Merge pull request #20613 from maribu/cpu/msp430/pm

cpu/msp430: implement power management

cpu/msp430/clock.c

@@ -20,9 +20,11 @@
  * @}
  */
 
+#include <assert.h>
 #include <stdbool.h>
 #include <stdint.h>
 
+#include "atomic_utils.h"
 #include "busy_wait.h"
 #include "macros/math.h"
 #include "macros/units.h"
@@ -38,6 +40,7 @@
 #endif
 
 uint32_t msp430_dco_freq;
+static uint8_t msp430_clock_refcounts[MSP430_CLOCK_NUMOF];
 
 static inline bool is_dco_in_use(const msp430_clock_params_t *params)
 {
@@ -361,3 +364,57 @@ uint32_t PURE msp430_auxiliary_clock_freq(void)
     uint16_t shift = (clock_params.auxiliary_clock_divier >> 4) & 0x3;
     return clock_params.lfxt1_frequency >> shift;
 }
+
+void msp430_clock_acquire(msp430_clock_t clock)
+{
+    assume((unsigned)clock < MSP430_CLOCK_NUMOF);
+    uint8_t before = atomic_fetch_add_u8(&msp430_clock_refcounts[clock], 1);
+    (void)before;
+    assert(before < UINT8_MAX);
+}
+
+void msp430_clock_release(msp430_clock_t clock)
+{
+    assume((unsigned)clock < MSP430_CLOCK_NUMOF);
+    uint8_t before = atomic_fetch_sub_u8(&msp430_clock_refcounts[clock], 1);
+    (void)before;
+    assert(before > 0);
+}
+
+void pm_set_lowest(void)
+{
+    /* disable IRQs, wait two cycles for this to take effect, backup
+     * state register */
+    uint16_t state;
+    __asm__ volatile(
+        "bic %[gie], SR"                    "\n\t"
+        "nop"                               "\n\t"
+        "nop"                               "\n\t"
+        "mov.w SR, %[state]"                "\n\t"
+        : [state]   "=r"(state)
+        : [gie]     "i"(GIE)
+        : "memory"
+    );
+
+    /* When applying the power safe mode, we want to be able to wake up again.
+     * So set global interrupt enable then. */
+    state |= GIE;
+    /* disabling CPU works always, even when keeping the clocks running */
+    state |= CPUOFF | SCG0;
+
+    if (msp430_clock_refcounts[MSP430_CLOCK_SUBMAIN] == 0) {
+        state |= SCG1;
+    }
+
+    if (msp430_clock_refcounts[MSP430_CLOCK_AUXILIARY] == 0) {
+        state |= OSCOFF;
+    }
+
+    /* write new state */
+    __asm__ volatile(
+        "mov.w %[state], SR"                "\n\t"
+        : /* no outputs */
+        : [state]   "r"(state)
+        : "memory"
+    );
+}

cpu/msp430/include/cpu.h

@@ -36,6 +36,11 @@ extern "C" {
  */
 #define WORDSIZE 16
 
+/**
+ * @brief   MSP430 has power management support
+ */
+#define PROVIDES_PM_SET_LOWEST
+
 /**
  * @brief   Macro for defining interrupt service routines
  */
@@ -94,6 +99,14 @@ static inline void __attribute__((always_inline)) __restore_context(void)
  */
 static inline void __attribute__((always_inline)) __enter_isr(void)
 {
+    /* modify state register pushed to stack to not got to power saving
+     * mode right again */
+    __asm__ volatile(
+        "bic %[mask], 0(SP)"            "\n\t"
+        : /* no outputs */
+        : [mask]    "i"(CPUOFF | SCG0 | SCG1 | OSCOFF)
+        : "memory"
+    );
     extern char __stack;    /* defined by linker script to end of RAM */
     __save_context();
     __asm__("mov.w %0,r1" : : "i"(&__stack));

