drivers: bus: Add Simple Power-Managed Bus Driver

Add a driver for transparent busses that don't need a real driver, but
where the bus controller is part of a PM domain, or under the control of
a functional clock.  Typically, 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.

Hence the sole purpose of this driver is to enable its clock and PM
domain (if exist(s)), which are specified in the DT and managed from
platform and PM domain code, and to probe for child devices.

Due to the child-parent relationship with devices connected to the bus,
PM domain and clock state transitions are handled in the correct order.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 626960819e6df16c2314151799f0d266d6ee6974..7e9c2674af81d6e9704aa7e35cda8bec73844809 100644 (file)
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -58,6 +58,19 @@ config OMAP_OCP2SCP
          OCP2SCP and in OMAP5, both USB PHY and SATA PHY is connected via
          OCP2SCP.
 
+config SIMPLE_PM_BUS
+       bool "Simple Power-Managed Bus Driver"
+       depends on OF && PM
+       depends on ARCH_SHMOBILE || COMPILE_TEST
+       help
+         Driver for transparent busses that don't need a real driver, but
+         where the bus controller is part of a PM domain, or under the control
+         of a functional clock, and thus relies on runtime PM for managing
+         this PM domain and/or clock.
+         An example of such a bus controller is the Renesas Bus State
+         Controller (BSC, sometimes called "LBSC within Bus Bridge", or
+         "External Bus Interface") as found on several Renesas ARM SoCs.
+
 config VEXPRESS_CONFIG
        bool "Versatile Express configuration bus"
        default y if ARCH_VEXPRESS

diff --git a/drivers/bus/Makefile b/drivers/bus/Makefile
index 3cfaf2c7f25ac4f0d37342e65cc0916306e2e7c5..e023a2bec664d90035c7227725ee777f0cd69fd6 100644 (file)
--- a/drivers/bus/Makefile
+++ b/drivers/bus/Makefile
@@ -14,4 +14,5 @@ obj-$(CONFIG_MVEBU_MBUS)      += mvebu-mbus.o
 obj-$(CONFIG_OMAP_INTERCONNECT)        += omap_l3_smx.o omap_l3_noc.o
 
 obj-$(CONFIG_OMAP_OCP2SCP)     += omap-ocp2scp.o
+obj-$(CONFIG_SIMPLE_PM_BUS)    += simple-pm-bus.o
 obj-$(CONFIG_VEXPRESS_CONFIG)  += vexpress-config.o

diff --git a/drivers/bus/simple-pm-bus.c b/drivers/bus/simple-pm-bus.c
new file mode 100644 (file)
index 0000000..c5eb46c
--- /dev/null
+++ b/drivers/bus/simple-pm-bus.c
@@ -0,0 +1,58 @@
+/*
+ * Simple Power-Managed Bus Driver
+ *
+ * Copyright (C) 2014-2015 Glider bvba
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/of_platform.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+
+
+static int simple_pm_bus_probe(struct platform_device *pdev)
+{
+       struct device_node *np = pdev->dev.of_node;
+
+       dev_dbg(&pdev->dev, "%s\n", __func__);
+
+       pm_runtime_enable(&pdev->dev);
+
+       if (np)
+               of_platform_populate(np, NULL, NULL, &pdev->dev);
+
+       return 0;
+}
+
+static int simple_pm_bus_remove(struct platform_device *pdev)
+{
+       dev_dbg(&pdev->dev, "%s\n", __func__);
+
+       pm_runtime_disable(&pdev->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 platform_driver simple_pm_bus_driver = {
+       .probe = simple_pm_bus_probe,
+       .remove = simple_pm_bus_remove,
+       .driver = {
+               .name = "simple-pm-bus",
+               .of_match_table = simple_pm_bus_of_match,
+       },
+};
+
+module_platform_driver(simple_pm_bus_driver);
+
+MODULE_DESCRIPTION("Simple Power-Managed Bus Driver");
+MODULE_AUTHOR("Geert Uytterhoeven <geert+renesas@glider.be>");
+MODULE_LICENSE("GPL v2");