This type of bus is used in Linux to designate busses 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 <sean...@gmail.com>
---
Changes for v3:
- New
.../bus/simple-pm-bus.txt | 44 ++++++++++++++
drivers/core/simple-bus.c | 57 ++++++++++++++++++-
2 files changed, 99 insertions(+), 2 deletions(-)
create mode 100644 doc/device-tree-bindings/bus/simple-pm-bus.txt
diff --git a/doc/device-tree-bindings/bus/simple-pm-bus.txt
b/doc/device-tree-bindings/bus/simple-pm-bus.txt
new file mode 100644
index 0000000000..6f15037131
--- /dev/null
+++ b/doc/device-tree-bindings/bus/simple-pm-bus.txt
@@ -0,0 +1,44 @@
+Simple Power-Managed Bus
+========================
+
+A Simple Power-Managed Bus is a transparent bus that doesn't need a real
+driver, as it's typically initialized by the boot loader.
+
+However, its bus controller is part of a PM domain, or under the control of a
+functional clock. Hence, the bus controller's PM domain and/or clock must be
+enabled for child devices connected to the bus (either on-SoC or externally)
+to function.
+
+While "simple-pm-bus" follows the "simple-bus" set of properties, as specified
+in the Devicetree Specification, it is not an extension of "simple-bus".
+
+
+Required properties:
+ - compatible: Must contain at least "simple-pm-bus".
+ Must not contain "simple-bus".
+ It's recommended to let this be preceded by one or more
+ vendor-specific compatible values.
+ - #address-cells, #size-cells, ranges: Must describe the mapping between
+ parent address and child address spaces.
+
+Optional platform-specific properties for clock or PM domain control (at least
+one of them is required):
+ - clocks: Must contain a reference to the functional clock(s),
+ - power-domains: Must contain a reference to the PM domain.
+Please refer to the binding documentation for the clock and/or PM domain
+providers for more details.
+
+
+Example:
+
+ bsc: bus@fec10000 {
+ compatible = "renesas,bsc-sh73a0", "renesas,bsc",
+ "simple-pm-bus";
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges = <0 0 0x20000000>;
+ reg = <0xfec10000 0x400>;
+ interrupts = <0 39 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&zb_clk>;
+ power-domains = <&pd_a4s>;
+ };
diff --git a/drivers/core/simple-bus.c b/drivers/core/simple-bus.c
index 7fc23ef82d..d94567e98d 100644
--- a/drivers/core/simple-bus.c
+++ b/drivers/core/simple-bus.c
@@ -5,6 +5,11 @@
#include <common.h>
#include <dm.h>
+#include <clk.h>
+
+#define SIMPLE_BUS 0
+#define SIMPLE_MFD 1
+#define SIMPLE_PM_BUS 2
struct simple_bus_plat {
u32 base;
@@ -50,9 +55,55 @@ UCLASS_DRIVER(simple_bus) = {
.per_device_platdata_auto_alloc_size = sizeof(struct simple_bus_plat),
};
+static const int generic_simple_bus_probe(struct udevice *dev)
+{
+#if CONFIG_IS_ENABLED(CLK)
+ int ret;
+ struct clk_bulk *bulk;
+ ulong type = dev_get_driver_data(dev);
+
+ if (type == SIMPLE_PM_BUS) {
+ bulk = kzalloc(sizeof(*bulk), GFP_KERNEL);
+ if (!bulk)
+ return -ENOMEM;
+
+ 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;
+ }
+ dev->priv = bulk;
+ }
+#endif
+ return 0;
+}
+
+static const int generic_simple_bus_remove(struct udevice *dev)
+{
+ int ret = 0;
+#if CONFIG_IS_ENABLED(CLK)
+ struct clk_bulk *bulk;
+ ulong type = dev_get_driver_data(dev);
+
+ if (type == SIMPLE_PM_BUS) {
+ bulk = dev_get_priv(dev);
+ ret = clk_release_bulk(bulk);
+ kfree(bulk);
+ if (ret == -ENOSYS)
+ ret = 0;
+ }
+#endif
+ return ret;
+}
+
static const struct udevice_id generic_simple_bus_ids[] = {
- { .compatible = "simple-bus" },
- { .compatible = "simple-mfd" },
+ { .compatible = "simple-bus", .data = SIMPLE_BUS },
+ { .compatible = "simple-mfd", .data = SIMPLE_MFD },
+ { .compatible = "simple-pm-bus", .data = SIMPLE_PM_BUS },
{ }
};
@@ -60,5 +111,7 @@ U_BOOT_DRIVER(simple_bus_drv) = {
.name = "generic_simple_bus",
.id = UCLASS_SIMPLE_BUS,
.of_match = generic_simple_bus_ids,
+ .probe = generic_simple_bus_probe,
+ .remove = generic_simple_bus_remove,
.flags = DM_FLAG_PRE_RELOC,
};
--
2.25.0
