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>

1 files changed, 184 insertions, 0 deletions

diff --git a/drivers/irqchip/irq-gic-pm.c b/drivers/irqchip/irq-gic-pm.c
new file mode 100644
index 000000000000..4cbffba3ff13
--- /dev/null
+++ b/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);