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Commit 81c22ad0 authored by Philipp Zabel's avatar Philipp Zabel
Browse files

reset: add reset-simple to unify socfpga, stm32, sunxi, and zx2967 



Copy reusable parts from the sunxi driver, to add a driver for simple
reset controllers with reset lines that can be controlled by toggling
bits in exclusive, contiguous register ranges using read-modify-write
cycles under a spinlock.

The following patches will replace compatible reset drivers with
reset-simple, extending it where necessary.

Signed-off-by: default avatarPhilipp Zabel <p.zabel@pengutronix.de>
Reviewed-by: default avatarAlexandru Gagniuc <alex.g@adaptrum.com>
Reviewed-by: default avatarChen-Yu Tsai <wens@csie.org>
parent 7e8838fe

drivers/reset/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -75,6 +75,16 @@ config RESET_PISTACHIO 
	help

	  This enables the reset driver for ImgTec Pistachio SoCs.



config RESET_SIMPLE

	bool "Simple Reset Controller Driver" if COMPILE_TEST

	default ARCH_SUNXI

	help

	  This enables a simple reset controller driver for reset lines that

	  that can be asserted and deasserted by toggling bits in a contiguous,

	  exclusive register space.



	  Currently this driver supports Allwinner SoCs.



config RESET_SOCFPGA

	bool "SoCFPGA Reset Driver" if COMPILE_TEST

	default ARCH_SOCFPGA || ARCH_STRATIX10

drivers/reset/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -12,6 +12,7 @@ obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o 
obj-$(CONFIG_RESET_MESON) += reset-meson.o

obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o

obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o

obj-$(CONFIG_RESET_SIMPLE) += reset-simple.o

obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o

obj-$(CONFIG_RESET_STM32) += reset-stm32.o

obj-$(CONFIG_RESET_SUNXI) += reset-sunxi.o

drivers/reset/reset-simple.c

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+134 −0
Original line number Diff line number Diff line 
/*

 * Simple Reset Controller Driver

 *

 * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>

 *

 * Based on Allwinner SoCs Reset Controller driver

 *

 * Copyright 2013 Maxime Ripard

 *

 * Maxime Ripard <maxime.ripard@free-electrons.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.

 */



#include <linux/device.h>

#include <linux/err.h>

#include <linux/io.h>

#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/platform_device.h>

#include <linux/reset-controller.h>

#include <linux/spinlock.h>



#include "reset-simple.h"



static inline struct reset_simple_data *

to_reset_simple_data(struct reset_controller_dev *rcdev)

{

	return container_of(rcdev, struct reset_simple_data, rcdev);

}



static int reset_simple_update(struct reset_controller_dev *rcdev,

			       unsigned long id, bool assert)

{

	struct reset_simple_data *data = to_reset_simple_data(rcdev);

	int reg_width = sizeof(u32);

	int bank = id / (reg_width * BITS_PER_BYTE);

	int offset = id % (reg_width * BITS_PER_BYTE);

	unsigned long flags;

	u32 reg;



	spin_lock_irqsave(&data->lock, flags);



	reg = readl(data->membase + (bank * reg_width));

	if (assert ^ data->active_low)

		reg |= BIT(offset);

	else

		reg &= ~BIT(offset);

	writel(reg, data->membase + (bank * reg_width));



	spin_unlock_irqrestore(&data->lock, flags);



	return 0;

}



static int reset_simple_assert(struct reset_controller_dev *rcdev,

			       unsigned long id)

{

	return reset_simple_update(rcdev, id, true);

}



static int reset_simple_deassert(struct reset_controller_dev *rcdev,

				 unsigned long id)

{

	return reset_simple_update(rcdev, id, false);

}



const struct reset_control_ops reset_simple_ops = {

	.assert		= reset_simple_assert,

	.deassert	= reset_simple_deassert,

};



/**

 * struct reset_simple_devdata - simple reset controller properties

 * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits

 *              are set to assert the reset.

 */

struct reset_simple_devdata {

	bool active_low;

};



static const struct reset_simple_devdata reset_simple_active_low = {

	.active_low = true,

};



static const struct of_device_id reset_simple_dt_ids[] = {

	{ .compatible = "allwinner,sun6i-a31-clock-reset",

		.data = &reset_simple_active_low },

	{ /* sentinel */ },

};



static int reset_simple_probe(struct platform_device *pdev)

{

	struct device *dev = &pdev->dev;

	const struct reset_simple_devdata *devdata;

	struct reset_simple_data *data;

	void __iomem *membase;

	struct resource *res;



	devdata = of_device_get_match_data(dev);



	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	membase = devm_ioremap_resource(dev, res);

	if (IS_ERR(membase))

		return PTR_ERR(membase);



	spin_lock_init(&data->lock);

	data->membase = membase;

	data->rcdev.owner = THIS_MODULE;

	data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;

	data->rcdev.ops = &reset_simple_ops;

	data->rcdev.of_node = dev->of_node;



	if (devdata)

		data->active_low = devdata->active_low;



	return devm_reset_controller_register(dev, &data->rcdev);

}



static struct platform_driver reset_simple_driver = {

	.probe	= reset_simple_probe,

	.driver = {

		.name		= "simple-reset",

		.of_match_table	= reset_simple_dt_ids,

	},

};

builtin_platform_driver(reset_simple_driver);

drivers/reset/reset-simple.h

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+41 −0
Original line number Diff line number Diff line 
/*

 * Simple Reset Controller ops

 *

 * Based on Allwinner SoCs Reset Controller driver

 *

 * Copyright 2013 Maxime Ripard

 *

 * Maxime Ripard <maxime.ripard@free-electrons.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.

 */



#ifndef __RESET_SIMPLE_H__

#define __RESET_SIMPLE_H__



#include <linux/io.h>

#include <linux/reset-controller.h>

#include <linux/spinlock.h>



/**

 * struct reset_simple_data - driver data for simple reset controllers

 * @lock: spinlock to protect registers during read-modify-write cycles

 * @membase: memory mapped I/O register range

 * @rcdev: reset controller device base structure

 * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits

 *              are set to assert the reset. Note that this says nothing about

 *              the voltage level of the actual reset line.

 */

struct reset_simple_data {

	spinlock_t			lock;

	void __iomem			*membase;

	struct reset_controller_dev	rcdev;

	bool				active_low;

};



extern const struct reset_control_ops reset_simple_ops;



#endif /* __RESET_SIMPLE_H__ */