ARC: reset: introduce HSDKv1 reset driver

The HSDK v1 periphery IPs can be reset by accessing some registers
from the CGU block.

The list of available reset lines is documented in the DT bindings.
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

MAINTAINERS

@@ -11662,6 +11662,13 @@ L:	linux-mmc@vger.kernel.org
 S:	Maintained
 F:	drivers/mmc/host/dw_mmc*
 
+SYNOPSYS HSDK RESET CONTROLLER DRIVER
+M:	Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
+S:	Supported
+F:	drivers/reset/reset-hsdk-v1.c
+F:	include/dt-bindings/reset/snps,hsdk-v1-reset.h
+F:	Documentation/devicetree/bindings/reset/snps,hsdk-v1-reset.txt
+
 SYSTEM TRACE MODULE CLASS
 M:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
 S:	Maintained

drivers/reset/Kconfig

@@ -41,6 +41,12 @@ config RESET_GEMINI
 	help
 	  This enables the reset controller driver for Cortina Systems Gemini.
 
+config RESET_HSDK_V1
+	bool "HSDK v1 Reset Driver"
+	default n
+	help
+	  This enables the reset controller driver for HSDK v1.
+
 config RESET_IMX7
 	bool "i.MX7 Reset Driver" if COMPILE_TEST
 	default SOC_IMX7D

drivers/reset/Makefile

@@ -6,6 +6,7 @@ obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
 obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
 obj-$(CONFIG_RESET_GEMINI) += reset-gemini.o
+obj-$(CONFIG_RESET_HSDK_V1) += reset-hsdk-v1.o
 obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_RESET_MESON) += reset-meson.o

drivers/reset/reset-hsdk-v1.c

+/*
+ * Copyright (C) 2017 Synopsys.
+ *
+ * Synopsys HSDKv1 SDP 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/delay.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define to_hsdkv1_rst(p)	container_of((p), struct hsdkv1_rst, rcdev)
+
+struct hsdkv1_rst {
+	void __iomem			*regs_ctl;
+	void __iomem			*regs_rst;
+	spinlock_t			lock;
+	struct reset_controller_dev	rcdev;
+};
+
+static const u32 rst_map[] = {
+	BIT(16), /* APB_RST  */
+	BIT(17), /* AXI_RST  */
+	BIT(18), /* ETH_RST  */
+	BIT(19), /* USB_RST  */
+	BIT(20), /* SDIO_RST */
+	BIT(21), /* HDMI_RST */
+	BIT(22), /* GFX_RST  */
+	BIT(25), /* DMAC_RST */
+	BIT(31), /* EBI_RST  */
+};
+
+#define HSDK_MAX_RESETS			ARRAY_SIZE(rst_map)
+
+#define CGU_SYS_RST_CTRL		0x0
+#define CGU_IP_SW_RESET			0x0
+#define CGU_IP_SW_RESET_DELAY_SHIFT	16
+#define CGU_IP_SW_RESET_DELAY_MASK	GENMASK(31, CGU_IP_SW_RESET_DELAY_SHIFT)
+#define CGU_IP_SW_RESET_DELAY		0
+#define CGU_IP_SW_RESET_RESET		BIT(0)
+#define SW_RESET_TIMEOUT		10000
+
+static void hsdkv1_reset_config(struct hsdkv1_rst *rst, unsigned long id)
+{
+	writel(rst_map[id], rst->regs_ctl + CGU_SYS_RST_CTRL);
+}
+
+static int hsdkv1_reset_do(struct hsdkv1_rst *rst)
+{
+	u32 reg;
+
+	reg = readl(rst->regs_rst + CGU_IP_SW_RESET);
+	reg &= ~CGU_IP_SW_RESET_DELAY_MASK;
+	reg |= CGU_IP_SW_RESET_DELAY << CGU_IP_SW_RESET_DELAY_SHIFT;
+	reg |= CGU_IP_SW_RESET_RESET;
+	writel(reg, rst->regs_rst + CGU_IP_SW_RESET);
+
+	/* wait till reset bit is back to 0 */
+	return readl_poll_timeout_atomic(rst->regs_rst + CGU_IP_SW_RESET, reg,
+		!(reg & CGU_IP_SW_RESET_RESET), 5, SW_RESET_TIMEOUT);
+}
+
+static int hsdkv1_reset_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct hsdkv1_rst *rst = to_hsdkv1_rst(rcdev);
+	unsigned long flags;
+	int ret;
+
+	spin_lock_irqsave(&rst->lock, flags);
+	hsdkv1_reset_config(rst, id);
+	ret = hsdkv1_reset_do(rst);
+	spin_unlock_irqrestore(&rst->lock, flags);
+
+	return ret;
+}
+
+static const struct reset_control_ops hsdkv1_reset_ops = {
+	.reset	= hsdkv1_reset_reset,
+};
+
+static int hsdkv1_reset_probe(struct platform_device *pdev)
+{
+	struct hsdkv1_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_ctl = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(rst->regs_ctl))
+		return PTR_ERR(rst->regs_ctl);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	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 = &hsdkv1_reset_ops;
+	rst->rcdev.of_node = pdev->dev.of_node;
+	rst->rcdev.nr_resets = HSDK_MAX_RESETS;
+	rst->rcdev.of_reset_n_cells = 1;
+
+	return reset_controller_register(&rst->rcdev);
+}
+
+static const struct of_device_id hsdkv1_reset_dt_match[] = {
+	{ .compatible = "snps,hsdk-v1.0-reset" },
+	{ },
+};
+
+static struct platform_driver hsdkv1_reset_driver = {
+	.probe	= hsdkv1_reset_probe,
+	.driver	= {
+		.name = "hsdk-v1.0-reset",
+		.of_match_table = hsdkv1_reset_dt_match,
+	},
+};
+builtin_platform_driver(hsdkv1_reset_driver);
+
+MODULE_AUTHOR("Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>");
+MODULE_DESCRIPTION("Synopsys HSDKv1 SDP reset driver");
+MODULE_LICENSE("GPL v2");

include/dt-bindings/reset/snps,hsdk-v1-reset.h

+/**
+ * This header provides index for the HSDK v1 reset controller.
+ */
+#ifndef _DT_BINDINGS_RESET_CONTROLLER_HSDK_V1
+#define _DT_BINDINGS_RESET_CONTROLLER_HSDK_V1
+
+#define HSDK_V1_APB_RESET	0
+#define HSDK_V1_AXI_RESET	1
+#define HSDK_V1_ETH_RESET	2
+#define HSDK_V1_USB_RESET	3
+#define HSDK_V1_SDIO_RESET	4
+#define HSDK_V1_HDMI_RESET	5
+#define HSDK_V1_GFX_RESET	6
+#define HSDK_V1_DMAC_RESET	7
+#define HSDK_V1_EBI_RESET	8
+
+#endif /*_DT_BINDINGS_RESET_CONTROLLER_HSDK_V1*/