Re: [PATCH v10 04/12] mfd: zx297520v3: Add a clock and reset MFD driver
From: Lee Jones <lee@kernel.org>
Date: 2026-08-12 13:15:27
Also in:
linux-clk, linux-devicetree, linux-phy, lkml
On Mon, 10 Aug 2026, Stefan Dösinger wrote:
quoted hunk ↗ jump to hunk
This driver registers child devices for the zx297520v3 clock and reset controllers. The clk-zx297520v3 and reset-zte-zx297520v3 submitted in the next patches will drive the respective functionalities. Signed-off-by: Stefan Dösinger <stefandoesinger@gmail.com> --- What I am still unsure about: How much sense does it make to have this module-capable and able to unbind: In practice, the board doesn't work without this driver and its clock and reset children. Changes v9: Deassert the LSP reset and enable the LSP pclk here. In practice the boot rom needs to do that because it prints to an LSP-connected UART and reads the boot policy from the LSP connected flash chip. In doing so, I migrated the match data to an enum as mfd.md suggests. Changes v8: *) Remove .of_compatible from PHY mfd child *) Move to drivers/mfd (Sashiko) For me either soc/zte or mfd/ is fine. Note though that this MFD parent is very specific to the zx297520v3 SoC. I don't expect this to be reused anywhere else. There are two more MFD-ish devices in there: soc_sys at 0x140000, which I plan to handle in the same driver, and an i2c PMIC, which would get its own host driver. *) Use PLATFORM_DEVID_AUTO (Sashiko). NONE was intentional as I only ever expect one instance, but I don't see any harm in doing the standard thing and use AUTO *) On the suggestion not to put the link to mfd_cells[] into match data: I see that it is spelled out in Sashiko's mfd.md, written by Lee Jones, the MFD maintainer. I would appreciate some education on the rationale behind it: Putting a pointer into the void *data is a common pattern in the kernel. I don't understand in which situation this can possibly break? Both structs are static const in the same compilation unit. data is a const void *, not a uintptr_t or kernel_ulong_t, so it seems passing a pointer is the intended use. What am I missing? Changes v7: Add phy MFD child Changes v6: Make the ZTE SoC driver section depend on HAS_IOMEM (Sashiko). The entire MFD section, which contains MFD_CORE, depends on HAS_IOMEM even with COMPILE_TEST. Add a NULL ptr check for of_device_get_match_data (Sashiko). While not uniform, rave-sp, rohm-bd9576, atc260x, da9052-i2c protect against incorrect manual attachment that way. Add lspclk here as well in an attempt to satisfy both Conor Dooley, who asks for MFD for top and matrix, and Philipp Zabel, who prefers aux but at least wants the reset driver limited to one driver type. Changes v5: Use MFD instead of Aux bus for top and matrix crm because of extra functionality: Reboot in top, hwlock in Matrix. LSP clocks stay with the aux bus and are thus not handled in this driver. The clk driver will bind directly to the lspcrm node. --- MAINTAINERS | 1 + drivers/mfd/Kconfig | 13 +++++ drivers/mfd/Makefile | 2 + drivers/mfd/zte-zx297520v3-crm.c | 117 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 133 insertions(+)diff --git a/MAINTAINERS b/MAINTAINERS index 61dbe959acf5..d50c03fd5a76 100644 --- a/MAINTAINERS +++ b/MAINTAINERS@@ -3909,6 +3909,7 @@ F: Documentation/devicetree/bindings/clock/zte,zx297520v3-matrixcrm.yaml F: Documentation/devicetree/bindings/clock/zte,zx297520v3-topcrm.yaml F: arch/arm/boot/dts/zte/ F: arch/arm/mach-zte/ +F: drivers/mfd/zte-zx297520v3-crm.c F: include/dt-bindings/clock/zte,zx297520v3-clk.h F: include/dt-bindings/phy/zte,zx297520v3-topcrm.h F: include/dt-bindings/reset/zte,zx297520v3-reset.hdiff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig index e4fd4572472f..08138713dfc0 100644 --- a/drivers/mfd/Kconfig +++ b/drivers/mfd/Kconfig@@ -2578,5 +2578,18 @@ config MFD_MAX7360 additional drivers must be enabled in order to use the functionality of the device. +config MFD_ZTE_ZX297520V3_CRM + tristate "ZTE zx297520v3 Clock and Reset Manager" + depends on ARCH_ZTE || COMPILE_TEST + select MFD_CORE + select REGMAP_MMIO
Is this used?
quoted hunk ↗ jump to hunk
default SOC_ZX297520V3 help Say yes here to enable the driver for the ZTE zx297520v3 clock and reset manager MFD driver. This driver provides the host device for the clock and reset drivers and is required to boot the SoC. You will also need to enable CLK_ZTE_ZX297520V3 and RESET_ZTE_ZX297520V3 to build the actual clock and reset child drivers. + endmenu endifdiff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile index 72d3944b0ad8..ab0cba2042a2 100644 --- a/drivers/mfd/Makefile +++ b/drivers/mfd/Makefile@@ -304,3 +304,5 @@ obj-$(CONFIG_MFD_RSMU_SPI) += rsmu_spi.o rsmu_core.o obj-$(CONFIG_MFD_UPBOARD_FPGA) += upboard-fpga.o obj-$(CONFIG_MFD_LOONGSON_SE) += loongson-se.o + +obj-$(CONFIG_MFD_ZTE_ZX297520V3_CRM) += zte-zx297520v3-crm.odiff --git a/drivers/mfd/zte-zx297520v3-crm.c b/drivers/mfd/zte-zx297520v3-crm.c new file mode 100644 index 000000000000..550ce4ad7ec5 --- /dev/null +++ b/drivers/mfd/zte-zx297520v3-crm.c@@ -0,0 +1,117 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) 2026 Stefan Dösinger
Personal copyright, are you sure? Is that okay with ZTE?
