Re: [PATCH v4 06/22] mux: Add driver for Renesas RZ/V2H USB VBUS_SEL mux

Jian Hui Lee
2025-11-27T02:29:07Z

On Fri, Nov 21, 2025 at 04:11:55PM +0100, Tommaso Merciai wrote:
> As per the RZ/V2H(P) HW manual, VBUSEN can be controlled by the VBUS_SEL
> bit of the VBENCTL Control Register. This register is mapped in the
> reset framework. The reset driver expose this register as mux-controller
> and instantiates this driver. The consumer will use the mux API to
> control the VBUS_SEL bit.
>
> Signed-off-by: Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>
> ---
> v3->v4:
> - Removed mux_chip->dev.of_node not needed.
>
> v2->v3:
> - Added mux_chip->dev.of_node = dev->of_node->child as the mux-controller
> is an internal node.
> - Fixed auxiliary_device_id name.
> - Get rdev using from platform_data.
> - Drop struct auxiliary_device adev from reset_rzv2h_usb2phy_adev
> as it is needed.
> - Drop to_reset_rzv2h_usb2phy_adev() as it is not needed.
>
> v1->v2:
> - New patch
>
> drivers/mux/Kconfig | 10 +++
> drivers/mux/Makefile | 2 +
> drivers/mux/rzv2h-usb-vbus.c | 97 +++++++++++++++++++++++
> include/linux/reset/reset_rzv2h_usb2phy.h | 11 +++
> 4 files changed, 120 insertions(+)
> create mode 100644 drivers/mux/rzv2h-usb-vbus.c
> create mode 100644 include/linux/reset/reset_rzv2h_usb2phy.h
>
> diff --git a/drivers/mux/Kconfig b/drivers/mux/Kconfig
> index c68132e38138..604f625544ed 100644
> --- a/drivers/mux/Kconfig
> +++ b/drivers/mux/Kconfig
> @@ -59,4 +59,14 @@ config MUX_MMIO
> To compile the driver as a module, choose M here: the module will
> be called mux-mmio.
>
> +config MUX_RZV2H_VBENCTL
> + tristate "Renesas RZ/V2H USB VBUS mux driver"
> + depends on RESET_RZV2H_USB2PHY || COMPILE_TEST
> + depends on OF
> + select REGMAP_MMIO
> + select AUXILIARY_BUS
> + default RESET_RZV2H_USB2PHY
> + help
> + Support for VBUS mux implemented on Renesas RZ/V2H SoCs.
> +
> endmenu
> diff --git a/drivers/mux/Makefile b/drivers/mux/Makefile
> index 6e9fa47daf56..9421660399af 100644
> --- a/drivers/mux/Makefile
> +++ b/drivers/mux/Makefile
> @@ -8,9 +8,11 @@ mux-adg792a-objs := adg792a.o
> mux-adgs1408-objs := adgs1408.o
> mux-gpio-objs := gpio.o
> mux-mmio-objs := mmio.o
> +mux-rzv2h-usb-vbus-objs := rzv2h-usb-vbus.o
>
> obj-$(CONFIG_MULTIPLEXER) += mux-core.o
> obj-$(CONFIG_MUX_ADG792A) += mux-adg792a.o
> obj-$(CONFIG_MUX_ADGS1408) += mux-adgs1408.o
> obj-$(CONFIG_MUX_GPIO) += mux-gpio.o
> obj-$(CONFIG_MUX_MMIO) += mux-mmio.o
> +obj-$(CONFIG_MUX_RZV2H_VBENCTL) += mux-rzv2h-usb-vbus.o
