regulator: core: Introduce API for regulators coupling customization
authorDmitry Osipenko <digetx@gmail.com>
Sun, 23 Jun 2019 21:08:31 +0000 (00:08 +0300)
committerMark Brown <broonie@kernel.org>
Tue, 25 Jun 2019 11:15:32 +0000 (12:15 +0100)
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@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
drivers/regulator/core.c
drivers/regulator/of_regulator.c
include/linux/regulator/coupler.h [new file with mode: 0644]
include/linux/regulator/driver.h
include/linux/regulator/machine.h

index 955a0a15b9cb662c0ebbd728f6df3d1b55242eb3..12c870f790f5266ef23c4dcba01275b3ff8b3c06 100644 (file)
@@ -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;
 }
 
index 6dca0ba044d8aa91ba50546af2441a1e540b7453..db1cb2714b92a6c20ad1095cc59021f80772977f 100644 (file)
@@ -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 (file)
index 0000000..98dd1f7
--- /dev/null
@@ -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
index 377da235711895321220522f3d3595817c1485a9..31b38a2b6995e3da295ec3936392babf086d0b0c 100644 (file)
@@ -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
index 1d34a70ffda27e58e109835933b57344687b8aaa..21db06e5c1edfe567399f417573f4dfc20b076a6 100644 (file)
@@ -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;