[RFC 01/11] drivers: reset: TI: SoC reset controller support.

From: Dan Murphy <dmurphy@ti.com>
To: linux-omap@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	tony@atomide.com, devicetree@vger.kernel.org
Cc: t-kristo@ti.com, s-anna@ti.com, p.zabel@pengutronix.de,
	Dan Murphy <dmurphy@ti.com>
Subject: [RFC 01/11] drivers: reset: TI: SoC reset controller support.
Date: Tue, 29 Apr 2014 15:19:40 -0500	[thread overview]
Message-ID: <1398802790-29287-2-git-send-email-dmurphy@ti.com> (raw)
In-Reply-To: <1398802790-29287-1-git-send-email-dmurphy@ti.com>

The TI SoC reset controller support utilizes the
reset controller framework to give device drivers or
function drivers a common set of APIs to call to reset
a module.

The reset-ti is a common interface to the reset framework.
 The register data is retrieved during initialization
 of the reset driver through the reset-ti-data
file.  The array of data is associated with the compatible from the
respective DT entry.

Once the data is available then this is derefenced within the common
interface.

The device driver has the ability to assert, deassert or perform a
complete reset.

This code was derived from previous work by Rajendra Nayak and Afzal Mohammed.
The code was changed to adopt to the reset core and abstract away the SoC information.

Signed-off-by: Dan Murphy <dmurphy@ti.com>
---
 drivers/reset/Kconfig            |    1 +
 drivers/reset/Makefile           |    1 +
 drivers/reset/ti/Kconfig         |    8 ++
 drivers/reset/ti/Makefile        |    1 +
 drivers/reset/ti/reset-ti-data.h |   58 ++++++++++++
 drivers/reset/ti/reset-ti.c      |  195 ++++++++++++++++++++++++++++++++++++++
 include/linux/reset_ti.h         |   25 +++++
 7 files changed, 289 insertions(+)
 create mode 100644 drivers/reset/ti/Kconfig
 create mode 100644 drivers/reset/ti/Makefile
 create mode 100644 drivers/reset/ti/reset-ti-data.h
 create mode 100644 drivers/reset/ti/reset-ti.c
 create mode 100644 include/linux/reset_ti.h

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 0615f50..a58d789 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -13,3 +13,4 @@ menuconfig RESET_CONTROLLER
 	  If unsure, say no.
 