cpu/msp430/include/irq_arch.h

@@ -44,8 +44,8 @@ __attribute__((always_inline)) static inline unsigned int irq_disable(void)
 {
     unsigned int state;
     __asm__ volatile(
-        "mov.w r2, %[state]"                "\n\t"
-        "bic %[gie], r2"                    "\n\t"
+        "mov.w SR, %[state]"                "\n\t"
+        "bic %[gie], SR"                    "\n\t"
         "nop"                               "\n\t"
         "and %[gie], %[state]"              "\n\t"
         : [state]   "=r"(state)
@@ -60,9 +60,9 @@ __attribute__((always_inline)) static inline unsigned int irq_enable(void)
 {
     unsigned int state;
     __asm__ volatile(
-        "mov.w r2, %[state]"                "\n\t"
+        "mov.w SR, %[state]"                "\n\t"
         "nop"                               "\n\t"
-        "bis %[gie], r2"                    "\n\t"
+        "bis %[gie], SR"                    "\n\t"
         "nop"                               "\n\t"
         "and %[gie], %[state]"              "\n\t"
         : [state]   "=r"(state)
@@ -76,7 +76,7 @@ __attribute__((always_inline)) static inline unsigned int irq_enable(void)
 __attribute__((always_inline)) static inline void irq_restore(unsigned int state)
 {
     __asm__ volatile(
-        "bis %[state], r2"                    "\n\t"
+        "bis %[state], SR"                    "\n\t"
         "nop"                                 "\n\t"
         : /* no outputs */
         : [state]   "r"(state)
@@ -93,7 +93,7 @@ __attribute__((always_inline)) static inline bool irq_is_enabled(void)
 {
     unsigned int state;
     __asm__ volatile(
-        "mov.w r2,%[state]"                   "\n\t"
+        "mov.w SR,%[state]"                   "\n\t"
         : [state]   "=r"(state)
         : /* no inputs */
         : "memory"

cpu/msp430/include/periph_cpu_common.h

@@ -311,6 +311,17 @@ typedef enum {
     TIMER_CLOCK_SOURCE_INCLK = TXSSEL_INCLK,            /**< External INCLK as clock source */
 } msp430_timer_clock_source_t;
 
+/**
+ * @brief   IDs of the different clock domains on the MSP430
+ *
+ * These can be used as internal clock sources for peripherals
+ */
+typedef enum {
+    MSP430_CLOCK_SUBMAIN,                               /**< Subsystem main clock */
+    MSP430_CLOCK_AUXILIARY,                             /**< Auxiliary clock */
+    MSP430_CLOCK_NUMOF,                                 /**< Number of clock domains */
+} msp430_clock_t;
+
 /**
  * @brief   Timer configuration on an MSP430 timer
  */
@@ -367,6 +378,28 @@ uint32_t PURE msp430_submain_clock_freq(void);
  */
 uint32_t PURE msp430_auxiliary_clock_freq(void);
 
+/**
+ * @brief   Increase the refcount of the given clock
+ *
+ * @param[in]   clock       clock domain to acquire
+ *
+ * @warning This is an internal function and must only be called from
+ *          peripheral drivers
+ * @note    An assertion will blow when the count exceeds capacity
+ */
+void msp430_clock_acquire(msp430_clock_t clock);
+
+/**
+ * @brief   Decrease the refcount of the subsystem main clock
+ *
+ * @param[in]   clock       clock domain to acquire
+ *
+ * @warning This is an internal function and must only be called from
+ *          peripheral drivers
+ * @note    An assertion will blow when the count drops below zero
+ */
+void msp430_clock_release(msp430_clock_t clock);
+
 #ifdef __cplusplus
 }
 #endif

cpu/msp430/periph/timer.c

@@ -30,8 +30,6 @@
 #include "compiler_hints.h"
 #include "cpu.h"
 #include "periph/timer.h"
-#include "periph_conf.h"
-#include "periph_cpu.h"
 
