[PATCH v11 3/6] mfd: khadas-mcu: Add support for VIM4 MCU variant
Lee Jones
lee at kernel.org
Thu Sep 10 07:21:53 PDT 2026
On Wed, 02 Sep 2026, Ronald Claveau via B4 Relay wrote:
> From: Ronald Claveau <linux-kernel-dev at aliel.fr>
>
> Refactor probe() to use per-variant values
> instead of hardcoded globals.
>
> Add dedicated regmap configuration for the VIM4 MCU,
> with its own volatile/writeable registers.
>
> Introduce struct khadas_mcu_fan_pdata to pass the fan
> control register and duty-cycle levels per variant.
> VIM4 uses a different register and level set (0-100)
> declared as a list (0, 30, 40, 55, 75, 100) compared
> to previous boards (0-3).
>
> Add a new compatible string "khadas,vim4-mcu".
>
> Reviewed-by: Neil Armstrong <neil.armstrong at linaro.org>
> Signed-off-by: Ronald Claveau <linux-kernel-dev at aliel.fr>
Generally fine.
> ---
> drivers/mfd/khadas-mcu.c | 120 +++++++++++++++++++++++++++++++++++++++++------
> 1 file changed, 106 insertions(+), 14 deletions(-)
>
> diff --git a/drivers/mfd/khadas-mcu.c b/drivers/mfd/khadas-mcu.c
> index 0e74efe14f367..4cb305ac915e1 100644
> --- a/drivers/mfd/khadas-mcu.c
> +++ b/drivers/mfd/khadas-mcu.c
> @@ -75,47 +75,138 @@ static const struct regmap_config khadas_mcu_regmap_config = {
> .cache_type = REGCACHE_MAPLE,
> };
>
> +static const unsigned int khadas_mcu_fan_levels[] = {
> + 0, 1, 2, 3,
> +};
> +
> +static const struct khadas_mcu_fan_pdata khadas_mcu_fan_pdata = {
> + .fan_reg = KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
> + .levels = khadas_mcu_fan_levels,
> + .nlevels = ARRAY_SIZE(khadas_mcu_fan_levels),
> +};
I still don't think these belong in here.
> static const struct mfd_cell khadas_mcu_fan_cells[] = {
> /* VIM1/2 Rev13+ and VIM3 only */
> - MFD_CELL_NAME("khadas-mcu-fan-ctrl"),
> + MFD_CELL_BASIC("khadas-mcu-fan-ctrl", NULL, &khadas_mcu_fan_pdata,
> + sizeof(khadas_mcu_fan_pdata), 0),
> };
>
> static const struct mfd_cell khadas_mcu_cells[] = {
> MFD_CELL_NAME("khadas-mcu-user-mem"),
> };
>
> +static bool khadas_mcu_vim4_reg_volatile(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case KHADAS_MCU_PWR_OFF_CMD_REG:
> + case KHADAS_MCU_VIM4_REST_CONF_REG:
> + case KHADAS_MCU_WOL_INIT_START_REG:
> + case KHADAS_MCU_VIM4_LED_ON_RAM_REG:
> + case KHADAS_MCU_VIM4_FAN_CTRL_REG:
> + case KHADAS_MCU_VIM4_WDT_EN_REG:
> + case KHADAS_MCU_VIM4_SYS_RST_REG:
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static bool khadas_mcu_vim4_reg_writeable(struct device *dev, unsigned int reg)
> +{
> + switch (reg) {
> + case KHADAS_MCU_VERSION_0_REG:
> + case KHADAS_MCU_VERSION_1_REG:
> + case KHADAS_MCU_SHUTDOWN_NORMAL_STATUS_REG:
> + return false;
> + default:
> + return true;
> + }
> +}
> +
> +static const struct regmap_config khadas_mcu_vim4_regmap_config = {
> + .reg_bits = 8,
> + .reg_stride = 1,
> + .val_bits = 8,
> + .max_register = KHADAS_MCU_VIM4_SYS_RST_REG,
> + .volatile_reg = khadas_mcu_vim4_reg_volatile,
> + .writeable_reg = khadas_mcu_vim4_reg_writeable,
> + .cache_type = REGCACHE_MAPLE,
> +};
> +
