[PATCH v5 0/2] Add support for SYSCON reset

[PATCH v5 0/2] Add support for SYSCON reset

[Andrew F. Davis]

Some SoCs contain reset controls for modules that are memory-mapped to
areas shared with other module configuration settings. This requires
synchronization across all drivers accessing this memory area. This
series adds a generic SYSCON reset driver to allow resets toggled
by bits in memory-mapped registers through SYSCON.

Changes from v4:
 - Added two more cells to DT ti,reset-bits property
 - Re-organized ti,reset-bits flag property defines
 - Moved TI_SYSCON_RESET in Kconfig
 - Other small fixes based on comments on v4

Changes from v3:
 - Add depends on HAS_IOMEM to Kconfig
 - Re-worked naming to be more TI specific for now
 - Changed DT binding to Philipp's suggestion

Changes from v2:
 - Rebased on v4.7-rc1
 - Removed the need to give reset specifier nodes an index address

Changes from v1:
 - Reset control information is now described in the reset node, this
   keeps the reset information centralized for easy verification
 - Other small fixups

Andrew F. Davis (2):
  Documentation: dt: reset: Add TI syscon reset binding
  reset: add TI SYSCON based reset driver

 .../devicetree/bindings/reset/ti-syscon-reset.txt  |  91 ++++++++
 drivers/reset/Kconfig                              |  10 +
 drivers/reset/Makefile                             |   1 +
 drivers/reset/reset-ti-syscon.c                    | 237 +++++++++++++++++++++
 include/dt-bindings/reset/ti-syscon.h              |  38 ++++
 5 files changed, 377 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
 create mode 100644 drivers/reset/reset-ti-syscon.c
 create mode 100644 include/dt-bindings/reset/ti-syscon.h

-- 
2.9.0

[PATCH v5 1/2] Documentation: dt: reset: Add TI syscon reset binding

[Andrew F. Davis]

Add TI syscon reset controller binding. This will hook to the reset
framework and use syscon/regmap to set reset bits. This allows reset
control of individual SoC subsytems and devices with memory-mapped
reset registers in a common register memory space.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Suman Anna <s-anna@ti.com>
---
 .../devicetree/bindings/reset/ti-syscon-reset.txt  | 91 ++++++++++++++++++++++
 include/dt-bindings/reset/ti-syscon.h              | 38 +++++++++
 2 files changed, 129 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
 create mode 100644 include/dt-bindings/reset/ti-syscon.h

