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Commit cc7c2bb1 authored by Andrew F. Davis's avatar Andrew F. Davis Committed by Philipp Zabel
Browse files

reset: add TI SYSCON based reset driver 



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: default avatarAndrew F. Davis <afd@ti.com>
[s-anna@ti.com: add documentation, syscon name change]
Signed-off-by: default avatarSuman Anna <s-anna@ti.com>
Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
parent a3828519

drivers/reset/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -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"

drivers/reset/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -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

drivers/reset/reset-ti-syscon.c

0 → 100644
+237 −0
Original line number Diff line number Diff line 
/*

 * 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");