[PATCH v2] ARC: reset: introduce AXS10x reset driver

From: Eugeniy Paltsev
Date: Thu Sep 14 2017 - 10:28:53 EST

ARC AXS10x boards support custom IP-block which allows to control
reset signals of selected peripherals. For example DW GMAC, etc...
This block is controlled via memory-mapped register (AKA CREG) which
represents up-to 32 reset lines. This regiter is self-clearing so we
don't need to deassert line after reset.

As of today only the following lines are used:
- DW GMAC - line 5

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
---
Changes v1 -> v2:
* The creg reset register is self-clearing so we don't need to clear it
manually. Fixed it.
* Use reset callback instead of assert/deassert pair.
* Rename reset node in documentation to "reset-controller" for consistency
with the other bindings.
* Use devm_reset_controller_register instead of reset_controller_register

NOTE:
This driver couldn't be replaced by reset-simple driver as we mustn't
read from reset register or clear it.

.../bindings/reset/snps,axs10x-reset.txt | 33 +++++++++
MAINTAINERS | 6 ++
drivers/reset/Kconfig | 6 ++
drivers/reset/Makefile | 1 +
drivers/reset/reset-axs10x.c | 83 ++++++++++++++++++++++
5 files changed, 129 insertions(+)
create mode 100644 Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
create mode 100644 drivers/reset/reset-axs10x.c

diff --git a/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt b/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
new file mode 100644
index 0000000..32d8435
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
@@ -0,0 +1,33 @@
+Binding for the AXS10x reset controller
+
+This binding describes the ARC AXS10x boards custom IP-block which allows
+to control reset signals of selected peripherals. For example DW GMAC, etc...
+This block is controlled via memory-mapped register (AKA CREG) which
+represents up-to 32 reset lines.
+
+As of today only the following lines are used:
+ - DW GMAC - line 5
+
+This binding uses the common reset binding[1].
+
+[1] Documentation/devicetree/bindings/reset/reset.txt
+
+Required properties:
+- compatible: should be "snps,axs10x-reset".
+- reg: should always contain pair address - length: for creg reset
+ bits register.
+- #reset-cells: from common reset binding; Should always be set to 1.
+
+Example:
+ reset: reset-controller@11220 {
+ compatible = "snps,axs10x-reset";
+ #reset-cells = <1>;
+ reg = <0x11220 0x4>;
+ };
+
+Specifying reset lines connected to IP modules:
+ ethernet@.... {
+ ....
+ resets = <&reset 5>;
+ ....
+ };
diff --git a/MAINTAINERS b/MAINTAINERS
index 93dfb9d..f14e804 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12711,6 +12711,12 @@ F: arch/arc/plat-axs10x
F: arch/arc/boot/dts/ax*
F: Documentation/devicetree/bindings/arc/axs10*

+SYNOPSYS AXS10x RESET CONTROLLER DRIVER
+M: Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>
+S: Supported
+F: drivers/reset/reset-axs10x.c
+F: Documentation/devicetree/bindings/reset/snps,axs10x-reset.txt
+
SYNOPSYS DESIGNWARE DMAC DRIVER
M: Viresh Kumar <vireshk@xxxxxxxxxx>
M: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 52d5251..65d13f4 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -28,6 +28,12 @@ config RESET_ATH79
This enables the ATH79 reset controller driver that supports the
AR71xx SoC reset controller.

+config RESET_AXS10X
+ bool "AXS10x Reset Driver" if COMPILE_TEST
+ default ARC_PLAT_AXS10X
+ help
+ This enables the reset controller driver for AXS10x.
+
config RESET_BERLIN
bool "Berlin Reset Driver" if COMPILE_TEST
default ARCH_BERLIN
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index b62783f..45000a5 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_ARCH_STI) += sti/
obj-$(CONFIG_ARCH_TEGRA) += tegra/
obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
+obj-$(CONFIG_RESET_AXS10X) += reset-axs10x.o
obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
obj-$(CONFIG_RESET_HSDK) += reset-hsdk.o
obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
diff --git a/drivers/reset/reset-axs10x.c b/drivers/reset/reset-axs10x.c
new file mode 100644
index 0000000..afb298e
--- /dev/null
+++ b/drivers/reset/reset-axs10x.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (C) 2017 Synopsys.
+ *
+ * Synopsys AXS10x reset driver.
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#define to_axs10x_rst(p) container_of((p), struct axs10x_rst, rcdev)
+
+#define AXS10X_MAX_RESETS 32
+
+struct axs10x_rst {
+ void __iomem *regs_rst;
+ spinlock_t lock;
+ struct reset_controller_dev rcdev;
+};
+
+static int axs10x_reset_reset(struct reset_controller_dev *rcdev,
+ unsigned long id)
+{
+ struct axs10x_rst *rst = to_axs10x_rst(rcdev);
+ unsigned long flags;
+
+ spin_lock_irqsave(&rst->lock, flags);
+ writel(BIT(id), rst->regs_rst);
+ spin_unlock_irqrestore(&rst->lock, flags);
+
+ return 0;
+}
+
+static const struct reset_control_ops axs10x_reset_ops = {
+ .reset = axs10x_reset_reset,
+};
+
+static int axs10x_reset_probe(struct platform_device *pdev)
+{
+ struct axs10x_rst *rst;
+ struct resource *mem;
+
+ rst = devm_kzalloc(&pdev->dev, sizeof(*rst), GFP_KERNEL);
+ if (!rst)
+ return -ENOMEM;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ rst->regs_rst = devm_ioremap_resource(&pdev->dev, mem);
+ if (IS_ERR(rst->regs_rst))
+ return PTR_ERR(rst->regs_rst);
+
+ spin_lock_init(&rst->lock);
+
+ rst->rcdev.owner = THIS_MODULE;
+ rst->rcdev.ops = &axs10x_reset_ops;
+ rst->rcdev.of_node = pdev->dev.of_node;
+ rst->rcdev.nr_resets = AXS10X_MAX_RESETS;
+
+ return devm_reset_controller_register(&pdev->dev, &rst->rcdev);
+}
+
+static const struct of_device_id axs10x_reset_dt_match[] = {
+ { .compatible = "snps,axs10x-reset" },
+ { },
+};
+
+static struct platform_driver axs10x_reset_driver = {
+ .probe = axs10x_reset_probe,
+ .driver = {
+ .name = "axs10x-reset",
+ .of_match_table = axs10x_reset_dt_match,
+ },
+};
+builtin_platform_driver(axs10x_reset_driver);
+
+MODULE_AUTHOR("Eugeniy Paltsev <Eugeniy.Paltsev@xxxxxxxxxxxx>");
+MODULE_DESCRIPTION("Synopsys AXS10x reset driver");
+MODULE_LICENSE("GPL v2");
--
2.9.3