[PATCH v2 1/2] regulator: implement basic reference counter

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[QUESTION] Clear a local variable...

Eugen Hristev

28 Mar 2023 28 Mar '23

3:01 p.m.

Some devices share a regulator supply, when the first one will request regulator disable, the second device will have it's supply cut off before graciously shutting down. Hence there will be timeouts and other failed operations. Implement a reference counter mechanism similar with what is done in Linux, to keep track of enable and disable requests, and only disable the regulator when the last of the consumers has requested shutdown.

Signed-off-by: Eugen Hristev eugen.hristev@collabora.com --- Changes in v2: - add info in header regarding the function

drivers/power/regulator/regulator_common.c | 22 ++++++++++++++++++++++ drivers/power/regulator/regulator_common.h | 13 +++++++++++++ 2 files changed, 35 insertions(+)

diff --git a/drivers/power/regulator/regulator_common.c b/drivers/power/regulator/regulator_common.c index 93d8196b381e..edda25336176 100644 --- a/drivers/power/regulator/regulator_common.c +++ b/drivers/power/regulator/regulator_common.c @@ -73,6 +73,23 @@ int regulator_common_set_enable(const struct udevice *dev, return 0; }

+ /* If previously enabled, increase count */ + if (enable && dev_pdata->enable_count > 0) { + dev_pdata->enable_count++; + return 0; + } + + if (!enable) { + if (dev_pdata->enable_count > 1) { + /* If enabled multiple times, decrease count */ + dev_pdata->enable_count--; + return 0; + } else if (!dev_pdata->enable_count) { + /* If already disabled, do nothing */ + return 0; + } + } + ret = dm_gpio_set_value(&dev_pdata->gpio, enable); if (ret) { pr_err("Can't set regulator : %s gpio to: %d\n", dev->name, @@ -87,5 +104,10 @@ int regulator_common_set_enable(const struct udevice *dev, if (!enable && dev_pdata->off_on_delay_us) udelay(dev_pdata->off_on_delay_us);

+ if (enable) + dev_pdata->enable_count++; + else + dev_pdata->enable_count--; + return 0; } diff --git a/drivers/power/regulator/regulator_common.h b/drivers/power/regulator/regulator_common.h index c10492f01675..7c701b69245d 100644 --- a/drivers/power/regulator/regulator_common.h +++ b/drivers/power/regulator/regulator_common.h @@ -13,6 +13,7 @@ struct regulator_common_plat { struct gpio_desc gpio; /* GPIO for regulator enable control */ unsigned int startup_delay_us; unsigned int off_on_delay_us; + unsigned int enable_count; };

int regulator_common_of_to_plat(struct udevice *dev, @@ -20,6 +21,18 @@ int regulator_common_of_to_plat(struct udevice *dev, char *enable_gpio_name); int regulator_common_get_enable(const struct udevice *dev, struct regulator_common_plat *dev_pdata); +/* + * Enable or Disable a regulator + * + * This is a reentrant function and subsequent calls that enable will + * increase an internal counter, and disable calls will decrease the counter. + * The actual resource will be enabled when the counter gets to 1 coming from 0, + * and disabled when it reaches 0 coming from 1. + * + * @dev: regulator device + * @dev_pdata: Platform data + * @enable: bool indicating whether to enable or disable the regulator + */ int regulator_common_set_enable(const struct udevice *dev, struct regulator_common_plat *dev_pdata, bool enable);

-- 2.34.1

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Eugen Hristev

28 Mar 28 Mar

3:01 p.m.

New subject: [PATCH v2 2/2] regulator: rename dev_pdata to plat

Simplify the subsystem by renaming `dev_pdata` to just `plat`. No functional change, just trivial renaming.

Suggested-by: Simon Glass sjg@chromium.org Signed-off-by: Eugen Hristev eugen.hristev@collabora.com --- Changes in v2: - this is a new patch

drivers/power/regulator/fan53555.c | 10 ++-- drivers/power/regulator/fixed.c | 16 +++---- drivers/power/regulator/gpio-regulator.c | 46 +++++++++---------- drivers/power/regulator/regulator_common.c | 53 +++++++++++----------- drivers/power/regulator/regulator_common.h | 8 ++-- 5 files changed, 66 insertions(+), 67 deletions(-)

diff --git a/drivers/power/regulator/fan53555.c b/drivers/power/regulator/fan53555.c index 5681206bbafe..815f96beef61 100644 --- a/drivers/power/regulator/fan53555.c +++ b/drivers/power/regulator/fan53555.c @@ -101,7 +101,7 @@ struct fan53555_priv {

