[PATCH v5 0/2] Add TI SCI Reset Driver

[PATCH v5 0/2] Add TI SCI Reset Driver

[Suman Anna]

Hi Philipp,

This series adds a reset controller driver that uses the TI SCI protocol
to manage resets on some TI SoCs. It is a repost of the previous v4 [1]
submission that has already been acked by Rob and Santosh, but with some
minor changes. This series has been waiting for the ti-sci-pm-domains
series to make it to mainline and because of the dependencies against
a DT header file including the device id values. The ti-sci-pm-domains
series is now merged and available in 4.12-rc1.

The main changes in v5 is to drop the include/dt-bindings/reset/k2g.h
file based on some comments received from Arnd on a similar header usage
in the ti-sci-pm-domains series. The ti-sci-pm-domains usage is being
addressed in [2] and this reset series is refreshed to follow the same
rule and drop the reset header file.

Patches are on top of 4.12-rc1 plus the recent Kconfig name change on
the TI SYSCON reset driver [3].

Rob, Santosh,
I have retained the Acks received from you on v4, but I am not sure
since there are some minor changes to the series. Please provide any
comments if you do not agree with the changes.

regards
Suman

Changes from v4 [1]:
 - Removed the include/dt-bindings/reset/k2g.h, and updated the
   bindings document
 - Minor checkpatch fixes to the driver patch

Changes from v3:
 - Addressed Rob Herring's comments
 - Added Santosh Shilimkar's Ack

Changes from v2:
 - Merged DT binding patch and reset header patch
 - Added locking for reset bit mask

Changes from v1:
 - Revised dt binding
 - CC Linux ARM list

[1] http://marc.info/?l=devicetree&m=147976458332492&w=2
[2] http://marc.info/?l=linux-arm-kernel&m=149547831708124&w=2
[3] https://patchwork.kernel.org/patch/9744909/

Andrew F. Davis (2):
  Documentation: dt: reset: Add TI SCI reset binding
  reset: Add the TI SCI reset driver

 .../devicetree/bindings/reset/ti,sci-reset.txt     |  62 +++++
 MAINTAINERS                                        |   2 +
 drivers/reset/Kconfig                              |   8 +
 drivers/reset/Makefile                             |   1 +
 drivers/reset/reset-ti-sci.c                       | 269 +++++++++++++++++++++
 5 files changed, 342 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 create mode 100644 drivers/reset/reset-ti-sci.c

-- 
2.12.0

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

[Suman Anna]

From: "Andrew F. Davis" <afd@ti.com>

Add TI SCI reset controller binding. This describes the DT binding
details for a reset controller node providing reset management services
to hardware blocks (reset consumers) using the Texas Instrument's System
Control Interface (TI SCI) protocol to communicate to a system controller
block present on the SoC.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: revise the binding format]
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Acked-by: Rob Herring <robh@kernel.org>
---
Changes in v5:
 - Dropped the include/dt-bindings/reset/k2g.h file and its references
 - Updated description for the resets property in the TI-SCI Reset
   Consumer Nodes section
 - Updated the example as well to not use the macros from before

 .../devicetree/bindings/reset/ti,sci-reset.txt     | 62 ++++++++++++++++++++++
 MAINTAINERS                                        |  1 +
 2 files changed, 63 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/ti,sci-reset.txt

