Add FreeRTOS-Plus directory.

FreeRTOS/Demo/Common/drivers/Atmel/at91lib/peripherals/tc/tc.c

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+/* ----------------------------------------------------------------------------
+ *         ATMEL Microcontroller Software Support 
+ * ----------------------------------------------------------------------------
+ * Copyright (c) 2008, Atmel Corporation
+ *
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * - Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the disclaimer below.
+ *
+ * Atmel's name may not be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * DISCLAIMER: THIS SOFTWARE IS PROVIDED BY ATMEL "AS IS" AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT ARE
+ * DISCLAIMED. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
+ * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ----------------------------------------------------------------------------
+ */
+
+//------------------------------------------------------------------------------
+//         Headers
+//------------------------------------------------------------------------------
+
+#include "tc.h"
+
+//------------------------------------------------------------------------------
+//         Global functions
+//------------------------------------------------------------------------------
+
+//------------------------------------------------------------------------------
+/// Configures a Timer Counter to operate in the given mode. Timer is stopped
+/// after configuration and must be restarted with TC_Start().
+/// to obtain the target frequency.
+/// \param pTc  Pointer to an AT91S_TC instance.
+/// \param mode  Operating mode.
+//------------------------------------------------------------------------------
+void TC_Configure(AT91S_TC *pTc, unsigned int mode)
+{
+    // Disable TC clock
+    pTc->TC_CCR = AT91C_TC_CLKDIS;
+
+    // Disable interrupts
+    pTc->TC_IDR = 0xFFFFFFFF;
+
+    // Clear status register
+    pTc->TC_SR;
+
+    // Set mode
+    pTc->TC_CMR = mode;
+}
+
+//------------------------------------------------------------------------------
+/// Starts the timer clock.
+/// \param pTc  Pointer to an AT91S_TC instance.
+//------------------------------------------------------------------------------
+void TC_Start(AT91S_TC *pTc)
+{
+    pTc->TC_CCR = AT91C_TC_CLKEN | AT91C_TC_SWTRG;
+}
+
+//------------------------------------------------------------------------------
+/// Stops the timer clock.
+/// \param pTc  Pointer to an AT91S_TC instance.
+//------------------------------------------------------------------------------
+void TC_Stop(AT91S_TC *pTc)
+{
+    pTc->TC_CCR = AT91C_TC_CLKDIS;
+}
+
+//------------------------------------------------------------------------------
+/// Finds the best MCK divisor given the timer frequency and MCK. The result
+/// is guaranteed to satisfy the following equation:
+///   (MCK / (DIV * 65536)) <= freq <= (MCK / DIV)
+/// with DIV being the highest possible value.
+/// Returns 1 if a divisor could be found; otherwise returns 0.
+/// \param freq  Desired timer frequency.
+/// \param mck  Master clock frequency.
+/// \param div  Divisor value.
+/// \param tcclks  TCCLKS field value for divisor.
+//------------------------------------------------------------------------------
+unsigned char TC_FindMckDivisor(
+    unsigned int freq,
+    unsigned int mck,
+    unsigned int *div,
+    unsigned int *tcclks)
+{
+    const unsigned int divisors[5] = {2, 8, 32, 128,
+#if defined(at91sam9260) || defined(at91sam9261) || defined(at91sam9263) \
+    || defined(at91sam9xe) || defined(at91sam9rl64) || defined(at91cap9)
+        BOARD_MCK / 32768};
+#else
+        1024};
+#endif
+    unsigned int index = 0;
+
+    // Satisfy lower bound
+    while (freq < ((mck / divisors[index]) / 65536)) {
+
+        index++;
+
+        // If no divisor can be found, return 0
+        if (index == 5) {
+
+            return 0;
+        }
+    }
+
+    // Try to maximise DIV while satisfying upper bound
+    while (index < 4) {
+
+        if (freq > (mck / divisors[index + 1])) {
+
+            break;
+        }
+        index++;
+    }
+
+    // Store results
+    if (div) {
+
+        *div = divisors[index];
+    }
+    if (tcclks) {
+
+        *tcclks = index;
+    }
+
+    return 1;
+}
+