log: Add a 'log level' command

Add a command for adjusting the log level.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

cmd/Kconfig

@@ -1502,6 +1502,13 @@ config CMD_KGDB
 	  single-stepping, inspecting variables, etc. This is supported only
 	  on PowerPC at present.
 
+config CMD_LOG
+	bool "log - Generation, control and access to logging"
+	help
+	  This provides access to logging features. It allows the output of
+	  log data to be controlled to a limited extent (setting up the default
+	  maximum log level for emitting of records).
+
 config CMD_TRACE
 	bool "trace - Support tracing of function calls and timing"
 	help

cmd/Makefile

@@ -76,6 +76,7 @@ obj-$(CONFIG_LED_STATUS_CMD) += legacy_led.o
 obj-$(CONFIG_CMD_LED) += led.o
 obj-$(CONFIG_CMD_LICENSE) += license.o
 obj-y += load.o
+obj-$(CONFIG_CMD_LOG) += log.o
 obj-$(CONFIG_ID_EEPROM) += mac.o
 obj-$(CONFIG_CMD_MD5SUM) += md5sum.o
 obj-$(CONFIG_CMD_MEMORY) += mem.o

cmd/log.c

@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2017 Google, Inc
+ * Written by Simon Glass <sjg@chromium.org>
+ *
+ * SPDX-License-Identifier:     GPL-2.0+
+ */
+
+#include <common.h>
+#include <command.h>
+#include <dm.h>
+#include <log.h>
+
+static int do_log_level(cmd_tbl_t *cmdtp, int flag, int argc,
+			char * const argv[])
+{
+	if (argc > 1)
+		gd->default_log_level = simple_strtol(argv[1], NULL, 10);
+	else
+		printf("Default log level: %d\n", gd->default_log_level);
+
+	return 0;
+}
+
+static cmd_tbl_t log_sub[] = {
+	U_BOOT_CMD_MKENT(level, CONFIG_SYS_MAXARGS, 1, do_log_level, "", ""),
+};
+
+static int do_log(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	cmd_tbl_t *cp;
+
+	if (argc < 2)
+		return CMD_RET_USAGE;
+
+	/* drop initial "log" arg */
+	argc--;
+	argv++;
+
+	cp = find_cmd_tbl(argv[0], log_sub, ARRAY_SIZE(log_sub));
+	if (cp)
+		return cp->cmd(cmdtp, flag, argc, argv);
+
+	return CMD_RET_USAGE;
+}
+
+#ifdef CONFIG_SYS_LONGHELP
+static char log_help_text[] =
+	"level - get/set log level\n"
+	;
+#endif
+
+U_BOOT_CMD(
+	log, CONFIG_SYS_MAXARGS, 1, do_log,
+	"log system", log_help_text
+);