clk: Port Linux common clock framework [CCF] for imx6q to U-boot (tag: v5.1.12)

This patch brings the files from Linux kernel (linux-stable/linux-5.1.y
SHA1: 5752b50477da)to provide clocks support as it is used on the Linux
kernel with Common Clock Framework [CCF] setup.

The directory structure has been preserved. The ported code only supports
reading information from PLL, MUX, Divider, etc and enabling/disabling
the clocks USDHCx/ECSPIx depending on used bus. Moreover, it is agnostic
to the alias numbering as the information about the clock is read from the
device tree.

One needs to pay attention to the comments indicating necessary for U-Boot's
driver model changes.

If needed, the code can be extended to support the "set" part of the clock
management.

Signed-off-by: Lukasz Majewski <lukma@denx.de>

1 files changed, 57 insertions, 0 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
new file mode 100644
index 0000000..7d748c9
--- /dev/null
+++ b/drivers/clk/clk.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2019 DENX Software Engineering
+ * Lukasz Majewski, DENX Software Engineering, lukma@denx.de
+ */
+
+#include <common.h>
+#include <clk-uclass.h>
+#include <dm/device.h>
+#include <dm/uclass.h>
+#include <dm/lists.h>
+#include <dm/device-internal.h>
+#include <clk.h>
+
+int clk_register(struct clk *clk, const char *drv_name,
+		 const char *name, const char *parent_name)
+{
+	struct udevice *parent;
+	struct driver *drv;
+	int ret;
+
+	ret = uclass_get_device_by_name(UCLASS_CLK, parent_name, &parent);
+	if (ret)
+		printf("%s: UCLASS parent: 0x%p\n", __func__, parent);
+
+	debug("%s: name: %s parent: %s [0x%p]\n", __func__, name, parent->name,
+	      parent);
+
+	drv = lists_driver_lookup_name(drv_name);
+	if (!drv) {
+		printf("%s: %s is not a valid driver name\n",
+		       __func__, drv_name);
+		return -ENOENT;
+	}
+
+	ret = device_bind(parent, drv, name, NULL, -1, &clk->dev);
+	if (ret) {
+		printf("%s: CLK: %s driver bind error [%d]!\n", __func__, name,
+		       ret);
+		return ret;
+	}
+
+	/* Store back pointer to clk from udevice */
+	clk->dev->uclass_priv = clk;
+
+	return 0;
+}
+
+ulong clk_generic_get_rate(struct clk *clk)
+{
+	return clk_get_parent_rate(clk);
+}
+
+const char *clk_hw_get_name(const struct clk *hw)
+{
+	return hw->dev->name;
+}