OPP: Make dev_pm_opp_set_regulators() accept NULL terminated list

Make dev_pm_opp_set_regulators() accept a NULL terminated list of names
instead of making the callers keep the two parameters in sync, which
creates an opportunity for bugs to get in.

Suggested-by: Greg Kroah-Hartman <[e-mail]>
Reviewed-by: Steven Price <[e-mail]> # panfrost
Reviewed-by: Chanwoo Choi <[e-mail]>
Signed-off-by: Viresh Kumar <[e-mail]>

drivers/cpufreq/cpufreq-dt.c

···
 	struct private_data *priv;
 	struct device *cpu_dev;
 	bool fallback = false;
-	const char *reg_name;
+	const char *reg_name[] = { NULL, NULL };
 	int ret;
 
 	/* Check if this CPU is already covered by some other policy */
···
 	 * OPP layer will be taking care of regulators now, but it needs to know
 	 * the name of the regulator first.
 	 */
-	reg_name = find_supply_name(cpu_dev);
-	if (reg_name) {
-		priv->opp_table = dev_pm_opp_set_regulators(cpu_dev, &reg_name,
-							    1);
+	reg_name[0] = find_supply_name(cpu_dev);
+	if (reg_name[0]) {
+		priv->opp_table = dev_pm_opp_set_regulators(cpu_dev, reg_name);
 		if (IS_ERR(priv->opp_table)) {
 			ret = PTR_ERR(priv->opp_table);
 			if (ret != -EPROBE_DEFER)

drivers/cpufreq/ti-cpufreq.c

···
  *    seems to always read as 0).
  */
 
-static const char * const omap3_reg_names[] = {"cpu0", "vbb"};
+static const char * const omap3_reg_names[] = {"cpu0", "vbb", NULL};
 
 static struct ti_cpufreq_soc_data omap36xx_soc_data = {
 	.reg_names = omap3_reg_names,
···
 	const struct of_device_id *match;
 	struct opp_table *ti_opp_table;
 	struct ti_cpufreq_data *opp_data;
-	const char * const default_reg_names[] = {"vdd", "vbb"};
+	const char * const default_reg_names[] = {"vdd", "vbb", NULL};
 	int ret;
 
 	match = dev_get_platdata(&pdev->dev);
···
 		if (opp_data->soc_data->reg_names)
 			reg_names = opp_data->soc_data->reg_names;
 		ti_opp_table = dev_pm_opp_set_regulators(opp_data->cpu_dev,
-							 reg_names,
-							 ARRAY_SIZE(default_reg_names));
+							 reg_names);
 		if (IS_ERR(ti_opp_table)) {
 			dev_pm_opp_put_supported_hw(opp_data->opp_table);
 			ret =  PTR_ERR(ti_opp_table);

drivers/devfreq/exynos-bus.c

···
 {
 	struct device *dev = bus->dev;
 	struct opp_table *opp_table;
-	const char *vdd = "vdd";
+	const char *supplies[] = { "vdd", NULL };
 	int i, ret, count, size;
 
-	opp_table = dev_pm_opp_set_regulators(dev, &vdd, 1);
+	opp_table = dev_pm_opp_set_regulators(dev, supplies);
 	if (IS_ERR(opp_table)) {
 		ret = PTR_ERR(opp_table);
 		dev_err(dev, "failed to set regulators %d\n", ret);

drivers/gpu/drm/lima/lima_devfreq.c

···
 	struct dev_pm_opp *opp;
 	unsigned long cur_freq;
 	int ret;
+	const char *regulator_names[] = { "mali", NULL };
 
 	if (!device_property_present(dev, "operating-points-v2"))
 		/* Optional, continue without devfreq */
···
 	if (ret)
 		return ret;
 
-	ret = devm_pm_opp_set_regulators(dev, (const char *[]){ "mali" }, 1);
+	ret = devm_pm_opp_set_regulators(dev, regulator_names);
 	if (ret) {
 		/* Continue if the optional regulator is missing */
 		if (ret != -ENODEV)

drivers/gpu/drm/panfrost/panfrost_devfreq.c

···
 		return 0;
 	}
 
-	ret = devm_pm_opp_set_regulators(dev, pfdev->comp->supply_names,
-					 pfdev->comp->num_supplies);
+	ret = devm_pm_opp_set_regulators(dev, pfdev->comp->supply_names);
 	if (ret) {
 		/* Continue if the optional regulator is missing */
 		if (ret != -ENODEV) {

drivers/gpu/drm/panfrost/panfrost_drv.c

···
 	return 0;
 }
 
-static const char * const default_supplies[] = { "mali" };
+/*
+ * The OPP core wants the supply names to be NULL terminated, but we need the
+ * correct num_supplies value for regulator core. Hence, we NULL terminate here
+ * and then initialize num_supplies with ARRAY_SIZE - 1.
+ */
+static const char * const default_supplies[] = { "mali", NULL };
 static const struct panfrost_compatible default_data = {
-	.num_supplies = ARRAY_SIZE(default_supplies),
+	.num_supplies = ARRAY_SIZE(default_supplies) - 1,
 	.supply_names = default_supplies,
 	.num_pm_domains = 1, /* optional */
 	.pm_domain_names = NULL,
 };
 
 static const struct panfrost_compatible amlogic_data = {
-	.num_supplies = ARRAY_SIZE(default_supplies),
+	.num_supplies = ARRAY_SIZE(default_supplies) - 1,
 	.supply_names = default_supplies,
 	.vendor_quirk = panfrost_gpu_amlogic_quirk,
 };
 
