Merge branch 'master' into wip/handover

1 files changed, 73 insertions, 0 deletions

diff --git a/lib/pbdrv/drv/rp2040/mod.c b/lib/pbdrv/drv/rp2040/mod.c
new file mode 100644
index 0000000..6becdee
--- /dev/null
+++ b/lib/pbdrv/drv/rp2040/mod.c
@@ -0,0 +1,73 @@
+#include "mod.h"
+
+#include "../../pb.h"
+#include "../../pb-types.h"
+#include "../../pb-mod.h"
+
+#include <hardware/i2c.h>
+#include <hardware/gpio.h>
+#include <pico/i2c_slave.h>
+
+#define PBDRV_I2C i2c0
+#define BUF_SIZE 256
+
+static volatile bool pbdrv_i2c_msg_avail = false;
+static uint8_t data[BUF_SIZE];
+static size_t size = 0;
+
+// TODO: create event group instead of pbdrv_i2c_msg_avail
+// TODO: create freertos task that monitors the pbdrv_i2c_msg_avail flag and
+// calls pbdrv_i2c_recv when a message is received
+
+
+/**
+ * \note this function is called from the I2C ISR, and should return as quickly
+ * as possible.
+ */
+static void recv_event(i2c_inst_t *i2c, i2c_slave_event_t event) {
+	// message needs to be handled first
+	if (pbdrv_i2c_msg_avail) return;
+
+	switch (event) {
+		case I2C_SLAVE_RECEIVE: {
+			if (size == BUF_SIZE) return;
+			data[size++] = i2c_read_byte_raw(PBDRV_I2C);
+			break;
+		}
+		case I2C_SLAVE_FINISH: {
+			// TODO: handle this w/ queue mechanism instead?
+			// pbdrv_i2c_recv(data, size);
+			pbdrv_i2c_msg_avail = true;
+			size = 0;
+			break;
+		}
+		default: break;
+	}
+}
+
+void pbdrv_setup() {
+	i2c_init(PBDRV_I2C, PB_CLOCK_SPEED_HZ);
+	i2c_slave_init(PBDRV_I2C, PBDRV_MOD_ADDR, &recv_event);
+}
+
+/**
+ * While the RP2040's datasheet claims it supports multi-master configurations
+ * by implementing bus arbitration, it does not natively support a mode where
+ * it is configured as a (multi-)master with a slave address, such that it can
+ * be addressed by other multi-masters. This function includes a hacky
+ * workaround that teporarily sets the RP2040 to I2C master mode to send a
+ * message, and then restores it back to slave mode.
+ *
+ * This approach results in some received frames being (partially) dropped in
+ * the time period between the invocation of this function and the bus becoming
+ * idle (and the message is sent).
+ */
+__weak void pbdrv_i2c_send(i2c_addr_t addr, const uint8_t * buf, size_t sz) {
+	i2c_set_slave_mode(PBDRV_I2C, false, PBDRV_MOD_ADDR);
+
+	// false to write stop condition to i2c bus
+	i2c_write_timeout_us(PBDRV_I2C, addr, buf, sz, false, PB_TIMEOUT_US);
+
+	i2c_set_slave_mode(PBDRV_I2C, true, PBDRV_MOD_ADDR);
+}
+