 /**
  * @brief   Interrupt context for each configured timer
@@ -114,8 +112,8 @@ int timer_init(tim_t dev, uint32_t freq, timer_cb_t cb, void *arg)
     for (unsigned i = 0; i < timer_query_channel_numof(dev); i++) {
         msptimer->CCTL[i] = 0;
     }
-    /* start the timer in continuous mode */
-    msptimer->CTL = ctl | TXMC_CONT;
+
+    timer_start(dev);
     return 0;
 }
 
@@ -157,14 +155,39 @@ void timer_start(tim_t dev)
 {
     assume((unsigned)dev < TIMER_NUMOF);
     msp430_timer_t *msptimer = timer_conf[dev].timer;
+    /* acquire clock */
+    switch (timer_conf[dev].clock_source) {
+    case TIMER_CLOCK_SOURCE_SUBMAIN_CLOCK:
+        msp430_clock_acquire(MSP430_CLOCK_SUBMAIN);
+        break;
+    case TIMER_CLOCK_SOURCE_AUXILIARY_CLOCK:
+        msp430_clock_acquire(MSP430_CLOCK_AUXILIARY);
+        break;
+    default:
+        /* external clock source, safe to disable internal clocks */
+        break;
+    }
     msptimer->CTL |= TXMC_CONT;
 }
 
 void timer_stop(tim_t dev)
 {
     assume((unsigned)dev < TIMER_NUMOF);
     msp430_timer_t *msptimer = timer_conf[dev].timer;
-    msptimer->CTL &= ~(TXMC_MASK);
+    msptimer->CTL &= ~(TXMC_CONT);
+
+    /* release clock */
+    switch (timer_conf[dev].clock_source) {
+    case TIMER_CLOCK_SOURCE_SUBMAIN_CLOCK:
+        msp430_clock_release(MSP430_CLOCK_SUBMAIN);
+        break;
+    case TIMER_CLOCK_SOURCE_AUXILIARY_CLOCK:
+        msp430_clock_release(MSP430_CLOCK_AUXILIARY);
+        break;
+    default:
+        /* external clock source, nothing to release */
+        break;
+    }
 }
 
 __attribute__((pure))

cpu/msp430/periph/usart.c

@@ -64,16 +64,32 @@ static mutex_t usart_locks[USART_NUMOF] = {
     MUTEX_INIT,
 };
 
+/* store the clock acquired by each USART, so it can be release again */
+static msp430_usart_clk_t _clocks_acquired[USART_NUMOF];
+
 void msp430_usart_acquire(const msp430_usart_params_t *params,
-                       const msp430_usart_conf_t *conf,
-                       uint8_t enable_mask)
+                          const msp430_usart_conf_t *conf,
+                          uint8_t enable_mask)
 {
     assume(params->num < USART_NUMOF);
 
     mutex_lock(&usart_locks[params->num]);
     msp430_usart_t *dev = params->dev;
     msp430_usart_sfr_t *sfr = params->sfr;
 
+    _clocks_acquired[params->num] = conf->prescaler.clk_source;
+    switch (_clocks_acquired[params->num]) {
+    case USART_CLK_SUBMAIN:
+        msp430_clock_acquire(MSP430_CLOCK_SUBMAIN);
+        break;
+    case USART_CLK_AUX:
+        msp430_clock_acquire(MSP430_CLOCK_AUXILIARY);
+        break;
+    default:
+        /* external clock from GPIO, safe to disable internal clocks */
+        break;
+    }
+
     /* first, make sure USART is off before reconfiguring it */
     sfr->ME = 0;
     /* reset USART */
@@ -105,6 +121,18 @@ void msp430_usart_release(const msp430_usart_params_t *params)
     sfr->IE = 0;
     sfr->IFG = 0;
 
