[PATCH] regulator: core: Introduce API for regulators coupling customization

From: Dmitry Osipenko
Date: Sun Jun 23 2019 - 17:08:31 EST

Right now regulator core supports only one type of regulators coupling,
the "voltage max-spread" which keeps voltages of coupled regulators in a
given range from each other. A more sophisticated coupling may be required
in practice, one example is the NVIDIA Tegra SoCs which besides the
max-spreading have other restrictions that must be adhered. Introduce API
that allow platforms to provide their own customized coupling algorithms.

Signed-off-by: Dmitry Osipenko <digetx@xxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
drivers/regulator/core.c | 136 +++++++++++++++++++++++++-----
drivers/regulator/of_regulator.c | 63 +++++++++-----
include/linux/regulator/coupler.h | 62 ++++++++++++++
include/linux/regulator/driver.h | 6 +-
include/linux/regulator/machine.h | 2 +-
5 files changed, 225 insertions(+), 44 deletions(-)
create mode 100644 include/linux/regulator/coupler.h

diff --git a/drivers/regulator/core.c b/drivers/regulator/core.c
index 955a0a15b9cb..12c870f790f5 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -28,6 +28,7 @@
#include <linux/regmap.h>
#include <linux/regulator/of_regulator.h>
#include <linux/regulator/consumer.h>
+#include <linux/regulator/coupler.h>
#include <linux/regulator/driver.h>
#include <linux/regulator/machine.h>
#include <linux/module.h>
@@ -55,6 +56,7 @@ static DEFINE_MUTEX(regulator_list_mutex);
static LIST_HEAD(regulator_map_list);
static LIST_HEAD(regulator_ena_gpio_list);
static LIST_HEAD(regulator_supply_alias_list);
+static LIST_HEAD(regulator_coupler_list);
static bool has_full_constraints;

static struct dentry *debugfs_root;
@@ -3439,11 +3441,10 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
struct coupling_desc *c_desc = &rdev->coupling_desc;
struct regulator_dev **c_rdevs = c_desc->coupled_rdevs;
struct regulation_constraints *constraints = rdev->constraints;
- int max_spread = constraints->max_spread;
int desired_min_uV = 0, desired_max_uV = INT_MAX;
int max_current_uV = 0, min_current_uV = INT_MAX;
int highest_min_uV = 0, target_uV, possible_uV;
- int i, ret;
+ int i, ret, max_spread;
bool done;

*current_uV = -1;
@@ -3497,6 +3498,8 @@ static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
}
}

+ max_spread = constraints->max_spread[0];
+
/*
* Let target_uV be equal to the desired one if possible.
* If not, set it to minimum voltage, allowed by other coupled
@@ -3578,9 +3581,11 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
struct regulator_dev **c_rdevs;
struct regulator_dev *best_rdev;
struct coupling_desc *c_desc = &rdev->coupling_desc;
+ struct regulator_coupler *coupler = c_desc->coupler;
int i, ret, n_coupled, best_min_uV, best_max_uV, best_c_rdev;
- bool best_c_rdev_done, c_rdev_done[MAX_COUPLED];
unsigned int delta, best_delta;
+ unsigned long c_rdev_done = 0;
+ bool best_c_rdev_done;

c_rdevs = c_desc->coupled_rdevs;
n_coupled = c_desc->n_coupled;
@@ -3597,8 +3602,9 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
return -EPERM;
}

- for (i = 0; i < n_coupled; i++)
- c_rdev_done[i] = false;
+ /* Invoke custom balancer for customized couplers */
+ if (coupler && coupler->balance_voltage)
+ return coupler->balance_voltage(coupler, rdev, state);

/*
* Find the best possible voltage change on each loop. Leave the loop
@@ -3625,7 +3631,7 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
*/
int optimal_uV = 0, optimal_max_uV = 0, current_uV = 0;

- if (c_rdev_done[i])
+ if (test_bit(i, &c_rdev_done))
continue;

ret = regulator_get_optimal_voltage(c_rdevs[i],
@@ -3660,7 +3666,8 @@ static int regulator_balance_voltage(struct regulator_dev *rdev,
if (ret < 0)
goto out;

