linux-kernel - Re: [PATCH 3/7] reset: add BCM6345 reset controller driver

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Message-Id: <729976E9-CAF7-47B6-8783-5FD3D85F9EFD@gmail.com>
Date:   Tue, 9 Jun 2020 17:14:02 +0200
From:   Álvaro Fernández Rojas <noltari@...il.com>
To:     Philipp Zabel <p.zabel@...gutronix.de>
Cc:     robh+dt@...nel.org, tsbogend@...ha.franken.de,
        Florian Fainelli <f.fainelli@...il.com>,
        jonas.gorski@...il.com, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH 3/7] reset: add BCM6345 reset controller driver

Hi Philipp,

> El 9 jun 2020, a las 17:06, Philipp Zabel <p.zabel@...gutronix.de> escribió:
> 
> Hi Álvaro,
> 
> On Tue, 2020-06-09 at 15:42 +0200, Álvaro Fernández Rojas wrote:
>> Add support for resetting blocks through the Linux reset controller
>> subsystem for BCM63xx SoCs.
>> 
>> Signed-off-by: Álvaro Fernández Rojas <noltari@...il.com>
>> ---
>> drivers/reset/Kconfig         |   7 ++
>> drivers/reset/Makefile        |   1 +
>> drivers/reset/reset-bcm6345.c | 149 ++++++++++++++++++++++++++++++++++
>> 3 files changed, 157 insertions(+)
>> create mode 100644 drivers/reset/reset-bcm6345.c
>> 
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>> index d9efbfd29646..9f1da978cef6 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -41,6 +41,13 @@ config RESET_BERLIN
>> 	help
>> 	  This enables the reset controller driver for Marvell Berlin SoCs.
>> 
>> +config RESET_BCM6345
>> +	bool "BCM6345 Reset Controller"
>> +	depends on BMIPS_GENERIC || COMPILE_TEST
>> +	default BMIPS_GENERIC
>> +	help
>> +	  This enables the reset controller driver for BCM6345 SoCs.
>> +
>> config RESET_BRCMSTB
>> 	tristate "Broadcom STB reset controller"
>> 	depends on ARCH_BRCMSTB || COMPILE_TEST
>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
>> index 249ed357c997..e642aae42f0f 100644
>> --- a/drivers/reset/Makefile
>> +++ b/drivers/reset/Makefile
>> @@ -6,6 +6,7 @@ obj-$(CONFIG_ARCH_TEGRA) += tegra/
>> obj-$(CONFIG_RESET_A10SR) += reset-a10sr.o
>> obj-$(CONFIG_RESET_ATH79) += reset-ath79.o
>> obj-$(CONFIG_RESET_AXS10X) += reset-axs10x.o
>> +obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
>> obj-$(CONFIG_RESET_BERLIN) += reset-berlin.o
>> obj-$(CONFIG_RESET_BRCMSTB) += reset-brcmstb.o
>> obj-$(CONFIG_RESET_BRCMSTB_RESCAL) += reset-brcmstb-rescal.o
>> diff --git a/drivers/reset/reset-bcm6345.c b/drivers/reset/reset-bcm6345.c
>> new file mode 100644
>> index 000000000000..088b7fdb896b
>> --- /dev/null
>> +++ b/drivers/reset/reset-bcm6345.c
>> @@ -0,0 +1,149 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * BCM6345 Reset Controller Driver
>> + *
>> + * Copyright (C) 2020 Álvaro Fernández Rojas <noltari@...il.com>
>> + */
>> +
>> +#include <linux/delay.h>
>> +#include <linux/init.h>
>> +#include <linux/io.h>
>> +#include <linux/mod_devicetable.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +
>> +#define BCM6345_RESET_NUM		32
>> +#define BCM6345_RESET_SLEEP_MIN_US	10000
>> +#define BCM6345_RESET_SLEEP_MAX_US	20000
>> +
>> +struct bcm6345_reset {
>> +	struct reset_controller_dev rcdev;
>> +	void __iomem *base;
>> +	spinlock_t lock;
>> +};
>> +
>> +static int bcm6345_reset_update(struct bcm6345_reset *bcm6345_reset,
>> +				unsigned long id, bool assert)
>> +{
>> +	uint32_t val;
>> +
>> +	val = __raw_readl(bcm6345_reset->base);
>> +	if (assert)
>> +		val &= ~BIT(id);
>> +	else
>> +		val |= BIT(id);
>> +	__raw_writel(val, bcm6345_reset->base);
>> +
>> +	return 0;
>> +}
>> +
>> +static int bcm6345_reset_assert(struct reset_controller_dev *rcdev,
>> +				unsigned long id)
>> +{
>> +	struct bcm6345_reset *bcm6345_reset =
>> +		container_of(rcdev, struct bcm6345_reset, rcdev);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&bcm6345_reset->lock, flags);
>> +	bcm6345_reset_update(bcm6345_reset, id, true);
>> +	spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
>> +
>> +	return 0;
>> +}
>> +
>> +static int bcm6345_reset_deassert(struct reset_controller_dev *rcdev,
>> +				  unsigned long id)
>> +{
>> +	struct bcm6345_reset *bcm6345_reset =
>> +		container_of(rcdev, struct bcm6345_reset, rcdev);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&bcm6345_reset->lock, flags);
>> +	bcm6345_reset_update(bcm6345_reset, id, false);
>> +	spin_unlock_irqrestore(&bcm6345_reset->lock, flags);
>> +
>> +	return 0;
>> +}
>> +
>> +static int bcm6345_reset_reset(struct reset_controller_dev *rcdev,
>> +			       unsigned long id)
>> +{
>> +	struct bcm6345_reset *bcm6345_reset =
>> +		container_of(rcdev, struct bcm6345_reset, rcdev);
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&bcm6345_reset->lock, flags);
>> +	usleep_range(BCM6345_RESET_SLEEP_MIN_US,
>> +		     BCM6345_RESET_SLEEP_MAX_US);
> 
> What is the purpose of sleeping before reset assertion?

None, I must have introduced that for testing something and then I forgot to remove it. Sorry for that...

> 
> If you can do without this, with I think this driver could be made to
> use reset-simple.

Yes, but only if I can add reset support with a configurable sleep range to reset-simple. Is this possible?

> 
> regards
> Philipp

Best regards,
Álvaro.