Re: [PATCH 2/2] regulator: mp8899: Add MPS MP8899 PMIC regulator driver

[Vignesh Viswanathan]

On 5/20/2026 4:09 PM, Krzysztof Kozlowski wrote:
> On Tue, May 19, 2026 at 11:51:06PM +0530, Vignesh Viswanathan wrote:
>> +static int mp8899_parse_cb(struct device_node *np,
>> +			   const struct regulator_desc *desc,
>> +			   struct regulator_config *config)
>> +{
>> +	struct mp8899_regulator_info *info = config->driver_data;
>> +	struct regulator_desc *rdesc;
>> +	int buck_id = desc->id;
>> +	int ret;
>> +	u8 val;
>> +
>> +	/* Read buck phase delay from DTS */
>> +	ret = of_property_read_u8(np, "mps,buck-phase-delay", &val);
> 
> NAK

Will Drop this property as this is not used.
> 
>> +	if (!ret) {
>> +		ret = regmap_update_bits(config->regmap,
>> +					 MP8899_BUCK_REG(buck_id, MP8899_BUCK1_CTL1),
>> +					 MP8899_PHASE_DELAY_MASK,
>> +					 (val & 3) << MP8899_PHASE_DELAY_SHIFT);
>> +		if (ret) {
>> +			dev_err(config->dev, "Failed to set phase delay for buck%d: %d\n",
>> +				buck_id + 1, ret);
>> +			return ret;
>> +		}
>> +	}
>> +
>> +	/* Read buck soft start from DTS */
>> +	ret = of_property_read_u8(np, "mps,buck-softstart", &val);
>> +	if (!ret) {
>> +		rdesc = &info->rdesc[buck_id];
>> +		rdesc->soft_start_val_on = (val & 3) << MP8899_SOFT_START_TIME_SHIFT;
>> +	}
>> +
>> +	/* Read buck soft stop enable and configuration from DTS */
>> +	if (of_property_read_bool(np, "mps,buck-softstop-enable")) {
>> +		/* Enable soft stop */
>> +		ret = regmap_update_bits(config->regmap,
>> +					 MP8899_BUCK_REG(buck_id, MP8899_BUCK1_CTL2),
>> +					 MP8899_SOFT_STOP_EN_MASK,
>> +					 MP8899_SOFT_STOP_EN_MASK);
>> +		if (ret) {
>> +			dev_err(config->dev, "Failed to enable soft stop for buck%d: %d\n",
>> +				buck_id + 1, ret);
>> +			return ret;
>> +		}
>> +
>> +		/* Read soft stop timing configuration */
>> +		ret = of_property_read_u8(np, "mps,buck-softstop", &val);
>> +		if (!ret) {
>> +			ret = regmap_update_bits(config->regmap,
>> +						 MP8899_BUCK_REG(buck_id, MP8899_BUCK1_CTL2),
>> +						 MP8899_SOFT_STOP_TIME_MASK,
>> +						 val & 3);
>> +			if (ret) {
>> +				dev_err(config->dev, "Failed to set soft stop timing for buck%d: %d\n",
>> +					buck_id + 1, ret);
>> +				return ret;
>> +			}
>> +		}
>> +	}
>> +
>> +	/* OVP disable configuration */
>> +	if (of_property_read_bool(np, "mps,buck-ovp-disable")) {
>> +		ret = regmap_update_bits(config->regmap,
>> +					 MP8899_BUCK_REG(buck_id, MP8899_BUCK1_CTL1),
>> +					 MP8899_VOUT_OVP_EN_MASK, 0);
>> +		if (ret) {
>> +			dev_err(config->dev, "Failed to disable OVP for buck%d: %d\n",
>> +				buck_id + 1, ret);
>> +			return ret;
>> +		}
>> +		dev_info(config->dev, "OVP disabled for buck%d\n", buck_id + 1);
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * mp8899_parse_dt() - Parse global device tree properties
>> + * @dev: Device pointer
>> + * @info: Pointer to mp8899_regulator_info structure
>> + *
>> + * Parses global device tree properties that apply to all buck converters,
>> + * such as switching frequency configuration.
>> + */
>> +static void mp8899_parse_dt(struct device *dev,
>> +			    struct mp8899_regulator_info *info)
>> +{
>> +	struct device_node *np = dev->of_node;
>> +	int ret;
>> +	u8 freq;
>> +
>> +	np = of_get_child_by_name(np, "regulators");
>> +	if (!np) {
>> +		dev_err(dev, "missing 'regulators' subnode in DT\n");
>> +		return;
>> +	}
>> +
>> +	/* Read switching frequency from DTS */
>> +	ret = of_property_read_u8(np, "mps,switch-freq", &freq);
> 
> NAK, you don't have such property. Test your DTS first.
> 
> This is not really acceptable quality of a driver.

Will Drop this property as this is not used.

