clk: add support for setting clk rate from cmdline

Add new clk subcommand "clk setfreq", for setting up a clock rate
directly from u-boot cmdline. This is handy for any debugging purposes
towards clocks.

Acked-by: Lukasz Majewski <lukma@denx.de>
Signed-off-by: Tero Kristo <t-kristo@ti.com>
Signed-off-by: Tero Kristo <kristo@kernel.org>

cmd/clk.c

@@ -98,8 +98,56 @@ static int do_clk_dump(struct cmd_tbl *cmdtp, int flag, int argc,
 	return ret;
 }
 
+#if CONFIG_IS_ENABLED(DM) && CONFIG_IS_ENABLED(CLK)
+struct udevice *clk_lookup(const char *name)
+{
+	int i = 0;
+	struct udevice *dev;
+
+	do {
+		uclass_get_device(UCLASS_CLK, i++, &dev);
+		if (!strcmp(name, dev->name))
+			return dev;
+	} while (dev);
+
+	return NULL;
+}
+
+static int do_clk_setfreq(struct cmd_tbl *cmdtp, int flag, int argc,
+			  char *const argv[])
+{
+	struct clk *clk = NULL;
+	s32 freq;
+	struct udevice *dev;
+
+	freq = simple_strtoul(argv[2], NULL, 10);
+
+	dev = clk_lookup(argv[1]);
+
+	if (dev)
+		clk = dev_get_clk_ptr(dev);
+
+	if (!clk) {
+		printf("clock '%s' not found.\n", argv[1]);
+		return -EINVAL;
+	}
+
+	freq = clk_set_rate(clk, freq);
+	if (freq < 0) {
+		printf("set_rate failed: %d\n", freq);
+		return CMD_RET_FAILURE;
+	}
+
+	printf("set_rate returns %u\n", freq);
+	return 0;
+}
+#endif
+
 static struct cmd_tbl cmd_clk_sub[] = {
 	U_BOOT_CMD_MKENT(dump, 1, 1, do_clk_dump, "", ""),
+#if CONFIG_IS_ENABLED(DM) && CONFIG_IS_ENABLED(CLK)
+	U_BOOT_CMD_MKENT(setfreq, 3, 1, do_clk_setfreq, "", ""),
+#endif
 };
 
 static int do_clk(struct cmd_tbl *cmdtp, int flag, int argc,
@@ -124,7 +172,8 @@ static int do_clk(struct cmd_tbl *cmdtp, int flag, int argc,
 
 #ifdef CONFIG_SYS_LONGHELP
 static char clk_help_text[] =
-	"dump - Print clock frequencies";
+	"dump - Print clock frequencies\n"
+	"setfreq [clk] [freq] - Set clock frequency";
 #endif
 
-U_BOOT_CMD(clk, 2, 1, do_clk, "CLK sub-system", clk_help_text);
+U_BOOT_CMD(clk, 4, 1, do_clk, "CLK sub-system", clk_help_text);