- c_rdev_done[best_c_rdev] = best_c_rdev_done;
+ if (best_c_rdev_done)
+ set_bit(best_c_rdev, &c_rdev_done);

} while (n_coupled > 1);

@@ -4712,8 +4719,60 @@ static int regulator_register_resolve_supply(struct device *dev, void *data)
return 0;
}

+int regulator_coupler_register(struct regulator_coupler *coupler)
+{
+ mutex_lock(&regulator_list_mutex);
+ list_add_tail(&coupler->list, &regulator_coupler_list);
+ mutex_unlock(&regulator_list_mutex);
+
+ return 0;
+}
+
+static struct regulator_coupler *
+regulator_find_coupler(struct regulator_dev *rdev)
+{
+ struct regulator_coupler *coupler;
+ int err;
+
+ /*
+ * Note that regulators are appended to the list and the generic
+ * coupler is registered first, hence it will be attached at last
+ * if nobody cared.
+ */
+ list_for_each_entry_reverse(coupler, &regulator_coupler_list, list) {
+ err = coupler->attach_regulator(coupler, rdev);
+ if (!err) {
+ if (!coupler->balance_voltage &&
+ rdev->coupling_desc.n_coupled > 2)
+ goto err_unsupported;
+
+ return coupler;
+ }
+
+ if (err < 0)
+ return ERR_PTR(err);
+
+ if (err == 1)
+ continue;
+
+ break;
+ }
+
+ return ERR_PTR(-EINVAL);
+
+err_unsupported:
+ if (coupler->detach_regulator)
+ coupler->detach_regulator(coupler, rdev);
+
+ rdev_err(rdev,
+ "Voltage balancing for multiple regulator couples is unimplemented\n");
+
+ return ERR_PTR(-EPERM);
+}
+
static void regulator_resolve_coupling(struct regulator_dev *rdev)
{
+ struct regulator_coupler *coupler = rdev->coupling_desc.coupler;
struct coupling_desc *c_desc = &rdev->coupling_desc;
int n_coupled = c_desc->n_coupled;
struct regulator_dev *c_rdev;
@@ -4729,6 +4788,12 @@ static void regulator_resolve_coupling(struct regulator_dev *rdev)
if (!c_rdev)
continue;

+ if (c_rdev->coupling_desc.coupler != coupler) {
+ rdev_err(rdev, "coupler mismatch with %s\n",
+ rdev_get_name(c_rdev));
+ return;
+ }
+
regulator_lock(c_rdev);

c_desc->coupled_rdevs[i] = c_rdev;
@@ -4742,10 +4807,12 @@ static void regulator_resolve_coupling(struct regulator_dev *rdev)

static void regulator_remove_coupling(struct regulator_dev *rdev)
{
+ struct regulator_coupler *coupler = rdev->coupling_desc.coupler;
struct coupling_desc *__c_desc, *c_desc = &rdev->coupling_desc;
struct regulator_dev *__c_rdev, *c_rdev;
unsigned int __n_coupled, n_coupled;
int i, k;
+ int err;

n_coupled = c_desc->n_coupled;

@@ -4775,21 +4842,33 @@ static void regulator_remove_coupling(struct regulator_dev *rdev)
c_desc->coupled_rdevs[i] = NULL;
c_desc->n_resolved--;
}
+
+ if (coupler && coupler->detach_regulator) {
+ err = coupler->detach_regulator(coupler, rdev);
+ if (err)
+ rdev_err(rdev, "failed to detach from coupler: %d\n",
+ err);
+ }
+
+ kfree(rdev->coupling_desc.coupled_rdevs);
+ rdev->coupling_desc.coupled_rdevs = NULL;
}

static int regulator_init_coupling(struct regulator_dev *rdev)
{
- int n_phandles;
+ int err, n_phandles;
+ size_t alloc_size;

if (!IS_ENABLED(CONFIG_OF))
n_phandles = 0;
else
n_phandles = of_get_n_coupled(rdev);

