irqchip/gic: Add platform driver for non-root GICs that require RPM

Add a platform driver to support non-root GICs that require runtime
power-management. Currently, only non-root GICs are supported because
the functions, smp_cross_call() and set_handle_irq(), that need to
be called for a root controller are located in the __init section and
so cannot be called by the platform driver.

The GIC platform driver re-uses many functions from the existing GIC
driver including some functions to save and restore the GIC context
during power transitions. The functions for saving and restoring the
GIC context are currently only defined if CONFIG_CPU_PM is enabled and
to ensure that these functions are always defined when the platform
driver is enabled, a dependency on CONFIG_ARM_GIC_PM (which selects the
platform driver) has been added.

In order to re-use the private GIC initialisation code, a new public
function, gic_of_init_child(), has been added which calls various
private functions to initialise the GIC. This is different from the
existing gic_of_init() because it only supports non-root GICs (ie. does
not call smp_cross_call() is set_handle_irq()) and is not located in
the __init section (so can be used by platform drivers). Furthermore,
gic_of_init_child() dynamically allocates memory for the GIC chip data
which is also different from gic_of_init().

There is no specific suspend handling for GICs registered as platform
devices. Non-wakeup interrupts will be disabled by the kernel during
late suspend, however, this alone will not power down the GIC if
interrupts have been requested and not freed. Therefore, requestors of
non-wakeup interrupts will need to free them on entering suspend in
order to power-down the GIC.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

drivers/irqchip/Kconfig

@@ -8,6 +8,12 @@ config ARM_GIC
 	select IRQ_DOMAIN_HIERARCHY
 	select MULTI_IRQ_HANDLER
 
+config ARM_GIC_PM
+	bool
+	depends on PM
+	select ARM_GIC
+	select PM_CLK
+
 config ARM_GIC_MAX_NR
 	int
 	default 2 if ARCH_REALVIEW

drivers/irqchip/Makefile

@@ -24,6 +24,7 @@ obj-$(CONFIG_ARCH_SUNXI)		+= irq-sun4i.o
 obj-$(CONFIG_ARCH_SUNXI)		+= irq-sunxi-nmi.o
 obj-$(CONFIG_ARCH_SPEAR3XX)		+= spear-shirq.o
 obj-$(CONFIG_ARM_GIC)			+= irq-gic.o irq-gic-common.o
+obj-$(CONFIG_ARM_GIC_PM)		+= irq-gic-pm.o
 obj-$(CONFIG_REALVIEW_DT)		+= irq-gic-realview.o
 obj-$(CONFIG_ARM_GIC_V2M)		+= irq-gic-v2m.o
 obj-$(CONFIG_ARM_GIC_V3)		+= irq-gic-v3.o irq-gic-common.o

drivers/irqchip/irq-gic-pm.c

@@ -0,0 +1,184 @@
+/*
+ * Copyright (C) 2016 NVIDIA CORPORATION, All Rights Reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <linux/module.h>
+#include <linux/clk.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/irqchip/arm-gic.h>
+#include <linux/platform_device.h>
+#include <linux/pm_clock.h>
+#include <linux/pm_runtime.h>
+#include <linux/slab.h>
+
+struct gic_clk_data {
+	unsigned int num_clocks;
+	const char *const *clocks;
+};
+
+static int gic_runtime_resume(struct device *dev)
+{
+	struct gic_chip_data *gic = dev_get_drvdata(dev);
+	int ret;
+
+	ret = pm_clk_resume(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * On the very first resume, the pointer to the driver data
+	 * will be NULL and this is intentional, because we do not
+	 * want to restore the GIC on the very first resume. So if
+	 * the pointer is not valid just return.
+	 */
+	if (!gic)
+		return 0;
+
+	gic_dist_restore(gic);
+	gic_cpu_restore(gic);
+
+	return 0;
+}
+
+static int gic_runtime_suspend(struct device *dev)
+{
+	struct gic_chip_data *gic = dev_get_drvdata(dev);
+
+	gic_dist_save(gic);
+	gic_cpu_save(gic);
+
+	return pm_clk_suspend(dev);
+}
+
+static int gic_get_clocks(struct device *dev, const struct gic_clk_data *data)
+{
+	struct clk *clk;
+	unsigned int i;
+	int ret;
+
+	if (!dev || !data)
+		return -EINVAL;
+
+	ret = pm_clk_create(dev);
+	if (ret)
+		return ret;
+
+	for (i = 0; i < data->num_clocks; i++) {
+		clk = of_clk_get_by_name(dev->of_node, data->clocks[i]);
+		if (IS_ERR(clk)) {
+			dev_err(dev, "failed to get clock %s\n",
+				data->clocks[i]);
+			ret = PTR_ERR(clk);
+			goto error;
+		}
+
+		ret = pm_clk_add_clk(dev, clk);
+		if (ret) {
+			dev_err(dev, "failed to add clock at index %d\n", i);
+			clk_put(clk);
+			goto error;
+		}
+	}
+
+	return 0;
+
+error:
+	pm_clk_destroy(dev);
+
+	return ret;
+}
+
+static int gic_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct gic_clk_data *data;
+	struct gic_chip_data *gic;
+	int ret, irq;
+
+	data = of_device_get_match_data(&pdev->dev);
+	if (!data) {
+		dev_err(&pdev->dev, "no device match found\n");
+		return -ENODEV;
+	}
+
+	irq = irq_of_parse_and_map(dev->of_node, 0);
+	if (!irq) {
+		dev_err(dev, "no parent interrupt found!\n");
+		return -EINVAL;
+	}
+
+	ret = gic_get_clocks(dev, data);
+	if (ret)
+		goto irq_dispose;
+
+	pm_runtime_enable(dev);
+
+	ret = pm_runtime_get_sync(dev);
+	if (ret < 0)
+		goto rpm_disable;
+
+	ret = gic_of_init_child(dev, &gic, irq);
+	if (ret)
+		goto rpm_put;
+
+	platform_set_drvdata(pdev, gic);
+
+	pm_runtime_put(dev);
+
+	dev_info(dev, "GIC IRQ controller registered\n");
+
+	return 0;
+
+rpm_put:
+	pm_runtime_put_sync(dev);
+rpm_disable:
+	pm_runtime_disable(dev);
+	pm_clk_destroy(dev);
+irq_dispose:
+	irq_dispose_mapping(irq);
+
+	return ret;
+}
+
+static const struct dev_pm_ops gic_pm_ops = {
+	SET_RUNTIME_PM_OPS(gic_runtime_suspend,
+			   gic_runtime_resume, NULL)
+};
+
+static const char * const gic400_clocks[] = {
+	"clk",
+};
+
+static const struct gic_clk_data gic400_data = {
+	.num_clocks = ARRAY_SIZE(gic400_clocks),
+	.clocks = gic400_clocks,
+};
+
+static const struct of_device_id gic_match[] = {
+	{ .compatible = "nvidia,tegra210-agic",	.data = &gic400_data },
+	{},
+};
+MODULE_DEVICE_TABLE(of, gic_match);
+
+static struct platform_driver gic_driver = {
+	.probe		= gic_probe,
+	.driver		= {
+		.name	= "gic",
+		.of_match_table	= gic_match,
+		.pm	= &gic_pm_ops,
+	}
+};
+
+builtin_platform_driver(gic_driver);

