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Message-ID: <fc91b997-f90b-4e3c-9a89-5db932ba148c@marvell.com>
Date: Mon, 20 May 2024 20:11:22 +0530
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH 2/4] reset: add driver for imx8ulp SIM reset controller
To: Frank Li <Frank.li@nxp.com>
Cc: Laurentiu Mihalcea <laurentiumihalcea111@gmail.com>,
        Rob Herring <robh@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.org>, Lee Jones <lee@kernel.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Philipp Zabel <p.zabel@pengutronix.de>, Liu Ying <victor.liu@nxp.com>,
        Sascha Hauer <s.hauer@pengutronix.de>, laurentiu.mihalcea@nxp.com,
        devicetree@vger.kernel.org, imx@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
References: <20240516204031.171920-1-laurentiumihalcea111@gmail.com>
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From: Amit Singh Tomar <amitsinght@marvell.com>
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> 
> ----------------------------------------------------------------------
> On Fri, May 17, 2024 at 11:51:30AM +0530, Amit Singh Tomar wrote:
>> Hi,
>>
>>> ----------------------------------------------------------------------
>>> From: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
>>>
>>> Certain components can be reset via the SIM module.
>>> Add reset controller driver for the SIM module to
>>> allow drivers for said components to control the
>>> reset signal(s).
>>>
>>> Signed-off-by: Liu Ying <victor.liu@nxp.com>
>>> Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@nxp.com>
>>> ---
>>>    drivers/reset/Kconfig                         |  7 ++
>>>    drivers/reset/Makefile                        |  1 +
>>>    drivers/reset/reset-imx8ulp-sim.c             | 98 +++++++++++++++++++
>>
>> Just out of curiosity, can't this be accomplished using a generic reset
>> driver?
>>
>> https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_latest_source_drivers_reset_reset-2Dsimple.c&d=DwIBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=V_GK7jRuCHDErm6txmgDK1-MbUihtnSQ3gPgB-A-JKU&m=MnEcoegPnKc-F7TNf8PB3icMf8uCGrxsh6mEDWgNq3YA-OugL6Y53LxytlBGcsKp&s=6mBPHYYYXoyyxPPbUeOiIpwR3CXdnui1W3nkUJQ76Vo&e=
> 
> reset-simple have not use regmap. I think it can use ti's
> https://urldefense.proofpoint.com/v2/url?u=https-3A__elixir.bootlin.com_linux_latest_source_drivers_reset_reset-2Dti-2Dsyscon.c&d=DwIBAg&c=nKjWec2b6R0mOyPaz7xtfQ&r=V_GK7jRuCHDErm6txmgDK1-MbUihtnSQ3gPgB-A-JKU&m=MnEcoegPnKc-F7TNf8PB3icMf8uCGrxsh6mEDWgNq3YA-OugL6Y53LxytlBGcsKp&s=D6tqLNYrUbsdG_gYg4G-ORlC9YKz4XRAlVeo1hyoYS4&e=
> 
> Or should change ti to reset-simple-syscon?  or add regmap support for
> reset-simple.c
> 

Quickly looked into U-Boot (not sure if it's the right reference), and 
it has a separate reset-syscon.c file:

https://elixir.bootlin.com/u-boot/latest/source/drivers/reset/reset-syscon.c

So, converting reset-ti-syscon.c to reset-syscon.c might be the way to go.

