255149

150+
static void tmr1_vec(void)
151+
{
152+
TIMER_ClearIntFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
153+
TIMER_ClearWakeupFlag((TIMER_T *) NU_MODBASE(TIMER_MODINIT.modname));
154+
155+
// NOTE: lp_ticker_set_interrupt() may get called in lp_ticker_irq_handler();
156+
lp_ticker_irq_handler();
157+
}
158+
256159
#endif

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