diff --git a/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt b/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
new file mode 100644
index 0000000..164c7f3
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
@@ -0,0 +1,91 @@
+TI SysCon Reset Controller
+=======================
+
+Almost all SoCs have hardware modules that require reset control in addition
+to clock and power control for their functionality. The reset control is
+typically provided by means of memory-mapped I/O registers. These registers are
+sometimes a part of a larger register space region implementing various
+functionalities. This register range is best represented as a syscon node to
+allow multiple entities to access their relevant registers in the common
+register space.
+
+A SysCon Reset Controller node defines a device that uses a syscon node
+and provides reset management functionality for various hardware modules
+present on the SoC.
+
+SysCon Reset Controller Node
+============================
+Each of the reset provider/controller nodes should be a child of a syscon
+node and have the following properties.
+
+Required properties:
+--------------------
+ - compatible		: Should be,
+			    "ti,k2e-pscrst"
+			    "ti,k2l-pscrst"
+			    "ti,k2hk-pscrst"
+			    "ti,syscon-reset"
+ - #reset-cells		: Should be 1. Please see the reset consumer node below
+			  for usage details
+ - ti,reset-bits	: Contains the reset control register information
+			  Should contain 7 cells for each reset exposed to
+			  consumers, defined as:
+			    Cell #1 : offset of the reset assert control
+			              register from the syscon register base
+			    Cell #2 : bit position of the reset in the reset
+			              assert control register
+			    Cell #3 : offset of the reset deassert control
+			              register from the syscon register base
+			    Cell #4 : bit position of the reset in the reset
+			              deassert control register
+			    Cell #5 : offset of the reset status register
+			              from the syscon register base
+			    Cell #6 : bit position of the reset in the
+			              reset status register
+			    Cell #7 : Flags used to control reset behavior,
+			              availible flags defined in the DT include
+			              file <dt-bindings/reset/ti-syscon.h>
+
+SysCon Reset Consumer Nodes
+===========================
+Each of the reset consumer nodes should have the following properties,
+in addition to their own properties.
+
+Required properties:
+--------------------
+ - resets	: A phandle to the reset controller node and an index number
+		  to a reset specifier as defined above.
+
+Please also refer to Documentation/devicetree/bindings/reset/reset.txt for
+common reset controller usage by consumers.
+
+Example:
+--------
+The following example demonstrates a syscon node, the reset controller node
+using the syscon node, and a consumer (a DSP device) on the TI Keystone 2
+Edison SoC.
+
+/ {
+	soc {
+		psc: power-sleep-controller@02350000 {
+			compatible = "syscon", "simple-mfd";
+			reg = <0x02350000 0x1000>;
+
+			pscrst: psc-reset {
+				compatible = "ti,k2e-pscrst", "ti,syscon-reset";
+				#reset-cells = <1>;
+
+				ti,reset-bits = <
+					0xa3c 8 0xa3c 8 0x83c 8 (ASSERT_SET|DEASSERT_CLEAR|STATUS_SET)   /* 0: pcrst-dsp0 */
+					0xa40 5 0xa44 3 0     0 (ASSERT_SET|DEASSERT_CLEAR|STATUS_NONE)  /* 1: pcrst-example */
+				>;
+			};
+		};
+
+		dsp0: dsp0 {
+			...
+			resets = <&pscrst 0>;
+			...
+		};
+	};
+};
diff --git a/include/dt-bindings/reset/ti-syscon.h b/include/dt-bindings/reset/ti-syscon.h
new file mode 100644
index 0000000..884fd91
--- /dev/null
+++ b/include/dt-bindings/reset/ti-syscon.h
@@ -0,0 +1,38 @@
+/*
+ * TI Syscon Reset definitions
+ *
+ * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.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; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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.
+ */
+
+#ifndef __DT_BINDINGS_RESET_TI_SYSCON_H__
+#define __DT_BINDINGS_RESET_TI_SYSCON_H__
+
+/*
+ * The reset does not support the feature and corresponding
+ * values are not valid
+ */
+#define ASSERT_NONE	(1 << 0)
+#define DEASSERT_NONE	(1 << 1)
+#define STATUS_NONE	(1 << 2)
+
+/* When set this function is activated by setting(vs clearing) this bit */
+#define ASSERT_SET	(1 << 3)
+#define DEASSERT_SET	(1 << 4)
+#define STATUS_SET	(1 << 5)
+
+/* The following are the inverse of the above and are added for consistency */
+#define ASSERT_CLEAR	(0 << 3)
+#define DEASSERT_CLEAR	(0 << 4)
+#define STATUS_CLEAR	(0 << 5)
+
+#endif
-- 
2.9.0

[PATCH v5 2/2] reset: add TI SYSCON based reset driver

[Andrew F. Davis]

Add a reset-controller driver for performing reset management of
various devices present on the SoC, with the reset registers shared
between devices in a common register memory space. This driver uses
the syscon/regmap frameworks to actually implement the various reset
functionalities needed by the reset consumer devices.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: add documentation, syscon name change]
Signed-off-by: Suman Anna <s-anna@ti.com>
---
 drivers/reset/Kconfig           |  10 ++
 drivers/reset/Makefile          |   1 +
 drivers/reset/reset-ti-syscon.c | 237 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 248 insertions(+)
 create mode 100644 drivers/reset/reset-ti-syscon.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index ab37f4d..4be1b8c 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -17,6 +17,16 @@ if RESET_CONTROLLER
 config RESET_OXNAS
 	bool
 
+config TI_SYSCON_RESET
+	tristate "TI SYSCON Reset Driver"
+	depends on HAS_IOMEM
+	select MFD_SYSCON
+	help
+	  This enables the reset driver support for TI devices with
+	  memory-mapped reset registers as part of a syscon device node. If
+	  you wish to use the reset framework for such memory-mapped devices,
+	  say Y here. Otherwise, say N.
+
 source "drivers/reset/sti/Kconfig"
 source "drivers/reset/hisilicon/Kconfig"
 
