altos/lpc: Add fast timer

[fw/altos] / src / lpc / ao_fast_timer_lpc.c

diff --git a/src/lpc/ao_fast_timer_lpc.c b/src/lpc/ao_fast_timer_lpc.c
new file mode 100644 (file)
index 0000000..c4f26fc
--- /dev/null
+++ b/src/lpc/ao_fast_timer_lpc.c
@@ -0,0 +1,110 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include <ao.h>
+#include <ao_fast_timer.h>
+
+static void (*ao_fast_timer_callback[AO_FAST_TIMER_MAX])(void);
+static uint8_t ao_fast_timer_count;
+static uint8_t ao_fast_timer_users;
+
+static void
+ao_fast_timer_enable(void)
+{
+       lpc_ct16b0.tcr = ((1 << LPC_CT16B_TCR_CEN) |
+                         (1 << LPC_CT16B_TCR_CRST));
+}
+
+static void
+ao_fast_timer_disable(void)
+{
+       lpc_ct16b0.tcr = ((0 << LPC_CT16B_TCR_CEN) |
+                         (0 << LPC_CT16B_TCR_CRST));
+}
+
+void
+ao_fast_timer_on(void (*callback)(void))
+{
+       ao_fast_timer_callback[ao_fast_timer_count] = callback;
+       if (!ao_fast_timer_count++)
+               ao_fast_timer_enable();
+}
+
+void
+ao_fast_timer_off(void (*callback)(void))
+{
+       uint8_t n;
+
+       for (n = 0; n < ao_fast_timer_count; n++)
+               if (ao_fast_timer_callback[n] == callback) {
+                       for (; n < ao_fast_timer_count-1; n++) {
+                               ao_fast_timer_callback[n] = ao_fast_timer_callback[n+1];
+                       }
+                       if (!--ao_fast_timer_count)
+                               ao_fast_timer_disable();
+                       break;
+               }
+}
+
+void lpc_ct16b0_isr(void)
+{
+       uint32_t        v = lpc_ct16b0.ir;
+       int             i;
+
+       lpc_ct16b0.ir = v;
+       if (v & (1 << LPC_CT16B_IR_MR0INT)) {
+               for (i = 0; i < ao_fast_timer_count; i++)
+                       (*ao_fast_timer_callback[i])();
+       }
+}
+
+#ifndef FAST_TIMER_FREQ
+#define FAST_TIMER_FREQ        10000
+#endif
+
+#define TIMER_FAST     (AO_LPC_SYSCLK / FAST_TIMER_FREQ)
+
+void
+ao_fast_timer_init(void)
+{
+       if (!ao_fast_timer_users) {
+
+               lpc_nvic_set_enable(LPC_ISR_CT16B0_POS);
+               lpc_nvic_set_priority(LPC_ISR_CT16B0_POS, AO_LPC_NVIC_CLOCK_PRIORITY);
+               /* Turn on 16-bit timer CT16B0 */
+
+               lpc_scb.sysahbclkctrl |= 1 << LPC_SCB_SYSAHBCLKCTRL_CT16B0;
+
+               /* Disable timer */
+               lpc_ct16b0.tcr = 0;
+
+               /* scale factor 1 */
+               lpc_ct16b0.pr = 0;
+               lpc_ct16b0.pc = 0;
+
+               lpc_ct16b0.mcr = ((1 << LPC_CT16B_MCR_MR0I) |
+                                 (1 << LPC_CT16B_MCR_MR0R));
+
+               lpc_ct16b0.mr[0] = TIMER_FAST;
+
+               ao_fast_timer_disable();
+       }
+       if (ao_fast_timer_users == AO_FAST_TIMER_MAX)
+               ao_panic(AO_PANIC_FAST_TIMER);
+       ao_fast_timer_users++;
+}
+