Message-ID: <07a3b881-9ddf-477d-a027-32b3f9ee3d36@gmail.com>
Date: Mon, 20 Oct 2025 04:40:20 -0700
From: Laurentiu Mihalcea <laurentiumihalcea111@...il.com>
To: Frank Li <Frank.li@....com>
Cc: Abel Vesa <abelvesa@...nel.org>, Peng Fan <peng.fan@....com>,
 Michael Turquette <mturquette@...libre.com>, Stephen Boyd
 <sboyd@...nel.org>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
 Fabio Estevam <festevam@...il.com>, Philipp Zabel <p.zabel@...gutronix.de>,
 Daniel Baluta <daniel.baluta@....com>, Shengjiu Wang
 <shengjiu.wang@....com>, linux-clk@...r.kernel.org, imx@...ts.linux.dev,
 devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-kernel@...r.kernel.org, Pengutronix Kernel Team <kernel@...gutronix.de>
Subject: Re: [PATCH v2 3/8] clk: imx: add driver for imx8ulp's sim lpav


On 10/17/2025 7:41 AM, Frank Li wrote:
> On Fri, Oct 17, 2025 at 04:20:20AM -0700, Laurentiu Mihalcea wrote:
>> From: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>>
>> The i.MX8ULP System Integration Module (SIM) LPAV module is a block
>> control module found inside the LPAV subsystem, which offers some clock
>> gating options and reset line assertion/de-assertion capabilities.
>>
>> Therefore, the clock gate management is supported by registering the
>> module's driver as a clock provider, while the reset capabilities are
>> managed via the auxiliary device API to allow the DT node to act as a
>> reset and clock provider.
>>
>> Signed-off-by: Laurentiu Mihalcea <laurentiu.mihalcea@....com>
>> ---
>>  drivers/clk/imx/Makefile               |   1 +
>>  drivers/clk/imx/clk-imx8ulp-sim-lpav.c | 211 +++++++++++++++++++++++++
>>  2 files changed, 212 insertions(+)
>>  create mode 100644 drivers/clk/imx/clk-imx8ulp-sim-lpav.c
>>
>> diff --git a/drivers/clk/imx/Makefile b/drivers/clk/imx/Makefile
>> index 03f2b2a1ab63..208b46873a18 100644
>> --- a/drivers/clk/imx/Makefile
>> +++ b/drivers/clk/imx/Makefile
>> @@ -41,6 +41,7 @@ clk-imx-lpcg-scu-$(CONFIG_CLK_IMX8QXP) += clk-lpcg-scu.o clk-imx8qxp-lpcg.o
>>  clk-imx-acm-$(CONFIG_CLK_IMX8QXP) = clk-imx8-acm.o
>>
>>  obj-$(CONFIG_CLK_IMX8ULP) += clk-imx8ulp.o
>> +obj-$(CONFIG_CLK_IMX8ULP) += clk-imx8ulp-sim-lpav.o
>>
>>  obj-$(CONFIG_CLK_IMX1)   += clk-imx1.o
>>  obj-$(CONFIG_CLK_IMX25)  += clk-imx25.o
>> diff --git a/drivers/clk/imx/clk-imx8ulp-sim-lpav.c b/drivers/clk/imx/clk-imx8ulp-sim-lpav.c
>> new file mode 100644
>> index 000000000000..a67a0e50e1ce
>> --- /dev/null
>> +++ b/drivers/clk/imx/clk-imx8ulp-sim-lpav.c
>> @@ -0,0 +1,211 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright 2025 NXP
>> + */
>> +
>> +#include <dt-bindings/clock/imx8ulp-clock.h>
>> +
>> +#include <linux/auxiliary_bus.h>
>> +#include <linux/clk-provider.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +
>> +#define SYSCTRL0 0x8
>> +
>> +#define IMX8ULP_HIFI_CLK_GATE(gname, cname, pname, bidx)	\
>> +	{							\
>> +		.name = gname "_cg",				\
>> +		.id = IMX8ULP_CLK_SIM_LPAV_HIFI_##cname,	\
>> +		.parent = { .fw_name = pname, .name = pname },	\
>> +		.bit = bidx,					\
>> +	}
>> +
>> +struct clk_imx8ulp_sim_lpav_data {
>> +	void __iomem *base;
>> +	struct regmap *regmap;
>> +	spinlock_t lock; /* shared by MUX, clock gate and reset */
>> +	unsigned long flags; /* for spinlock usage */
>> +	struct clk_hw_onecell_data clk_data; /*  keep last */
>> +};
>> +
>> +struct clk_imx8ulp_sim_lpav_gate {
>> +	const char *name;
>> +	int id;
>> +	const struct clk_parent_data parent;
>> +	u8 bit;
>> +};
>> +
>> +static struct clk_imx8ulp_sim_lpav_gate gates[] = {
>> +	IMX8ULP_HIFI_CLK_GATE("hifi_core", CORE, "hifi_core", 17),
>> +	IMX8ULP_HIFI_CLK_GATE("hifi_pbclk", PBCLK, "lpav_bus", 18),
>> +	IMX8ULP_HIFI_CLK_GATE("hifi_plat", PLAT, "hifi_plat", 19)
>> +};
>> +
>> +#ifdef CONFIG_RESET_CONTROLLER
> Needn't this ifdef because if CONFIG_RESET_CONTROLLER, reset driver will
> not probe, just register aux device is not harmful.


