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Date: Fri, 17 May 2024 11:16:08 -0400
From: Frank Li <Frank.li@nxp.com>
To: Amit Singh Tomar <amitsinght@marvell.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
Subject: Re: [PATCH 2/4] reset: add driver for imx8ulp SIM reset controller
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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://elixir.bootlin.com/linux/latest/source/drivers/reset/reset-simple.c

reset-simple have not use regmap. I think it can use ti's
https://elixir.bootlin.com/linux/latest/source/drivers/reset/reset-ti-syscon.c

Or should change ti to reset-simple-syscon?  or add regmap support for
reset-simple.c 

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 */
>