legacy_apps: zynqmp_r5: add trace buffer support

trace buffer is a circular buffer to store logs. Linux remoteproc
subsystem creates a debugfs file that can be used to print these logs on
linux side.

Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>

Author: tnmysh

examples/legacy_apps/machine/xlnx/zynqmp_r5/platform_info.c

@@ -122,7 +122,7 @@
 #define XLNX_METAL_LOG_LEVEL METAL_LOG_INFO
 #endif
 
-void xlnx_log_handler(enum metal_log_level level, const char *format, ...);
+static void xlnx_log_handler(enum metal_log_level level, const char *format, ...);
 
 #define XLNX_PLATFORM_METAL_INIT_PARAMS \
 { \
@@ -184,6 +184,21 @@ int xlnx_hw_to_bsp_irq(int sys_irq);
 /* RPMsg virtio shared buffer pool */
 static struct rpmsg_virtio_shm_pool shpool;
 
+/* circular buffer for trace buffer */
+static struct {
+	char *c_buf;
+	uint32_t c_len;
+	uint32_t c_pos;
+	uint32_t c_cnt;
+} circ;
+
+static void rsc_trace_putchar(char c)
+{
+	circ.c_buf[circ.c_pos++] = c;
+	if (circ.c_pos >= circ.c_len)
+		circ.c_pos = 0;
+}
+
 static void xlnx_irq_isr(void *arg)
 {
 	int vector;
@@ -248,12 +263,58 @@ platform_create_proc(int proc_index, int rsc_index)
 	return &rproc_inst;
 }
 
+static void xlnx_log_handler(enum metal_log_level level,
+			   const char *format, ...)
+{
+	static const char * const level_strs[] = {
+		"emergency",
+		"alert",
+		"critical",
+		"error",
+		"warning",
+		"notice",
+		"info",
+		"debug",
+	};
+	char msg[128];
+	char *p;
+	int32_t len;
+	va_list args;
+
+	/*
+	 * print unexpected log level with "emergency" level to notify user
+	 * about the error.
+	 */
+	if (level > METAL_LOG_DEBUG)
+		level = METAL_LOG_EMERGENCY;
+
+	len = snprintf(msg, sizeof(msg), "RPU%d: %s: ", XPAR_CPU_ID,
+		       level_strs[level]);
+
+	circ.c_cnt++;
+
+	va_start(args, format);
+	vsnprintf(msg + len, (int32_t)sizeof(msg) - len, format, args);
+	va_end(args);
+
+	/* copy at most sizeof(msg) to the circular buffer */
+	for (len = 0, p = msg; *p && len < (int32_t)sizeof(msg); ++len, ++p)
+		rsc_trace_putchar(*p);
+
+	xil_printf("%s", msg);
+}
+
 static int xlnx_machine_init(void)
 {
 
 	struct metal_init_params metal_param = XLNX_PLATFORM_METAL_INIT_PARAMS;
 	int ret;
 
+	/* Init circular buffer */
+	circ.c_buf = get_rsc_trace_info(&circ.c_len);
+	if (circ.c_buf && circ.c_len)
+		circ.c_pos = circ.c_cnt = 0;
+
 	metal_init(&metal_param);
 
 	if (!kick_device.irq_info) {
@@ -297,21 +358,6 @@ static void xlnx_machine_cleanup(void)
 	Xil_ICacheInvalidate();
 }
 
-void xlnx_log_handler(enum metal_log_level level, const char *format, ...)
-{
-	char msg[1024];
-	va_list args;
-
-	va_start(args, format);
-	vsnprintf(msg, sizeof(msg), format, args);
-	va_end(args);
-
-	if (level > metal_get_log_level())
-		return;
-
-	xil_printf("RPU%d: %s", XPAR_CPU_ID, msg);
-}
-
 int platform_init(int argc, char *argv[], void **platform)
 {
 	unsigned long proc_id = 0;

examples/legacy_apps/machine/xlnx/zynqmp_r5/rsc_table.c

@@ -37,9 +37,11 @@
 #endif /* RING_RX */
 #define VRING_SIZE                  256
 
-#define NUM_TABLE_ENTRIES           1
+#define NUM_TABLE_ENTRIES           2
+#define RSC_TRACE_SZ		    4096
 
 static struct remote_resource_table *initial_resources;
+static char rsc_trace_buf[RSC_TRACE_SZ];
 
 struct remote_resource_table __resource resources = {
 	/* Version */
@@ -51,19 +53,27 @@ struct remote_resource_table __resource resources = {
 	{0, 0,},
 
 	/* Offsets of rsc entries */
-	{
-	 offsetof(struct remote_resource_table, rpmsg_vdev),
-	 },
+	.offset[0] = offsetof(struct remote_resource_table, rpmsg_vdev),
+	.offset[1] = offsetof(struct remote_resource_table, rsc_trace),
 
 	/* Virtio device entry */
-	{
-	 RSC_VDEV, VIRTIO_ID_RPMSG_, 31, RPMSG_VDEV_DFEATURES, 0, 0, 0,
-	 NUM_VRINGS, {0, 0},
-	 },
+	.rpmsg_vdev = {
+		RSC_VDEV, VIRTIO_ID_RPMSG_, 31, RPMSG_VDEV_DFEATURES, 0, 0, 0,
+		NUM_VRINGS, {0, 0},
+	},
 
 	/* Vring rsc entry - part of vdev rsc entry */
 	{RING_TX, VRING_ALIGN, VRING_SIZE, 1, 0},
 	{RING_RX, VRING_ALIGN, VRING_SIZE, 2, 0},
+
+	/* trace buffer for logs, accessible via debugfs */
+	.rsc_trace = {
+		.type =		RSC_TRACE,
+		.da =		(uint32_t)rsc_trace_buf,
+		.len =		sizeof(rsc_trace_buf),
+		.reserved =	0,
+		.name =		"r5_trace",
+	},
 };
 
 struct remote_resource_table_metadata __resource_metadata resources_metadata = {
@@ -74,6 +84,12 @@ struct remote_resource_table_metadata __resource_metadata resources_metadata = {
 	.rsc_tbl = (uintptr_t)&resources
 };
 
+char *get_rsc_trace_info(uint32_t *len)
+{
+	*len = sizeof(rsc_trace_buf);
+	return rsc_trace_buf;
+}
+
 void *get_resource_table (int rsc_id, int *len)
 {
 	(void) rsc_id;

examples/legacy_apps/machine/xlnx/zynqmp_r5/rsc_table.h

@@ -34,6 +34,7 @@ struct remote_resource_table {
 	struct fw_rsc_vdev rpmsg_vdev;
 	struct fw_rsc_vdev_vring rpmsg_vring0;
 	struct fw_rsc_vdev_vring rpmsg_vring1;
+	struct fw_rsc_trace rsc_trace;
 }__attribute__((packed, aligned(0x100)));
 
 struct remote_resource_table_metadata {
@@ -44,6 +45,7 @@ struct remote_resource_table_metadata {
 	const uintptr_t rsc_tbl;
 }__attribute__((packed));
 
+char *get_rsc_trace_info(uint32_t *len);
 void *get_resource_table (int rsc_id, int *len);
 void free_resource_table (void);
 void restore_initial_rsc_table (void);