iio: imu: add BNO055 serdev driver

Add a serdev driver for communicating to a BNO055 IMU via serial bus, and
enable the BNO055 core driver to work in this scenario.
Signed-off-by: Andrea Merello <andrea.merello@iit.it>
Link: https://lore.kernel.org/r/20220907132205.28021-13-andrea.merello@iit.itSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/bno055/Kconfig

@@ -2,3 +2,13 @@
 
 config BOSCH_BNO055
 	tristate
+
+config BOSCH_BNO055_SERIAL
+	tristate "Bosch BNO055 attached via UART"
+	depends on SERIAL_DEV_BUS
+	select BOSCH_BNO055
+	help
+	  Enable this to support Bosch BNO055 IMUs attached via UART.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called bno055_sl.

drivers/iio/imu/bno055/Makefile

 # SPDX-License-Identifier: GPL-2.0
 
 obj-$(CONFIG_BOSCH_BNO055) += bno055.o
+obj-$(CONFIG_BOSCH_BNO055_SERIAL) += bno055_ser.o
+bno055_ser-y := bno055_ser_core.o
+# define_trace.h needs to know how to find our header
+CFLAGS_bno055_ser_trace.o := -I$(src)
+bno055_ser-$(CONFIG_TRACING) += bno055_ser_trace.o

drivers/iio/imu/bno055/bno055_ser_trace.c

+//SPDX-License-Identifier: GPL-2.0
+
+/*
+ * bno055_ser Trace Support
+ * Copyright (C) 2022 Istituto Italiano di Tecnologia
+ * Electronic Design Laboratory
+ *
+ * Based on:
+ *   Device core Trace Support
+ *   Copyright (C) 2021, Intel Corporation
+ */
+
+#define CREATE_TRACE_POINTS
+#include "bno055_ser_trace.h"

drivers/iio/imu/bno055/bno055_ser_trace.h

+/* SPDX-License-Identifier: GPL-2.0 */
+
+#if !defined(__BNO055_SERDEV_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ)
+#define __BNO055_SERDEV_TRACE_H__
+
+#include <linux/tracepoint.h>
+
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM bno055_ser
+
+TRACE_EVENT(send_chunk,
+	    TP_PROTO(int len, const u8 *data),
+	    TP_ARGS(len, data),
+	    TP_STRUCT__entry(
+		    __field(int, len)
+		    __dynamic_array(u8, chunk, len)
+	    ),
+	    TP_fast_assign(
+		    __entry->len = len;
+		    memcpy(__get_dynamic_array(chunk),
+			   data, __entry->len);
+	    ),
+	    TP_printk("len: %d, data: = %*ph",
+		      __entry->len, __entry->len, __get_dynamic_array(chunk)
+	    )
+);
+
+TRACE_EVENT(cmd_retry,
+	    TP_PROTO(bool read, int addr, int retry),
+	    TP_ARGS(read, addr, retry),
+	    TP_STRUCT__entry(
+		    __field(bool, read)
+		    __field(int, addr)
+		    __field(int, retry)
+	    ),
+	    TP_fast_assign(
+		    __entry->read = read;
+		    __entry->addr = addr;
+		    __entry->retry = retry;
+	    ),
+	    TP_printk("%s addr 0x%x retry #%d",
+		      __entry->read ? "read" : "write",
+		      __entry->addr, __entry->retry
+	    )
+);
+
+TRACE_EVENT(write_reg,
+	    TP_PROTO(u8 addr, u8 value),
+	    TP_ARGS(addr, value),
+	    TP_STRUCT__entry(
+		    __field(u8, addr)
+		    __field(u8, value)
+	    ),
+	    TP_fast_assign(
+		    __entry->addr = addr;
+		    __entry->value = value;
+	    ),
+	    TP_printk("reg 0x%x = 0x%x",
+		      __entry->addr, __entry->value
+	    )
+);
+
+TRACE_EVENT(read_reg,
+	    TP_PROTO(int addr, size_t len),
+	    TP_ARGS(addr, len),
+	    TP_STRUCT__entry(
+		    __field(int, addr)
+		    __field(size_t, len)
+	    ),
+	    TP_fast_assign(
+		    __entry->addr = addr;
+		    __entry->len = len;
+	    ),
+	    TP_printk("reg 0x%x (len %zu)",
+		      __entry->addr, __entry->len
+	    )
+);
+
+TRACE_EVENT(recv,
+	    TP_PROTO(size_t len, const unsigned char *buf),
+	    TP_ARGS(len, buf),
+	    TP_STRUCT__entry(
+		    __field(size_t, len)
+		    __dynamic_array(unsigned char, buf, len)
+	    ),
+	    TP_fast_assign(
+		    __entry->len = len;
+		    memcpy(__get_dynamic_array(buf),
+			   buf, __entry->len);
+	    ),
+	    TP_printk("len: %zu, data: = %*ph",
+		      __entry->len, (int)__entry->len, __get_dynamic_array(buf)
+	    )
+);
+
+#endif /* __BNO055_SERDEV_TRACE_H__ || TRACE_HEADER_MULTI_READ */
+
+#undef TRACE_INCLUDE_PATH
+#define TRACE_INCLUDE_PATH .
+#undef TRACE_INCLUDE_FILE
+#define TRACE_INCLUDE_FILE bno055_ser_trace
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>