- if (n_phandles + 1 > MAX_COUPLED) {
- rdev_err(rdev, "too many regulators coupled\n");
- return -EPERM;
- }
+ alloc_size = sizeof(*rdev) * (n_phandles + 1);
+
+ rdev->coupling_desc.coupled_rdevs = kzalloc(alloc_size, GFP_KERNEL);
+ if (!rdev->coupling_desc.coupled_rdevs)
+ return -ENOMEM;

/*
* Every regulator should always have coupling descriptor filled with
@@ -4803,23 +4882,35 @@ static int regulator_init_coupling(struct regulator_dev *rdev)
if (n_phandles == 0)
return 0;

- /* regulator, which can't change its voltage, can't be coupled */
- if (!regulator_ops_is_valid(rdev, REGULATOR_CHANGE_VOLTAGE)) {
- rdev_err(rdev, "voltage operation not allowed\n");
+ if (!of_check_coupling_data(rdev))
return -EPERM;
- }

- if (rdev->constraints->max_spread <= 0) {
- rdev_err(rdev, "wrong max_spread value\n");
- return -EPERM;
+ rdev->coupling_desc.coupler = regulator_find_coupler(rdev);
+ if (IS_ERR(rdev->coupling_desc.coupler)) {
+ err = PTR_ERR(rdev->coupling_desc.coupler);
+ rdev_err(rdev, "failed to get coupler: %d\n", err);
+ return err;
}

- if (!of_check_coupling_data(rdev))
+ return 0;
+}
+
+static int generic_coupler_attach(struct regulator_coupler *coupler,
+ struct regulator_dev *rdev)
+{
+ if (rdev->coupling_desc.n_coupled > 2) {
+ rdev_err(rdev,
+ "Voltage balancing for multiple regulator couples is unimplemented\n");
return -EPERM;
+ }

return 0;
}

+static struct regulator_coupler generic_regulator_coupler = {
+ .attach_regulator = generic_coupler_attach,
+};
+
/**
* regulator_register - register regulator
* @regulator_desc: regulator to register
@@ -4981,7 +5072,9 @@ regulator_register(const struct regulator_desc *regulator_desc,
if (ret < 0)
goto wash;

+ mutex_lock(&regulator_list_mutex);
ret = regulator_init_coupling(rdev);
+ mutex_unlock(&regulator_list_mutex);
if (ret < 0)
goto wash;

@@ -5030,6 +5123,7 @@ regulator_register(const struct regulator_desc *regulator_desc,
unset_supplies:
mutex_lock(&regulator_list_mutex);
unset_regulator_supplies(rdev);
+ regulator_remove_coupling(rdev);
mutex_unlock(&regulator_list_mutex);
wash:
kfree(rdev->constraints);
@@ -5485,6 +5579,8 @@ static int __init regulator_init(void)
#endif
regulator_dummy_init();

+ regulator_coupler_register(&generic_regulator_coupler);
+
return ret;
}

diff --git a/drivers/regulator/of_regulator.c b/drivers/regulator/of_regulator.c
index 6dca0ba044d8..db1cb2714b92 100644
--- a/drivers/regulator/of_regulator.c
+++ b/drivers/regulator/of_regulator.c
@@ -25,7 +25,8 @@ static const char *const regulator_states[PM_SUSPEND_MAX + 1] = {
[PM_SUSPEND_MAX] = "regulator-state-disk",
};

-static void of_get_regulation_constraints(struct device_node *np,
+static int of_get_regulation_constraints(struct device *dev,
+ struct device_node *np,
struct regulator_init_data **init_data,
const struct regulator_desc *desc)
{
@@ -34,8 +35,13 @@ static void of_get_regulation_constraints(struct device_node *np,
struct device_node *suspend_np;
unsigned int mode;
int ret, i, len;
+ int n_phandles;
u32 pval;

