[PATCH v6 11/12] reset: zte: Add a zx297520v3 reset driver

["Stefan Dösinger" <stefandoesinger@gmail.com>]

This drives the MFD child devices created by the zx297520v3-crm driver
as well as the aux device created by the zx297520v3-lspclk driver.

Signed-off-by: Stefan Dösinger <stefandoesinger@gmail.com>

---

v6:
Add a comment wrt checking all bits in .status() (Philipp)
include cleanup (Philipp, Sashiko)

v5:
Make top and matrix MFD children instead of aux devices
Split USB PHY reset into its own reset ID
Remove USB reset wait code - this will be handled via syscon from a
future minimal phy-zx29-usb driver
---
 MAINTAINERS                          |   1 +
 drivers/reset/Kconfig                |  10 ++
 drivers/reset/Makefile               |   1 +
 drivers/reset/reset-zte-zx297520v3.c | 234 +++++++++++++++++++++++++++++++++++
 4 files changed, 246 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 8f2e436cb42b..084d30fec1cd 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -3883,6 +3883,7 @@ F:	Documentation/devicetree/bindings/soc/zte/
 F:	arch/arm/boot/dts/zte/
 F:	arch/arm/mach-zte/
 F:	drivers/clk/zte/
+F:	drivers/reset/reset-zte-zx297520v3.c
 F:	drivers/soc/zte/
 F:	include/dt-bindings/clock/zte,zx297520v3-clk.h
 F:	include/dt-bindings/reset/zte,zx297520v3-reset.h
diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index d009eb0849a3..4dca1f89d22b 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -404,6 +404,16 @@ config RESET_UNIPHIER_GLUE
 	  on UniPhier SoCs. Say Y if you want to control reset signals
 	  provided by the glue layer.
 
