reset: Add i.MX7 SRC reset driver

Add reset controller driver exposing various reset faculties,
implemented by System Reset Controller IP block.

Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: devicetree@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Documentation/devicetree/bindings/reset/fsl,imx7-src.txt

+Freescale i.MX7 System Reset Controller
+======================================
+
+Please also refer to reset.txt in this directory for common reset
+controller binding usage.
+
+Required properties:
+- compatible: Should be "fsl,imx7-src", "syscon"
+- reg: should be register base and length as documented in the
+  datasheet
+- interrupts: Should contain SRC interrupt
+- #reset-cells: 1, see below
+
+example:
+
+src: reset-controller@30390000 {
+     compatible = "fsl,imx7d-src", "syscon";
+     reg = <0x30390000 0x2000>;
+     interrupts = <GIC_SPI 89 IRQ_TYPE_LEVEL_HIGH>;
+     #reset-cells = <1>;
+};
+
+
+Specifying reset lines connected to IP modules
+==============================================
+
+The system reset controller can be used to reset various set of
+peripherals. Device nodes that need access to reset lines should
+specify them as a reset phandle in their corresponding node as
+specified in reset.txt.
+
+Example:
+
+	pcie: pcie@33800000 {
+
+		...
+
+		resets = <&src IMX7_RESET_PCIEPHY>,
+			 <&src IMX7_RESET_PCIE_CTRL_APPS_EN>;
+		reset-names = "pciephy", "apps";
+
+		...
+        };
+
+
+For list of all valid reset indicies see
+<dt-bindings/reset/imx7-reset.h>

drivers/reset/Kconfig

@@ -27,6 +27,13 @@ config RESET_BERLIN
 	help
 	  This enables the reset controller driver for Marvell Berlin SoCs.
 
+config RESET_IMX7
+	bool "i.MX7 Reset Driver" if COMPILE_TEST
+	default SOC_IMX7D
+	select MFD_SYSCON
+	help
+	  This enables the reset controller driver for i.MX7 SoCs.
+
 config RESET_LPC18XX
 	bool "LPC18xx/43xx Reset Driver" if COMPILE_TEST
 	default ARCH_LPC18XX

drivers/reset/Makefile

@@ -4,6 +4,7 @@ obj-$(CONFIG_ARCH_STI) += sti/
 obj-$(CONFIG_ARCH_TEGRA) += tegra/
 obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
 obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
+obj-$(CONFIG_RESET_IMX7) += reset-imx7.o
 obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_RESET_MESON) += reset-meson.o
 obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
@@ -15,3 +16,4 @@ 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
+