 source "drivers/reset/sti/Kconfig"
+source "drivers/reset/ti/Kconfig"
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 4f60caf..1c8c444 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,3 +1,4 @@
 obj-$(CONFIG_RESET_CONTROLLER) += core.o
 obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
 obj-$(CONFIG_ARCH_STI) += sti/
+obj-$(CONFIG_RESET_TI) += ti/
diff --git a/drivers/reset/ti/Kconfig b/drivers/reset/ti/Kconfig
new file mode 100644
index 0000000..dcdce90
--- /dev/null
+++ b/drivers/reset/ti/Kconfig
@@ -0,0 +1,8 @@
+config RESET_TI
+	depends on RESET_CONTROLLER
+	bool "TI reset controller"
+	help
+	  Reset controller support for TI SoC's
+
+	  Reset controller found in TI's AM series of SoC's like
+	  AM335x and AM43x and OMAP SoC's like OMAP5 and DRA7
diff --git a/drivers/reset/ti/Makefile b/drivers/reset/ti/Makefile
new file mode 100644
index 0000000..55ab3f5
--- /dev/null
+++ b/drivers/reset/ti/Makefile
@@ -0,0 +1 @@
+obj-$(CONFIG_RESET_TI) += reset-ti.o
diff --git a/drivers/reset/ti/reset-ti-data.h b/drivers/reset/ti/reset-ti-data.h
new file mode 100644
index 0000000..6afdf37
--- /dev/null
+++ b/drivers/reset/ti/reset-ti-data.h
@@ -0,0 +1,58 @@
+/*
+ * PRCM reset driver for TI SoC's
+ *
+ * Copyright 2014 Texas Instruments Inc.
+ *
+ * Author: Dan Murphy <dmurphy@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _RESET_TI_DATA_H_
+#define _RESET_TI_DATA_H_
+
+#include <linux/kernel.h>
+#include <linux/of_device.h>
+#include <linux/reset-controller.h>
+
+/**
+ * struct ti_reset_reg_data - Structure of the reset register information
+ * 	for a particular SoC.
+ * @rstctrl_offs: This is the reset control offset value from
+ *		from the parent reset node.
+ * @rstst_offs: This is the reset status offset value from
+ *		from the parent reset node.
+ * @rstctrl_bit: This is the reset control bit for the module.
+ * @rstst_bit: This is the reset status bit for the module.
+ *
+ * This structure describes the reset register control and status offsets.
+ * The bits are also defined for the same.
+ */
+struct ti_reset_reg_data {
+	u32	rstctrl_offs;
+	u32	rstst_offs;
+	u8	rstctrl_bit;
+	u8	rstst_bit;
+};
+
+/**
+ * struct ti_reset_data - Structure that contains the reset register data
+ *	as well as the total number of resets for a particular SoC.
+ * @reg_data:	Pointer to the register data structure.
+ * @nr_resets:	Total number of resets for the SoC in the reset array.
+ *
+ * This structure contains a pointer to the register data and the modules
+ * register base.  The number of resets and reset controller device data is
+ * stored within this structure.
+ * 
+ */
+struct ti_reset_data {
+	struct ti_reset_reg_data *reg_data;
+	struct reset_controller_dev rcdev;
+	void __iomem *reg_base;
+	u8	nr_resets;
+};
+
+#endif
diff --git a/drivers/reset/ti/reset-ti.c b/drivers/reset/ti/reset-ti.c
new file mode 100644
index 0000000..1d38069
--- /dev/null
+++ b/drivers/reset/ti/reset-ti.c
@@ -0,0 +1,195 @@
+/*
+ * PRCM reset driver for TI SoC's
+ *
+ * Copyright 2014 Texas Instruments Inc.
+ *
+ * Author: Dan Murphy <dmurphy@ti.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/slab.h>
+
+#include <linux/reset_ti.h>
+#include <linux/reset.h>
+
+#include "reset-ti-data.h"
+
+static void ti_reset_wait_on_reset(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct ti_reset_data *reset_data = container_of(rcdev,
+													struct ti_reset_data,
+													rcdev);
+	void __iomem *status_reg;
+	u32 val = 0;
+	u8 status_bit = 0;
+
+	if (id < 0) {
+		pr_err("%s: ID passed is invalid\n", __func__);
+		return;
+	}
+
+	/* Clear the reset status bit to reflect the current status */
+	status_reg = reset_data->reg_base + reset_data->reg_data[id].rstst_offs;
+	status_bit = reset_data->reg_data[id].rstst_bit;
+	do {
+		val = readl(status_reg);
+		if (!(val & (1 << status_bit)))
+			break;
+	} while (1);
+}
+
+static int ti_reset_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct ti_reset_data *reset_data = container_of(rcdev,
