2023-06-22 07:38:08

by Andrej Picej

Subject: [PATCH v2] rtc: rv3028: Improve trickle charger logic

Property "trickle-resistor-ohms" allows us to set trickle charger
resistor. However there is no possibility to disable it afterwards.

From now on, disable trickle charger circuit in case device-tree
property "trickle-resistor-ohms" is set to -1.

Additionally, lets make sure we only update internal EEPROM in case of a
change. This prevents wear due to excessive EEPROM writes on each probe.

Signed-off-by: Andrej Picej <[email protected]>
---
Changes in v2:
- disable trickle charger if device tree property trickle-resistor-ohms
is set to -1.
---
drivers/rtc/rtc-rv3028.c | 45 +++++++++++++++++++++++++++++-----------
1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
index ec5d7a614e2d..da2ae81fe7c8 100644
--- a/drivers/rtc/rtc-rv3028.c
+++ b/drivers/rtc/rtc-rv3028.c
@@ -859,7 +859,8 @@ static int rv3028_probe(struct i2c_client *client)
{
struct rv3028_data *rv3028;
int ret, status;
- u32 ohms;
+ s32 ohms;
+ int val_old, val;
struct nvmem_config nvmem_cfg = {
.name = "rv3028_nvram",
.word_size = 1,
@@ -937,22 +938,42 @@ static int rv3028_probe(struct i2c_client *client)
if (ret)
return ret;

- /* setup trickle charger */
- if (!device_property_read_u32(&client->dev, "trickle-resistor-ohms",
- &ohms)) {
- int i;
+ ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &val_old);
+ if (ret < 0)
+ return ret;
+
+ /* mask out only trickle charger bits */
+ val_old = val_old & (RV3028_BACKUP_TCE | RV3028_BACKUP_TCR_MASK);

- for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
- if (ohms == rv3028_trickle_resistors[i])
- break;
+ /* setup trickle charger */
+ if (!of_property_read_s32(client->dev.of_node, "trickle-resistor-ohms",
+ &ohms)) {
+ /* disable trickle charger if trickle-resistor-ohms = <(-1)>; */
+ if (ohms == -1) {
+ val = val_old & ~RV3028_BACKUP_TCE;
+ } else {
+ int i;
+
+ for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
+ if (ohms == rv3028_trickle_resistors[i])
+ break;
+
+ if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
+ /* enable trickle charger and its resistor */
+ val = RV3028_BACKUP_TCE | i;
+ } else {
+ dev_warn(&client->dev, "invalid trickle resistor value\n");
+ /* don't update the trickle charger regs */
+ val = val_old;
+ }
+ }

- if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
+ /* only update EEPROM if changes are necessary */
+ if (val_old != val) {
ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, RV3028_BACKUP_TCE |
- RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | i);
+ RV3028_BACKUP_TCR_MASK, val);
if (ret)
return ret;
- } else {
- dev_warn(&client->dev, "invalid trickle resistor value\n");
}
}

--
2.25.1

2023-06-22 07:48:09

by Alexandre Belloni

Subject: Re: [PATCH v2] rtc: rv3028: Improve trickle charger logic

On 22/06/2023 09:16:09+0200, Andrej Picej wrote:
> Property "trickle-resistor-ohms" allows us to set trickle charger
> resistor. However there is no possibility to disable it afterwards.
>
> From now on, disable trickle charger circuit in case device-tree
> property "trickle-resistor-ohms" is set to -1.
>
> Additionally, lets make sure we only update internal EEPROM in case of a
> change. This prevents wear due to excessive EEPROM writes on each probe.
>
> Signed-off-by: Andrej Picej <[email protected]>
> ---
> Changes in v2:
> - disable trickle charger if device tree property trickle-resistor-ohms
> is set to -1.

What about using aux-voltage-chargeable which is the generic property
for this?

> ---
> drivers/rtc/rtc-rv3028.c | 45 +++++++++++++++++++++++++++++-----------
> 1 file changed, 33 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
> index ec5d7a614e2d..da2ae81fe7c8 100644
> --- a/drivers/rtc/rtc-rv3028.c
> +++ b/drivers/rtc/rtc-rv3028.c
> @@ -859,7 +859,8 @@ static int rv3028_probe(struct i2c_client *client)
> {
> struct rv3028_data *rv3028;
> int ret, status;
> - u32 ohms;
> + s32 ohms;
> + int val_old, val;
> struct nvmem_config nvmem_cfg = {
> .name = "rv3028_nvram",
> .word_size = 1,
> @@ -937,22 +938,42 @@ static int rv3028_probe(struct i2c_client *client)
> if (ret)
> return ret;
>
> - /* setup trickle charger */
> - if (!device_property_read_u32(&client->dev, "trickle-resistor-ohms",
> - &ohms)) {
> - int i;
> + ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &val_old);
> + if (ret < 0)
> + return ret;
> +
> + /* mask out only trickle charger bits */
> + val_old = val_old & (RV3028_BACKUP_TCE | RV3028_BACKUP_TCR_MASK);
>
> - for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
> - if (ohms == rv3028_trickle_resistors[i])
> - break;
> + /* setup trickle charger */
> + if (!of_property_read_s32(client->dev.of_node, "trickle-resistor-ohms",
> + &ohms)) {
> + /* disable trickle charger if trickle-resistor-ohms = <(-1)>; */
> + if (ohms == -1) {
> + val = val_old & ~RV3028_BACKUP_TCE;
> + } else {
> + int i;
> +
> + for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
> + if (ohms == rv3028_trickle_resistors[i])
> + break;
> +
> + if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
> + /* enable trickle charger and its resistor */
> + val = RV3028_BACKUP_TCE | i;
> + } else {
> + dev_warn(&client->dev, "invalid trickle resistor value\n");
> + /* don't update the trickle charger regs */
> + val = val_old;
> + }
> + }
>
> - if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
> + /* only update EEPROM if changes are necessary */
> + if (val_old != val) {
> ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, RV3028_BACKUP_TCE |
> - RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | i);
> + RV3028_BACKUP_TCR_MASK, val);
> if (ret)
> return ret;
> - } else {
> - dev_warn(&client->dev, "invalid trickle resistor value\n");
> }
> }
>
> --
> 2.25.1
>