drivers/reset/reset-imx7.c

+/*
+ * Copyright (c) 2017, Impinj, Inc.
+ *
+ * i.MX7 System Reset Controller (SRC) driver
+ *
+ * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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.
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/regmap.h>
+#include <dt-bindings/reset/imx7-reset.h>
+
+struct imx7_src {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+};
+
+enum imx7_src_registers {
+	SRC_A7RCR0		= 0x0004,
+	SRC_M4RCR		= 0x000c,
+	SRC_ERCR		= 0x0014,
+	SRC_HSICPHY_RCR		= 0x001c,
+	SRC_USBOPHY1_RCR	= 0x0020,
+	SRC_USBOPHY2_RCR	= 0x0024,
+	SRC_MIPIPHY_RCR		= 0x0028,
+	SRC_PCIEPHY_RCR		= 0x002c,
+	SRC_DDRC_RCR		= 0x1000,
+};
+
+struct imx7_src_signal {
+	unsigned int offset, bit;
+};
+
+static const struct imx7_src_signal imx7_src_signals[IMX7_RESET_NUM] = {
+	[IMX7_RESET_A7_CORE_POR_RESET0] = { SRC_A7RCR0, BIT(0) },
+	[IMX7_RESET_A7_CORE_POR_RESET1] = { SRC_A7RCR0, BIT(1) },
+	[IMX7_RESET_A7_CORE_RESET0]     = { SRC_A7RCR0, BIT(4) },
+	[IMX7_RESET_A7_CORE_RESET1]	= { SRC_A7RCR0, BIT(5) },
+	[IMX7_RESET_A7_DBG_RESET0]	= { SRC_A7RCR0, BIT(8) },
+	[IMX7_RESET_A7_DBG_RESET1]	= { SRC_A7RCR0, BIT(9) },
+	[IMX7_RESET_A7_ETM_RESET0]	= { SRC_A7RCR0, BIT(12) },
+	[IMX7_RESET_A7_ETM_RESET1]	= { SRC_A7RCR0, BIT(13) },
+	[IMX7_RESET_A7_SOC_DBG_RESET]	= { SRC_A7RCR0, BIT(20) },
+	[IMX7_RESET_A7_L2RESET]		= { SRC_A7RCR0, BIT(21) },
+	[IMX7_RESET_SW_M4C_RST]		= { SRC_M4RCR, BIT(1) },
+	[IMX7_RESET_SW_M4P_RST]		= { SRC_M4RCR, BIT(2) },
+	[IMX7_RESET_EIM_RST]		= { SRC_ERCR, BIT(0) },
+	[IMX7_RESET_HSICPHY_PORT_RST]	= { SRC_HSICPHY_RCR, BIT(1) },
+	[IMX7_RESET_USBPHY1_POR]	= { SRC_USBOPHY1_RCR, BIT(0) },
+	[IMX7_RESET_USBPHY1_PORT_RST]	= { SRC_USBOPHY1_RCR, BIT(1) },
+	[IMX7_RESET_USBPHY2_POR]	= { SRC_USBOPHY2_RCR, BIT(0) },
+	[IMX7_RESET_USBPHY2_PORT_RST]	= { SRC_USBOPHY2_RCR, BIT(1) },
+	[IMX7_RESET_MIPI_PHY_MRST]	= { SRC_MIPIPHY_RCR, BIT(1) },
+	[IMX7_RESET_MIPI_PHY_SRST]	= { SRC_MIPIPHY_RCR, BIT(2) },
+	[IMX7_RESET_PCIEPHY]		= { SRC_PCIEPHY_RCR, BIT(2) | BIT(1) },
+	[IMX7_RESET_PCIEPHY_PERST]	= { SRC_PCIEPHY_RCR, BIT(3) },
+	[IMX7_RESET_PCIE_CTRL_APPS_EN]	= { SRC_PCIEPHY_RCR, BIT(6) },
+	[IMX7_RESET_DDRC_PRST]		= { SRC_DDRC_RCR, BIT(0) },
+	[IMX7_RESET_DDRC_CORE_RST]	= { SRC_DDRC_RCR, BIT(1) },
+};
+
+static struct imx7_src *to_imx7_src(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct imx7_src, rcdev);
+}
+
+static int imx7_reset_set(struct reset_controller_dev *rcdev,
+			  unsigned long id, bool assert)
+{
+	struct imx7_src *imx7src = to_imx7_src(rcdev);
+	const struct imx7_src_signal *signal = &imx7_src_signals[id];
+	unsigned int value = 0;
+
+	switch (id) {
+	case IMX7_RESET_PCIEPHY:
+		/*
+		 * wait for more than 10us to release phy g_rst and
+		 * btnrst
+		 */
+		if (!assert)
+			udelay(10);
+		break;
+
+	case IMX7_RESET_PCIE_CTRL_APPS_EN:
+		value = (assert) ? 0 : signal->bit;
+		break;
+	}
+
+	return regmap_update_bits(imx7src->regmap,
+				  signal->offset, signal->bit, value);
+}
+
+static int imx7_reset_assert(struct reset_controller_dev *rcdev,
+			     unsigned long id)
+{
+	return imx7_reset_set(rcdev, id, true);
+}
+
+static int imx7_reset_deassert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	return imx7_reset_set(rcdev, id, false);
+}
+
+static const struct reset_control_ops imx7_reset_ops = {
+	.assert		= imx7_reset_assert,
+	.deassert	= imx7_reset_deassert,
+};
+
+static int imx7_reset_probe(struct platform_device *pdev)
+{
+	struct imx7_src *imx7src;
+	struct device *dev = &pdev->dev;
+	struct regmap_config config = { .name = "src" };
+
+	imx7src = devm_kzalloc(dev, sizeof(*imx7src), GFP_KERNEL);
+	if (!imx7src)
+		return -ENOMEM;
+
+	imx7src->regmap = syscon_node_to_regmap(dev->of_node);
+	if (IS_ERR(imx7src->regmap)) {
+		dev_err(dev, "Unable to get imx7-src regmap");
+		return PTR_ERR(imx7src->regmap);
+	}
+	regmap_attach_dev(dev, imx7src->regmap, &config);
+
+	imx7src->rcdev.owner     = THIS_MODULE;
+	imx7src->rcdev.nr_resets = IMX7_RESET_NUM;
+	imx7src->rcdev.ops       = &imx7_reset_ops;
+	imx7src->rcdev.of_node   = dev->of_node;
+
+	return devm_reset_controller_register(dev, &imx7src->rcdev);
+}
+
+static const struct of_device_id imx7_reset_dt_ids[] = {
+	{ .compatible = "fsl,imx7d-src", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver imx7_reset_driver = {
+	.probe	= imx7_reset_probe,
+	.driver = {
+		.name		= KBUILD_MODNAME,
+		.of_match_table	= imx7_reset_dt_ids,
+	},
+};
+builtin_platform_driver(imx7_reset_driver);