+config RESET_ZTE_ZX297520V3
+	tristate "ZTE zx297520v3 Reset Driver"
+	depends on ZTE_ZX297520V3_CRM || COMPILE_TEST
+	default SOC_ZX297520V3
+	help
+	  This enables the reset controllers for ZTE zx297520v3 SoCs. The reset
+	  controllers are part of the clock and reset management controllers on
+	  this board, so you will also need ZTE_ZX297520V3_CRM. Enable this if
+	  you are building a kernel for a ZTE x297520v3 based board.
+
 config RESET_ZYNQ
 	bool "ZYNQ Reset Driver" if COMPILE_TEST
 	default ARCH_ZYNQ
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 3e52569bd276..9a8a48d44dc4 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -50,5 +50,6 @@ obj-$(CONFIG_RESET_TI_TPS380X) += reset-tps380x.o
 obj-$(CONFIG_RESET_TN48M_CPLD) += reset-tn48m.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_UNIPHIER_GLUE) += reset-uniphier-glue.o
+obj-$(CONFIG_RESET_ZTE_ZX297520V3) += reset-zte-zx297520v3.o
 obj-$(CONFIG_RESET_ZYNQ) += reset-zynq.o
 obj-$(CONFIG_RESET_ZYNQMP) += reset-zynqmp.o
diff --git a/drivers/reset/reset-zte-zx297520v3.c b/drivers/reset/reset-zte-zx297520v3.c
new file mode 100644
index 000000000000..75a9e6e93cda
--- /dev/null
+++ b/drivers/reset/reset-zte-zx297520v3.c
@@ -0,0 +1,234 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2026 Stefan Dösinger
+ */
+#include <dt-bindings/reset/zte,zx297520v3-reset.h>
+#include <linux/reset-controller.h>
+#include <linux/platform_device.h>
+#include <linux/mfd/syscon.h>
+#include <linux/regmap.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/bits.h>
+#include <linux/err.h>
+
+/* Most devices on the zx297520v3 SoC have one reset bit per clock line. As a rule of thumb, the
+ * lower bit disconnects the device from the bus, similarly to turning off PCLK - registers read 0
+ * or hang indefinitely. Unlike PCLK, this reset may have a lingering effect after deasserting.
+ * E.g. timers will be disabled, but retain their counter value.
+ *
+ * The other bit resets the actual device registers.
+ *
+ * For some devices, e.g. GMAC, both reset bits behave in the same way: They disconnect the device
+ * and registers will have their default state after deasserting. For devices that have two reset
+ * bits, both need to be deasserted for the device to function.
+ */
+struct zte_reset_reg {
+	u32 mask;
+	u16 reg;
+};
+
+struct zte_reset_data {
+	const struct zte_reset_reg *resets;
+	unsigned int num;
+};
+
+struct zte_reset {
+	struct reset_controller_dev rcdev;
+	struct regmap *map;
+	const struct zte_reset_reg *resets;
+};
+
+static inline struct zte_reset *to_zte_reset(struct reset_controller_dev *rcdev)
+{
+	return container_of(rcdev, struct zte_reset, rcdev);
+}
+
+static int zx29_rst_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct zte_reset *rst = to_zte_reset(rcdev);
+
+	return regmap_clear_bits(rst->map, rst->resets[id].reg, rst->resets[id].mask);
+}
+
+static int zx29_rst_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct zte_reset *rst = to_zte_reset(rcdev);
+
+	return regmap_set_bits(rst->map, rst->resets[id].reg, rst->resets[id].mask);
+}
+
+static int zx29_rst_status(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct zte_reset *rst = to_zte_reset(rcdev);
+	int res;
+
+	/* Devices with two reset bits need both deasserted to work. So only report them as
+	 * deasserted if both bits are set.
+	 *
+	 * assert()/deassert() will always clear/set both. The only reason a device might be in a
+	 * hybrid state is an unexpected handover state from the bootloader.
+	 */
+	res = regmap_test_bits(rst->map, rst->resets[id].reg, rst->resets[id].mask);
+	if (res < 0)
+		return res;
+
+	return !res;
+}
+
+static const struct reset_control_ops zx29_rst_ops = {
+	.assert		= zx29_rst_assert,
+	.deassert	= zx29_rst_deassert,
+	.status		= zx29_rst_status,
+};
+
+static const struct zte_reset_reg zx297520v3_top_resets[] = {
+	/* This bit is set by ZTE's cpko.ko blob, it looks like a reset bit for the LTE DSP
+	 * coprocessor. Clocks for it are in matrixcrm.
+	 */
+	[ZX297520V3_ZSP_RESET]       = { .reg = 0x13c, .mask = BIT(0)            },
+
+	[ZX297520V3_UART0_RESET]     = { .reg =  0x78, .mask = BIT(6)  | BIT(7)  },
+	[ZX297520V3_I2C0_RESET]      = { .reg =  0x74, .mask = BIT(8)  | BIT(9)  },
+	/* Only one reset. Bit 5 is settable but does not do anything observable */
+	[ZX297520V3_RTC_RESET]       = { .reg =  0x74, .mask = BIT(4)            },
+	[ZX297520V3_TIMER_T08_RESET] = { .reg =  0x78, .mask = BIT(4)  | BIT(5)  },
+	[ZX297520V3_TIMER_T09_RESET] = { .reg =  0x78, .mask = BIT(2)  | BIT(3)  },
+	/* Only one reset. Bit 0 is settable but does not do anything observable */
+	[ZX297520V3_PMM_RESET]       = { .reg =  0x74, .mask = BIT(1)            },
+
+	/* I haven't found any clocks for GPIO. It probably wouldn't make much
+	 * sense anyway. Only one reset bit per controller.
+	 */
+	[ZX297520V3_GPIO_RESET]      = { .reg =  0x74, .mask = BIT(3)            },
+	[ZX297520V3_GPIO8_RESET]     = { .reg =  0x74, .mask = BIT(2)            },
+
+	[ZX297520V3_TIMER_T12_RESET] = { .reg =  0x74, .mask = BIT(6)  | BIT(7)  },
+	[ZX297520V3_TIMER_T13_RESET] = { .reg =  0x7c, .mask = BIT(0)  | BIT(1)  },
+	[ZX297520V3_TIMER_T14_RESET] = { .reg =  0x7c, .mask = BIT(2)  | BIT(3)  },
+	[ZX297520V3_TIMER_T15_RESET] = { .reg =  0x74, .mask = BIT(10) | BIT(11) },
+	[ZX297520V3_TIMER_T16_RESET] = { .reg =  0x7c, .mask = BIT(4)  | BIT(5)  },