> diff --git a/drivers/mux/rzv2h-usb-vbus.c b/drivers/mux/rzv2h-usb-vbus.c
> new file mode 100644
> index 000000000000..9513bc8f35ff
> --- /dev/null
> +++ b/drivers/mux/rzv2h-usb-vbus.c
> @@ -0,0 +1,97 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Renesas RZ/V2H(P) USB2 VBUS_SEL mux driver
> + *
> + * Copyright (C) 2025 Renesas Electronics Corp.
> + */
> +
> +#include <linux/auxiliary_bus.h>
> +#include <linux/bitops.h>
> +#include <linux/err.h>
> +#include <linux/module.h>
> +#include <linux/mux/driver.h>
> +#include <linux/of.h>
> +#include <linux/property.h>
> +#include <linux/regmap.h>
> +#include <linux/reset/reset_rzv2h_usb2phy.h>
> +
> +#define RZV2H_VBENCTL 0xf0c
> +
> +struct mux_rzv2h_usb_vbus_priv {
> + struct regmap_field *field;
> +};
> +
> +static int mux_rzv2h_usb_vbus_set(struct mux_control *mux, int state)
> +{
> + struct mux_rzv2h_usb_vbus_priv *priv = mux_chip_priv(mux->chip);
> +
> + return regmap_field_write(priv->field, state);
> +}
> +
> +static const struct mux_control_ops mux_rzv2h_usb_vbus_ops = {
> + .set = mux_rzv2h_usb_vbus_set,
> +};
> +
> +static const struct regmap_config rzv2h_usb_vbus_regconf = {
> + .reg_bits = 32,
> + .val_bits = 32,
> + .reg_stride = 4,
> + .max_register = RZV2H_VBENCTL,
> +};
> +
> +static int mux_rzv2h_usb_vbus_probe(struct auxiliary_device *adev,
> + const struct auxiliary_device_id *id)
> +{
> + struct reset_rzv2h_usb2phy_adev *rdev = adev->dev.platform_data;
> + struct mux_rzv2h_usb_vbus_priv *priv;
> + struct device *dev = &adev->dev;
> + struct mux_chip *mux_chip;
> + struct regmap *regmap;
> + struct reg_field reg_field = {
> + .reg = RZV2H_VBENCTL,
> + .lsb = 0,
> + .msb = 0,
> + };
> + int ret;
> +
> + regmap = devm_regmap_init_mmio(dev, rdev->base, &rzv2h_usb_vbus_regconf);
> + if (IS_ERR(regmap))
> + return PTR_ERR(regmap);
> +
> + mux_chip = devm_mux_chip_alloc(dev, 1, sizeof(*priv));
> + if (IS_ERR(mux_chip))
> + return PTR_ERR(mux_chip);
> +
> + priv = mux_chip_priv(mux_chip);
> +
> + priv->field = devm_regmap_field_alloc(dev, regmap, reg_field);
> + if (IS_ERR(priv->field))
> + return PTR_ERR(priv->field);
> +
> + mux_chip->ops = &mux_rzv2h_usb_vbus_ops;
> + mux_chip->mux[0].states = 2;
> + mux_chip->mux[0].idle_state = MUX_IDLE_AS_IS;
> +
> + ret = devm_mux_chip_register(dev, mux_chip);
> + if (ret < 0)
> + return dev_err_probe(dev, ret, "Failed to register mux chip\n");
> +
> + return 0;
> +}
> +
> +static const struct auxiliary_device_id mux_rzv2h_usb_vbus_ids[] = {
> + { .name = "rzv2h_usb2phy_reset.vbus-sel-mux" },