> Frank Li
> 
> 
>>
>>>    include/dt-bindings/reset/imx8ulp-sim-reset.h | 16 +++
>>>    4 files changed, 122 insertions(+)
>>>    create mode 100644 drivers/reset/reset-imx8ulp-sim.c
>>>    create mode 100644 include/dt-bindings/reset/imx8ulp-sim-reset.h
>>>
>>> diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
>>> index 85b27c42cf65..c1f4d9ebd0fd 100644
>>> --- a/drivers/reset/Kconfig
>>> +++ b/drivers/reset/Kconfig
>>> @@ -91,6 +91,13 @@ config RESET_IMX7
>>>    	help
>>>    	  This enables the reset controller driver for i.MX7 SoCs.
>>> +config RESET_IMX8ULP_SIM
>>> +	tristate "i.MX8ULP SIM Reset Driver"
>>> +	depends on ARCH_MXC
>>> +	help
>>> +	  This enables the SIM (System Integration Module) reset driver
>>> +	  for the i.MX8ULP SoC.
>>> +
>>>    config RESET_INTEL_GW
>>>    	bool "Intel Reset Controller Driver"
>>>    	depends on X86 || COMPILE_TEST
>>> diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
>>> index fd8b49fa46fc..f257d6a41f1e 100644
>>> --- a/drivers/reset/Makefile
>>> +++ b/drivers/reset/Makefile
>>> @@ -42,3 +42,4 @@ obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
>>>    obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
>>>    obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
>>>    obj-$(CONFIG_ARCH_ZYNQMP) += reset-zynqmp.o
>>> +obj-$(CONFIG_RESET_IMX8ULP_SIM) += reset-imx8ulp-sim.o
>>> diff --git a/drivers/reset/reset-imx8ulp-sim.c b/drivers/reset/reset-imx8ulp-sim.c
>>> new file mode 100644
>>> index 000000000000..27923b9cd454
>>> --- /dev/null
>>> +++ b/drivers/reset/reset-imx8ulp-sim.c
>>> @@ -0,0 +1,98 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +
>>> +/*
>>> + * Copyright 2024 NXP
>>> + */
>>> +
>>> +#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/imx8ulp-sim-reset.h>
>>> +
>>> +#define AVD_SIM_SYSCTRL0        0x8
>>> +
>>> +struct imx8ulp_sim_reset {
>>> +	struct reset_controller_dev     rcdev;
>>> +	struct regmap                   *regmap;
>>> +};
>>> +
>>> +static const u32 imx8ulp_sim_reset_bits[IMX8ULP_SIM_RESET_NUM] = {
>>> +	[IMX8ULP_SIM_RESET_MIPI_DSI_RST_DPI_N] = BIT(3),
>>> +	[IMX8ULP_SIM_RESET_MIPI_DSI_RST_ESC_N] = BIT(4),
>>> +	[IMX8ULP_SIM_RESET_MIPI_DSI_RST_BYTE_N] = BIT(5),
>>> +};
>>> +
>>> +static inline struct imx8ulp_sim_reset *
>>> +to_imx8ulp_sim_reset(struct reset_controller_dev *rcdev)
>>> +{
>>> +	return container_of(rcdev, struct imx8ulp_sim_reset, rcdev);
>>> +}
>>> +
>>> +static int imx8ulp_sim_reset_assert(struct reset_controller_dev *rcdev,
>>> +				    unsigned long id)
>>> +{
>>> +	struct imx8ulp_sim_reset *simr = to_imx8ulp_sim_reset(rcdev);
>>> +	const u32 bit = imx8ulp_sim_reset_bits[id];
>>> +
>>> +	return regmap_update_bits(simr->regmap, AVD_SIM_SYSCTRL0, bit, 0);
>>> +}
>>> +
>>> +static int imx8ulp_sim_reset_deassert(struct reset_controller_dev *rcdev,
>>> +				      unsigned long id)
>>> +{
>>> +	struct imx8ulp_sim_reset *simr = to_imx8ulp_sim_reset(rcdev);
>>> +	const u32 bit = imx8ulp_sim_reset_bits[id];
>>> +
>>> +	return regmap_update_bits(simr->regmap, AVD_SIM_SYSCTRL0, bit, bit);
>>> +}
>>> +
>>> +static const struct reset_control_ops imx8ulp_sim_reset_ops = {
>>> +	.assert         = imx8ulp_sim_reset_assert,
>>> +	.deassert       = imx8ulp_sim_reset_deassert,
>>> +};
>>> +
>>> +static const struct of_device_id imx8ulp_sim_reset_dt_ids[] = {
>>> +	{ .compatible = "nxp,imx8ulp-avd-sim-reset", },
>>> +	{ /* sentinel */ },
>>> +};
>>> +
>>> +static int imx8ulp_sim_reset_probe(struct platform_device *pdev)
>>> +{
>>> +	struct device *dev = &pdev->dev;
>>> +	struct imx8ulp_sim_reset *simr;
>>> +	int ret;
>>> +
>>> +	simr = devm_kzalloc(dev, sizeof(*simr), GFP_KERNEL);
>>> +	if (!simr)
>>> +		return -ENOMEM;
>>> +
>>> +	simr->regmap = syscon_node_to_regmap(dev->of_node->parent);
>>> +	if (IS_ERR(simr->regmap)) {
>>> +		ret = PTR_ERR(simr->regmap);
>>> +		dev_err(dev, "failed to get regmap: %d\n", ret);
>>> +		return ret;
>>> +	}
>>> +
>>> +	simr->rcdev.owner = THIS_MODULE;
>>> +	simr->rcdev.nr_resets = IMX8ULP_SIM_RESET_NUM;
>>> +	simr->rcdev.ops = &imx8ulp_sim_reset_ops;
>>> +	simr->rcdev.of_node = dev->of_node;
>>> +
>>> +	return devm_reset_controller_register(dev, &simr->rcdev);
>>> +}
>>> +
>>> +static struct platform_driver imx8ulp_sim_reset_driver = {
>>> +	.probe  = imx8ulp_sim_reset_probe,
>>> +	.driver = {
>>> +		.name           = KBUILD_MODNAME,
>>> +		.of_match_table = imx8ulp_sim_reset_dt_ids,
>>> +	},
>>> +};
>>> +module_platform_driver(imx8ulp_sim_reset_driver);
>>> +
>>> +MODULE_AUTHOR("Liu Ying <victor.liu@nxp.com>");
>>> +MODULE_DESCRIPTION("NXP i.MX8ULP System Integration Module Reset driver");
>>> +MODULE_LICENSE("GPL");
>>> diff --git a/include/dt-bindings/reset/imx8ulp-sim-reset.h b/include/dt-bindings/reset/imx8ulp-sim-reset.h
>>> new file mode 100644
>>> index 000000000000..a3cee0d60773
>>> --- /dev/null
>>> +++ b/include/dt-bindings/reset/imx8ulp-sim-reset.h
>>> @@ -0,0 +1,16 @@
>>> +/* SPDX-License-Identifier: GPL-2.0-only OR BSD-3-Clause */
>>> +
>>> +/*
>>> + * Copyright 2024 NXP
>>> + */
>>> +
>>> +#ifndef DT_BINDINGS_RESET_IMX8ULP_SIM_RESET_H
>>> +#define DT_BINDINGS_RESET_IMX8ULP_SIM_RESET_H
>>> +
>>> +#define IMX8ULP_SIM_RESET_MIPI_DSI_RST_DPI_N    0
>>> +#define IMX8ULP_SIM_RESET_MIPI_DSI_RST_ESC_N    1
>>> +#define IMX8ULP_SIM_RESET_MIPI_DSI_RST_BYTE_N   2
>>> +
>>> +#define IMX8ULP_SIM_RESET_NUM                   3
>>> +
>>> +#endif /* DT_BINDINGS_RESET_IMX8ULP_SIM_RESET_H */
>>