Date:   Wed, 18 Oct 2017 14:00:23 +0100
From:   Andre Przywara <andre.przywara@....com>
To:     Philipp Zabel <p.zabel@...gutronix.de>,
        linux-kernel@...r.kernel.org
Cc:     Alexandru Gagniuc <alex.g@...ptrum.com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Baoyou Xie <baoyou.xie@...aro.org>,
        Eugeniy Paltsev <Eugeniy.Paltsev@...opsys.com>,
        Steffen Trumtrar <s.trumtrar@...gutronix.de>,
        Dinh Nguyen <dinguyen@...nel.org>,
        Andreas Färber <afaerber@...e.de>,
        linux-arm-kernel@...ts.infradead.org, kernel@...gutronix.de
Subject: Re: [PATCH v4 3/5] reset: socfpga: use the reset-simple driver

Hi,

On 17/10/17 14:03, Philipp Zabel wrote:
> Add reset line status readback, inverted status support, and socfpga
> device tree quirks to the simple reset driver, and use it to replace
> the socfpga driver.
> 
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> ---
> Changes since v3:
>  - Rebased onto reset/next
>  - Only warn about missing altr,modrst-offset property on socfpga
> ---
>  drivers/reset/Kconfig         |  10 +--
>  drivers/reset/Makefile        |   1 -
>  drivers/reset/reset-simple.c  |  51 +++++++++++++-
>  drivers/reset/reset-simple.h  |   4 ++
>  drivers/reset/reset-socfpga.c | 157 ------------------------------------------
>  5 files changed, 56 insertions(+), 167 deletions(-)
>  delete mode 100644 drivers/reset/reset-socfpga.c
> 
> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
> index a14c0fe498771..2d6770b210ed7 100644
> --- a/drivers/reset/Kconfig
> +++ b/drivers/reset/Kconfig
> @@ -77,19 +77,13 @@ config RESET_PISTACHIO
>  
>  config RESET_SIMPLE
>  	bool "Simple Reset Controller Driver" if COMPILE_TEST
> -	default ARCH_SUNXI
> +	default ARCH_SOCFPGA || ARCH_STRATIX10 || 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
> -	help
> -	  This enables the reset controller driver for Altera SoCFPGAs.
> +	  Currently this driver supports Altera SoCFPGAs and Allwinner SoCs.
>  
>  config RESET_STM32
>  	bool "STM32 Reset Driver" if COMPILE_TEST
> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
> index ddd3eeb193567..3bf3b4e6a9fd2 100644
> --- a/drivers/reset/Makefile
> +++ b/drivers/reset/Makefile
> @@ -13,7 +13,6 @@ 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-$(CONFIG_RESET_SUNXI) += reset-sunxi.o
>  obj-$(CONFIG_RESET_TI_SCI) += reset-ti-sci.o
> diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
> index a5119457cec61..98ff0f924948e 100644
> --- a/drivers/reset/reset-simple.c
> +++ b/drivers/reset/reset-simple.c
> @@ -68,25 +68,58 @@ static int reset_simple_deassert(struct reset_controller_dev *rcdev,
>  	return reset_simple_update(rcdev, id, false);
>  }
>  
> +static int reset_simple_status(struct reset_controller_dev *rcdev,
> +			       unsigned long id)
> +{
> +	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);
> +	u32 reg;
> +
> +	reg = readl(data->membase + (bank * reg_width));
> +
> +	return !(reg & BIT(offset)) ^ !data->status_active_low;
> +}
> +
>  const struct reset_control_ops reset_simple_ops = {
>  	.assert		= reset_simple_assert,
>  	.deassert	= reset_simple_deassert,
> +	.status		= reset_simple_status,
>  };
>  
>  /**
>   * struct reset_simple_devdata - simple reset controller properties
> + * @reg_offset: offset between base address and first reset register.
> + * @nr_resets: number of resets. If not set, default to resource size in bits.
>   * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits
>   *              are set to assert the reset.
> + * @status_active_low: if true, bits read back as cleared while the reset is
> + *                     asserted. Otherwise, bits read back as set while the
> + *                     reset is asserted.
>   */
>  struct reset_simple_devdata {
> +	u32 reg_offset;
> +	u32 nr_resets;
>  	bool active_low;
> +	bool status_active_low;
> +};
> +
> +#define SOCFPGA_NR_BANKS	8
> +
> +static const struct reset_simple_devdata reset_simple_socfpga = {
> +	.reg_offset = 0x10,
> +	.nr_resets = SOCFPGA_NR_BANKS * 32,
> +	.status_active_low = true,
>  };
>  
>  static const struct reset_simple_devdata reset_simple_active_low = {
>  	.active_low = true,
> +	.status_active_low = true,
>  };
>  
>  static const struct of_device_id reset_simple_dt_ids[] = {
> +	{ .compatible = "altr,rst-mgr", .data = &reset_simple_socfpga },
>  	{ .compatible = "allwinner,sun6i-a31-clock-reset",
>  		.data = &reset_simple_active_low },
>  	{ /* sentinel */ },
> @@ -99,6 +132,7 @@ static int reset_simple_probe(struct platform_device *pdev)
>  	struct reset_simple_data *data;
>  	void __iomem *membase;
>  	struct resource *res;
> +	u32 reg_offset = 0;
>  
>  	devdata = of_device_get_match_data(dev);
>  
> @@ -118,8 +152,23 @@ static int reset_simple_probe(struct platform_device *pdev)
>  	data->rcdev.ops = &reset_simple_ops;
>  	data->rcdev.of_node = dev->of_node;
>  
> -	if (devdata)
> +	if (devdata) {
> +		reg_offset = devdata->reg_offset;
> +		if (devdata->nr_resets)
> +			data->rcdev.nr_resets = devdata->nr_resets;
>  		data->active_low = devdata->active_low;
> +		data->status_active_low = devdata->status_active_low;
> +	}
> +
> +	if (devdata == &reset_simple_socfpga &&