drivers/irqchip/irq-gic.c

@@ -75,7 +75,7 @@ struct gic_chip_data {
 	void __iomem *raw_dist_base;
 	void __iomem *raw_cpu_base;
 	u32 percpu_offset;
-#ifdef CONFIG_CPU_PM
+#if defined(CONFIG_CPU_PM) || defined(CONFIG_ARM_GIC_PM)
 	u32 saved_spi_enable[DIV_ROUND_UP(1020, 32)];
 	u32 saved_spi_active[DIV_ROUND_UP(1020, 32)];
 	u32 saved_spi_conf[DIV_ROUND_UP(1020, 16)];
@@ -528,7 +528,7 @@ int gic_cpu_if_down(unsigned int gic_nr)
 	return 0;
 }
 
-#ifdef CONFIG_CPU_PM
+#if defined(CONFIG_CPU_PM) || defined(CONFIG_ARM_GIC_PM)
 /*
  * Saves the GIC distributor registers during suspend or idle.  Must be called
  * with interrupts disabled but before powering down the GIC.  After calling
@@ -1272,7 +1272,7 @@ static bool gic_check_eoimode(struct device_node *node, void __iomem **base)
 	return true;
 }
 
-static int __init gic_of_setup(struct gic_chip_data *gic, struct device_node *node)
+static int gic_of_setup(struct gic_chip_data *gic, struct device_node *node)
 {
 	if (!gic || !node)
 		return -EINVAL;
@@ -1296,6 +1296,34 @@ error:
 	return -ENOMEM;
 }
 
+int gic_of_init_child(struct device *dev, struct gic_chip_data **gic, int irq)
+{
+	int ret;
+
+	if (!dev || !dev->of_node || !gic || !irq)
+		return -EINVAL;
+
+	*gic = devm_kzalloc(dev, sizeof(**gic), GFP_KERNEL);
+	if (!*gic)
+		return -ENOMEM;
+
+	gic_init_chip(*gic, dev, dev->of_node->name, false);
+
+	ret = gic_of_setup(*gic, dev->of_node);
+	if (ret)
+		return ret;
+
+	ret = gic_init_bases(*gic, -1, &dev->of_node->fwnode);
+	if (ret) {
+		gic_teardown(*gic);
+		return ret;
+	}
+
+	irq_set_chained_handler_and_data(irq, gic_handle_cascade_irq, *gic);
+
+	return 0;
+}
+
 static void __init gic_of_setup_kvm_info(struct device_node *node)
 {
 	int ret;
@@ -1375,7 +1403,11 @@ IRQCHIP_DECLARE(cortex_a7_gic, "arm,cortex-a7-gic", gic_of_init);
 IRQCHIP_DECLARE(msm_8660_qgic, "qcom,msm-8660-qgic", gic_of_init);
 IRQCHIP_DECLARE(msm_qgic2, "qcom,msm-qgic2", gic_of_init);
 IRQCHIP_DECLARE(pl390, "arm,pl390", gic_of_init);
-
+#else
+int gic_of_init_child(struct device *dev, struct gic_chip_data **gic, int irq)
+{
+	return -ENOTSUPP;
+}
 #endif
 
 #ifdef CONFIG_ACPI

include/linux/irqchip/arm-gic.h

@@ -116,6 +116,12 @@ void gic_dist_restore(struct gic_chip_data *gic);
  */
 int gic_of_init(struct device_node *node, struct device_node *parent);
 
+/*
+ * Initialises and registers a non-root or child GIC chip. Memory for
+ * the gic_chip_data structure is dynamically allocated.
+ */
+int gic_of_init_child(struct device *dev, struct gic_chip_data **gic, int irq);
+
 /*
  * Legacy platforms not converted to DT yet must use this to init
  * their GIC