--
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

2023-06-22 08:10:52

by Andrej Picej

Subject: Re: [PATCH v2] rtc: rv3028: Improve trickle charger logic

Hi Alexandre,

On 22. 06. 23 09:34, Alexandre Belloni wrote:
> On 22/06/2023 09:16:09+0200, Andrej Picej wrote:
>> Property "trickle-resistor-ohms" allows us to set trickle charger
>> resistor. However there is no possibility to disable it afterwards.
>>
>> From now on, disable trickle charger circuit in case device-tree
>> property "trickle-resistor-ohms" is set to -1.
>>
>> Additionally, lets make sure we only update internal EEPROM in case of a
>> change. This prevents wear due to excessive EEPROM writes on each probe.
>>
>> Signed-off-by: Andrej Picej <[email protected]>
>> ---
>> Changes in v2:
>> - disable trickle charger if device tree property trickle-resistor-ohms
>> is set to -1.
>
> What about using aux-voltage-chargeable which is the generic property
> for this?

I thought that this is more of a property for specifying if connected
battery/supercap has charging capabilities. I guess at the end it would
be the same thing as knowingly disabling the trickle charger even if
battery/supercap can be charged.
Do you want that I change and use "aux-voltage-chargeable"?

BR,
Andrej

>
>> ---
>> drivers/rtc/rtc-rv3028.c | 45 +++++++++++++++++++++++++++++-----------
>> 1 file changed, 33 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/rtc/rtc-rv3028.c b/drivers/rtc/rtc-rv3028.c
>> index ec5d7a614e2d..da2ae81fe7c8 100644
>> --- a/drivers/rtc/rtc-rv3028.c
>> +++ b/drivers/rtc/rtc-rv3028.c
>> @@ -859,7 +859,8 @@ static int rv3028_probe(struct i2c_client *client)
>> {
>> struct rv3028_data *rv3028;
>> int ret, status;
>> - u32 ohms;
>> + s32 ohms;
>> + int val_old, val;
>> struct nvmem_config nvmem_cfg = {
>> .name = "rv3028_nvram",
>> .word_size = 1,
>> @@ -937,22 +938,42 @@ static int rv3028_probe(struct i2c_client *client)
>> if (ret)
>> return ret;
>>
>> - /* setup trickle charger */
>> - if (!device_property_read_u32(&client->dev, "trickle-resistor-ohms",
>> - &ohms)) {
>> - int i;
>> + ret = regmap_read(rv3028->regmap, RV3028_BACKUP, &val_old);
>> + if (ret < 0)
>> + return ret;
>> +
>> + /* mask out only trickle charger bits */
>> + val_old = val_old & (RV3028_BACKUP_TCE | RV3028_BACKUP_TCR_MASK);
>>
>> - for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
>> - if (ohms == rv3028_trickle_resistors[i])
>> - break;
>> + /* setup trickle charger */
>> + if (!of_property_read_s32(client->dev.of_node, "trickle-resistor-ohms",
>> + &ohms)) {
>> + /* disable trickle charger if trickle-resistor-ohms = <(-1)>; */
>> + if (ohms == -1) {
>> + val = val_old & ~RV3028_BACKUP_TCE;
>> + } else {
>> + int i;
>> +
>> + for (i = 0; i < ARRAY_SIZE(rv3028_trickle_resistors); i++)
>> + if (ohms == rv3028_trickle_resistors[i])
>> + break;
>> +
>> + if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
>> + /* enable trickle charger and its resistor */
>> + val = RV3028_BACKUP_TCE | i;
>> + } else {
>> + dev_warn(&client->dev, "invalid trickle resistor value\n");
>> + /* don't update the trickle charger regs */
>> + val = val_old;
>> + }
>> + }
>>
>> - if (i < ARRAY_SIZE(rv3028_trickle_resistors)) {
>> + /* only update EEPROM if changes are necessary */
>> + if (val_old != val) {
>> ret = rv3028_update_cfg(rv3028, RV3028_BACKUP, RV3028_BACKUP_TCE |
>> - RV3028_BACKUP_TCR_MASK, RV3028_BACKUP_TCE | i);
>> + RV3028_BACKUP_TCR_MASK, val);
>> if (ret)
>> return ret;
>> - } else {
>> - dev_warn(&client->dev, "invalid trickle resistor value\n");
>> }
>> }
>>
>> --
>> 2.25.1
>>
>