clk: imx: add driver for imx8ulp's sim lpav

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 <[e-mail]>
Reviewed-by: Daniel Baluta <[e-mail]>
Reviewed-by: Peng Fan <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Abel Vesa <[e-mail]>

drivers/clk/imx/Kconfig

···
 	tristate "IMX8ULP CCM Clock Driver"
 	depends on ARCH_MXC || COMPILE_TEST
 	select MXC_CLK
+	select AUXILIARY_BUS
 	help
 	    Build the driver for i.MX8ULP CCM Clock Driver
 

drivers/clk/imx/Makefile

···
 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

drivers/clk/imx/clk-imx8ulp-sim-lpav.c

···
+// 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>
+#include <linux/slab.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 },			\
+		.bit = bidx,					\
+	}
+
+struct clk_imx8ulp_sim_lpav_data {
+	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, "core", 17),
+	IMX8ULP_HIFI_CLK_GATE("hifi_pbclk", PBCLK, "bus", 18),
+	IMX8ULP_HIFI_CLK_GATE("hifi_plat", PLAT, "plat", 19)
+};
+
+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 int clk_imx8ulp_sim_lpav_probe(struct platform_device *pdev)
+{
+	const struct regmap_config regmap_config = {
+		.reg_bits = 32,
+		.val_bits = 32,
+		.reg_stride = 4,
+		.lock = clk_imx8ulp_sim_lpav_lock,
+		.unlock = clk_imx8ulp_sim_lpav_unlock,
+		.lock_arg = &pdev->dev,
+	};
+	struct clk_imx8ulp_sim_lpav_data *data;
+	struct auxiliary_device *adev;
+	struct regmap *regmap;
+	void __iomem *base;
+	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);
+
+	/*
+	 * 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);
+
+	base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(base))
+		return dev_err_probe(&pdev->dev, PTR_ERR(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
+	 */
+	regmap = devm_regmap_init_mmio(&pdev->dev, base, &regmap_config);
+	if (IS_ERR(regmap))
+		return dev_err_probe(&pdev->dev, PTR_ERR(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,
+							   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;
+	}
+
+	adev = devm_auxiliary_device_create(&pdev->dev, "reset", NULL);
+	if (!adev)
+		return dev_err_probe(&pdev->dev, -ENODEV,
+				     "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 <[e-mail]>");