Re: [PATCH v2 3/8] clk: imx: add driver for imx8ulp's sim lpav

Laurentiu Mihalcea
2025-10-20T11:40:26Z

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@nxp.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@nxp.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@nxp.com>");
>> --
>> 2.43.0
>>