+ n_phandles = of_count_phandle_with_args(np, "regulator-coupled-with",
+ NULL);
+ n_phandles = max(n_phandles, 0);
+
constraints->name = of_get_property(np, "regulator-name", NULL);

if (!of_property_read_u32(np, "regulator-min-microvolt", &pval))
@@ -167,9 +173,17 @@ static void of_get_regulation_constraints(struct device_node *np,
if (!of_property_read_u32(np, "regulator-system-load", &pval))
constraints->system_load = pval;

- if (!of_property_read_u32(np, "regulator-coupled-max-spread",
- &pval))
- constraints->max_spread = pval;
+ if (n_phandles) {
+ constraints->max_spread = devm_kzalloc(dev,
+ sizeof(*constraints->max_spread) * n_phandles,
+ GFP_KERNEL);
+
+ if (!constraints->max_spread)
+ return -ENOMEM;
+
+ of_property_read_u32_array(np, "regulator-coupled-max-spread",
+ constraints->max_spread, n_phandles);
+ }

if (!of_property_read_u32(np, "regulator-max-step-microvolt",
&pval))
@@ -246,6 +260,8 @@ static void of_get_regulation_constraints(struct device_node *np,
suspend_state = NULL;
suspend_np = NULL;
}
+
+ return 0;
}

/**
@@ -271,7 +287,9 @@ struct regulator_init_data *of_get_regulator_init_data(struct device *dev,
if (!init_data)
return NULL; /* Out of memory? */

- of_get_regulation_constraints(node, &init_data, desc);
+ if (of_get_regulation_constraints(dev, node, &init_data, desc))
+ return NULL;
+
return init_data;
}
EXPORT_SYMBOL_GPL(of_get_regulator_init_data);
@@ -477,7 +495,8 @@ int of_get_n_coupled(struct regulator_dev *rdev)

/* Looks for "to_find" device_node in src's "regulator-coupled-with" property */
static bool of_coupling_find_node(struct device_node *src,
- struct device_node *to_find)
+ struct device_node *to_find,
+ int *index)
{
int n_phandles, i;
bool found = false;
@@ -499,8 +518,10 @@ static bool of_coupling_find_node(struct device_node *src,

of_node_put(tmp);

- if (found)
+ if (found) {
+ *index = i;
break;
+ }
}

return found;
@@ -521,22 +542,23 @@ static bool of_coupling_find_node(struct device_node *src,
*/
bool of_check_coupling_data(struct regulator_dev *rdev)
{
- int max_spread = rdev->constraints->max_spread;
struct device_node *node = rdev->dev.of_node;
int n_phandles = of_get_n_coupled(rdev);
struct device_node *c_node;
+ int index;
int i;
bool ret = true;

- if (max_spread <= 0) {
- dev_err(&rdev->dev, "max_spread value invalid\n");
- return false;
- }
-
/* iterate over rdev's phandles */
for (i = 0; i < n_phandles; i++) {
+ int max_spread = rdev->constraints->max_spread[i];
int c_max_spread, c_n_phandles;

+ if (max_spread <= 0) {
+ dev_err(&rdev->dev, "max_spread value invalid\n");
+ return false;
+ }
+
c_node = of_parse_phandle(node,
"regulator-coupled-with", i);

@@ -553,22 +575,23 @@ bool of_check_coupling_data(struct regulator_dev *rdev)
goto clean;
}

- if (of_property_read_u32(c_node, "regulator-coupled-max-spread",
- &c_max_spread)) {
+ if (!of_coupling_find_node(c_node, node, &index)) {
+ dev_err(&rdev->dev, "missing 2-way linking for coupled regulators\n");
ret = false;
goto clean;
}

- if (c_max_spread != max_spread) {
- dev_err(&rdev->dev,
- "coupled regulators max_spread mismatch\n");
+ if (of_property_read_u32_index(c_node, "regulator-coupled-max-spread",
+ index, &c_max_spread)) {
ret = false;
goto clean;
}