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 03dc1bb..5d65a93 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_ARCH_HISI) += hisilicon/
 obj-$(CONFIG_ARCH_ZYNQ) += reset-zynq.o
 obj-$(CONFIG_ATH79) += reset-ath79.o
 obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
+obj-$(CONFIG_TI_SYSCON_RESET) += reset-ti-syscon.o
diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
new file mode 100644
index 0000000..47f0ffd
--- /dev/null
+++ b/drivers/reset/reset-ti-syscon.c
@@ -0,0 +1,237 @@
+/*
+ * TI SYSCON regmap reset driver
+ *
+ * Copyright (C) 2015-2016 Texas Instruments Incorporated - http://www.ti.com/
+ *	Andrew F. Davis <afd@ti.com>
+ *	Suman Anna <afd@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.
+ *
+ * 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.
+ */
+
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/ti-syscon.h>
+
+/**
+ * struct ti_syscon_reset_control - reset control structure
+ * @assert_offset: reset assert control register offset from syscon base
+ * @assert_bit: reset assert bit in the reset assert control register
+ * @deassert_offset: reset deassert control register offset from syscon base
+ * @deassert_bit: reset deassert bit in the reset deassert control register
+ * @status_offset: reset status register offset from syscon base
+ * @status_bit: reset status bit in the reset status register
+ * @flags: reset flag indicating how the (de)assert and status are handled
+ */
+struct ti_syscon_reset_control {
+	unsigned int assert_offset;
+	unsigned int assert_bit;
+	unsigned int deassert_offset;
+	unsigned int deassert_bit;
+	unsigned int status_offset;
+	unsigned int status_bit;
+	u32 flags;
+};
+
+/**
+ * struct ti_syscon_reset_data - reset controller information structure
+ * @rcdev: reset controller entity
+ * @regmap: regmap handle containing the memory-mapped reset registers
+ * @controls: array of reset controls
+ * @nr_controls: number of controls in control array
+ */
+struct ti_syscon_reset_data {
+	struct reset_controller_dev rcdev;
+	struct regmap *regmap;
+	struct ti_syscon_reset_control *controls;
+	unsigned int nr_controls;
+};
+
+#define to_ti_syscon_reset_data(rcdev)	\
+	container_of(rcdev, struct ti_syscon_reset_data, rcdev)
+
+/**
+ * ti_syscon_reset_assert() - assert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be asserted
+ *
+ * This function implements the reset driver op to assert a device's reset.
+ * This asserts the reset in a manner prescribed by the reset flags.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
+	struct ti_syscon_reset_control *control;
+	unsigned int mask, value;
+
+	if (id >= data->nr_controls)
+		return -EINVAL;
+
+	control = &data->controls[id];
+
+	if (control->flags & ASSERT_NONE)
+		return -ENOTSUPP; /* assert not supported for this reset */
+
+	mask = BIT(control->assert_bit);
+	value = (control->flags & ASSERT_SET) ? mask : 0x0;
+
+	return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
+}
+
+/**
+ * ti_syscon_reset_deassert() - deassert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of reset to be deasserted
+ *
+ * This function implements the reset driver op to deassert a device's reset.
+ * This deasserts the reset in a manner prescribed by the reset flags.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
+				    unsigned long id)
+{
+	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
+	struct ti_syscon_reset_control *control;
+	unsigned int mask, value;
+
+	if (id >= data->nr_controls)
+		return -EINVAL;
+
+	control = &data->controls[id];
+
+	if (control->flags & DEASSERT_NONE)
+		return -ENOTSUPP; /* deassert not supported for this reset */
+
+	mask = BIT(control->deassert_bit);
+	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
+
+	return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
+}
+
+/**
+ * ti_syscon_reset_status() - check device reset status
+ * @rcdev: reset controller entity
+ * @id: ID of the reset for which the status is being requested
+ *
+ * This function implements the reset driver op to return the status of a
+ * device's reset.
+ *
+ * Return: 0 if reset is deasserted, true if reset is asserted, else a
+ * corresponding error value
+ */
+static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
+	struct ti_syscon_reset_control *control;
+	unsigned int reset_state;
+	int ret;
+
+	if (id >= data->nr_controls)
+		return -EINVAL;
+
+	control = &data->controls[id];
+
+	if (control->flags & STATUS_NONE)
+		return -ENOTSUPP; /* status not supported for this reset */
+
+	ret = regmap_read(data->regmap, control->status_offset, &reset_state);
+	if (ret)
+		return ret;
+
+	return (reset_state & BIT(control->status_bit)) &&
+			(control->flags & STATUS_SET);
+}
+
+static struct reset_control_ops ti_syscon_reset_ops = {
+	.assert		= ti_syscon_reset_assert,
+	.deassert	= ti_syscon_reset_deassert,
+	.status		= ti_syscon_reset_status,
+};
+
+static int ti_syscon_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
+	struct ti_syscon_reset_data *data;
+	struct regmap *regmap;
+	const __be32 *list;
+	struct ti_syscon_reset_control *controls;
+	int size, nr_controls, i;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	regmap = syscon_node_to_regmap(np->parent);
+	if (IS_ERR(regmap))
+		return PTR_ERR(regmap);
+
+	list = of_get_property(np, "ti,reset-bits", &size);
+	if (!list || (size / sizeof(*list)) % 7 != 0) {
+		dev_err(dev, "invalid DT reset description\n");
+		return -EINVAL;
+	}
+
+	nr_controls = (size / sizeof(*list)) / 7;
+	controls = devm_kzalloc(dev, nr_controls * sizeof(*controls), GFP_KERNEL);
+	if (!controls)
+		return -ENOMEM;
+
+	for (i = 0; i < nr_controls; i++) {
+		controls[i].assert_offset = be32_to_cpup(list++);
+		controls[i].assert_bit = be32_to_cpup(list++);
+		controls[i].deassert_offset = be32_to_cpup(list++);
+		controls[i].deassert_bit = be32_to_cpup(list++);
+		controls[i].status_offset = be32_to_cpup(list++);
+		controls[i].status_bit = be32_to_cpup(list++);
+		controls[i].flags = be32_to_cpup(list++);
+	}
+
+	data->rcdev.ops = &ti_syscon_reset_ops;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.of_node = np;
+	data->rcdev.nr_resets = nr_controls;
+	data->regmap = regmap;
+	data->controls = controls;
+	data->nr_controls = nr_controls;
+
+	platform_set_drvdata(pdev, data);
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct of_device_id ti_syscon_reset_of_match[] = {
+	{ .compatible = "ti,syscon-reset", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
+
+static struct platform_driver ti_syscon_reset_driver = {
+	.probe = ti_syscon_reset_probe,
+	.driver = {
+		.name = "ti-syscon-reset",
+		.of_match_table = ti_syscon_reset_of_match,
+	},
+};
+module_platform_driver(ti_syscon_reset_driver);
+
+MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
+MODULE_AUTHOR("Suman Anna <s-anna@ti.com>");
+MODULE_DESCRIPTION("TI SYSCON Regmap Reset Driver");
+MODULE_LICENSE("GPL v2");
-- 
2.9.0