> +static const unsigned int khadas_mcu_vim4_fan_levels[] = {
> + 0, 30, 40, 55, 75, 100,
> +};
> +
> +static const struct khadas_mcu_fan_pdata khadas_mcu_vim4_fan_pdata = {
> + .fan_reg = KHADAS_MCU_VIM4_FAN_CTRL_REG,
> + .levels = khadas_mcu_vim4_fan_levels,
> + .nlevels = ARRAY_SIZE(khadas_mcu_vim4_fan_levels),
> +};
> +
> +static const struct mfd_cell khadas_mcu_vim4_fan_cells[] = {
> + MFD_CELL_BASIC("khadas-mcu-fan-ctrl", NULL, &khadas_mcu_vim4_fan_pdata,
> + sizeof(khadas_mcu_vim4_fan_pdata), 0),
> +};
> +
> static int khadas_mcu_probe(struct i2c_client *client)
> {
> + const struct mfd_cell *cells, *fan_cells;
> + const struct regmap_config *regmap_cfg;
> struct device *dev = &client->dev;
> + int ncells, nfan_cells, ret;
> struct khadas_mcu *ddata;
> - int ret;
> + const void *match;
>
> ddata = devm_kzalloc(dev, sizeof(*ddata), GFP_KERNEL);
> if (!ddata)
> return -ENOMEM;
>
> + match = i2c_get_match_data(client);
The nomenclature can be improved here.
What are these? Device ID? Chip ID? Revision?
> + if (!match)
> + return -ENODEV;
> +
> + switch ((uintptr_t)match) {
> + case KHADAS_MCU_GENERIC:
> + regmap_cfg = &khadas_mcu_regmap_config;
> + cells = khadas_mcu_cells;
> + ncells = ARRAY_SIZE(khadas_mcu_cells);
> + fan_cells = khadas_mcu_fan_cells;
> + nfan_cells = ARRAY_SIZE(khadas_mcu_fan_cells);
> + break;
> + case KHADAS_MCU_VIM4:
> + regmap_cfg = &khadas_mcu_vim4_regmap_config;
> + cells = NULL;
> + ncells = 0;
> + fan_cells = khadas_mcu_vim4_fan_cells;
> + nfan_cells = ARRAY_SIZE(khadas_mcu_vim4_fan_cells);
> + break;
> + default:
> + return -ENODEV;
> + }
> +
> i2c_set_clientdata(client, ddata);
>
> ddata->dev = dev;
>
> - ddata->regmap = devm_regmap_init_i2c(client, &khadas_mcu_regmap_config);
> + ddata->regmap = devm_regmap_init_i2c(client, regmap_cfg);
> if (IS_ERR(ddata->regmap)) {
> ret = PTR_ERR(ddata->regmap);
> - dev_err(dev, "Failed to allocate register map: %d\n", ret);
> - return ret;
> + return dev_err_probe(dev, ret, "Failed to allocate register map\n");
> }
>
> - ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> - khadas_mcu_cells,
> - ARRAY_SIZE(khadas_mcu_cells),
> - NULL, 0, NULL);
> - if (ret)
> - return ret;
> + if (cells && ncells) {
> + ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> + cells,
> + ncells,
> + NULL, 0, NULL);
> + if (ret)
> + return ret;
> + }
>
> if (of_property_present(dev->of_node, "#cooling-cells"))
> return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
> - khadas_mcu_fan_cells,
> - ARRAY_SIZE(khadas_mcu_fan_cells),
> + fan_cells,
> + nfan_cells,
> NULL, 0, NULL);
>
> return 0;
> @@ -123,7 +214,8 @@ static int khadas_mcu_probe(struct i2c_client *client)
>
> #ifdef CONFIG_OF
> static const struct of_device_id khadas_mcu_of_match[] = {
> - { .compatible = "khadas,mcu", },
> + { .compatible = "khadas,mcu", .data = (void *)KHADAS_MCU_GENERIC },
> + { .compatible = "khadas,vim4-mcu", .data = (void *)KHADAS_MCU_VIM4 },
> {},
> };
> MODULE_DEVICE_TABLE(of, khadas_mcu_of_match);
>
> --
> 2.49.0
>
>
--
Lee Jones
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