diff --git a/Documentation/devicetree/bindings/reset/ti,sci-reset.txt b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt
new file mode 100644
index 000000000000..8b1cf022f18a
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/ti,sci-reset.txt
@@ -0,0 +1,62 @@
+Texas Instruments System Control Interface (TI-SCI) Reset Controller
+=====================================================================
+
+Some TI SoCs contain a system controller (like the Power Management Micro
+Controller (PMMC) on Keystone 66AK2G SoC) that are responsible for controlling
+the state of the various hardware modules present on the SoC. Communication
+between the host processor running an OS and the system controller happens
+through a protocol called TI System Control Interface (TI-SCI protocol).
+For TI SCI details, please refer to the document,
+Documentation/devicetree/bindings/arm/keystone/ti,sci.txt
+
+TI-SCI Reset Controller Node
+============================
+This reset controller node uses the TI SCI protocol to perform the reset
+management of various hardware modules present on the SoC. Must be a child
+node of the associated TI-SCI system controller node.
+
+Required properties:
+--------------------
+ - compatible	: Should be "ti,sci-reset"
+ - #reset-cells	: Should be 2. Please see the reset consumer node below for
+		  usage details.
+
+TI-SCI 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 and reset specifier pair, one pair for each reset
+		  signal that affects the device, or that the device manages.
+		  The phandle should point to the TI-SCI reset controller node,
+		  and the reset specifier should have 2 cell-values. The first
+		  cell should contain the device ID. The second cell should
+		  contain the reset mask value used by system controller.
+		  Please refer to the protocol documentation for these values
+		  to be used for different devices,
+		  http://processors.wiki.ti.com/index.php/TISCI#66AK2G02_Data
+
+Please also refer to Documentation/devicetree/bindings/reset/reset.txt for
+common reset controller usage by consumers.
+
+Example:
+--------
+The following example demonstrates both a TI-SCI reset controller node and a
+consumer (a DSP device) on the 66AK2G SoC.
+
+pmmc: pmmc {
+	compatible = "ti,k2g-sci";
+
+	k2g_reset: reset-controller {
+		compatible = "ti,sci-reset";
+		#reset-cells = <2>;
+	};
+};
+
+dsp0: dsp@10800000 {
+	...
+	resets = <&k2g_reset 0x0046 0x1>;
+	...
+};
diff --git a/MAINTAINERS b/MAINTAINERS
index f7d568b8f133..a4c48ec23a11 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12630,6 +12630,7 @@ F:	include/linux/soc/ti/ti_sci_protocol.h
 F:	Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
 F:	include/dt-bindings/genpd/k2g.h
 F:	drivers/soc/ti/ti_sci_pm_domains.c
+F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
 
 THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
 M:	Hans Verkuil <hverkuil@xs4all.nl>
-- 
2.12.0

[PATCH v5 2/2] reset: Add the TI SCI reset driver

[Suman Anna]

From: "Andrew F. Davis" <afd@ti.com>

Some TI Keystone family of SoCs contain a system controller (like the
Power Management Micro Controller (PMMC) on 66AK2G SoCs) that manage
the low-level device control (like clocks, resets etc) for the various
hardware modules present on the SoC. These device control operations
are provided to the host processor OS through a communication protocol
called the TI System Control Interface (TI SCI) protocol.

This patch adds a reset driver that communicates to the system
controller over the TI SCI protocol for performing reset management
of various devices present on the SoC. Various reset functionalities
are achieved by the means of different TI SCI device operations
provided by the TI SCI framework.

Signed-off-by: Andrew F. Davis <afd@ti.com>
[s-anna@ti.com: documentation changes, revised commit message]
Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
---
v5 Changes:
 - Dropped the dependency line on RESET_CONTROLLER in Kconfig
 - Updated license year to include 2017
 - Checkpatch fixes at the dev_ops->get_device_resets callsites

 MAINTAINERS                  |   1 +
 drivers/reset/Kconfig        |   8 ++
 drivers/reset/Makefile       |   1 +
 drivers/reset/reset-ti-sci.c | 269 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 279 insertions(+)
 create mode 100644 drivers/reset/reset-ti-sci.c

diff --git a/MAINTAINERS b/MAINTAINERS
index a4c48ec23a11..545ab28f006a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12631,6 +12631,7 @@ F:	Documentation/devicetree/bindings/soc/ti/sci-pm-domain.txt
 F:	include/dt-bindings/genpd/k2g.h
 F:	drivers/soc/ti/ti_sci_pm_domains.c
 F:	Documentation/devicetree/bindings/reset/ti,sci-reset.txt
+F:	drivers/reset/reset-ti-sci.c
 
 THANKO'S RAREMONO AM/FM/SW RADIO RECEIVER USB DRIVER
 M:	Hans Verkuil <hverkuil@xs4all.nl>
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 42d5631c6da0..671ef2a01529 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -80,6 +80,14 @@ config RESET_SUNXI
 	help
 	  This enables the reset driver for Allwinner SoCs.
 