- if (!of_coupling_find_node(c_node, node)) {
- dev_err(&rdev->dev, "missing 2-way linking for coupled regulators\n");
+ if (c_max_spread != max_spread) {
+ dev_err(&rdev->dev,
+ "coupled regulators max_spread mismatch\n");
ret = false;
+ goto clean;
}

clean:
diff --git a/include/linux/regulator/coupler.h b/include/linux/regulator/coupler.h
new file mode 100644
index 000000000000..98dd1f74d605
--- /dev/null
+++ b/include/linux/regulator/coupler.h
@@ -0,0 +1,62 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * coupler.h -- SoC Regulator support, coupler API.
+ *
+ * Regulator Coupler Interface.
+ */
+
+#ifndef __LINUX_REGULATOR_COUPLER_H_
+#define __LINUX_REGULATOR_COUPLER_H_
+
+#include <linux/kernel.h>
+#include <linux/suspend.h>
+
+struct regulator_coupler;
+struct regulator_dev;
+
+/**
+ * struct regulator_coupler - customized regulator's coupler
+ *
+ * Regulator's coupler allows to customize coupling algorithm.
+ *
+ * @list: couplers list entry
+ * @attach_regulator: Callback invoked on creation of a coupled regulator,
+ * couples are unresolved at this point. The callee should
+ * check that it could handle the regulator and return 0 on
+ * success, -errno on failure and 1 if given regulator is
+ * not suitable for this coupler (case of having multiple
+ * regulators in a system). Callback shall be implemented.
+ * @detach_regulator: Callback invoked on destruction of a coupled regulator.
+ * This callback is optional and could be NULL.
+ * @balance_voltage: Callback invoked when voltage of a coupled regulator is
+ * changing. Called with all of the coupled rdev's being held
+ * under "consumer lock". The callee should perform voltage
+ * balancing, changing voltage of the coupled regulators as
+ * needed. It's up to the coupler to verify the voltage
+ * before changing it in hardware, i.e. coupler should
+ * check consumer's min/max and etc. This callback is
+ * optional and could be NULL, in which case a generic
+ * voltage balancer will be used.
+ */
+struct regulator_coupler {
+ struct list_head list;
+
+ int (*attach_regulator)(struct regulator_coupler *coupler,
+ struct regulator_dev *rdev);
+ int (*detach_regulator)(struct regulator_coupler *coupler,
+ struct regulator_dev *rdev);
+ int (*balance_voltage)(struct regulator_coupler *coupler,
+ struct regulator_dev *rdev,
+ suspend_state_t state);
+};
+
+#ifdef CONFIG_REGULATOR
+int regulator_coupler_register(struct regulator_coupler *coupler);
+#else
+static inline int regulator_coupler_register(struct regulator_coupler *coupler)
+{
+ return 0;
+}
+#endif
+
+#endif
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index 377da2357118..31b38a2b6995 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -15,8 +15,6 @@
#ifndef __LINUX_REGULATOR_DRIVER_H_
#define __LINUX_REGULATOR_DRIVER_H_

-#define MAX_COUPLED 2
-
#include <linux/device.h>
#include <linux/notifier.h>
#include <linux/regulator/consumer.h>
@@ -426,7 +424,8 @@ struct regulator_config {
* incremented.
*/
struct coupling_desc {
- struct regulator_dev *coupled_rdevs[MAX_COUPLED];
+ struct regulator_dev **coupled_rdevs;
+ struct regulator_coupler *coupler;
int n_resolved;
int n_coupled;
};
@@ -552,4 +551,5 @@ void regulator_unlock(struct regulator_dev *rdev);
*/
int regulator_desc_list_voltage_linear_range(const struct regulator_desc *desc,
unsigned int selector);
+
#endif
diff --git a/include/linux/regulator/machine.h b/include/linux/regulator/machine.h
index 1d34a70ffda2..21db06e5c1ed 100644
--- a/include/linux/regulator/machine.h
+++ b/include/linux/regulator/machine.h
@@ -156,7 +156,7 @@ struct regulation_constraints {
int system_load;

/* used for coupled regulators */
- int max_spread;
+ u32 *max_spread;

/* used for changing voltage in steps */
int max_uV_step;
--
2.20.1