Mmh, this pointer comparison looks a bit dodgy. Isn't
of_device_is_compatible() the right solution here? Also semantically, as
the property is tied to a certain compatible string (and not to our data
structure)?

> +	    of_property_read_u32(dev->of_node, "altr,modrst-offset",
> +				 &reg_offset)) {
> +		dev_warn(dev,
> +			 "missing altr,modrst-offset property, assuming 0x%x!\n",
> +			 reg_offset);

The existing driver falls back to 0x10 if no explicit property is found.
Should we copy this here for compatibility reasons? We could simply use:
"reg_offset = 0x10;" before the dev_warn().

The rest looks good to me.

Cheers,
Andre.

> +	}
> +
> +	data->membase += reg_offset;
>  
>  	return devm_reset_controller_register(dev, &data->rcdev);
>  }
> diff --git a/drivers/reset/reset-simple.h b/drivers/reset/reset-simple.h
> index 39af2014b5f12..8a496022baeff 100644
> --- a/drivers/reset/reset-simple.h
> +++ b/drivers/reset/reset-simple.h
> @@ -28,12 +28,16 @@
>   * @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.
> + * @status_active_low: if true, bits read back as cleared while the reset is
> + *                     asserted. Otherwise, bits read back as set while the
> + *                     reset is asserted.
>   */
>  struct reset_simple_data {
>  	spinlock_t			lock;
>  	void __iomem			*membase;
>  	struct reset_controller_dev	rcdev;
>  	bool				active_low;
> +	bool				status_active_low;
>  };
>  
>  extern const struct reset_control_ops reset_simple_ops;
> diff --git a/drivers/reset/reset-socfpga.c b/drivers/reset/reset-socfpga.c
> deleted file mode 100644
> index 3907bbc9c6cf7..0000000000000
> --- a/drivers/reset/reset-socfpga.c
> +++ /dev/null
> @@ -1,157 +0,0 @@
> -/*
> - * Socfpga Reset Controller Driver
> - *
> - * Copyright 2014 Steffen Trumtrar <s.trumtrar@...gutronix.de>
> - *
> - * based on
> - * Allwinner SoCs Reset Controller driver
> - *
> - * Copyright 2013 Maxime Ripard
> - *
> - * Maxime Ripard <maxime.ripard@...e-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/err.h>
> -#include <linux/io.h>
> -#include <linux/init.h>
> -#include <linux/of.h>
> -#include <linux/platform_device.h>
> -#include <linux/reset-controller.h>
> -#include <linux/spinlock.h>
> -#include <linux/types.h>
> -
> -#define BANK_INCREMENT		4
> -#define NR_BANKS		8
> -
> -struct socfpga_reset_data {
> -	spinlock_t			lock;
> -	void __iomem			*membase;
> -	struct reset_controller_dev	rcdev;
> -};
> -
> -static int socfpga_reset_assert(struct reset_controller_dev *rcdev,
> -				unsigned long id)
> -{
> -	struct socfpga_reset_data *data = container_of(rcdev,
> -						     struct socfpga_reset_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 * BANK_INCREMENT));
> -	writel(reg | BIT(offset), data->membase + (bank * BANK_INCREMENT));
> -	spin_unlock_irqrestore(&data->lock, flags);
> -
> -	return 0;
> -}
> -