+config RESET_TI_SCI
+	tristate "TI System Control Interface (TI-SCI) reset driver"
+	depends on TI_SCI_PROTOCOL
+	help
+	  This enables the reset driver support over TI System Control Interface
+	  available on some new TI's SoCs. If you wish to use reset resources
+	  managed by the TI System Controller, say Y here. Otherwise, say N.
+
 config RESET_TI_SYSCON
 	tristate "TI SYSCON Reset Driver"
 	depends on HAS_IOMEM
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 26270e0f8342..063dfdc7c400 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
 obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
 obj-$(CONFIG_RESET_STM32) += reset-stm32.o
 obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
+obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
 obj-$(CONFIG_RESET_TI_SYSCON) += reset-ti-syscon.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_ZX2967) += reset-zx2967.o
diff --git a/drivers/reset/reset-ti-sci.c b/drivers/reset/reset-ti-sci.c
new file mode 100644
index 000000000000..2097abe1706a
--- /dev/null
+++ b/drivers/reset/reset-ti-sci.c
@@ -0,0 +1,269 @@
+/*
+ * Texas Instrument's System Control Interface (TI-SCI) reset driver
+ *
+ * Copyright (C) 2015-2017 Texas Instruments Incorporated - http://www.ti.com/
+ *	Andrew F. Davis <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/idr.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/soc/ti/ti_sci_protocol.h>
+
+/**
+ * struct ti_sci_reset_control - reset control structure
+ * @dev_id: SoC-specific device identifier
+ * @reset_mask: reset mask to use for toggling reset
+ * @lock: synchronize reset_mask read-modify-writes
+ */
+struct ti_sci_reset_control {
+	u32 dev_id;
+	u32 reset_mask;
+	struct mutex lock;
+};
+
+/**
+ * struct ti_sci_reset_data - reset controller information structure
+ * @rcdev: reset controller entity
+ * @dev: reset controller device pointer
+ * @sci: TI SCI handle used for communication with system controller
+ * @idr: idr structure for mapping ids to reset control structures
+ */
+struct ti_sci_reset_data {
+	struct reset_controller_dev rcdev;
+	struct device *dev;
+	const struct ti_sci_handle *sci;
+	struct idr idr;
+};
+
+#define to_ti_sci_reset_data(p)	\
+	container_of((p), struct ti_sci_reset_data, rcdev)
+
+/**
+ * ti_sci_reset_set() - program a device's reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to toggle
+ * @assert: boolean flag to indicate assert or deassert
+ *
+ * This is a common internal function used to assert or deassert a device's
+ * reset using the TI SCI protocol. The device's reset is asserted if the
+ * @assert argument is true, or deasserted if @assert argument is false.
+ * The mechanism itself is a read-modify-write procedure, the current device
+ * reset register is read using a TI SCI device operation, the new value is
+ * set or un-set using the reset's mask, and the new reset value written by
+ * using another TI SCI device operation.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_set(struct reset_controller_dev *rcdev,
+			    unsigned long id, bool assert)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	const struct ti_sci_handle *sci = data->sci;
+	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
+	struct ti_sci_reset_control *control;
+	u32 reset_state;
+	int ret;
+
+	control = idr_find(&data->idr, id);
+	if (!control)
+		return -EINVAL;
+
+	mutex_lock(&control->lock);
+
+	ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
+	if (ret)
+		goto out;
+
+	if (assert)
+		reset_state |= control->reset_mask;
+	else
+		reset_state &= ~control->reset_mask;
+
+	ret = dev_ops->set_device_resets(sci, control->dev_id, reset_state);
+out:
+	mutex_unlock(&control->lock);
+
+	return ret;
+}
+
+/**
+ * ti_sci_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
+ * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
+ * with the corresponding parameters as passed in, but with the @assert
+ * argument set to true for asserting the reset.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_assert(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	return ti_sci_reset_set(rcdev, id, true);
+}
+
+/**
+ * ti_sci_reset_deassert() - deassert device reset
+ * @rcdev: reset controller entity
+ * @id: ID of the reset to be deasserted
+ *
+ * This function implements the reset driver op to deassert a device's reset
