device: store device pm busy status in the state structure

Move the busy status from a global atomic bit sequence to atomic flags in the device PM state. While this temporarily adds 4 bytes to each PM structure the whole device PM infrastructure will be refactored and it's likely the extra memory can be recovered. Signed-off-by: Peter Bigot <[email protected]>
zephyrproject-rtos · Feb 19, 2021 · d1a0568 · d1a0568
1 parent 65eee5c
commit d1a0568
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Showing 3 changed files with 26 additions and 43 deletions.
diff --git a/include/device.h b/include/device.h
@@ -270,8 +270,11 @@ struct device_pm {
  const struct device *dev;
  /** Lock to synchronize the get/put operations */
  struct k_sem lock;
+ /* Following are packed fields protected by #lock. */
  /** Device pm enable flag */
- bool enable;
+ bool enable : 1;
+ /* Following are packed fields accessed with atomic bit operations. */
+ atomic_t atomic_flags;
  /** Device usage count */
  atomic_t usage;
  /** Device idle internal power state */
@@ -284,6 +287,11 @@ struct device_pm {
  struct k_poll_signal signal;
 };
 
+/** Bit position in device_pm::atomic_flags that records whether the
+ * device is busy.
+ */
+#define DEVICE_PM_ATOMIC_FLAGS_BUSY_BIT 0
+
 /**
  * @brief Runtime device dynamic structure (in RAM) per driver instance
  *

diff --git a/include/linker/common-ram.ld b/include/linker/common-ram.ld
@@ -13,27 +13,6 @@
  } GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 #endif
 
-/*
- * Space for storing per device init status and busy bitmap in case PM is
- * enabled. Since we do not know beforehand the number of devices,
- * we go through the below mechanism to allocate the required space.
- * Both are made of 1 bit per-device instance, so we compute the size of
- * of an entire bitfield, aligned on 32bits.
- */
-#define DEVICE_COUNT \
- ((__device_end - __device_start) / _DEVICE_STRUCT_SIZEOF)
-#define DEVICE_BITFIELD_SIZE (((DEVICE_COUNT + 31) / 32) * 4)
-
-#ifdef CONFIG_PM_DEVICE
-#define DEVICE_BUSY_BITFIELD() \
- FILL(0x00); \
- __device_busy_start = .; \
- . = . + DEVICE_BITFIELD_SIZE; \
- __device_busy_end = .;
-#else
-#define DEVICE_BUSY_BITFIELD()
-#endif
-
  SECTION_DATA_PROLOGUE(devices,,)
  {
  /* link in devices objects, which are tied to the init ones;
@@ -47,7 +26,6 @@
  CREATE_OBJ_LEVEL(device, APPLICATION)
  CREATE_OBJ_LEVEL(device, SMP)
  __device_end = .;
- DEVICE_BUSY_BITFIELD()
  } GROUP_DATA_LINK_IN(RAMABLE_REGION, ROMABLE_REGION)
 
  SECTION_DATA_PROLOGUE(initshell,,)

diff --git a/kernel/device.c b/kernel/device.c
@@ -25,12 +25,6 @@ extern const struct device __device_end[];
 
 extern uint32_t __device_init_status_start[];
 
-#ifdef CONFIG_PM_DEVICE
-extern uint32_t __device_busy_start[];
-extern uint32_t __device_busy_end[];
-#define DEVICE_BUSY_SIZE (__device_busy_end - __device_busy_start)
-#endif
-
 static inline void device_pm_state_init(const struct device *dev)
 {
 #ifdef CONFIG_PM_DEVICE
@@ -180,43 +174,46 @@ int device_pm_control_nop(const struct device *unused_device,
 
 int device_any_busy_check(void)
 {
- int i = 0;
+ const struct device *dev = __device_start;
 
- for (i = 0; i < DEVICE_BUSY_SIZE; i++) {
- if (__device_busy_start[i] != 0U) {
+ while (dev < __device_end) {
+ if (atomic_test_bit(&dev->pm->atomic_flags,
+ DEVICE_PM_ATOMIC_FLAGS_BUSY_BIT)) {
  return -EBUSY;
  }
+ ++dev;
  }
+
  return 0;
 }
 
-int device_busy_check(const struct device *chk_dev)
+int device_busy_check(const struct device *dev)
 {
- if (atomic_test_bit((const atomic_t *)__device_busy_start,
- (chk_dev - __device_start))) {
+ if (atomic_test_bit(&dev->pm->atomic_flags,
+ DEVICE_PM_ATOMIC_FLAGS_BUSY_BIT)) {
  return -EBUSY;
  }
  return 0;
 }
 
 #endif
 
-void device_busy_set(const struct device *busy_dev)
+void device_busy_set(const struct device *dev)
 {
 #ifdef CONFIG_PM_DEVICE
- atomic_set_bit((atomic_t *) __device_busy_start,
- (busy_dev - __device_start));
+ atomic_set_bit(&dev->pm->atomic_flags,
+ DEVICE_PM_ATOMIC_FLAGS_BUSY_BIT);
 #else
- ARG_UNUSED(busy_dev);
+ ARG_UNUSED(dev);
 #endif
 }
 
-void device_busy_clear(const struct device *busy_dev)
+void device_busy_clear(const struct device *dev)
 {
 #ifdef CONFIG_PM_DEVICE
- atomic_clear_bit((atomic_t *) __device_busy_start,
- (busy_dev - __device_start));
+ atomic_clear_bit(&dev->pm->atomic_flags,
+ DEVICE_PM_ATOMIC_FLAGS_BUSY_BIT);
 #else
- ARG_UNUSED(busy_dev);
+ ARG_UNUSED(dev);
 #endif
 }