dm: Add support for simple-pm-bus

This type of bus is used in Linux to designate buses which have power
domains and/or clocks which need to be enabled before their child devices
can be used. Because power domains are automatically enabled before probing
in U-Boot, we just need to enable any clocks present.

Signed-off-by: Sean Anderson <seanga2@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

1 files changed, 56 insertions, 0 deletions

diff --git a/drivers/core/simple-pm-bus.c b/drivers/core/simple-pm-bus.c
new file mode 100644
index 0000000000..51dc9b206f
--- /dev/null
+++ b/drivers/core/simple-pm-bus.c
@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2020 Sean Anderson <seanga2@gmail.com>
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+
+/*
+ * Power domains are taken care of by driver_probe, so we just have to enable
+ * clocks
+ */
+static int simple_pm_bus_probe(struct udevice *dev)
+{
+	int ret;
+	struct clk_bulk *bulk = dev_get_priv(dev);
+
+	ret = clk_get_bulk(dev, bulk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable_bulk(bulk);
+	if (ret && ret != -ENOSYS && ret != -ENOTSUPP) {
+		clk_release_bulk(bulk);
+		return ret;
+	}
+	return 0;
+}
+
+static int simple_pm_bus_remove(struct udevice *dev)
+{
+	int ret;
+	struct clk_bulk *bulk = dev_get_priv(dev);
+
+	ret = clk_release_bulk(bulk);
+	if (ret && ret != -ENOSYS && ret != -ENOTSUPP)
+		return ret;
+	else
+		return 0;
+}
+
+static const struct udevice_id simple_pm_bus_ids[] = {
+	{ .compatible = "simple-pm-bus" },
+	{ }
+};
+
+U_BOOT_DRIVER(simple_pm_bus_drv) = {
+	.name	= "simple_pm_bus",
+	.id	= UCLASS_SIMPLE_BUS,
+	.of_match = simple_pm_bus_ids,
+	.probe = simple_pm_bus_probe,
+	.remove = simple_pm_bus_remove,
+	.priv_auto_alloc_size = sizeof(struct clk_bulk),
+	.flags	= DM_FLAG_PRE_RELOC,
+};