libmaple/stm32.h: Add STM32_TIMER_MASK, STM32_HAVE_TIMER.

Feature-test macros for dealing with the fact that timer support has
holes. STM32_TIMER_MASK is a bitmask where bit n is set when TIMERn is
present. STM32_HAVE_TIMER(n) just tests whether bit n is set in
STM32_TIMER_MASK.

This is necessary because e.g. the STM32F100RB has timers 1-4, 6, 7,
and 15-17.  Because of this, the usual STM32_NR_whatever won't work,
and we use a bitmask instead.

For F1 performance line (F103s), STM32_TIMER_MASK can be derived from
the density. For F1 value line, I'm not as sure, so just add it for
the single MCU we support (the STM32F100RB). Same story for F2: add it
for the STM32F207IC. We can fix this up later if necessary.

Signed-off-by: Marti Bolivar <mbolivar@leaflabs.com>

3 files changed, 48 insertions, 4 deletions

diff --git a/libmaple/include/libmaple/stm32.h b/libmaple/include/libmaple/stm32.h
index 097a016..94fb689 100644
--- a/libmaple/include/libmaple/stm32.h
+++ b/libmaple/include/libmaple/stm32.h
@@ -70,14 +70,36 @@ extern "C" {
 #include <series/stm32.h>
 
 /* Ensure the series header isn't broken. */
-#if (!defined(STM32_PCLK1)         || !defined(STM32_PCLK2)         || \
-     !defined(STM32_MCU_SERIES)    || !defined(STM32_NR_INTERRUPTS) || \
-     !defined(STM32_NR_GPIO_PORTS) || !defined(STM32_DELAY_US_MULT) || \
-     !defined(STM32_SRAM_END)      || !defined(STM32_HAVE_FSMC)     || \
+#if (!defined(STM32_PCLK1)         ||     \
+     !defined(STM32_PCLK2)         ||     \
+     !defined(STM32_MCU_SERIES)    ||     \
+     !defined(STM32_NR_INTERRUPTS) ||     \
+     !defined(STM32_NR_GPIO_PORTS) ||     \
+     !defined(STM32_TIMER_MASK)    ||     \
+     !defined(STM32_DELAY_US_MULT) ||     \
+     !defined(STM32_SRAM_END)      ||     \
+     !defined(STM32_HAVE_FSMC)     ||     \
      !defined(STM32_HAVE_USB))
 #error "Bad STM32F1 configuration. Check <series/stm32.h> header for your MCU."
 #endif
 
+/*
+ * Derived macros
+ */
+
+/* FIXME [0.0.13] add this to ReST API page */
+/**
+ * @brief Statically determine whether a timer is present.
+ *
+ * Given a constant timer number n (starting from 1), this macro has a
+ * nonzero value exactly when TIMERn is available.
+ */
+#define STM32_HAVE_TIMER(n) (STM32_TIMER_MASK & (1 << (n)))
+
+/*
+ * Doxygen for functionality provided by series header.
+ */
+
 #ifdef __DOXYGEN__
 
 /*
@@ -128,6 +150,19 @@ extern "C" {
  */
 #define STM32_NR_GPIO_PORTS
 
+/* FIXME [0.0.13] add this to ReST API page */
+/**
+ * @brief Bitmask of timers available on the MCU.
+ *
+ * That is, if TIMERn is available, then STM32_TIMER_MASK & (1 << n)
+ * will be nonzero. For example, a nonzero value of "STM32_TIMER_MASK
+ * & 0x2" means TIMER1 is available.
+ *
+ * A bitmask is necessary as some STM32 MCUs have "holes" in the range
+ * of available timers.
+ */
+#define STM32_TIMER_MASK
+
 /**
  * @brief Multiplier to convert microseconds into loop iterations
  *        in delay_us().
diff --git a/libmaple/stm32f1/include/series/stm32.h b/libmaple/stm32f1/include/series/stm32.h
index e01c494..59205c3 100644
--- a/libmaple/stm32f1/include/series/stm32.h
+++ b/libmaple/stm32f1/include/series/stm32.h
@@ -94,6 +94,7 @@ extern "C" {
 #elif defined(MCU_STM32F100RB)
 #   define STM32_F1_LINE                STM32_F1_LINE_VALUE
 #   define STM32_NR_GPIO_PORTS          4
+#   define STM32_TIMER_MASK             0x380DE /* Timers: 1-4, 6, 7, 15-17. */
 #   define STM32_SRAM_END               ((void*)0x20002000)
 #   define STM32_MEDIUM_DENSITY
 
@@ -112,9 +113,16 @@ extern "C" {
 
 #    ifdef STM32_MEDIUM_DENSITY
 #       define STM32_NR_INTERRUPTS      43
+#       define STM32_TIMER_MASK         0x1E /* TIMER1--TIMER4 */
 #       define STM32_HAVE_FSMC          0
 #    elif defined(STM32_HIGH_DENSITY)
 #       define STM32_NR_INTERRUPTS      60
+#       define STM32_TIMER_MASK         0x1FE /* TIMER1--TIMER8 */
+#       define STM32_HAVE_FSMC          1
+#    endif
+#    elif defined(STM32_XL_DENSITY)
+#       define STM32_NR_INTERRUPTS      60
+#       define STM32_TIMER_MASK         0x7FFE /* TIMER1--TIMER14 */
 #       define STM32_HAVE_FSMC          1
 #    endif
 
diff --git a/libmaple/stm32f2/include/series/stm32.h b/libmaple/stm32f2/include/series/stm32.h
index 9e88a70..b53b7b6 100644
--- a/libmaple/stm32f2/include/series/stm32.h
+++ b/libmaple/stm32f2/include/series/stm32.h
@@ -63,6 +63,7 @@ extern "C" {
 
 #if defined(MCU_STM32F207IC) || defined(MCU_STM32F207IG)
 #   define STM32_NR_GPIO_PORTS          9
+#   define STM32_TIMER_MASK             0x7FFE /* TIMER1-TIMER14. */
 #   define STM32_SRAM_END               ((void*)0x20020000)
 #else
 #error "Unrecognized STM32F2 MCU, or no MCU specified."