> -static int socfpga_reset_deassert(struct reset_controller_dev *rcdev,
> -				  unsigned long id)
> -{
> -	struct socfpga_reset_data *data = container_of(rcdev,
> -						     struct socfpga_reset_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 * BANK_INCREMENT));
> -	writel(reg & ~BIT(offset), data->membase + (bank * BANK_INCREMENT));
> -
> -	spin_unlock_irqrestore(&data->lock, flags);
> -
> -	return 0;
> -}
> -
> -static int socfpga_reset_status(struct reset_controller_dev *rcdev,
> -				unsigned long id)
> -{
> -	struct socfpga_reset_data *data = container_of(rcdev,
> -						struct socfpga_reset_data, rcdev);
> -	int reg_width = sizeof(u32);
> -	int bank = id / (reg_width * BITS_PER_BYTE);
> -	int offset = id % (reg_width * BITS_PER_BYTE);
> -	u32 reg;
> -
> -	reg = readl(data->membase + (bank * BANK_INCREMENT));
> -
> -	return !(reg & BIT(offset));
> -}
> -
> -static const struct reset_control_ops socfpga_reset_ops = {
> -	.assert		= socfpga_reset_assert,
> -	.deassert	= socfpga_reset_deassert,
> -	.status		= socfpga_reset_status,
> -};
> -
> -static int socfpga_reset_probe(struct platform_device *pdev)
> -{
> -	struct socfpga_reset_data *data;
> -	struct resource *res;
> -	struct device *dev = &pdev->dev;
> -	struct device_node *np = dev->of_node;
> -	u32 modrst_offset;
> -
> -	/*
> -	 * The binding was mainlined without the required property.
> -	 * Do not continue, when we encounter an old DT.
> -	 */
> -	if (!of_find_property(pdev->dev.of_node, "#reset-cells", NULL)) {
> -		dev_err(&pdev->dev, "%pOF missing #reset-cells property\n",
> -			pdev->dev.of_node);
> -		return -EINVAL;
> -	}
> -
> -	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> -	if (!data)
> -		return -ENOMEM;
> -
> -	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> -	data->membase = devm_ioremap_resource(&pdev->dev, res);
> -	if (IS_ERR(data->membase))
> -		return PTR_ERR(data->membase);
> -
> -	if (of_property_read_u32(np, "altr,modrst-offset", &modrst_offset)) {
> -		dev_warn(dev, "missing altr,modrst-offset property, assuming 0x10!\n");
> -		modrst_offset = 0x10;
> -	}
> -	data->membase += modrst_offset;
> -
> -	spin_lock_init(&data->lock);
> -
> -	data->rcdev.owner = THIS_MODULE;
> -	data->rcdev.nr_resets = NR_BANKS * (sizeof(u32) * BITS_PER_BYTE);
> -	data->rcdev.ops = &socfpga_reset_ops;
> -	data->rcdev.of_node = pdev->dev.of_node;
> -
> -	return devm_reset_controller_register(dev, &data->rcdev);
> -}
> -
> -static const struct of_device_id socfpga_reset_dt_ids[] = {
> -	{ .compatible = "altr,rst-mgr", },
> -	{ /* sentinel */ },
> -};
> -
> -static struct platform_driver socfpga_reset_driver = {
> -	.probe	= socfpga_reset_probe,
> -	.driver = {
> -		.name		= "socfpga-reset",
> -		.of_match_table	= socfpga_reset_dt_ids,
> -	},
> -};
> -builtin_platform_driver(socfpga_reset_driver);
> 

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