From: batt <batt@38d2e660-2303-0410-9eaa-f027e97ec537>
Date: Fri, 12 Mar 2010 18:02:46 +0000 (+0000)
Subject: Better detection of concurrent ADC access.
X-Git-Tag: 2.4.0~50
X-Git-Url: https://codewiz.org/gitweb?a=commitdiff_plain;h=fe0a14d1434098bfd0780d06a2a7e55f27940d27;p=bertos.git

Better detection of concurrent ADC access.

git-svn-id: https://src.develer.com/svnoss/bertos/trunk@3197 38d2e660-2303-0410-9eaa-f027e97ec537
---

diff --git a/bertos/cpu/arm/drv/adc_at91.c b/bertos/cpu/arm/drv/adc_at91.c
index bb6a8d11..faa0d181 100644
--- a/bertos/cpu/arm/drv/adc_at91.c
+++ b/bertos/cpu/arm/drv/adc_at91.c
@@ -126,13 +126,13 @@ void adc_hw_select_ch(uint8_t ch)
 /**
  * Start an ADC convertion.
  * If a kernel is present, preempt until convertion is complete, otherwise
- * a busy wait on ADCS bit is done.
+ * a busy wait on ADC_DRDY bit is done.
  */
 uint16_t adc_hw_read(void)
 {
-	ASSERT(!(ADC_SR & ADC_EOC_MASK));
-
 	#if CONFIG_KERN
+		/* Ensure ADC is not already in use by another process */
+		ASSERT(adc_process == NULL);
 		adc_process = proc_current();
 	#endif
 
@@ -143,13 +143,19 @@ uint16_t adc_hw_read(void)
 		// Ensure IRQs enabled.
 		IRQ_ASSERT_ENABLED();
 		sig_wait(SIG_ADC_COMPLETE);
+
+		/* Prevent race condition in case of preemptive kernel */
+		uint16_t ret = ADC_LCDR;
+		MEMORY_BARRIER;
+		adc_process = NULL;
+		return ret;
 	#else
 		//Wait in polling until is done
 		while (!(ADC_SR & BV(ADC_DRDY)));
-	#endif
 
-	//Return the last converted data
-	return(ADC_LCDR);
+		//Return the last converted data
+		return(ADC_LCDR);
+	#endif
 }
 
 /**