hi Tommaso,
this string causes buffer overflow, could you help to check on it?

[ 15.349036] strlen: detected buffer overflow: 33 byte read of buffer size 32
[ 15.349083] WARNING: CPU: 0 PID: 518 at lib/string_helpers.c:1035 __fortify_report+0x64/0xc8
[ 15.349110] Modules linked in: mux_rzv2h_usb_vbus(+) rcar_canfd(+) mtd sm4_ce(-) can_dev rz_dmac(+) pwm_rzg2l_gpt binfmt_misc dm_multipath efi_pstore nfnetlink ip_tables x_tables autofs4 btrfs blake2b_generic raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor xor_neon raid6_pq raid1 raid0 linear rtc_isl1208 micrel phy_package mmc_block raa215300 rpmb_core dwmac_renesas_gbeth spi_rpc_if pcs_rzn1_miic stmmac_platform stmmac polyval_ce renesas_sdhi_internal_dmac renesas_usbhs ghash_ce panfrost udc_core pcs_xpcs renesas_sdhi_core reset_rzv2h_usb2phy gpu_sched tmio_mmc_core xhci_rcar_hcd ehci_platform sm4 phy_rzg3e_usb3 phy_rcar_gen3_usb2 rzv2m_usb3drd xhci_plat_hcd ohci_platform renesas_rpc_if i2c_riic gpio_regulator gpio_keys fixed aes_neon_bs aes_neon_blk aes_ce_blk aes_ce_cipher
[ 15.349359] CPU: 0 UID: 0 PID: 518 Comm: (udev-worker) Not tainted 6.18.0-5.5 #3 PREEMPT(voluntary)
[ 15.349371] Hardware name: Renesas SMARC EVK version 2 based on r9a09g047e57 (DT)
[ 15.349380] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 15.349390] pc : __fortify_report+0x64/0xc8
[ 15.349400] lr : __fortify_report+0x64/0xc8
[ 15.349408] sp : ffff8000854fb830
[ 15.349413] x29: ffff8000854fb830 x28: ffff80007c7a41d8 x27: ffff80007c7a4300
[ 15.349430] x26: ffff800083c4d780 x25: 0000000000000000 x24: ffff0000c5de9de8
[ 15.349446] x23: ffff800081d23b68 x22: ffff0000c004b200 x21: ffff0000ca6dd080
[ 15.349462] x20: 0000000000000020 x19: ffff80007c7a6140 x18: ffff800084b870a8
[ 15.349477] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 15.349492] x14: 0000000000000000 x13: 323320657a697320 x12: 7265666675622066
[ 15.349507] x11: 0000000000000000 x10: 0000000000000000 x9 : ffff800080208f0c
[ 15.349522] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
[ 15.349536] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[ 15.349550] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[ 15.349565] Call trace:
[ 15.349572] __fortify_report+0x64/0xc8 (P)
[ 15.349583] __fortify_panic+0x14/0x18
[ 15.349595] auxiliary_match_id+0xf8/0x110
[ 15.349608] auxiliary_match+0x28/0x60
[ 15.349617] __driver_attach+0x34/0x2a8
[ 15.349629] bus_for_each_dev+0x88/0x110
[ 15.349639] driver_attach+0x30/0x60
[ 15.349649] bus_add_driver+0x178/0x2d8
[ 15.349658] driver_register+0x74/0x178
[ 15.349668] __auxiliary_driver_register+0x7c/0x150
[ 15.349677] mux_rzv2h_usb_vbus_driver_init+0x34/0xfd0 [mux_rzv2h_usb_vbus]

> + { /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(auxiliary, mux_rzv2h_usb_vbus_ids);
> +
> +static struct auxiliary_driver mux_rzv2h_usb_vbus_driver = {
> + .name = "vbus-sel-mux",
> + .probe = mux_rzv2h_usb_vbus_probe,
> + .id_table = mux_rzv2h_usb_vbus_ids,
> +};
> +module_auxiliary_driver(mux_rzv2h_usb_vbus_driver);
> +
> +MODULE_DESCRIPTION("RZ/V2H USB VBUS_SEL mux driver");
> +MODULE_AUTHOR("Tommaso Merciai <tommaso.merciai.xr@bp.renesas.com>");
> +MODULE_LICENSE("GPL");
> diff --git a/include/linux/reset/reset_rzv2h_usb2phy.h b/include/linux/reset/reset_rzv2h_usb2phy.h
> new file mode 100644
> index 000000000000..06247080a66c
> --- /dev/null
> +++ b/include/linux/reset/reset_rzv2h_usb2phy.h
> @@ -0,0 +1,11 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +#ifndef _RESET_RZV2H_USB2PHY_H
> +#define _RESET_RZV2H_USB2PHY_H
> +
> +#include <linux/auxiliary_bus.h>
> +
> +struct reset_rzv2h_usb2phy_adev {
> + void __iomem *base;
> +};
> +
> +#endif
> --
> 2.43.0
>
>
> --
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