[PATCH v3 4/6] of: add proper driver for simple-pm-bus

[Ahmad Fatoum <a.fatoum@barebox.org>]

From: Ahmad Fatoum <a.fatoum@pengutronix.de>

simple-pm-bus is currently handled exactly the same as simple-bus in
barebox with the assumption that clocks/power-domains are already
enabled.

This is not necessarily the case, so let's add a driver for
simple-pm-bus that actually does power management and keep the old
behavior the same for devices without deep probe.

Signed-off-by: Ahmad Fatoum <a.fatoum@barebox.org>
---
v2 -> v3:
  - new change
---
 drivers/bus/Kconfig         | 10 ++++++++
 drivers/bus/Makefile        |  1 +
 drivers/bus/simple-pm-bus.c | 47 +++++++++++++++++++++++++++++++++++++
 drivers/of/base.c           |  2 ++
 4 files changed, 60 insertions(+)
 create mode 100644 drivers/bus/simple-pm-bus.c

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index b480cf8bff0f..9b2e0c0ae8ea 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -34,4 +34,14 @@ config ACPI
 	  Driver needed for supporting drivers probed from ACPI tables.
 	  The root SDT is found via UEFI.
 
+config OF_SIMPLE_PM_BUS
+	def_bool PM_GENERIC_DOMAINS
+	prompt "Simple Power-managed bus" if COMPILE_TEST
+	depends on OFDEVICE
+	help
+	  simple-pm-bus is a bus that may have clocks and power domains
+	  that need to be enabled before the bus may be accessed.
+	  If this option is disabled or deep probe is not enabled at
+	  runtime, simple-pm-bus will be treated identically to simple-bus.
+
 endmenu
diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 2c54b3ea307d..1e18c14b970c 100644
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -4,3 +4,4 @@ obj-$(CONFIG_IMX_WEIM)		+= imx-weim.o
 obj-$(CONFIG_MVEBU_MBUS)	+= mvebu-mbus.o
 obj-$(CONFIG_TI_SYSC)		+= ti-sysc.o
 obj-$(CONFIG_ACPI)		+= acpi.o
+obj-$(CONFIG_OF_SIMPLE_PM_BUS)	+= simple-pm-bus.o
diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
new file mode 100644
index 000000000000..8536982b69c4
--- /dev/null
+++ b/drivers/bus/simple-pm-bus.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Simple Power-Managed Bus Driver
+ *
+ * Copyright (C) 2014-2015 Glider bvba
+ */
+
+#include <linux/clk.h>
+#include <driver.h>
+#include <of.h>
+
+static int simple_pm_bus_probe(struct device *dev)
+{
+	struct device_node *np = dev->of_node;
+	struct clk_bulk_data *clks;
+	int num_clks;
+
+	if (deep_probe_is_supported()) {
+		num_clks = clk_bulk_get_all(dev, &clks);
+		if (num_clks < 0)
+			return dev_err_probe(dev, num_clks, "failed to get clocks\n");
+
+		num_clks = clk_bulk_prepare_enable(num_clks, clks);
+		if (num_clks)
+			return dev_err_probe(dev, num_clks, "failed to enable clocks\n");
+	}
+
+	of_platform_populate(np, NULL, dev);
+
+	return 0;
+}
+
+static const struct of_device_id simple_pm_bus_of_match[] = {
+	{ .compatible = "simple-pm-bus", },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match);
+
+static struct driver simple_pm_bus_driver = {
+	.probe = simple_pm_bus_probe,
+	.name = "simple-pm-bus",
+	.of_match_table = simple_pm_bus_of_match,
+};
+core_platform_driver(simple_pm_bus_driver);
+
+MODULE_DESCRIPTION("Simple Power-Managed Bus Driver");
+MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
diff --git a/drivers/of/base.c b/drivers/of/base.c
index 15265dc22623..3cec2878efab 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -2875,8 +2875,10 @@ const struct of_device_id of_default_bus_match_table[] = {
 	{
 		.compatible = "simple-bus",
 	}, {
+#ifndef CONFIG_OF_SIMPLE_PM_BUS
 		.compatible = "simple-pm-bus",
 	}, {
+#endif
 		.compatible = "simple-mfd",
 	}, {
 		/* sentinel */
-- 
2.47.3