+ * using the TI SCI protocol. This invokes the function ti_sci_reset_set()
+ * with the corresponding parameters as passed in, but with the @assert
+ * argument set to false for deasserting the reset.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_deassert(struct reset_controller_dev *rcdev,
+				 unsigned long id)
+{
+	return ti_sci_reset_set(rcdev, id, false);
+}
+
+/**
+ * ti_sci_reset_status() - check device reset status
+ * @rcdev: reset controller entity
+ * @id: ID of reset to be checked
+ *
+ * This function implements the reset driver op to return the status of a
+ * device's reset using the TI SCI protocol. The reset register value is read
+ * by invoking the TI SCI device operation .get_device_resets(), and the
+ * status of the specific reset is extracted and returned using this reset's
+ * reset mask.
+ *
+ * Return: 0 if reset is deasserted, or a non-zero value if reset is asserted
+ */
+static int ti_sci_reset_status(struct reset_controller_dev *rcdev,
+			       unsigned long id)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	const struct ti_sci_handle *sci = data->sci;
+	const struct ti_sci_dev_ops *dev_ops = &sci->ops.dev_ops;
+	struct ti_sci_reset_control *control;
+	u32 reset_state;
+	int ret;
+
+	control = idr_find(&data->idr, id);
+	if (!control)
+		return -EINVAL;
+
+	ret = dev_ops->get_device_resets(sci, control->dev_id, &reset_state);
+	if (ret)
+		return ret;
+
+	return reset_state & control->reset_mask;
+}
+
+static struct reset_control_ops ti_sci_reset_ops = {
+	.assert		= ti_sci_reset_assert,
+	.deassert	= ti_sci_reset_deassert,
+	.status		= ti_sci_reset_status,
+};
+
+/**
+ * ti_sci_reset_of_xlate() - translate a set of OF arguments to a reset ID
+ * @rcdev: reset controller entity
+ * @reset_spec: OF reset argument specifier
+ *
+ * This function performs the translation of the reset argument specifier
+ * values defined in a reset consumer device node. The function allocates a
+ * reset control structure for that device reset, and will be used by the
+ * driver for performing any reset functions on that reset. An idr structure
+ * is allocated and used to map to the reset control structure. This idr
+ * is used by the driver to do reset lookups.
+ *
+ * Return: 0 for successful request, else a corresponding error value
+ */
+static int ti_sci_reset_of_xlate(struct reset_controller_dev *rcdev,
+				 const struct of_phandle_args *reset_spec)
+{
+	struct ti_sci_reset_data *data = to_ti_sci_reset_data(rcdev);
+	struct ti_sci_reset_control *control;
+
+	if (WARN_ON(reset_spec->args_count != rcdev->of_reset_n_cells))
+		return -EINVAL;
+
+	control = devm_kzalloc(data->dev, sizeof(*control), GFP_KERNEL);
+	if (!control)
+		return -ENOMEM;
+
+	control->dev_id = reset_spec->args[0];
+	control->reset_mask = reset_spec->args[1];
+	mutex_init(&control->lock);
+
+	return idr_alloc(&data->idr, control, 0, 0, GFP_KERNEL);
+}
+
+static const struct of_device_id ti_sci_reset_of_match[] = {
+	{ .compatible = "ti,sci-reset", },
+	{ /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, ti_sci_reset_of_match);
+
+static int ti_sci_reset_probe(struct platform_device *pdev)
+{
+	struct ti_sci_reset_data *data;
+
+	if (!pdev->dev.of_node)
+		return -ENODEV;
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->sci = devm_ti_sci_get_handle(&pdev->dev);
+	if (IS_ERR(data->sci))
+		return PTR_ERR(data->sci);
+
+	data->rcdev.ops = &ti_sci_reset_ops;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.of_node = pdev->dev.of_node;
+	data->rcdev.of_reset_n_cells = 2;
+	data->rcdev.of_xlate = ti_sci_reset_of_xlate;
+	data->dev = &pdev->dev;
+	idr_init(&data->idr);
+
+	platform_set_drvdata(pdev, data);
+
+	return reset_controller_register(&data->rcdev);
+}
+
+static int ti_sci_reset_remove(struct platform_device *pdev)
+{
+	struct ti_sci_reset_data *data = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&data->rcdev);
+
+	idr_destroy(&data->idr);
+
+	return 0;
+}
+
+static struct platform_driver ti_sci_reset_driver = {
+	.probe = ti_sci_reset_probe,
+	.remove = ti_sci_reset_remove,
+	.driver = {
+		.name = "ti-sci-reset",
+		.of_match_table = ti_sci_reset_of_match,
+	},
+};
+module_platform_driver(ti_sci_reset_driver);
+
+MODULE_AUTHOR("Andrew F. Davis <afd@ti.com>");
+MODULE_DESCRIPTION("TI System Control Interface (TI SCI) Reset driver");
+MODULE_LICENSE("GPL v2");
-- 
2.12.0