static int fan53555_regulator_of_to_plat(struct udevice *dev) { - struct fan53555_plat *dev_pdata = dev_get_plat(dev); + struct fan53555_plat *plat = dev_get_plat(dev); struct dm_regulator_uclass_plat *uc_pdata = dev_get_uclass_plat(dev); u32 sleep_vsel; @@ -118,12 +118,12 @@ static int fan53555_regulator_of_to_plat(struct udevice *dev) */ switch (sleep_vsel) { case FAN53555_VSEL0: - dev_pdata->sleep_reg = FAN53555_VSEL0; - dev_pdata->vol_reg = FAN53555_VSEL1; + plat->sleep_reg = FAN53555_VSEL0; + plat->vol_reg = FAN53555_VSEL1; break; case FAN53555_VSEL1: - dev_pdata->sleep_reg = FAN53555_VSEL1; - dev_pdata->vol_reg = FAN53555_VSEL0; + plat->sleep_reg = FAN53555_VSEL1; + plat->vol_reg = FAN53555_VSEL0; break; default: pr_err("%s: invalid vsel id %d\n", dev->name, sleep_vsel); diff --git a/drivers/power/regulator/fixed.c b/drivers/power/regulator/fixed.c index 90004d1601a9..ad3b4b98d667 100644 --- a/drivers/power/regulator/fixed.c +++ b/drivers/power/regulator/fixed.c @@ -24,16 +24,16 @@ struct fixed_clock_regulator_plat { static int fixed_regulator_of_to_plat(struct udevice *dev) { struct dm_regulator_uclass_plat *uc_pdata; - struct regulator_common_plat *dev_pdata; + struct regulator_common_plat *plat;

- dev_pdata = dev_get_plat(dev); + plat = dev_get_plat(dev); uc_pdata = dev_get_uclass_plat(dev); if (!uc_pdata) return -ENXIO;

uc_pdata->type = REGULATOR_TYPE_FIXED;

- return regulator_common_of_to_plat(dev, dev_pdata, "gpio"); + return regulator_common_of_to_plat(dev, plat, "gpio"); }

static int fixed_regulator_get_value(struct udevice *dev) @@ -88,7 +88,7 @@ static int fixed_clock_regulator_get_enable(struct udevice *dev) static int fixed_clock_regulator_set_enable(struct udevice *dev, bool enable) { struct fixed_clock_regulator_plat *priv = dev_get_priv(dev); - struct regulator_common_plat *dev_pdata = dev_get_plat(dev); + struct regulator_common_plat *plat = dev_get_plat(dev); int ret = 0;

if (enable) { @@ -101,11 +101,11 @@ static int fixed_clock_regulator_set_enable(struct udevice *dev, bool enable) if (ret) return ret;

- if (enable && dev_pdata->startup_delay_us) - udelay(dev_pdata->startup_delay_us); + if (enable && plat->startup_delay_us) + udelay(plat->startup_delay_us);

- if (!enable && dev_pdata->off_on_delay_us) - udelay(dev_pdata->off_on_delay_us); + if (!enable && plat->off_on_delay_us) + udelay(plat->off_on_delay_us);

return ret; } diff --git a/drivers/power/regulator/gpio-regulator.c b/drivers/power/regulator/gpio-regulator.c index 9c0a68aa5af4..ded7be059bb0 100644 --- a/drivers/power/regulator/gpio-regulator.c +++ b/drivers/power/regulator/gpio-regulator.c @@ -27,12 +27,12 @@ struct gpio_regulator_plat { static int gpio_regulator_of_to_plat(struct udevice *dev) { struct dm_regulator_uclass_plat *uc_pdata; - struct gpio_regulator_plat *dev_pdata; + struct gpio_regulator_plat *plat; struct gpio_desc *gpio; int ret, count, i, j; u32 states_array[GPIO_REGULATOR_MAX_STATES * 2];