ah, yes, was meant to drop this. Will give it a try and do the change for V3 if everything

works well.


>
>> +static void clk_imx8ulp_sim_lpav_aux_reset_release(struct device *dev)
>> +{
>> +	struct auxiliary_device *adev = to_auxiliary_dev(dev);
>> +
>> +	kfree(adev);
>> +}
>> +
>> +static void clk_imx8ulp_sim_lpav_unregister_aux_reset(void *data)
>> +{
>> +	struct auxiliary_device *adev = data;
>> +
>> +	auxiliary_device_delete(adev);
>> +	auxiliary_device_uninit(adev);
>> +}
>> +
>> +static int clk_imx8ulp_sim_lpav_register_aux_reset(struct platform_device *pdev)
>> +{
>> +	struct auxiliary_device *adev __free(kfree) = NULL;
>> +	int ret;
>> +
>> +	adev = kzalloc(sizeof(*adev), GFP_KERNEL);
>> +	if (!adev)
>> +		return -ENOMEM;
>> +
>> +	adev->name = "reset";
>> +	adev->dev.parent = &pdev->dev;
>> +	adev->dev.release = clk_imx8ulp_sim_lpav_aux_reset_release;
>> +
>> +	ret = auxiliary_device_init(adev);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "failed to initialize aux dev\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = auxiliary_device_add(adev);
>> +	if (ret) {
>> +		auxiliary_device_uninit(adev);
>> +		dev_err(&pdev->dev, "failed to add aux dev\n");
>> +		return ret;
>> +	}
>> +
>> +	return devm_add_action_or_reset(&pdev->dev,
>> +					clk_imx8ulp_sim_lpav_unregister_aux_reset,
>> +					no_free_ptr(adev));
> use devm_auxiliary_device_create() to simple whole code.


good catch. Will give this a try and switch to it in next version if there's no issues.


>
>> +}
>> +#else
>> +static int clk_imx8ulp_sim_lpav_register_aux_reset(struct platform_device *pdev)
>> +{
>> +	return 0;
>> +}
>> +#endif /* CONFIG_RESET_CONTROLLER */
>> +
>> +static void clk_imx8ulp_sim_lpav_lock(void *arg) __acquires(&data->lock)
>> +{
>> +	struct clk_imx8ulp_sim_lpav_data *data = dev_get_drvdata(arg);
>> +
>> +	spin_lock_irqsave(&data->lock, data->flags);
>> +}
>> +
>> +static void clk_imx8ulp_sim_lpav_unlock(void *arg) __releases(&data->lock)
>> +{
>> +	struct clk_imx8ulp_sim_lpav_data *data = dev_get_drvdata(arg);
>> +
>> +	spin_unlock_irqrestore(&data->lock, data->flags);
>> +}
>> +
>> +static const struct regmap_config clk_imx8ulp_sim_lpav_regmap_cfg = {
>> +	.reg_bits = 32,
>> +	.val_bits = 32,
>> +	.reg_stride = 4,
>> +	.lock = clk_imx8ulp_sim_lpav_lock,
>> +	.unlock = clk_imx8ulp_sim_lpav_unlock,
> why need lock/unlock here, regmap already have lock to access one register.


yeah but we want to share the lock with the clock gate. I know we can theoretically do

something like "&regmap->spinlock" but the lock initialization (i.e. which lock we initialize)

depends on how we configure "struct regmap_config", which is why I think my proposal is

more robust since we don't depend on how we fill in the fields of "struct regmap_config"

(other than lock/unlock/lock_arg).


But then again I'm not fixated on current approach so if more people think it would

be better to just use "&regmap->spinlock" then I'll give that a try.


