Re: [PATCH 1/4] power: supply: add support for max77759 fuel gauge

André Draszik
2024-12-03T06:47:45Z

Hi Thomas,

Thanks for looking into this!

> From: Thomas Antoine <t.antoine@uclouvain.be>
>
> The Maxim max77759 fuel gauge has the same interface as the Maxim max1720x
> except for the non-volatile memory slave address which is not available.

It is not fully compatible, and it also has a lot more registers.

For example, the voltage now is not in register 0xda as this driver assumes.
With these changes, POWER_SUPPLY_PROP_VOLTAGE_NOW just reads as 0. 0xda
doesn't exist in max77759

I haven't compared in depth yet, though.

> No slave is available at address 0xb of the i2c bus, which is coherent
> with the following driver from google: line 5836 disables non-volatile
> memory for m5 gauge.
>
> Link:
> https://android.googlesource.com/kernel/google-modules/bms/+/1a68c36bef474573cc8629cc1d121eb6a81ab68c/max1720x_battery.c
>
> Add support for the max77759 by allowing to use the non-volatile
> memory or not based on the chip. Value for RSense comes from the following
> stock devicetree:
>
> Link:
> https://android.googlesource.com/kernel/devices/google/gs101/+/33eca36d43da6c2b6a546806eb3e7411bbe6d60d/dts/gs101-raviole-battery.dtsi
>
> Signed-off-by: Thomas Antoine <t.antoine@uclouvain.be>
> ---
>  drivers/power/supply/max1720x_battery.c | 71 +++++++++++++++++++++++++++-
> -----
>  1 file changed, 59 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/power/supply/max1720x_battery.c
> b/drivers/power/supply/max1720x_battery.c
> index
> 33105419e2427bb37963bda9948b647c239f8faa..faf336938dd4306dd2ceeb0a84b90ca8
> 0ad41a9f 100644
> --- a/drivers/power/supply/max1720x_battery.c
> +++ b/drivers/power/supply/max1720x_battery.c
> @@ -13,6 +13,7 @@
>  #include <linux/nvmem-provider.h>
>  #include <linux/power_supply.h>
>  #include <linux/regmap.h>
> +#include <linux/types.h>

Please keep file names in alphabetical order.

>
>  #include <linux/unaligned.h>
>
> @@ -39,6 +40,7 @@
>  #define MAX172XX_DEV_NAME_TYPE_MASK GENMASK(3, 0)
>  #define MAX172XX_DEV_NAME_TYPE_MAX17201 BIT(0)
>  #define MAX172XX_DEV_NAME_TYPE_MAX17205 (BIT(0) | BIT(2))
> +#define MAX172XX_DEV_NAME_TYPE_MAX77759 0
>  #define MAX172XX_QR_TABLE10 0x22
>  #define MAX172XX_BATT 0xDA /* Battery voltage */
>  #define MAX172XX_ATAVCAP 0xDF
> @@ -46,6 +48,7 @@
>  static const char *const max1720x_manufacturer = "Maxim Integrated";
>  static const char *const max17201_model = "MAX17201";
>  static const char *const max17205_model = "MAX17205";
> +static const char *const max77759_model = "MAX77759";
>
>  struct max1720x_device_info {
>   struct regmap *regmap;
> @@ -54,6 +57,21 @@ struct max1720x_device_info {
>   int rsense;
>  };
>
> +struct chip_data {
> + u16 default_nrsense; /* in regs in 10^-5 */
> + u8 has_nvmem;
> +};
> +
> +static const struct chip_data max1720x_data  = {
> + .default_nrsense = 1000,
> + .has_nvmem = 1,
> +};
> +
> +static const struct chip_data max77759_data = {
> + .default_nrsense = 500,
> + .has_nvmem = 0,
> +};

This should be made a required devicetree property instead, at least for
max77759, as it's completely board dependent, 'shunt-resistor-micro-ohms'
is widely used.

I also don't think there should be a default. The driver should just fail
to probe if not specified in DT (for max77759).

> +
>  /*
>   * Model Gauge M5 Algorithm output register
>   * Volatile data (must not be cached)
> @@ -369,6 +387,8 @@ static int max1720x_battery_get_property(struct
> power_supply *psy,
>   val->strval = max17201_model;
>   else if (reg_val == MAX172XX_DEV_NAME_TYPE_MAX17205)
>   val->strval = max17205_model;
> + else if (reg_val == MAX172XX_DEV_NAME_TYPE_MAX77759)
> + val->strval = max77759_model;
>   else

This is a 16 bit register, and while yes, MAX172XX_DEV_NAME_TYPE_MASK only
cares about the bottom 4 bits, the register is described as 'Firmware
Version Information'.