- dev_pdata = dev_get_plat(dev); + plat = dev_get_plat(dev); uc_pdata = dev_get_uclass_plat(dev); if (!uc_pdata) return -ENXIO; @@ -47,7 +47,7 @@ static int gpio_regulator_of_to_plat(struct udevice *dev) * per gpio-regulator. As of now no instance with multiple * gpios is presnt */ - gpio = &dev_pdata->gpio; + gpio = &plat->gpio; ret = gpio_request_by_name(dev, "gpios", 0, gpio, GPIOD_IS_OUT); if (ret) debug("regulator gpio - not found! Error: %d", ret); @@ -68,21 +68,21 @@ static int gpio_regulator_of_to_plat(struct udevice *dev) return ret;

for (i = 0, j = 0; i < count; i += 2) { - dev_pdata->voltages[j] = states_array[i]; - dev_pdata->states[j] = states_array[i + 1]; + plat->voltages[j] = states_array[i]; + plat->states[j] = states_array[i + 1]; j++; }

- return regulator_common_of_to_plat(dev, &dev_pdata->common, "enable-gpios"); + return regulator_common_of_to_plat(dev, &plat->common, "enable-gpios"); }

static int gpio_regulator_get_value(struct udevice *dev) { struct dm_regulator_uclass_plat *uc_pdata; - struct gpio_regulator_plat *dev_pdata = dev_get_plat(dev); + struct gpio_regulator_plat *plat = dev_get_plat(dev); int enable;

- if (!dev_pdata->gpio.dev) + if (!plat->gpio.dev) return -ENOSYS;

uc_pdata = dev_get_uclass_plat(dev); @@ -91,30 +91,30 @@ static int gpio_regulator_get_value(struct udevice *dev) return -EINVAL; }

- enable = dm_gpio_get_value(&dev_pdata->gpio); - if (enable == dev_pdata->states[0]) - return dev_pdata->voltages[0]; + enable = dm_gpio_get_value(&plat->gpio); + if (enable == plat->states[0]) + return plat->voltages[0]; else - return dev_pdata->voltages[1]; + return plat->voltages[1]; }

static int gpio_regulator_set_value(struct udevice *dev, int uV) { - struct gpio_regulator_plat *dev_pdata = dev_get_plat(dev); + struct gpio_regulator_plat *plat = dev_get_plat(dev); int ret; bool enable;

- if (!dev_pdata->gpio.dev) + if (!plat->gpio.dev) return -ENOSYS;

- if (uV == dev_pdata->voltages[0]) - enable = dev_pdata->states[0]; - else if (uV == dev_pdata->voltages[1]) - enable = dev_pdata->states[1]; + if (uV == plat->voltages[0]) + enable = plat->states[0]; + else if (uV == plat->voltages[1]) + enable = plat->states[1]; else return -EINVAL;

- ret = dm_gpio_set_value(&dev_pdata->gpio, enable); + ret = dm_gpio_set_value(&plat->gpio, enable); if (ret) { pr_err("Can't set regulator : %s gpio to: %d\n", dev->name, enable); @@ -126,14 +126,14 @@ static int gpio_regulator_set_value(struct udevice *dev, int uV)

static int gpio_regulator_get_enable(struct udevice *dev) { - struct gpio_regulator_plat *dev_pdata = dev_get_plat(dev); - return regulator_common_get_enable(dev, &dev_pdata->common); + struct gpio_regulator_plat *plat = dev_get_plat(dev); + return regulator_common_get_enable(dev, &plat->common); }

static int gpio_regulator_set_enable(struct udevice *dev, bool enable) { - struct gpio_regulator_plat *dev_pdata = dev_get_plat(dev); - return regulator_common_set_enable(dev, &dev_pdata->common, enable); + struct gpio_regulator_plat *plat = dev_get_plat(dev); + return regulator_common_set_enable(dev, &plat->common, enable); }

static const struct dm_regulator_ops gpio_regulator_ops = { diff --git a/drivers/power/regulator/regulator_common.c b/drivers/power/regulator/regulator_common.c index edda25336176..bd9e4b95e83d 100644 --- a/drivers/power/regulator/regulator_common.c +++ b/drivers/power/regulator/regulator_common.c @@ -13,7 +13,7 @@ #include "regulator_common.h"

int regulator_common_of_to_plat(struct udevice *dev, - struct regulator_common_plat *dev_pdata, + struct regulator_common_plat *plat, const char *enable_gpio_name) { struct gpio_desc *gpio; @@ -26,7 +26,7 @@ int regulator_common_of_to_plat(struct udevice *dev, flags |= GPIOD_IS_OUT_ACTIVE;

/* Get optional enable GPIO desc */ - gpio = &dev_pdata->gpio; + gpio = &plat->gpio; ret = gpio_request_by_name(dev, enable_gpio_name, 0, gpio, flags); if (ret) { debug("Regulator '%s' optional enable GPIO - not found! Error: %d\n", @@ -36,12 +36,11 @@ int regulator_common_of_to_plat(struct udevice *dev, }

