[PATCH v3 4/8] mfd: khadas-mcu: Add support for VIM4 MCU variant

Ronald Claveau
2026-04-17T16:37:21Z

Refactor probe() to use per-variant khadas_mcu_data
instead of hardcoded globals.

Add dedicated regmap configuration and device data for the VIM4 MCU,
with its own volatile/writeable registers.

Add the fan control register
(0–100 levels vs 0–3 for previous supported boards).

Add a new compatible string "khadas,vim4-mcu".

Signed-off-by: Ronald Claveau <linux-kernel-dev@aliel.fr>
---
drivers/mfd/khadas-mcu.c | 106 ++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 95 insertions(+), 11 deletions(-)

diff --git a/drivers/mfd/khadas-mcu.c b/drivers/mfd/khadas-mcu.c
index ba981a7886921..b36b3b3ab73c0 100644
--- a/drivers/mfd/khadas-mcu.c
+++ b/drivers/mfd/khadas-mcu.c
@@ -75,15 +75,91 @@ static const struct regmap_config khadas_mcu_regmap_config = {
.cache_type = REGCACHE_MAPLE,
};

+static const struct khadas_mcu_fan_pdata khadas_mcu_fan_pdata = {
+ .fan_reg = KHADAS_MCU_CMD_FAN_STATUS_CTRL_REG,
+ .max_level = 3,
+};
+
static struct mfd_cell khadas_mcu_fan_cells[] = {
/* VIM1/2 Rev13+ and VIM3 only */
- { .name = "khadas-mcu-fan-ctrl", },
+ {
+ .name = "khadas-mcu-fan-ctrl",
+ .platform_data = &khadas_mcu_fan_pdata,
+ .pdata_size = sizeof(khadas_mcu_fan_pdata),
+ },
};

static struct mfd_cell khadas_mcu_cells[] = {
{ .name = "khadas-mcu-user-mem", },
};

+static const struct khadas_mcu_data khadas_mcu_data = {
+ .regmap_config = &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),
+};
+
+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 struct khadas_mcu_fan_pdata khadas_vim4_fan_pdata = {
+ .fan_reg = KHADAS_MCU_VIM4_FAN_CTRL_REG,
+ .max_level = 0x64,
+};
+
+static const struct mfd_cell khadas_mcu_vim4_cells[] = {
+ {
+ .name = "khadas-mcu-fan-ctrl",
+ .platform_data = &khadas_vim4_fan_pdata,
+ .pdata_size = sizeof(khadas_vim4_fan_pdata),
+ },
+};
+
+static const struct khadas_mcu_data khadas_vim4_mcu_data = {
+ .regmap_config = &khadas_mcu_vim4_regmap_config,
+ .cells = NULL,
+ .ncells = 0,
+ .fan_cells = khadas_mcu_vim4_cells,
+ .nfan_cells = ARRAY_SIZE(khadas_mcu_vim4_cells),
+};
+
static int khadas_mcu_probe(struct i2c_client *client)
{
struct device *dev = &client->dev;
@@ -94,28 +170,35 @@ static int khadas_mcu_probe(struct i2c_client *client)
if (!ddata)
return -ENOMEM;

+ ddata->data = i2c_get_match_data(client);
+ if (!ddata->data)
+ return -EINVAL;
+
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,
+ ddata->data->regmap_config);
if (IS_ERR(ddata->regmap)) {
ret = PTR_ERR(ddata->regmap);
dev_err(dev, "Failed to allocate register map: %d\n", ret);
return ret;
}

- 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 (ddata->data->cells && ddata->data->ncells) {
+ ret = devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+ ddata->data->cells,
+ ddata->data->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),
+ ddata->data->fan_cells,
+ ddata->data->nfan_cells,
NULL, 0, NULL);

return 0;
@@ -123,7 +206,8 @@ 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 = &khadas_mcu_data },
+ { .compatible = "khadas,vim4-mcu", .data = &khadas_vim4_mcu_data },
{},
};
MODULE_DEVICE_TABLE(of, khadas_mcu_of_match);

--
2.49.0