Date:   Sun, 19 Mar 2023 21:10:38 +0800
From:   Jacky Huang <ychuang570808@...il.com>
To:     Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        lee@...nel.org, mturquette@...libre.com, sboyd@...nel.org,
        p.zabel@...gutronix.de, gregkh@...uxfoundation.org,
        jirislaby@...nel.org, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-serial@...r.kernel.org, schung@...oton.com,
        Jacky Huang <ychuang3@...oton.com>
Subject: Re: [PATCH 13/15] reset: Add Nuvoton ma35d1 reset driver support

Dear Ilpo,


On 2023/3/16 下午 11:05, Ilpo Järvinen wrote:
> On Wed, 15 Mar 2023, Jacky Huang wrote:
>
>> From: Jacky Huang <ychuang3@...oton.com>
>>
>> This driver supports individual IP reset for ma35d1. The reset
>> control registers is a subset of system control registers.
>>
>> Signed-off-by: Jacky Huang <ychuang3@...oton.com>
>> ---
>>   drivers/reset/Kconfig        |   6 ++
>>   drivers/reset/Makefile       |   1 +
>>   drivers/reset/reset-ma35d1.c | 152 +++++++++++++++++++++++++++++++++++
>>   3 files changed, 159 insertions(+)
>>   create mode 100644 drivers/reset/reset-ma35d1.c
>>
>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>> index 2a52c990d4fe..47671060d259 100644
>> --- a/drivers/reset/Kconfig
>> +++ b/drivers/reset/Kconfig
>> @@ -143,6 +143,12 @@ config RESET_NPCM
>>   	  This enables the reset controller driver for Nuvoton NPCM
>>   	  BMC SoCs.
>>   
>> +config RESET_NUVOTON_MA35D1
>> +	bool "Nuvton MA35D1 Reset Driver"
>> +	default ARCH_NUVOTON
>> +	help
>> +	  This enables the reset controller driver for Nuvoton MA35D1 SoC.
>> +
>>   config RESET_OXNAS
>>   	bool
>>   
>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
>> index 3e7e5fd633a8..fd52dcf66a99 100644
>> --- a/drivers/reset/Makefile
>> +++ b/drivers/reset/Makefile
>> @@ -20,6 +20,7 @@ obj-$(CONFIG_RESET_MCHP_SPARX5) += reset-microchip-sparx5.o
>>   obj-$(CONFIG_RESET_MESON) += reset-meson.o
>>   obj-$(CONFIG_RESET_MESON_AUDIO_ARB) += reset-meson-audio-arb.o
>>   obj-$(CONFIG_RESET_NPCM) += reset-npcm.o
>> +obj-$(CONFIG_RESET_NUVOTON_MA35D1) += reset-ma35d1.o
>>   obj-$(CONFIG_RESET_OXNAS) += reset-oxnas.o
>>   obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
>>   obj-$(CONFIG_RESET_POLARFIRE_SOC) += reset-mpfs.o
>> diff --git a/drivers/reset/reset-ma35d1.c b/drivers/reset/reset-ma35d1.c
>> new file mode 100644
>> index 000000000000..bdd39483ca4e
>> --- /dev/null
>> +++ b/drivers/reset/reset-ma35d1.c
>> @@ -0,0 +1,152 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Copyright (C) 2023 Nuvoton Technology Corp.
>> + * Author: Chi-Fang Li <cfli0@...oton.com>
>> + */
>> +
>> +#include <linux/device.h>
>> +#include <linux/err.h>
>> +#include <linux/mfd/syscon.h>
>> +#include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset-controller.h>
>> +#include <linux/mfd/ma35d1-sys.h>
>> +#include <dt-bindings/reset/nuvoton,ma35d1-reset.h>
>> +#include <linux/regmap.h>
>> +#include <linux/reboot.h>
>> +
>> +#define RST_PRE_REG	32
>> +
>> +struct ma35d1_reset_data {
>> +	struct reset_controller_dev rcdev;
>> +	struct regmap *regmap;
>> +};
>> +
>> +struct ma35d1_reboot_data {
>> +	struct notifier_block restart_handler;
>> +	struct regmap *regmap;
>> +};
>> +
>> +static int ma35d1_restart_handler(struct notifier_block *this,
>> +				  unsigned long mode, void *cmd)
>> +{
>> +	struct ma35d1_reboot_data *data =
>> +			container_of(this, struct ma35d1_reboot_data,
>> +				     restart_handler);
>> +	regmap_write(data->regmap, REG_SYS_IPRST0, 1 << MA35D1_RESET_CHIP);
>> +	return -EAGAIN;
> This results -EAGAIN always???


The chip will reset immediately after the write to REG_SYS_IPRST0.

The return line should never be executed. If yes, it must be failed to 
reset.