>
> Frank
>> +};
>> +
>> +static int clk_imx8ulp_sim_lpav_probe(struct platform_device *pdev)
>> +{
>> +	struct clk_imx8ulp_sim_lpav_data *data;
>> +	struct regmap_config regmap_config;
>> +	struct clk_hw *hw;
>> +	int i, ret;
>> +
>> +	data = devm_kzalloc(&pdev->dev,
>> +			    struct_size(data, clk_data.hws, ARRAY_SIZE(gates)),
>> +			    GFP_KERNEL);
>> +	if (!data)
>> +		return -ENOMEM;
>> +
>> +	dev_set_drvdata(&pdev->dev, data);
>> +
>> +	memcpy(&regmap_config, &clk_imx8ulp_sim_lpav_regmap_cfg, sizeof(regmap_config));
>> +	regmap_config.lock_arg = &pdev->dev;
>> +
>> +	/*
>> +	 * this lock is used directly by the clock gate and indirectly
>> +	 * by the reset and mux controller via the regmap API
>> +	 */
>> +	spin_lock_init(&data->lock);
>> +
>> +	data->base = devm_platform_ioremap_resource(pdev, 0);
>> +	if (IS_ERR(data->base))
>> +		return dev_err_probe(&pdev->dev, PTR_ERR(data->base),
>> +				     "failed to ioremap base\n");
>> +	/*
>> +	 * although the clock gate doesn't use the regmap API to modify the
>> +	 * registers, we still need the regmap because of the reset auxiliary
>> +	 * driver and the MUX drivers, which use the parent device's regmap
>> +	 */
>> +	data->regmap = devm_regmap_init_mmio(&pdev->dev, data->base, &regmap_config);
>> +	if (IS_ERR(data->regmap))
>> +		return dev_err_probe(&pdev->dev, PTR_ERR(data->regmap),
>> +				     "failed to initialize regmap\n");
>> +
>> +	data->clk_data.num = ARRAY_SIZE(gates);
>> +
>> +	for (i = 0; i < ARRAY_SIZE(gates); i++) {
>> +		hw = devm_clk_hw_register_gate_parent_data(&pdev->dev,
>> +							   gates[i].name,
>> +							   &gates[i].parent,
>> +							   CLK_SET_RATE_PARENT,
>> +							   data->base + SYSCTRL0,
>> +							   gates[i].bit,
>> +							   0x0, &data->lock);
>> +		if (IS_ERR(hw))
>> +			return dev_err_probe(&pdev->dev, PTR_ERR(hw),
>> +					     "failed to register %s gate\n",
>> +					     gates[i].name);
>> +
>> +		data->clk_data.hws[i] = hw;
>> +	}
>> +
>> +	ret = clk_imx8ulp_sim_lpav_register_aux_reset(pdev);
>> +	if (ret)
>> +		return dev_err_probe(&pdev->dev, ret,
>> +				     "failed to register aux reset\n");
>> +
>> +	ret = devm_of_clk_add_hw_provider(&pdev->dev,
>> +					  of_clk_hw_onecell_get,
>> +					  &data->clk_data);
>> +	if (ret)
>> +		return dev_err_probe(&pdev->dev, ret,
>> +				     "failed to register clk hw provider\n");
>> +
>> +	/* used to probe MUX child device */
>> +	return devm_of_platform_populate(&pdev->dev);
>> +}
>> +
>> +static const struct of_device_id clk_imx8ulp_sim_lpav_of_match[] = {
>> +	{ .compatible = "fsl,imx8ulp-sim-lpav" },
>> +	{ }
>> +};
>> +MODULE_DEVICE_TABLE(of, clk_imx8ulp_sim_lpav_of_match);
>> +
>> +static struct platform_driver clk_imx8ulp_sim_lpav_driver = {
>> +	.probe = clk_imx8ulp_sim_lpav_probe,
>> +	.driver = {
>> +		.name = "clk-imx8ulp-sim-lpav",
>> +		.of_match_table = clk_imx8ulp_sim_lpav_of_match,
>> +	},
>> +};
>> +module_platform_driver(clk_imx8ulp_sim_lpav_driver);
>> +
>> +MODULE_LICENSE("GPL");
>> +MODULE_DESCRIPTION("i.MX8ULP LPAV System Integration Module (SIM) clock driver");
>> +MODULE_AUTHOR("Laurentiu Mihalcea <laurentiu.mihalcea@....com>");
>> --
>> 2.43.0
>>

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