/* Get optional ramp up delay */ - dev_pdata->startup_delay_us = dev_read_u32_default(dev, - "startup-delay-us", 0); - dev_pdata->off_on_delay_us = - dev_read_u32_default(dev, "off-on-delay-us", 0); - if (!dev_pdata->off_on_delay_us) { - dev_pdata->off_on_delay_us = + plat->startup_delay_us = dev_read_u32_default(dev, + "startup-delay-us", 0); + plat->off_on_delay_us = dev_read_u32_default(dev, "off-on-delay-us", 0); + if (!plat->off_on_delay_us) { + plat->off_on_delay_us = dev_read_u32_default(dev, "u-boot,off-on-delay-us", 0); }

@@ -49,65 +48,65 @@ int regulator_common_of_to_plat(struct udevice *dev, }

int regulator_common_get_enable(const struct udevice *dev, - struct regulator_common_plat *dev_pdata) + struct regulator_common_plat *plat) { /* Enable GPIO is optional */ - if (!dev_pdata->gpio.dev) + if (!plat->gpio.dev) return true;

- return dm_gpio_get_value(&dev_pdata->gpio); + return dm_gpio_get_value(&plat->gpio); }

int regulator_common_set_enable(const struct udevice *dev, - struct regulator_common_plat *dev_pdata, bool enable) + struct regulator_common_plat *plat, bool enable) { int ret;

debug("%s: dev='%s', enable=%d, delay=%d, has_gpio=%d\n", __func__, - dev->name, enable, dev_pdata->startup_delay_us, - dm_gpio_is_valid(&dev_pdata->gpio)); + dev->name, enable, plat->startup_delay_us, + dm_gpio_is_valid(&plat->gpio)); /* Enable GPIO is optional */ - if (!dm_gpio_is_valid(&dev_pdata->gpio)) { + if (!dm_gpio_is_valid(&plat->gpio)) { if (!enable) return -ENOSYS; return 0; }

/* If previously enabled, increase count */ - if (enable && dev_pdata->enable_count > 0) { - dev_pdata->enable_count++; + if (enable && plat->enable_count > 0) { + plat->enable_count++; return 0; }

if (!enable) { - if (dev_pdata->enable_count > 1) { + if (plat->enable_count > 1) { /* If enabled multiple times, decrease count */ - dev_pdata->enable_count--; + plat->enable_count--; return 0; - } else if (!dev_pdata->enable_count) { + } else if (!plat->enable_count) { /* If already disabled, do nothing */ return 0; } }

- ret = dm_gpio_set_value(&dev_pdata->gpio, enable); + ret = dm_gpio_set_value(&plat->gpio, enable); if (ret) { pr_err("Can't set regulator : %s gpio to: %d\n", dev->name, enable); return ret; }

- if (enable && dev_pdata->startup_delay_us) - udelay(dev_pdata->startup_delay_us); + if (enable && plat->startup_delay_us) + udelay(plat->startup_delay_us); debug("%s: done\n", __func__);

- if (!enable && dev_pdata->off_on_delay_us) - udelay(dev_pdata->off_on_delay_us); + if (!enable && plat->off_on_delay_us) + udelay(plat->off_on_delay_us);

if (enable) - dev_pdata->enable_count++; + plat->enable_count++; else - dev_pdata->enable_count--; + plat->enable_count--;

return 0; } diff --git a/drivers/power/regulator/regulator_common.h b/drivers/power/regulator/regulator_common.h index 7c701b69245d..6e76068a3c58 100644 --- a/drivers/power/regulator/regulator_common.h +++ b/drivers/power/regulator/regulator_common.h @@ -17,10 +17,10 @@ struct regulator_common_plat { };

int regulator_common_of_to_plat(struct udevice *dev, - struct regulator_common_plat *dev_pdata, const + struct regulator_common_plat *plat, const char *enable_gpio_name); int regulator_common_get_enable(const struct udevice *dev, - struct regulator_common_plat *dev_pdata); + struct regulator_common_plat *plat); /* * Enable or Disable a regulator * @@ -30,10 +30,10 @@ int regulator_common_get_enable(const struct udevice *dev, * and disabled when it reaches 0 coming from 1. * * @dev: regulator device - * @dev_pdata: Platform data + * @plat: Platform data * @enable: bool indicating whether to enable or disable the regulator */ int regulator_common_set_enable(const struct udevice *dev, - struct regulator_common_plat *dev_pdata, bool enable); + struct regulator_common_plat *plat, bool enable);

#endif /* _REGULATOR_COMMON_H */

-- 2.34.1

Simon Glass

29 Mar 29 Mar

10:02 p.m.