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/errno.h>
+#include <linux/mfd/core.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset.h>
+
+enum zx297520v3_parent_type {
+ ZX297520V3_INVALID = 0,
+ ZX297520V3_TOPCRM,
+ ZX297520V3_MATRIXCRM,
+ ZX297520V3_LSPCRM,None of these are readable. I suggest you improve the nomenclature.
+};
+
+static const struct mfd_cell zx297520v3_topcrm_cells[] = {
+ {
+ .name = "zx297520v3-topclk",
+ },
+ {
+ .name = "zx297520v3-topreset",
+ },
+ {
+ .name = "reboot",
+ .of_compatible = "syscon-reboot",
+ },
+ {
+ .name = "zx297520v3-usb-phy",
+ },
+};
+
+static const struct mfd_cell zx297520v3_matrixcrm_cells[] = {
+ {
+ .name = "zx297520v3-matrixclk",
+ },
+ {
+ .name = "zx297520v3-matrixreset",
+ },
+ /* A set of hwlock controllers is found here as well, but no driver is implemented yet */Drop this.
+};
+
+static const struct mfd_cell zx297520v3_lspcrm_cells[] = {
+ {
+ .name = "zx297520v3-lspclk",
+ },
+ {
+ .name = "zx297520v3-lspreset",
+ },
+};Use MFD_CELL_*() in all of the above.
+
+static int zx297520v3_crm_probe(struct platform_device *pdev)
+{
+ enum zx297520v3_parent_type type;
+ struct device *dev = &pdev->dev;
+ const struct mfd_cell *cells;
+ struct reset_control *rst;
+ unsigned int num_cells;
+ struct clk *pclk;
+
+ type = (enum zx297520v3_parent_type)(kernel_ulong_t)of_device_get_match_data(dev);This should be firmware agnostic. device_get*()
+ switch (type) {
+ case ZX297520V3_TOPCRM:
+ cells = zx297520v3_topcrm_cells;
+ num_cells = ARRAY_SIZE(zx297520v3_topcrm_cells);
+ break;
+
+ case ZX297520V3_MATRIXCRM:
+ cells = zx297520v3_matrixcrm_cells;
+ num_cells = ARRAY_SIZE(zx297520v3_matrixcrm_cells);
+ break;
+
+ case ZX297520V3_LSPCRM:
+ cells = zx297520v3_lspcrm_cells;
+ num_cells = ARRAY_SIZE(zx297520v3_lspcrm_cells);
+
+ pclk = devm_clk_get_enabled(dev, "pclk");
+ if (IS_ERR(pclk))
+ return dev_err_probe(dev, PTR_ERR(pclk), "Could not get pclk\n");Place pclk in 's so we know that's its name.
+ + rst = devm_reset_control_get_exclusive_deasserted(dev, NULL);
Does 'rst' have to be shortened?
+ if (IS_ERR(rst)) + return dev_err_probe(dev, PTR_ERR(rst), "Could not get reset\n");
Could we make this error message more descriptive and clear, perhaps using 'Failed to deassert reset control'?
+ break;
+
+ default:
+ return -ENODEV;
+ }
+
+ return devm_mfd_add_devices(dev, PLATFORM_DEVID_AUTO, cells, num_cells, NULL, 0, NULL);
+}
+
+static const struct of_device_id of_match_zx297520v3_crm[] = {
+ { .compatible = "zte,zx297520v3-topcrm", .data = (void *)ZX297520V3_TOPCRM },
+ { .compatible = "zte,zx297520v3-matrixcrm", .data = (void *)ZX297520V3_MATRIXCRM },
+ { .compatible = "zte,zx297520v3-lspcrm", .data = (void *)ZX297520V3_LSPCRM },
+ { }
+};
+MODULE_DEVICE_TABLE(of, of_match_zx297520v3_crm);
+
+static struct platform_driver zx297520v3_crm = {
+ .probe = zx297520v3_crm_probe,
+ .driver = {
+ .name = "zx297520v3-crm",
+ .of_match_table = of_match_zx297520v3_crm,
+ },
+};
+module_platform_driver(zx297520v3_crm);
+
+MODULE_AUTHOR("Stefan Dösinger [off-list ref]");
+MODULE_DESCRIPTION("ZTE zx297520v3 CRM MFD host driver");Drop the term MFD.
+MODULE_LICENSE("GPL");
--
2.54.0-- Lee Jones