Re: [PATCH 3/5] reset: Add Altera Arria10 System Resource Reset Controller

From: Thor Thayer <thor.thayer-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>

This patch adds the reset controller functionality to the Arria10
System Resource Manager.

Signed-off-by: Thor Thayer <thor.thayer-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 MAINTAINERS                 |   1 +
 drivers/reset/Kconfig       |   7 ++
 drivers/reset/Makefile      |   1 +
 drivers/reset/reset-a10sr.c | 176 ++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 185 insertions(+)
 create mode 100644 drivers/reset/reset-a10sr.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a2c74db..3265cb2 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS

@@ -655,6 +655,7 @@ F:	drivers/gpio/gpio-altera-a10sr.c
 F:	drivers/mfd/altera-a10sr.c
 F:	include/linux/mfd/altera-a10sr.h
 F:	include/dt-bindings/reset/altr,rst-mgr-a10sr.h
+F:	drivers/reset/reset-a10sr.c
 
 ALTERA TRIPLE SPEED ETHERNET DRIVER
 M:	Vince Bridgers <vbridger-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org>

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index f4cdfe9..b821d1b 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig

@@ -39,6 +39,13 @@ config RESET_MESON
 	help
 	  This enables the reset driver for Amlogic Meson SoCs.
 
+config ALTERA_A10SR_RESET

+	tristate "Altera Arria10 System Resource Reset"
+	depends on MFD_ALTERA_A10SR
+	help
+	  This option enables support for the external reset functions for
+	  peripheral PHYs on the Altera Arria10 System Resource Chip.
+
 config RESET_OXNAS
 	bool
 

diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 2cd3f6c..d6a2a87 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile

@@ -15,3 +15,4 @@ obj-$(CONFIG_TI_SYSCON_RESET) += reset-ti-syscon.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_ZX2967) += reset-zx2967.o
 obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
+obj-$(CONFIG_ALTERA_A10SR_RESET) += reset-a10sr.o

diff --git a/drivers/reset/reset-a10sr.c b/drivers/reset/reset-a10sr.c
new file mode 100644
index 0000000..ed058f3
--- /dev/null
+++ b/drivers/reset/reset-a10sr.c

@@ -0,0 +1,176 @@
+/*
+ *  Copyright Intel Corporation (C) 2017. All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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/>.
+ *
+ * Reset driver for Altera Arria10 MAX5 System Resource Chip
+ *
+ * Adapted from reset-socfpga.c
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>

+#include <linux/mfd/altera-a10sr.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/types.h>
+
+#include <dt-bindings/reset/altr,rst-mgr-a10sr.h>
+
+/* Number of A10 System Controller Resets */
+#define A10SR_RESETS		16

+struct a10sr_reset {
+	struct reset_controller_dev     rcdev;
+	struct regmap *regmap;
+};
+
+static inline struct a10sr_reset *to_a10sr_rst(struct reset_controller_dev *rc)
+{
+	return container_of(rc, struct a10sr_reset, rcdev);
+}
+
+static inline int a10sr_reset_shift(unsigned long id)
+{
+	switch (id) {
+	case A10SR_RESET_ENET_HPS:
+		return 1;
+	case A10SR_RESET_PCIE:
+	case A10SR_RESET_FILE:
+	case A10SR_RESET_BQSPI:
+	case A10SR_RESET_USB:
+		return id + 11;

+	default:
+		return -EINVAL;
+	}
+}
+
+static int a10sr_reset_update(struct reset_controller_dev *rcdev,
+			      unsigned long id, bool assert)
+{
+	struct a10sr_reset *a10r = to_a10sr_rst(rcdev);
+	int offset = a10sr_reset_shift(id);
+	u8 mask = ALTR_A10SR_REG_BIT_MASK(offset);
+	int index = ALTR_A10SR_HPS_RST_REG + ALTR_A10SR_REG_OFFSET(offset);
+
+	if (id >= rcdev->nr_resets)
+		return -EINVAL;

+	return regmap_update_bits(a10r->regmap, index, mask, assert ? 0 : mask);
+}
+
+static int a10sr_reset_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	return a10sr_reset_update(rcdev, id, true);
+}
+
+static int a10sr_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	return a10sr_reset_update(rcdev, id, false);
+}
+
+static int a10sr_reset_status(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	int error;
+	struct a10sr_reset *a10r = to_a10sr_rst(rcdev);
+	int offset = a10sr_reset_shift(id);
+	u8 mask = ALTR_A10SR_REG_BIT_MASK(offset);
+	int index = ALTR_A10SR_HPS_RST_REG + ALTR_A10SR_REG_OFFSET(offset);
+	unsigned int value;
+
+	if (id >= rcdev->nr_resets)
+		return -EINVAL;

+	error = regmap_read(a10r->regmap, index, &value);
+	if (error < 0)
+		return -ENOMEM;

+
+	return !!(value & mask);
+}
+
+static const struct reset_control_ops a10sr_reset_ops = {
+	.assert		= a10sr_reset_assert,
+	.deassert	= a10sr_reset_deassert,
+	.status		= a10sr_reset_status,
+};
+
+static const struct of_device_id a10sr_reset_of_match[];

+static int a10sr_reset_probe(struct platform_device *pdev)
+{
+	struct altr_a10sr *a10sr = dev_get_drvdata(pdev->dev.parent);
+	struct a10sr_reset *a10r;
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;

+	if (!np) {
+		dev_err(&pdev->dev, "A10 Reset DT Entry not found\n");
+		return -EINVAL;
+	}
+
+	if (!of_find_property(np, "#reset-cells", NULL)) {
+		dev_err(&pdev->dev, "%s missing #reset-cells property\n",
+			np->full_name);
+		return -EINVAL;
+	}

+	a10r = devm_kzalloc(&pdev->dev, sizeof(struct a10sr_reset),
+			    GFP_KERNEL);
+	if (!a10r)
+		return -ENOMEM;
+
+	a10r->rcdev.owner = THIS_MODULE;
+	a10r->rcdev.nr_resets = A10SR_RESETS;
+	a10r->rcdev.ops = &a10sr_reset_ops;
+	a10r->rcdev.of_node = np;
+	a10r->regmap = a10sr->regmap;
+
+	platform_set_drvdata(pdev, a10r);
+
+	return devm_reset_controller_register(dev, &a10r->rcdev);
+}
+
+static int a10sr_reset_remove(struct platform_device *pdev)
+{
+	struct a10sr_reset *a10r = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&a10r->rcdev);

+
+	return 0;
+}
+
+static const struct of_device_id a10sr_reset_of_match[] = {
+	{ .compatible = "altr,a10sr-reset" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, a10sr_reset_of_match);
+
+static struct platform_driver a10sr_reset_driver = {
+	.probe	= a10sr_reset_probe,
+	.remove	= a10sr_reset_remove,
+	.driver = {
+		.name		= "altr_a10sr_reset",
+		.owner		= THIS_MODULE,

+	},
+};
+module_platform_driver(a10sr_reset_driver);
+
+MODULE_AUTHOR("Thor Thayer <thor.thayer-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>");
+MODULE_DESCRIPTION("Altera Arria10 System Resource Reset Controller Driver");
+MODULE_LICENSE("GPL v2");