include/dt-bindings/reset/imx7-reset.h

+/*
+ * Copyright (C) 2017 Impinj, Inc.
+ *
+ * Author: Andrey Smirnov <andrew.smirnov@gmail.com>
+ *
+ * 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/>.
+ */
+
+#ifndef DT_BINDING_RESET_IMX7_H
+#define DT_BINDING_RESET_IMX7_H
+
+#define IMX7_RESET_A7_CORE_POR_RESET0	0
+#define IMX7_RESET_A7_CORE_POR_RESET1	1
+#define IMX7_RESET_A7_CORE_RESET0	2
+#define IMX7_RESET_A7_CORE_RESET1	3
+#define IMX7_RESET_A7_DBG_RESET0	4
+#define IMX7_RESET_A7_DBG_RESET1	5
+#define IMX7_RESET_A7_ETM_RESET0	6
+#define IMX7_RESET_A7_ETM_RESET1	7
+#define IMX7_RESET_A7_SOC_DBG_RESET	8
+#define IMX7_RESET_A7_L2RESET		9
+#define IMX7_RESET_SW_M4C_RST		10
+#define IMX7_RESET_SW_M4P_RST		11
+#define IMX7_RESET_EIM_RST		12
+#define IMX7_RESET_HSICPHY_PORT_RST	13
+#define IMX7_RESET_USBPHY1_POR		14
+#define IMX7_RESET_USBPHY1_PORT_RST	15
+#define IMX7_RESET_USBPHY2_POR		16
+#define IMX7_RESET_USBPHY2_PORT_RST	17
+#define IMX7_RESET_MIPI_PHY_MRST	18
+#define IMX7_RESET_MIPI_PHY_SRST	19
+
+/*
+ * IMX7_RESET_PCIEPHY is a logical reset line combining PCIEPHY_BTN
+ * and PCIEPHY_G_RST
+ */
+#define IMX7_RESET_PCIEPHY		20
+#define IMX7_RESET_PCIEPHY_PERST	21
+
+/*
+ * IMX7_RESET_PCIE_CTRL_APPS_EN is not strictly a reset line, but it
+ * can be used to inhibit PCIe LTTSM, so, in a way, it can be thoguht
+ * of as one
+ */
+#define IMX7_RESET_PCIE_CTRL_APPS_EN	22
+#define IMX7_RESET_DDRC_PRST		23
+#define IMX7_RESET_DDRC_CORE_RST	24
+
+#define IMX7_RESET_NUM			25
+
+#endif
+