+    switch (_clocks_acquired[params->num]) {
+    case USART_CLK_SUBMAIN:
+        msp430_clock_release(MSP430_CLOCK_SUBMAIN);
+        break;
+    case USART_CLK_AUX:
+        msp430_clock_release(MSP430_CLOCK_AUXILIARY);
+        break;
+    default:
+        /* external clock from GPIO, not managed here */
+        break;
+    }
+
     /* Release mutex */
     mutex_unlock(&usart_locks[params->num]);
 }

cpu/msp430/periph/usci.c

@@ -93,6 +93,8 @@ static mutex_t _usci_locks[MSP430_USCI_ID_NUMOF] = {
     MUTEX_INIT,
 };
 
+static uint8_t _auxiliary_clock_acquired;
+
 void msp430_usci_acquire(const msp430_usci_params_t *params,
                          const msp430_usci_conf_t *conf)
 {
@@ -101,6 +103,23 @@ void msp430_usci_acquire(const msp430_usci_params_t *params,
     mutex_lock(&_usci_locks[params->id]);
     msp430_usci_b_t *dev = params->dev;
 
+    /* We only need to acquire the auxiliary (low frequency) clock domain, as
+     * the subsystem main clock (SMCLK) will be acquired on-demand when activity
+     * is detected on RXD, as per datasheet:
+     *
+     * > The USCI module provides automatic clock activation for SMCLK for use
+     * > with low-power modes.
+     */
+    switch (conf->prescaler.clk_source) {
+    case USCI_CLK_AUX:
+        msp430_clock_acquire(MSP430_CLOCK_AUXILIARY);
+        _auxiliary_clock_acquired |= 1U << params->id;
+        break;
+    default:
+        _auxiliary_clock_acquired &= ~(1U << params->id);
+        break;
+    }
+
     /* put device in disabled/reset state */
     dev->CTL1 = UCSWRST;
 
@@ -133,6 +152,10 @@ void msp430_usci_release(const msp430_usci_params_t *params)
     unsigned irq_mask = irq_disable();
     *params->interrupt_enable &= clear_irq_mask;
     *params->interrupt_flag &= clear_irq_mask;
+
+    if (_auxiliary_clock_acquired & (1U << params->id)) {
+        msp430_clock_release(MSP430_CLOCK_AUXILIARY);
+    }
     irq_restore(irq_mask);
 
     /* Release mutex */

examples/gnrc_lorawan/Makefile.ci

@@ -6,8 +6,6 @@ BOARD_INSUFFICIENT_MEMORY := \
     atmega328p \
     atmega328p-xplained-mini \
     atmega8 \
-    msb-430 \
-    msb-430h \
     nucleo-c031c6 \
     nucleo-f031k6 \
     nucleo-f042k6 \
@@ -17,6 +15,5 @@ BOARD_INSUFFICIENT_MEMORY := \
     stk3200 \
     stm32f030f4-demo \
     stm32f0discovery \
-    telosb \
     weact-g030f6 \
     #

examples/suit_update/Makefile.ci

@@ -8,8 +8,6 @@ BOARD_INSUFFICIENT_MEMORY := \
     e104-bt5011a-tb \
     gd32vf103c-start \
     lsn50 \
-    msb-430 \
-    msb-430h \
     nucleo-c031c6 \
     nucleo-f030r8 \
     nucleo-f031k6 \
@@ -32,5 +30,4 @@ BOARD_INSUFFICIENT_MEMORY := \
     slstk3400a \
     stk3200 \
     stm32f0discovery \
-    telosb \
     #

tests/drivers/atwinc15x0/Makefile.ci

@@ -9,8 +9,6 @@ BOARD_INSUFFICIENT_MEMORY := \
     atmega8 \
     bluepill-stm32f030c8 \
     i-nucleo-lrwan1 \
-    msb-430 \
-    msb-430h \
     nucleo-c031c6 \
     nucleo-f030r8 \
     nucleo-f031k6 \