ARC: reset: introduce AXS10x reset driver

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@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

3 files changed, 90 insertions, 0 deletions

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index e0c3932..23ec43f 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 d368367..7579dba 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-$(CONFIG_RESET_HSDK_V1) += reset-hsdk-v1.o
 obj-$(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@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys AXS10x reset driver");
+MODULE_LICENSE("GPL v2");