But maybe it's ok to do it like that, at least for now.

>   return -ENODEV;
>   break;
> @@ -416,7 +436,6 @@ static int max1720x_probe_nvmem(struct i2c_client
> *client,
>   .priv = info,
>   };
>   struct nvmem_device *nvmem;
> - unsigned int val;
>   int ret;
>
>   info->ancillary = i2c_new_ancillary_device(client, "nvmem", 0xb);
> @@ -438,6 +457,27 @@ static int max1720x_probe_nvmem(struct i2c_client
> *client,
>   return PTR_ERR(info->regmap_nv);
>   }
>
> + nvmem = devm_nvmem_register(dev, &nvmem_config);
> + if (IS_ERR(nvmem)) {
> + dev_err(dev, "Could not register nvmem!");
> + return PTR_ERR(nvmem);
> + }
> +
> + return 0;
> +}
> +
> +static int max1720x_get_rsense(struct device *dev,
> + struct max1720x_device_info
> *info,
> + const struct chip_data *data)
> +{
> + unsigned int val;
> + int ret;
> +
> + if (!data->has_nvmem) {
> + info->rsense = data->default_nrsense;
> + return 0;
> + }
> +
>   ret = regmap_read(info->regmap_nv, MAX1720X_NRSENSE, &val);
>   if (ret < 0) {
>   dev_err(dev, "Failed to read sense resistor value\n");
> @@ -446,14 +486,9 @@ static int max1720x_probe_nvmem(struct i2c_client
> *client,
>
>   info->rsense = val;
>   if (!info->rsense) {
> - dev_warn(dev, "RSense not calibrated, set 10 mOhms!\n");
> - info->rsense = 1000; /* in regs in 10^-5 */
> - }
> -
> - nvmem = devm_nvmem_register(dev, &nvmem_config);
> - if (IS_ERR(nvmem)) {
> - dev_err(dev, "Could not register nvmem!");
> - return PTR_ERR(nvmem);
> + dev_warn(dev, "RSense not calibrated, set %d mOhms!\n",
> + data-
> >default_nrsense/100);
> + info->rsense = data->default_nrsense;
>   }
>
>   return 0;
> @@ -474,6 +509,7 @@ static int max1720x_probe(struct i2c_client *client)
>   struct device *dev = &client->dev;
>   struct max1720x_device_info *info;
>   struct power_supply *bat;
> + const struct chip_data *data;
>   int ret;
>
>   info = devm_kzalloc(dev, sizeof(*info), GFP_KERNEL);
> @@ -488,9 +524,19 @@ static int max1720x_probe(struct i2c_client *client)
>   return dev_err_probe(dev, PTR_ERR(info->regmap),
>        "regmap initialization failed\n");
>
> - ret = max1720x_probe_nvmem(client, info);
> + data = device_get_match_data(dev);
> + if (!data)
> + return dev_err_probe(dev, ret, "Failed to get chip
> data\n");
> +
> + if (data->has_nvmem) {
> + ret = max1720x_probe_nvmem(client, info);
> + if (ret)
> + return dev_err_probe(dev, ret, "Failed to probe
> nvmem\n");
> + }
> +
> + ret = max1720x_get_rsense(dev, info, data);
>   if (ret)
> - return dev_err_probe(dev, ret, "Failed to probe
> nvmem\n");
> + return dev_err_probe(dev, ret, "Failed to get RSense");
>
>   bat = devm_power_supply_register(dev, &max1720x_bat_desc,
> &psy_cfg);
>   if (IS_ERR(bat))
> @@ -501,7 +547,8 @@ static int max1720x_probe(struct i2c_client *client)
>  }
>
>  static const struct of_device_id max1720x_of_match[] = {
> - { .compatible = "maxim,max17201" },
> + { .compatible = "maxim,max17201", .data = (void *) &max1720x_data
> },
> + { .compatible = "maxim,max77759-fg", .data = (void *)
> &max77759_data},

missing space before }

Cheers,
Andre'

>   {}
>  };
>  MODULE_DEVICE_TABLE(of, max1720x_of_match);
>