cc2538: usb: Use the new LPM peripheral registration

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>

cpu/cc2538/lpm.c

@@ -41,7 +41,6 @@
 #include "dev/sys-ctrl.h"
 #include "dev/scb.h"
 #include "dev/rfcore-xreg.h"
-#include "dev/usb-regs.h"
 #include "rtimer-arch.h"
 #include "lpm.h"
 #include "reg.h"
@@ -103,7 +102,7 @@ static uint8_t max_pm;
 #ifdef LPM_CONF_PERIPH_PERMIT_PM1_FUNCS_MAX
 #define LPM_PERIPH_PERMIT_PM1_FUNCS_MAX LPM_CONF_PERIPH_PERMIT_PM1_FUNCS_MAX
 #else
-#define LPM_PERIPH_PERMIT_PM1_FUNCS_MAX 0
+#define LPM_PERIPH_PERMIT_PM1_FUNCS_MAX 1
 #endif
 
 lpm_periph_permit_pm1_func_t
@@ -217,15 +216,12 @@ lpm_enter()
   rtimer_clock_t duration;
 
   /*
-   * If either the RF, the USB or the registered peripherals are on, dropping to
-   * PM1/2 would equal pulling the rug (32MHz XOSC) from under their feet. Thus,
-   * we only drop to PM0. PM0 is also used if max_pm==0.
-   *
-   * Note: USB Suspend/Resume/Remote Wake-Up are not supported. Once the PLL is
-   * on, it stays on.
+   * If either the RF or the registered peripherals are on, dropping to PM1/2
+   * would equal pulling the rug (32MHz XOSC) from under their feet. Thus, we
+   * only drop to PM0. PM0 is also used if max_pm==0.
    */
   if((REG(RFCORE_XREG_FSMSTAT0) & RFCORE_XREG_FSMSTAT0_FSM_FFCTRL_STATE) != 0
-     || REG(USB_CTRL) != 0 || !periph_permit_pm1() || max_pm == 0) {
+     || !periph_permit_pm1() || max_pm == 0) {
     enter_pm0();
 
     /* We reach here when the interrupt context that woke us up has returned */
@@ -233,8 +229,7 @@ lpm_enter()
   }
 
   /*
-   * Registered peripherals were off. USB PLL was off. Radio was off: Some Duty
-   * Cycling in place.
+   * Registered peripherals were off. Radio was off: Some Duty Cycling in place.
    * rtimers run on the Sleep Timer. Thus, if we have a scheduled rtimer
    * task, a Sleep Timer interrupt will fire and will wake us up.
    * Choose the most suitable PM based on anticipated deep sleep duration
@@ -251,7 +246,7 @@ lpm_enter()
   }
 
   /* If we reach here, we -may- (but may as well not) be dropping to PM1+. We
-   * know the registered peripherals, USB and RF are off so we can switch to the
+   * know the registered peripherals and RF are off so we can switch to the
    * 16MHz RCOSC. */
   select_16_mhz_rcosc();
 

cpu/cc2538/lpm.h

@@ -101,7 +101,6 @@ void lpm_init(void);
  *
  * This PM selection heuristic has the following primary criteria:
  * - Is the RF off?
- * - Is the USB PLL off?
  * - Are all registered peripherals permitting PM1+?
  * - Is the Sleep Timer scheduled to fire an interrupt?
  *
@@ -182,7 +181,8 @@ typedef bool (*lpm_periph_permit_pm1_func_t)(void);
  * module to get 'permission' to drop to PM1+
  * \param permit_pm1_func Pointer to the function
  *
- * Some peripherals are sensitive to PM changes.
+ * Some peripherals are sensitive to PM changes. For instance, we don't want to
+ * drop to PM1+ if the USB PLL is active.
  *
  * When changing power modes, the LPM driver will call all FPs registered with
  * this function. The peripheral's function will return true or false to permit

cpu/cc2538/usb/usb-arch.c

@@ -46,10 +46,12 @@
 #include "dev/ioc.h"
 #include "dev/udma.h"
 #include "sys/clock.h"
+#include "lpm.h"
 #include "reg.h"
 
 #include "dev/watchdog.h"
 
+#include <stdbool.h>
 #include <stdint.h>
 /*---------------------------------------------------------------------------*/
 /* EP max FIFO sizes without double buffering */
@@ -303,12 +305,24 @@ reset(void)
   usb_arch_setup_control_endpoint(0);
 }
 /*---------------------------------------------------------------------------*/
+static bool
+permit_pm1(void)
+{
+  /*
+   * Note: USB Suspend/Resume/Remote Wake-Up are not supported. Once the PLL is
+   * on, it stays on.
+   */
+  return REG(USB_CTRL) == 0;
+}
+/*---------------------------------------------------------------------------*/
 /* Init USB */
 void
 usb_arch_setup(void)
 {
   uint8_t i;
 
+  lpm_register_peripheral(permit_pm1);
+
   /* Switch on USB PLL & USB module */
   REG(USB_CTRL) = USB_CTRL_USB_EN | USB_CTRL_PLL_EN;
 

platform/cc2538dk/README.md

@@ -388,7 +388,6 @@ The Low-Power module uses a simple heuristic to determine the best power mode, d
 In a nutshell, the algorithm first answers the following questions:
 
 * Is the RF off?
-* Is the USB PLL off?
 * Are all registered peripherals permitting PM1+?
 * Is the Sleep Timer scheduled to fire an interrupt?