From 4a6e19ed3878839f80e74861b98fe6a65a5d7e35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Beno=C3=AEt=20Th=C3=A9baudeau?=
 <benoit.thebaudeau.dev@gmail.com>
Date: Sun, 13 Dec 2015 02:33:31 +0100
Subject: [PATCH] cc2538: pwm: Automatically disable PM1+ if running
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The peripheral core clocks of the PWM timers are gated in PM1+, so these
power modes must be disabled if a PWM timer is running. Use
lpm_register_peripheral() to handle this automatically and dynamically.

Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau.dev@gmail.com>
---
 cpu/cc2538/dev/pwm.c              | 18 ++++++++++++++++++
 cpu/cc2538/dev/pwm.h              |  3 +--
 cpu/cc2538/lpm.c                  |  2 +-
 examples/zolertia/zoul/test-pwm.c |  4 ----
 4 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/cpu/cc2538/dev/pwm.c b/cpu/cc2538/dev/pwm.c
index 837efcb14..d6b5b9286 100644
--- a/cpu/cc2538/dev/pwm.c
+++ b/cpu/cc2538/dev/pwm.c
@@ -46,6 +46,7 @@
 #include "dev/gpio.h"
 #include "dev/sys-ctrl.h"
 #include "dev/pwm.h"
+#include "lpm.h"
 #include <stdio.h>
 #include <stdlib.h>
 /*---------------------------------------------------------------------------*/
@@ -73,6 +74,21 @@ pwm_configured(uint8_t timer, uint8_t ab)
   return 0;
 }
 /*---------------------------------------------------------------------------*/
+static bool
+permit_pm1(void)
+{
+  uint8_t timer, ab;
+
+  for(timer = PWM_TIMER_0; timer <= PWM_TIMER_3; timer++)
+    for(ab = PWM_TIMER_A; ab <= PWM_TIMER_B; ab++)
+      if(pwm_configured(timer, ab) &&
+         REG(PWM_GPTIMER_NUM_TO_BASE(timer) + GPTIMER_CTL) &
+           (ab == PWM_TIMER_A ? GPTIMER_CTL_TAEN : GPTIMER_CTL_TBEN))
+        return false;
+
+  return true;
+}
+/*---------------------------------------------------------------------------*/
 int8_t
 pwm_enable(uint32_t freq, uint8_t duty, uint8_t timer, uint8_t ab)
 {
@@ -95,6 +111,8 @@ pwm_enable(uint32_t freq, uint8_t duty, uint8_t timer, uint8_t ab)
 
   PRINTF("PWM: F%08luHz: %u%% on GPT%u-%u\n", freq, duty, timer, ab);
 
+  lpm_register_peripheral(permit_pm1);
+
   gpt_base = PWM_GPTIMER_NUM_TO_BASE(timer);
   gpt_en = GPTIMER_CTL_TAEN;
   gpt_dir = GPTIMER_CTL_TAPWML;
diff --git a/cpu/cc2538/dev/pwm.h b/cpu/cc2538/dev/pwm.h
index f80402f31..744fa4b6c 100644
--- a/cpu/cc2538/dev/pwm.h
+++ b/cpu/cc2538/dev/pwm.h
@@ -47,8 +47,7 @@
  * Depending on the specific needs these limits can be changed to meet a given
  * duty cycle and lower frequencies by using the prescaler (GPTIMER_TnPR).
  *
- * The PWM timer is stopped when dropping below PM0, alternatively you can set
- * LPM_CONF_MAX_PM to zero, or call lpm_max_pm(0)
+ * Running a PWM timer prevents the LPM driver from dropping to PM1+.
  *
  * @{
  *
diff --git a/cpu/cc2538/lpm.c b/cpu/cc2538/lpm.c
index 3aacf5149..7e582c6fb 100644
--- a/cpu/cc2538/lpm.c
+++ b/cpu/cc2538/lpm.c
@@ -101,7 +101,7 @@ 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 4
+#define LPM_PERIPH_PERMIT_PM1_FUNCS_MAX 5
 #endif
 
 static lpm_periph_permit_pm1_func_t
diff --git a/examples/zolertia/zoul/test-pwm.c b/examples/zolertia/zoul/test-pwm.c
index 7048b2a01..a19412a9d 100644
--- a/examples/zolertia/zoul/test-pwm.c
+++ b/examples/zolertia/zoul/test-pwm.c
@@ -35,10 +35,6 @@
  * \defgroup remote-test-pwm Test the CC2538 PWM driver
  *
  * Demonstrates the use of the CC2538 PWM driver for the Zolertia's Zoul boards
- * The PWM timer is stopped when dropping below PM0, alternatively you can set
- * LPM_CONF_MAX_PM to zero, or call lpm_max_pm(0).  In this example is not 
- * needed as we disable RDC in the Makefile, and the CC2538 never drops below
- * PM0
  *
  * @{
  *