Initial Release

src/rp2_common/hardware_xosc/CMakeLists.txt

@@ -0,0 +1 @@
+pico_simple_hardware_target(xosc)

src/rp2_common/hardware_xosc/include/hardware/xosc.h

@@ -0,0 +1,50 @@
+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef _HARDWARE_XOSC_H_
+#define _HARDWARE_XOSC_H_
+
+#include "pico.h"
+#include "hardware/structs/xosc.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/** \file hardware/xosc.h
+ *  \defgroup hardware_xosc hardware_xosc
+ *
+ * Crystal Oscillator (XOSC) API
+ */
+
+/*! \brief  Initialise the crystal oscillator system
+ *  \ingroup hardware_xosc
+ *
+ * This function will block until the crystal oscillator has stabilised.
+ **/
+void xosc_init(void);
+
+/*! \brief  Disable the Crystal oscillator
+ *  \ingroup hardware_xosc
+ *
+ * Turns off the crystal oscillator source, and waits for it to become unstable
+ **/
+void xosc_disable(void);
+
+/*! \brief Set the crystal oscillator system to dormant
+ *  \ingroup hardware_xosc
+ *
+ * Turns off the crystal oscillator until it is woken by an interrupt. This will block and hence
+ * the entire system will stop, until an interrupt wakes it up. This function will
+ * continue to block until the oscillator becomes stable after its wakeup.
+ **/
+void xosc_dormant(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

src/rp2_common/hardware_xosc/xosc.c

@@ -0,0 +1,46 @@
+/*
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include "pico.h"
+
+// For MHZ definitions etc
+#include "hardware/clocks.h"
+
+#include "hardware/platform_defs.h"
+#include "hardware/regs/xosc.h"
+#include "hardware/structs/xosc.h"
+
+void xosc_init(void) {
+    // Assumes 1-15 MHz input
+    assert(XOSC_MHZ <= 15);
+    xosc_hw->ctrl = XOSC_CTRL_FREQ_RANGE_VALUE_1_15MHZ;
+
+    // Set xosc startup delay
+    uint32_t startup_delay = (((12 * MHZ) / 1000) + 128) / 256;
+    xosc_hw->startup = startup_delay;
+
+    // Set the enable bit now that we have set freq range and startup delay
+    hw_set_bits(&xosc_hw->ctrl, XOSC_CTRL_ENABLE_VALUE_ENABLE << XOSC_CTRL_ENABLE_LSB);
+
+    // Wait for XOSC to be stable
+    while(!(xosc_hw->status & XOSC_STATUS_STABLE_BITS));
+}
+
+void xosc_disable(void) {
+    uint32_t tmp = xosc_hw->ctrl;
+    tmp &= (~XOSC_CTRL_ENABLE_BITS);
+    tmp |= (XOSC_CTRL_ENABLE_VALUE_DISABLE << XOSC_CTRL_ENABLE_LSB);
+    xosc_hw->ctrl = tmp;
+    // Wait for stable to go away
+    while(xosc_hw->status & XOSC_STATUS_STABLE_BITS);
+}
+
+void xosc_dormant(void) {
+    // WARNING: This stops the xosc until woken up by an irq
+    xosc_hw->dormant = XOSC_DORMANT_VALUE_DORMANT;
+    // Wait for it to become stable once woken up
+    while(!(xosc_hw->status & XOSC_STATUS_STABLE_BITS));
+}