Anyway, I will modify it as

return regmap_write(data->regmap, REG_SYS_IPRST0, 1 << MA35D1_RESET_CHIP);

>
>> +}
>> +
>> +static int ma35d1_reset_update(struct reset_controller_dev *rcdev,
>> +			      unsigned long id, bool assert)
>> +{
>> +	int reg;
>> +	int offset = (id / RST_PRE_REG) * 4;
>> +	struct ma35d1_reset_data *data =
>> +			container_of(rcdev, struct ma35d1_reset_data, rcdev);
>> +
>> +	regmap_read(data->regmap, REG_SYS_IPRST0 + offset, &reg);
>> +	if (assert)
>> +		reg |= 1 << (id % RST_PRE_REG);
>> +	else
>> +		reg &= ~(1 << (id % RST_PRE_REG));
>> +
>> +	regmap_write(data->regmap, REG_SYS_IPRST0 + offset, reg);
>> +	return 0;
> This returns always 0. What about regmap_read/write() errors, should the
> be returned?


I will modify it as

return regmap_write(data->regmap, REG_SYS_IPRST0 + offset, reg);

And add return value check to the regmap_read().


>> +}
>> +
>> +static int ma35d1_reset_assert(struct reset_controller_dev *rcdev,
>> +			       unsigned long id)
>> +{
>> +	return ma35d1_reset_update(rcdev, id, true);
>> +}
>> +
>> +static int ma35d1_reset_deassert(struct reset_controller_dev *rcdev,
>> +				 unsigned long id)
>> +{
>> +	return ma35d1_reset_update(rcdev, id, false);
>> +}
>> +
>> +static int ma35d1_reset_status(struct reset_controller_dev *rcdev,
>> +			      unsigned long id)
>> +{
>> +	int reg;
>> +	int offset = id / RST_PRE_REG;
>> +	struct ma35d1_reset_data *data =
>> +			container_of(rcdev, struct ma35d1_reset_data, rcdev);
>> +
>> +	regmap_read(data->regmap, REG_SYS_IPRST0 + offset, &reg);
> Error handling?

I will modify it as

     ret = regmap_read(data->regmap, REG_SYS_IPRST0 + offset, &reg);
     if (ret < 0)
         return ret;

>
>> +	return !!(reg & BIT(id % RST_PRE_REG));
>> +}
>> +
>> +static const struct reset_control_ops ma35d1_reset_ops = {
>> +	.assert = ma35d1_reset_assert,
>> +	.deassert = ma35d1_reset_deassert,
>> +	.status = ma35d1_reset_status,
>> +};
>> +
>> +static const struct of_device_id ma35d1_reset_dt_ids[] = {
>> +	{ .compatible = "nuvoton,ma35d1-reset" },
>> +	{ },
>> +};
>> +
>> +static int ma35d1_reset_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct ma35d1_reset_data *reset_data;
>> +	struct ma35d1_reboot_data *reboot_data;
>> +	int err;
>> +
>> +	if (!pdev->dev.of_node) {
>> +		dev_err(&pdev->dev, "Device tree node not found\n");
>> +		return -EINVAL;
>> +	}
>> +
>> +	reset_data = devm_kzalloc(dev, sizeof(*reset_data), GFP_KERNEL);
>> +	if (!reset_data)
>> +		return -ENOMEM;
>> +
>> +	reboot_data = devm_kzalloc(dev, sizeof(*reboot_data), GFP_KERNEL);
>> +	if (!reboot_data) {
>> +		devm_kfree(dev, reset_data);
> Unnecessary.


OK, I will remove this devm_kfree().


>> +		return -ENOMEM;
>> +	}
>> +
>> +	reset_data->regmap  = syscon_regmap_lookup_by_phandle(
>> +			      pdev->dev.of_node, "regmap");
>> +	if (IS_ERR(reset_data->regmap)) {
>> +		dev_err(&pdev->dev, "Failed to get SYS register base\n");
>> +		err = PTR_ERR(reset_data->regmap);
>> +		goto err_out;
>> +	}
>> +	reset_data->rcdev.owner = THIS_MODULE;
>> +	reset_data->rcdev.nr_resets = MA35D1_RESET_COUNT;
>> +	reset_data->rcdev.ops = &ma35d1_reset_ops;
>> +	reset_data->rcdev.of_node = dev->of_node;
>> +
>> +	reboot_data->regmap = reset_data->regmap;
>> +	reboot_data->restart_handler.notifier_call = ma35d1_restart_handler;
>> +	reboot_data->restart_handler.priority = 192;
>> +
>> +	err = register_restart_handler(&reboot_data->restart_handler);
>> +	if (err)
>> +		dev_warn(&pdev->dev, "failed to register restart handler\n");
>> +
>> +	return devm_reset_controller_register(dev, &reset_data->rcdev);
>> +
>> +err_out:
>> +	devm_kfree(dev, reset_data);
>> +	devm_kfree(dev, reboot_data);
> These are unnecessary since the probe is failing.


OK, I will make it just return err.

>
>> +	return err;
>> +}
>> +
>> +static struct platform_driver ma35d1_reset_driver = {
>> +	.probe = ma35d1_reset_probe,
>> +	.driver = {
>> +		.name = "ma35d1-reset",
>> +		.of_match_table	= ma35d1_reset_dt_ids,
>> +	},
>> +};
>> +
>> +builtin_platform_driver(ma35d1_reset_driver);
>>
Best regards,

Jacky Huang

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