> 
>> +	if (!ret) {
>> +		ret = regmap_update_bits(info->regmap, MP8899_SYSTEM2,
>> +					 MP8899_FREQ_MASK,
>> +					 (freq & 7) << 5);
>> +		if (ret)
>> +			dev_err(dev, "Failed to set switching frequency: %d\n", ret);
>> +	}
>> +
>> +	of_node_put(np);
>> +}
>> +
>> +/* Initialize debugfs for reg_addr and reg_value only */
>> +static void mp8899_debugfs_init(struct mp8899_regulator_info *info,
>> +				struct i2c_client *client)
>> +{
>> +	char name[16];
>> +
>> +	/* Create root debugfs directory: /sys/kernel/debug/mp8899-<bus>-<addr> */
>> +	snprintf(name, sizeof(name), "mp8899-%d-%04x",
>> +		 client->adapter->nr, client->addr);
>> +	info->debugfs_root = debugfs_create_dir(name, NULL);
>> +	if (IS_ERR_OR_NULL(info->debugfs_root)) {
>> +		dev_warn(info->dev, "Failed to create debugfs root directory\n");
> 
> No, drop

Ack. Will drop entire debugfs in next patchset.
> 
>> +		info->debugfs_root = NULL;
>> +		return;
>> +	}
>> +
>> +	/* Create generic register access files at root level */
>> +	debugfs_create_file("reg_addr", 0644, info->debugfs_root, info,
>> +			    &mp8899_debugfs_reg_addr_fops);
>> +	debugfs_create_file("reg_value", 0644, info->debugfs_root, info,
>> +			    &mp8899_debugfs_reg_value_fops);
>> +}
>> +
>> +/* Cleanup debugfs */
>> +/**
>> + * mp8899_debugfs_exit() - Cleanup debugfs interface
>> + * @info: Pointer to mp8899_regulator_info structure
>> + *
>> + * Removes all debugfs entries created for the MP8899 device.
>> + */
>> +static void mp8899_debugfs_exit(struct mp8899_regulator_info *info)
>> +{
>> +	debugfs_remove_recursive(info->debugfs_root);
>> +}
>> +
>> +/**
>> + * mp8899_identify_device() - Verify MP8899 device presence
>> + * @info: Pointer to mp8899_regulator_info structure
>> + *
>> + * Reads and validates the vendor ID from SYSTEM4 register to confirm
>> + * the device is a genuine MP8899 PMIC.
>> + *
>> + * Return: 0 on success, -ENODEV if vendor ID doesn't match
>> + */
>> +static int mp8899_identify_device(struct mp8899_regulator_info *info)
>> +{
>> +	unsigned int vendor_id;
>> +	int ret;
>> +
>> +	ret = regmap_read(info->regmap, MP8899_SYSTEM4, &vendor_id);
>> +	if (ret) {
>> +		dev_err(info->dev, "Failed to read vendor ID: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	vendor_id = (vendor_id & MP8899_VENDOR_ID_MASK) >> 4;
>> +	if (vendor_id != MP8899_VENDOR_ID_VALUE) {
>> +		dev_err(info->dev, "Invalid vendor ID: 0x%x\n", vendor_id);
>> +		return -ENODEV;
>> +	}
>> +
>> +	dev_dbg(info->dev, "PMIC MP8899 device detected\n");
>> +	return 0;
>> +}
>> +
>> +/**
>> + * mp8899_i2c_probe() - I2C driver probe function
>> + * @client: I2C client device
>> + *
>> + * Initializes the MP8899 PMIC driver:
>> + * 1. Allocates driver data structures
>> + * 2. Initializes I2C regmap interface
>> + * 3. Verifies device identity
>> + * 4. Parses device tree configuration
>> + * 5. Read the BUCK1_CTL3 register of each buck and configure the linear ranges accordingly
>> + * 6. Registers regulator devices
>> + *
>> + * Return: 0 on success, negative error code on failure
> 
> Why do you have kerneldoc for probe? Actually - why do you have
> kerneldoc everywhere?
> 
Ack, will drop.

>> + */
>> +static int mp8899_i2c_probe(struct i2c_client *client)
>> +{
>> +	struct mp8899_regulator_info *info;
>> +	struct regulator_config config = {};
>> +	struct device *dev = &client->dev;
>> +	struct regulator_dev *rdev;
>> +	struct regmap *regmap;
>> +	unsigned int vout_select;
>> +	int i, ret;
>> +
>> +	info = devm_kzalloc(dev, sizeof(struct mp8899_regulator_info), GFP_KERNEL);
> 
> This is some very old code. If you were working on upstream, you would
> notice that syntax is sizeof(*). But NOW the syntax is even simpler: kzalloc_obj().