-static const char * const mediatek_mt8183_supplies[] = { "mali", "sram" };
+static const char * const mediatek_mt8183_supplies[] = { "mali", "sram", NULL };
 static const char * const mediatek_mt8183_pm_domains[] = { "core0", "core1", "core2" };
 static const struct panfrost_compatible mediatek_mt8183_data = {
-	.num_supplies = ARRAY_SIZE(mediatek_mt8183_supplies),
+	.num_supplies = ARRAY_SIZE(mediatek_mt8183_supplies) - 1,
 	.supply_names = mediatek_mt8183_supplies,
 	.num_pm_domains = ARRAY_SIZE(mediatek_mt8183_pm_domains),
 	.pm_domain_names = mediatek_mt8183_pm_domains,

drivers/opp/core.c

···
  * This must be called before any OPPs are initialized for the device.
  */
 struct opp_table *dev_pm_opp_set_regulators(struct device *dev,
-					    const char * const names[],
-					    unsigned int count)
+					    const char * const names[])
 {
 	struct dev_pm_opp_supply *supplies;
+	const char * const *temp = names;
 	struct opp_table *opp_table;
 	struct regulator *reg;
-	int ret, i;
+	int count = 0, ret, i;
+
+	/* Count number of regulators */
+	while (*temp++)
+		count++;
+
+	if (!count)
+		return ERR_PTR(-EINVAL);
 
 	opp_table = _add_opp_table(dev, false);
 	if (IS_ERR(opp_table))
···
  * Return: 0 on success and errorno otherwise.
  */
 int devm_pm_opp_set_regulators(struct device *dev,
-			       const char * const names[],
-			       unsigned int count)
+			       const char * const names[])
 {
 	struct opp_table *opp_table;
 
-	opp_table = dev_pm_opp_set_regulators(dev, names, count);
+	opp_table = dev_pm_opp_set_regulators(dev, names);
 	if (IS_ERR(opp_table))
 		return PTR_ERR(opp_table);
 

drivers/soc/tegra/pmc.c

···
 static int tegra_pmc_core_pd_add(struct tegra_pmc *pmc, struct device_node *np)
 {
 	struct generic_pm_domain *genpd;
-	const char *rname = "core";
+	const char *rname[] = { "core", NULL};
 	int err;
 
 	genpd = devm_kzalloc(pmc->dev, sizeof(*genpd), GFP_KERNEL);
···
 	genpd->set_performance_state = tegra_pmc_core_pd_set_performance_state;
 	genpd->opp_to_performance_state = tegra_pmc_core_pd_opp_to_performance_state;
 
-	err = devm_pm_opp_set_regulators(pmc->dev, &rname, 1);
+	err = devm_pm_opp_set_regulators(pmc->dev, rname);
 	if (err)
 		return dev_err_probe(pmc->dev, err,
 				     "failed to set core OPP regulator\n");

include/linux/pm_opp.h

···
 int devm_pm_opp_set_supported_hw(struct device *dev, const u32 *versions, unsigned int count);
 struct opp_table *dev_pm_opp_set_prop_name(struct device *dev, const char *name);
 void dev_pm_opp_put_prop_name(struct opp_table *opp_table);
-struct opp_table *dev_pm_opp_set_regulators(struct device *dev, const char * const names[], unsigned int count);
+struct opp_table *dev_pm_opp_set_regulators(struct device *dev, const char * const names[]);
 void dev_pm_opp_put_regulators(struct opp_table *opp_table);
-int devm_pm_opp_set_regulators(struct device *dev, const char * const names[], unsigned int count);
+int devm_pm_opp_set_regulators(struct device *dev, const char * const names[]);
 struct opp_table *dev_pm_opp_set_clkname(struct device *dev, const char *name);
 void dev_pm_opp_put_clkname(struct opp_table *opp_table);
 int devm_pm_opp_set_clkname(struct device *dev, const char *name);
···
 
 static inline void dev_pm_opp_put_prop_name(struct opp_table *opp_table) {}
 
-static inline struct opp_table *dev_pm_opp_set_regulators(struct device *dev, const char * const names[], unsigned int count)
+static inline struct opp_table *dev_pm_opp_set_regulators(struct device *dev, const char * const names[])
 {
 	return ERR_PTR(-EOPNOTSUPP);
 }
···
 static inline void dev_pm_opp_put_regulators(struct opp_table *opp_table) {}
 
 static inline int devm_pm_opp_set_regulators(struct device *dev,
-					     const char * const names[],
-					     unsigned int count)
+					     const char * const names[])
 {
 	return -EOPNOTSUPP;
 }