+													struct ti_reset_data,
+													rcdev);
+	void __iomem *reg;
+	void __iomem *status_reg;
+	u32 val = 0;
+	u8 bit = 0;
+	u8 status_bit = 0;
+
+	if (id < 0) {
+		pr_err("%s: ID passed is invalid\n", __func__);
+		return -ENODEV;
+	}
+
+	/* Clear the reset status bit to reflect the current status */
+	status_reg = reset_data->reg_base + reset_data->reg_data[id].rstst_offs;
+	status_bit = reset_data->reg_data[id].rstst_bit;
+	writel(1 << status_bit, status_reg);
+
+	reg = reset_data->reg_base + reset_data->reg_data[id].rstctrl_offs;
+	bit = reset_data->reg_data[id].rstctrl_bit;
+	val = readl(reg);
+	if (!(val & (1 << bit))) {
+		val |= (1 << bit);
+		writel(val, reg);
+	}
+
+	return 0;
+}
+
+static int ti_reset_deassert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+
+	struct ti_reset_data *reset_data;
+	void __iomem *reg;
+	void __iomem *status_reg;
+	u32 val = 0;
+	u8 bit = 0;
+	u8 status_bit = 0;
+
+	if (id < 0) {
+		pr_err("%s: reset ID passed is invalid\n", __func__);
+		return -ENODEV;
+	}
+
+	reset_data = container_of(rcdev, struct ti_reset_data, rcdev);
+
+	/* Clear the reset status bit to reflect the current status */
+	status_reg = reset_data->reg_base + reset_data->reg_data[id].rstst_offs;
+	status_bit = reset_data->reg_data[id].rstst_bit;
+	writel(1 << status_bit, status_reg);
+
+	reg = reset_data->reg_base + reset_data->reg_data[id].rstctrl_offs;
+	bit = reset_data->reg_data[id].rstctrl_bit;
+	val = readl(reg);
+	if (val & (1 << bit)) {
+		val &= ~(1 << bit);
+		writel(val, reg);
+	}
+
+	return 0;
+}
+
+static int ti_reset_reset(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	ti_reset_assert(rcdev, id);
+	ti_reset_deassert(rcdev, id);
+	ti_reset_wait_on_reset(rcdev, id);
+
+	return 0;
+}
+
+static struct reset_control_ops ti_reset_ops = {
+	.reset = ti_reset_reset,
+	.assert = ti_reset_assert,
+	.deassert = ti_reset_deassert,
+};
+
+static const struct of_device_id ti_reset_of_match[] = {
+	{},
+};
+
+const struct of_device_id *ti_reset_get_data(struct device_node *parent)
+{
+	const struct of_device_id *dev_node;
+
+	dev_node = of_match_node(ti_reset_of_match, parent);
+	if (!dev_node) {
+		pr_err("%s: No compatible for resets for %s\n",
+			__func__, parent->name);
+		return NULL;
+	}
+
+	return dev_node;
+}
+
+void __init ti_dt_reset_init(void)
+{
+	struct ti_reset_data *ti_data;
+	struct device_node *parent;
+	struct device_node *resets;
+	const struct of_device_id *dev_node;
+
+	resets = of_find_node_by_name(NULL, "resets");
+	if (!resets) {
+		pr_err("%s: missing 'resets' child node.\n", __func__);
+		return;
+	}
+
+	parent = of_get_parent(resets);
+	if (!parent) {
+		pr_err("%s: Cannot find parent reset node\n", __func__);
+		return;
+	}
+
+	ti_data = kzalloc(sizeof(*ti_data), GFP_KERNEL);
+	if (!ti_data)
+		return;
+
+	dev_node = ti_reset_get_data(resets);
+	if (!dev_node) {
+		pr_err("%s: Cannot find data for node\n", __func__);
+		return;
+	}
+
+	ti_data = (struct ti_reset_data *) dev_node->data;
+
+	ti_data->reg_base = of_iomap(parent, 0);
+	if (!ti_data->reg_base) {
+		pr_err("%s: Cannot map reset parent.\n", __func__);
+		return;
+	}
+
+	ti_data->rcdev.owner = THIS_MODULE;
+	ti_data->rcdev.nr_resets = ti_data->nr_resets;
+	ti_data->rcdev.of_node = resets;
+	ti_data->rcdev.ops = &ti_reset_ops;
+
+	reset_controller_register(&ti_data->rcdev);
+}
diff --git a/include/linux/reset_ti.h b/include/linux/reset_ti.h
new file mode 100644
index 0000000..d18f47f
--- /dev/null
+++ b/include/linux/reset_ti.h
@@ -0,0 +1,25 @@
+/*
+ * TI reset driver support
+ *
+ * Copyright (C) 2014 Texas Instruments, Inc.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed "as is" WITHOUT ANY WARRANTY of any
+ * kind, whether express or implied; without even the implied warranty
+ * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#ifndef _RESET_TI_H_
+#define _RESET_TI_H_
+
+#ifdef CONFIG_RESET_TI
+void ti_dt_reset_init(void);
+#else
+static inline void ti_dt_reset_init(void){ return; };
+#endif
+
+#endif
-- 
1.7.9.5