+	[ZX297520V3_TIMER_T17_RESET] = { .reg = 0x12c, .mask = BIT(0)  | BIT(1)  },
+	[ZX297520V3_WDT_T18_RESET]   = { .reg =  0x74, .mask = BIT(12) | BIT(13) },
+	[ZX297520V3_USIM1_RESET]     = { .reg =  0x74, .mask = BIT(14) | BIT(15) },
+	[ZX297520V3_AHB_RESET]       = { .reg =  0x70, .mask = BIT(0)  | BIT(1)  },
+
+	/* USB reset. 0x84 returns the USB device status (0x1 for HSIC up, 0x2 for USB up, but
+	 * all 3 bits (PCLK, WCLK, PHY) need to be deasserted for the device to report ready.
+	 * Thus polling the status is the responsibility of the USB PHY driver.
+	 */
+	[ZX297520V3_USB_PHY_RESET]   = { .reg =  0x80, .mask = BIT(3)            },
+	[ZX297520V3_USB_RESET]       = { .reg =  0x80, .mask = BIT(4) | BIT(5)   },
+	[ZX297520V3_HSIC_PHY_RESET]  = { .reg =  0x80, .mask = BIT(0)            },
+	[ZX297520V3_HSIC_RESET]      = { .reg =  0x80, .mask = BIT(1) | BIT(2)   },
+};
+
+static const struct zte_reset_data zx297520v3_topreset_data = {
+	.resets = zx297520v3_top_resets,
+	.num = ARRAY_SIZE(zx297520v3_top_resets),
+};
+
+static const struct zte_reset_reg zx297520v3_matrix_resets[] = {
+	[ZX297520V3_CPU_RESET]       = { .reg =  0x28, .mask = BIT(1)            },
+	[ZX297520V3_EDCP_RESET]      = { .reg =  0x68, .mask = BIT(0)            },
+	[ZX297520V3_SD0_RESET]       = { .reg =  0x58, .mask = BIT(1)            },
+	[ZX297520V3_SD1_RESET]       = { .reg =  0x58, .mask = BIT(0)            },
+	[ZX297520V3_NAND_RESET]      = { .reg =  0x58, .mask = BIT(4)            },
+	[ZX297520V3_PDCFG_RESET]     = { .reg =  0x94, .mask = BIT(20)           },
+	[ZX297520V3_SSC_RESET]       = { .reg =  0x94, .mask = BIT(24)           },
+	[ZX297520V3_GMAC_RESET]      = { .reg = 0x114, .mask = BIT(0)  | BIT(1)  },
+	[ZX297520V3_VOU_RESET]       = { .reg = 0x16c, .mask = BIT(0)            },
+};
+
+static const struct zte_reset_data zx297520v3_matrixreset_data = {
+	.resets = zx297520v3_matrix_resets,
+	.num = ARRAY_SIZE(zx297520v3_matrix_resets),
+};
+
+static const struct zte_reset_reg zx297520v3_lsp_resets[] = {
+	[ZX297520V3_TIMER_L1_RESET]  = { .reg = 0x04,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_WDT_L2_RESET]    = { .reg = 0x08,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_WDT_L3_RESET]    = { .reg = 0x0c,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_PWM_RESET]       = { .reg = 0x10,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_I2S0_RESET]      = { .reg = 0x14,  .mask = BIT(8)  | BIT(9)  },
+	/* 0x18: Not writeable */
+	[ZX297520V3_I2S1_RESET]      = { .reg = 0x1c,  .mask = BIT(8)  | BIT(9)  },
+	/* 0x20: Not writeable */
+	[ZX297520V3_QSPI_RESET]      = { .reg = 0x24,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_UART1_RESET]     = { .reg = 0x28,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_I2C1_RESET]      = { .reg = 0x2c,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_SPI0_RESET]      = { .reg = 0x30,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_TIMER_LB_RESET]  = { .reg = 0x34,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_TIMER_LC_RESET]  = { .reg = 0x38,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_UART2_RESET]     = { .reg = 0x3c,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_WDT_LE_RESET]    = { .reg = 0x40,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_TIMER_LF_RESET]  = { .reg = 0x44,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_SPI1_RESET]      = { .reg = 0x48,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_TIMER_L11_RESET] = { .reg = 0x4c,  .mask = BIT(8)  | BIT(9)  },
+	[ZX297520V3_TDM_RESET]       = { .reg = 0x50,  .mask = BIT(8)  | BIT(9)  },
+};
+
+static const struct zte_reset_data zx297520v3_lspreset_data = {
+	.resets = zx297520v3_lsp_resets,
+	.num = ARRAY_SIZE(zx297520v3_lsp_resets),
+};
+
+static int reset_zx297520v3_probe(struct platform_device *pdev)
+{
+	const struct platform_device_id *id = platform_get_device_id(pdev);
+	struct device *dev = &pdev->dev;
+	struct device_node *of_node = dev->parent->of_node;
+	const struct zte_reset_data *data;
+	struct zte_reset *rst;
+
+	if (!id)
+		return -ENODEV;
+	data = (const struct zte_reset_data *)id->driver_data;
+
+	rst = devm_kzalloc(dev, sizeof(*rst), GFP_KERNEL);
+	if (!rst)
+		return -ENOMEM;
+
+	rst->resets = data->resets;
+	rst->rcdev.owner = THIS_MODULE;
+	rst->rcdev.nr_resets = data->num;
+	rst->rcdev.ops = &zx29_rst_ops;
+	rst->rcdev.of_node = of_node;
+	rst->rcdev.dev = dev;
+
+	rst->map = device_node_to_regmap(of_node);
+	if (IS_ERR(rst->map))
+		return dev_err_probe(dev, PTR_ERR(rst->map), "Cannot get parent syscon regmap\n");
+
+	return devm_reset_controller_register(dev, &rst->rcdev);
+}
+
+static const struct platform_device_id reset_zx297520v3_ids[] = {
+	{
+		.name = "zx297520v3-topreset",
+		.driver_data = (kernel_ulong_t)&zx297520v3_topreset_data,
+	},
+	{
+		.name = "zx297520v3-matrixreset",
+		.driver_data = (kernel_ulong_t)&zx297520v3_matrixreset_data,
+	},
+	{
+		.name = "zx297520v3-lspreset",
+		.driver_data = (kernel_ulong_t)&zx297520v3_lspreset_data,
+	},
+	{ }
+};
+
+static struct platform_driver reset_zx297520v3 = {
+	.probe = reset_zx297520v3_probe,
+	.driver = {
+		.name = "reset-zx297520v3",
+	},
+	.id_table = reset_zx297520v3_ids,
+};
+module_platform_driver(reset_zx297520v3);
+
+MODULE_AUTHOR("Stefan Dösinger <stefandoesinger@gmail.com>");
+MODULE_DESCRIPTION("ZTE zx297520v3 reset driver");
+MODULE_LICENSE("GPL");

-- 
2.54.0