clk: implement clk_set_defaults()

Linux uses the properties 'assigned-clocks', 'assigned-clock-parents'
and 'assigned-clock-rates' to configure the clock subsystem for use
with various peripheral nodes.

This implements clk_set_defaults() and hooks it up with the general
device probibin in drivers/core/device.c: when a new device is probed,
clk_set_defaults() will be called for it and will process the
properties mentioned above.

Note that this functionality is designed to fail gracefully (i.e. if a
clock-driver does not implement set_parent(), we simply accept this
and ignore the error) as not to break existing board-support.

Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: David Wu <david.wu@rock-chips.com>

Series-changes: 2
- Fixed David's email address.

Series-version: 2

Cover-letter:
clk: support assigned-clock, assigned-clock-parents, assigned-clock-rates

For various peripherals on Rockchip SoCs (e.g. for the Ethernet GMAC),
the parent-clock needs to be set via the DTS.  This adds the required
plumbing and implements the GMAC case for the RK3399.
END

drivers/clk/clk-uclass.c

@@ -2,6 +2,7 @@
  * Copyright (C) 2015 Google, Inc
  * Written by Simon Glass <sjg@chromium.org>
  * Copyright (c) 2016, NVIDIA CORPORATION.
+ * Copyright (c) 2018, Theobroma Systems Design und Consulting GmbH
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
@@ -10,6 +11,7 @@
 #include <clk.h>
 #include <clk-uclass.h>
 #include <dm.h>
+#include <dm/read.h>
 #include <dt-structs.h>
 #include <errno.h>
 
@@ -101,6 +103,122 @@ int clk_get_by_index(struct udevice *dev, int index, struct clk *clk)
 {
 	return clk_get_by_indexed_prop(dev, "clocks", index, clk);
 }
+
+static int clk_set_default_parents(struct udevice *dev)
+{
+	struct clk clk, parent_clk;
+	int index;
+	int num_parents;
+	int ret;
+
+	num_parents = dev_count_phandle_with_args(dev, "assigned-clock-parents",
+						  "#clock-cells");
+	if (num_parents < 0) {
+		debug("%s: could not read assigned-clock-parents for %p\n",
+		      __func__, dev);
+		return 0;
+	}
+
+	for (index = 0; index < num_parents; index++) {
+		ret = clk_get_by_indexed_prop(dev, "assigned-clock-parents",
+					      index, &parent_clk);
+		if (ret) {
+			debug("%s: could not get parent clock %d for %s\n",
+			      __func__, index, dev_read_name(dev));
+			return ret;
+		}
+
+		ret = clk_get_by_indexed_prop(dev, "assigned-clocks",
+					      index, &clk);
+		if (ret) {
+			debug("%s: could not get assigned clock %d for %s\n",
+			      __func__, index, dev_read_name(dev));
+			return ret;
+		}
+
+		ret = clk_set_parent(&clk, &parent_clk);
+
+		/*
+		 * Not all drivers may support clock-reparenting (as of now).
+		 * Ignore errors due to this.
+		 */
+		if (ret == -ENOSYS)
+			continue;
+
+		if (ret) {
+			debug("%s: failed to reparent clock %d for %s\n",
+			      __func__, index, dev_read_name(dev));
+			return ret;
+		}
+	}
+
+	return 0;
+}
+
+static int clk_set_default_rates(struct udevice *dev)
+{
+	struct clk clk;
+	int index;
+	int num_rates;
+	int size;
+	int ret = 0;
+	u32 *rates = NULL;
+
+	size = dev_read_size(dev, "assigned-clock-rates");
+	if (size < 0)
+		return 0;
+
+	num_rates = size / sizeof(u32);
+	rates = calloc(num_rates, sizeof(u32));
+	if (!rates)
+		return -ENOMEM;
+
+	ret = dev_read_u32_array(dev, "assigned-clock-rates", rates, num_rates);
+	if (ret)
+		goto fail;
+
+	for (index = 0; index < num_rates; index++) {
+		ret = clk_get_by_indexed_prop(dev, "assigned-clocks",
+					      index, &clk);
+		if (ret) {
+			debug("%s: could not get assigned clock %d for %s\n",
+			      __func__, index, dev_read_name(dev));
+			continue;
+		}
+
+		ret = clk_set_rate(&clk, rates[index]);
+		if (ret < 0) {
+			debug("%s: failed to set rate on clock %d for %s\n",
+			      __func__, index, dev_read_name(dev));
+			break;
+		}
+	}
+
+fail:
+	free(rates);
+	return ret;
+}
+
+int clk_set_defaults(struct udevice *dev)
+{
+	int ret;
+
+	/* If this is running pre-reloc state, don't take any action. */
+	if (!(gd->flags & GD_FLG_RELOC))
+		return 0;
+
+	debug("%s(%s)\n", __func__, dev_read_name(dev));
+
+	ret = clk_set_default_parents(dev);
+	if (ret)
+		return ret;
+
+	ret = clk_set_default_rates(dev);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
 # endif /* OF_PLATDATA */
 
 int clk_get_by_name(struct udevice *dev, const char *name, struct clk *clk)

drivers/core/device.c

@@ -11,6 +11,7 @@
 
 #include <common.h>
 #include <asm/io.h>
+#include <clk.h>
 #include <fdtdec.h>
 #include <fdt_support.h>
 #include <malloc.h>
@@ -391,6 +392,11 @@ int device_probe(struct udevice *dev)
 			goto fail;
 	}
 
+	/* Process 'assigned-{clocks/clock-parents/clock-rates}' properties */
+	ret = clk_set_defaults(dev);
+	if (ret)
+		goto fail;
+
 	if (drv->probe) {
 		ret = drv->probe(dev);
 		if (ret) {

include/clk.h

@@ -133,6 +133,23 @@ static inline int clk_release_all(struct clk *clk, int count)
 
 #endif
 
+#if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) && \
+	CONFIG_IS_ENABLED(CLK)
+/**
+ * clk_set_defaults - Process 'assigned-{clocks/clock-parents/clock-rates}'
+ *                    properties to configure clocks
+ *
+ * @dev:        A device to process (the ofnode associated with this device
+ *              will be processed).
+ */
+int clk_set_defaults(struct udevice *dev);
+#else
+static inline int clk_set_defaults(struct udevice *dev)
+{
+	return 0;
+}
+#endif
+
 /**
  * clk_request - Request a clock by provider-specific ID.
  *