Re: [PATCH v5 0/2] Add TI SCI Reset Driver

[Suman Anna]

Hi Philipp,

On 05/24/2017 01:09 PM, Suman Anna wrote:
> Hi Philipp,
> 
> This series adds a reset controller driver that uses the TI SCI protocol
> to manage resets on some TI SoCs. It is a repost of the previous v4 [1]
> submission that has already been acked by Rob and Santosh, but with some
> minor changes. This series has been waiting for the ti-sci-pm-domains
> series to make it to mainline and because of the dependencies against
> a DT header file including the device id values. The ti-sci-pm-domains
> series is now merged and available in 4.12-rc1.
> 
> The main changes in v5 is to drop the include/dt-bindings/reset/k2g.h
> file based on some comments received from Arnd on a similar header usage
> in the ti-sci-pm-domains series. The ti-sci-pm-domains usage is being
> addressed in [2] and this reset series is refreshed to follow the same
> rule and drop the reset header file.
> 
> Patches are on top of 4.12-rc1 plus the recent Kconfig name change on
> the TI SYSCON reset driver [3].
> 
> Rob, Santosh,
> I have retained the Acks received from you on v4, but I am not sure
> since there are some minor changes to the series. Please provide any
> comments if you do not agree with the changes.
> 
> regards
> Suman
> 
> Changes from v4 [1]:
>  - Removed the include/dt-bindings/reset/k2g.h, and updated the
>    bindings document
>  - Minor checkpatch fixes to the driver patch
> 
> Changes from v3:
>  - Addressed Rob Herring's comments
>  - Added Santosh Shilimkar's Ack
> 
> Changes from v2:
>  - Merged DT binding patch and reset header patch
>  - Added locking for reset bit mask
> 
> Changes from v1:
>  - Revised dt binding
>  - CC Linux ARM list
> 
> [1] http://marc.info/?l=devicetree&m=147976458332492&w=2
> [2] http://marc.info/?l=linux-arm-kernel&m=149547831708124&w=2
> [3] https://patchwork.kernel.org/patch/9744909/
> 
> Andrew F. Davis (2):
>   Documentation: dt: reset: Add TI SCI reset binding
>   reset: Add the TI SCI reset driver
> 

Can you pick up this series for v4.13 if there are no comments. Btw, [2]
is acked by Rob. Will appreciate if you can fixup the patch header from
"Documentation: dt: reset: ..." to "dt-bindings: reset: ..." on the
first patch when applying. Thanks in advance.

regards
Suman

Re: [PATCH v5 0/2] Add TI SCI Reset Driver

[Philipp Zabel]

Hi Suman,

On Fri, 2017-06-02 at 11:45 -0500, Suman Anna wrote:
[...]
> > [1] http://marc.info/?l=devicetree&m=147976458332492&w=2
> > [2] http://marc.info/?l=linux-arm-kernel&m=149547831708124&w=2
> > [3] https://patchwork.kernel.org/patch/9744909/
> > 
> > Andrew F. Davis (2):
> >   Documentation: dt: reset: Add TI SCI reset binding
> >   reset: Add the TI SCI reset driver
> > 
> 
> Can you pick up this series for v4.13 if there are no comments. Btw, [2]
> is acked by Rob. Will appreciate if you can fixup the patch header from
> "Documentation: dt: reset: ..." to "dt-bindings: reset: ..." on the
> first patch when applying. Thanks in advance.

Thank you for the reminder, I've now applied both to the reset/next
branch. I've fixed the dt-bindings patch commit message as you suggested
and made the struct reset_control_ops const in the driver patch.

regards
Philipp