Hi Eugen,

On Wed, 29 Mar 2023 at 02:01, Eugen Hristev eugen.hristev@collabora.com wrote:

...

Some devices share a regulator supply, when the first one will request regulator disable, the second device will have it's supply cut off before graciously shutting down. Hence there will be timeouts and other failed operations. Implement a reference counter mechanism similar with what is done in Linux, to keep track of enable and disable requests, and only disable the regulator when the last of the consumers has requested shutdown.

Signed-off-by: Eugen Hristev eugen.hristev@collabora.com

Changes in v2:

add info in header regarding the function

drivers/power/regulator/regulator_common.c | 22 ++++++++++++++++++++++ drivers/power/regulator/regulator_common.h | 13 +++++++++++++ 2 files changed, 35 insertions(+)

diff --git a/drivers/power/regulator/regulator_common.c b/drivers/power/regulator/regulator_common.c index 93d8196b381e..edda25336176 100644 --- a/drivers/power/regulator/regulator_common.c +++ b/drivers/power/regulator/regulator_common.c @@ -73,6 +73,23 @@ int regulator_common_set_enable(const struct udevice *dev, return 0; }
  /* If previously enabled, increase count */
  if (enable && dev_pdata->enable_count > 0) {
          dev_pdata->enable_count++;
          return 0;
  }
  if (!enable) {
          if (dev_pdata->enable_count > 1) {
                  /* If enabled multiple times, decrease count */
                  dev_pdata->enable_count--;
                  return 0;

Perhaps -EBUSY for this?

You said:

...

Maybe here we could return an error, saying that it's already disabled, but since it's a shared resource, this could tell the caller whether someone else is using the resource, and I don't think we should leak this information. It might be used in a way to find out information about the state of the system which might be a security problem ? I think that a shared resource usage should be transparent to the caller , such that only the driver should manage it's power on/off and know who is using it.

...

Do you agree ?

No, that doesn't seem like a good argument. Suppressing an error for security reasons?

Any driver can access any other in the system. This is a bootloader, not an OS. Knowing the state of the system is important. Supressing errors creates a lot of confusion and makes bugs hard to track.

...

          } else if (!dev_pdata->enable_count) {

                  /* If already disabled, do nothing */

```
                  return 0;
```

This is a bug, so we should return -EALREADY or something else here. If this error code is reported, we need to fix the bug.

...

          }
  }
  ret = dm_gpio_set_value(&dev_pdata->gpio, enable);
  if (ret) {
          pr_err("Can't set regulator : %s gpio to: %d\n", dev->name,
@@ -87,5 +104,10 @@ int regulator_common_set_enable(const struct udevice *dev, if (!enable && dev_pdata->off_on_delay_us) udelay(dev_pdata->off_on_delay_us);
  if (enable)
          dev_pdata->enable_count++;
  else
          dev_pdata->enable_count--;
  return 0;
} diff --git a/drivers/power/regulator/regulator_common.h b/drivers/power/regulator/regulator_common.h index c10492f01675..7c701b69245d 100644 --- a/drivers/power/regulator/regulator_common.h +++ b/drivers/power/regulator/regulator_common.h @@ -13,6 +13,7 @@ struct regulator_common_plat { struct gpio_desc gpio; /* GPIO for regulator enable control */ unsigned int startup_delay_us; unsigned int off_on_delay_us;
  unsigned int enable_count;
};

int regulator_common_of_to_plat(struct udevice *dev, @@ -20,6 +21,18 @@ int regulator_common_of_to_plat(struct udevice *dev, char *enable_gpio_name); int regulator_common_get_enable(const struct udevice *dev, struct regulator_common_plat *dev_pdata); +/*

Enable or Disable a regulator

This is a reentrant function and subsequent calls that enable will

increase an internal counter, and disable calls will decrease the counter.

The actual resource will be enabled when the counter gets to 1 coming from 0,

and disabled when it reaches 0 coming from 1.

@dev: regulator device

@dev_pdata: Platform data

@enable: bool indicating whether to enable or disable the regulator

Returns

...

*/

int regulator_common_set_enable(const struct udevice *dev, struct regulator_common_plat *dev_pdata, bool enable);

-- 2.34.1

Regards, Simon

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Eugen Hristev
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