Ack, will fix this.
> 
> 
>> +	if (!info)
>> +		return -ENOMEM;
>> +
>> +	/* Allocate separate regulator_desc array for dynamic configuration */
>> +	info->rdesc = devm_kmemdup(dev, mp8899_regulators_desc,
>> +				   sizeof(mp8899_regulators_desc), GFP_KERNEL);
>> +	if (!info->rdesc)
>> +		return -ENOMEM;
>> +
>> +	info->dev = dev;
>> +
>> +	regmap = devm_regmap_init_i2c(client, &mp8899_regmap_config);
>> +	if (IS_ERR(regmap))
>> +		return dev_err_probe(dev, PTR_ERR(regmap), "Failed to allocate regmap\n");
>> +
>> +	info->regmap = regmap;
>> +	i2c_set_clientdata(client, info);
>> +
>> +	/* Identify the device */
>> +	ret = mp8899_identify_device(info);
>> +	if (ret)
>> +		return ret;
>> +
>> +	/* Parse device tree properties */
>> +	if (client->dev.of_node)
>> +		mp8899_parse_dt(&client->dev, info);
>> +
>> +	/* Configure linear ranges for each buck based on VOUT_SELECT */
>> +	for (i = 0; i < MP8899_MAX_REGULATORS; i++) {
>> +		ret = regmap_read(info->regmap,
>> +				  MP8899_BUCK_REG(i, MP8899_BUCK1_CTL3),
>> +				  &vout_select);
>> +		if (ret) {
>> +			dev_err(dev, "Failed to read VOUT_SELECT for buck%d: %d\n", i + 1, ret);
>> +			return ret;
>> +		}
>> +
>> +		if (vout_select & MP8899_VOUT_SELECT_MASK) {
>> +			/* 1.0mV step mode */
>> +			info->rdesc[i].linear_ranges = mp8899_buck_ranges_1000uv;
>> +			info->rdesc[i].n_linear_ranges = ARRAY_SIZE(mp8899_buck_ranges_1000uv);
>> +			info->rdesc[i].n_voltages = MP8899_N_VOLTAGES_1MV;  /* 3201 voltages */
>> +			dev_dbg(dev, "Buck%d: 1.0mV step mode\n", i + 1);
>> +		} else {
>> +			/* 0.5mV step mode */
>> +			info->rdesc[i].linear_ranges = mp8899_buck_ranges_500uv;
>> +			info->rdesc[i].n_linear_ranges = ARRAY_SIZE(mp8899_buck_ranges_500uv);
>> +			info->rdesc[i].n_voltages = MP8899_N_VOLTAGES;  /* 3296 voltages */
>> +			dev_dbg(dev, "Buck%d: 0.5mV step mode\n", i + 1);
>> +		}
>> +	}
>> +
>> +	config.dev = dev;
>> +	config.regmap = regmap;
>> +	config.driver_data = info;
>> +
>> +	/* Register regulators */
>> +	for (i = 0; i < MP8899_MAX_REGULATORS; i++) {
>> +		rdev = devm_regulator_register(dev, &info->rdesc[i], &config);
>> +		if (IS_ERR(rdev))
>> +			return dev_err_probe(dev,
>> +					     PTR_ERR(rdev),
>> +					     "Failed to register regulator %d\n",
>> +					     i);
>> +
>> +		info->rdev[i] = rdev;
>> +	}
>> +
>> +	/* Initialize debugfs interface */
>> +	mp8899_debugfs_init(info, client);
>> +
>> +	/* Register panic notifier for PMIC state dump */
>> +	info->panic_notifier.notifier_call = mp8899_panic_handler;
>> +	info->panic_notifier.priority = 0;
>> +	ret = atomic_notifier_chain_register(&panic_notifier_list, &info->panic_notifier);
>> +	if (ret)
>> +		dev_info(dev, "Failed to register panic notifier: %d\n", ret);
>> +
>> +	dev_info(dev, "MP8899 regulator driver registered successfully\n");
> 
> Drop

Ack.
> 
>> +
>> +	return 0;
>> +}
>> +
>> +/**
>> + * mp8899_i2c_remove() - I2C driver remove function
>> + * @client: I2C client device
>> + *
>> + * Cleanup function called when the driver is unloaded:
>> + * 1. Unregister panic handler from notifier chain
>> + * 2. Cleanup debugfs interface
>> + *
>> + * Return: 0 on success
>> + */
>> +static void mp8899_i2c_remove(struct i2c_client *client)
>> +{
>> +	struct mp8899_regulator_info *info = i2c_get_clientdata(client);
>> +
>> +	/* Unregister panic handler */
>> +	atomic_notifier_chain_unregister(&panic_notifier_list, &info->panic_notifier);
>> +
>> +	/* Cleanup debugfs */
>> +	mp8899_debugfs_exit(info);
>> +
>> +	dev_info(&client->dev, "MP8899 PMIC regulator driver removed\n");
> 
> Really, drop. We really do not print such messages in upstream. Look at
> other drivers.

Ack, will address all this in next version,

Thanks,
Vignesh
> 
> Best regards,
> Krzysztof
>