Re: [PATCH v5 1/2] Documentation: dt: reset: Add TI syscon reset binding

[Rob Herring]

On Mon, Jun 27, 2016 at 12:12:16PM -0500, Andrew F. Davis wrote:
> Add TI syscon reset controller binding. This will hook to the reset
> framework and use syscon/regmap to set reset bits. This allows reset
> control of individual SoC subsytems and devices with memory-mapped
> reset registers in a common register memory space.
> 
> Signed-off-by: Andrew F. Davis <afd@ti.com>
> Signed-off-by: Suman Anna <s-anna@ti.com>
> ---
>  .../devicetree/bindings/reset/ti-syscon-reset.txt  | 91 ++++++++++++++++++++++
>  include/dt-bindings/reset/ti-syscon.h              | 38 +++++++++
>  2 files changed, 129 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/reset/ti-syscon-reset.txt
>  create mode 100644 include/dt-bindings/reset/ti-syscon.h

Acked-by: Rob Herring <robh@kernel.org>

Re: [PATCH v5 0/2] Add support for SYSCON reset

[Philipp Zabel]

Hi Andrew,

Am Montag, den 27.06.2016, 12:12 -0500 schrieb Andrew F. Davis:
> Some SoCs contain reset controls for modules that are memory-mapped to
> areas shared with other module configuration settings. This requires
> synchronization across all drivers accessing this memory area. This
> series adds a generic SYSCON reset driver to allow resets toggled
> by bits in memory-mapped registers through SYSCON.
> 
> Changes from v4:
>  - Added two more cells to DT ti,reset-bits property
>  - Re-organized ti,reset-bits flag property defines
>  - Moved TI_SYSCON_RESET in Kconfig
>  - Other small fixes based on comments on v4

Thank you, I have applied both to
git://git.pengutronix.de/git/pza/linux.git reset/next
with Rob's ack.

regards
Philipp

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