cpufreq: ti-cpufreq: omap36xx use "cpu0","vbb" if run in multi_regulator mode

In preparation for using the multi_regulator capability of
this driver for handling the ABB LDO for OPP1G of the omap36xx
we have to take care that the (legacy) vdd-supply name is
cpu0-supply = <&vcc>;

To do this we add another field to the SoC description table which
optionally can specify a list of regulator names.

For omap36xx we define "cpu0-supply" and "vbb-supply".

The default remains "vdd-supply" and "vbb-supply".

Signed-off-by: H. Nikolaus Schaller <[e-mail]>
Acked-by: Tony Lindgren <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Tested-by: Adam Ford <[e-mail]>
Signed-off-by: Viresh Kumar <[e-mail]>

Documentation/devicetree/bindings/cpufreq/ti-cpufreq.txt

···
 
 In 'operating-points-v2' table:
 - compatible: Should be
-	- 'operating-points-v2-ti-cpu' for am335x, am43xx, and dra7xx/am57xx SoCs
+	- 'operating-points-v2-ti-cpu' for am335x, am43xx, and dra7xx/am57xx,
+	  omap34xx, omap36xx and am3517 SoCs
 - syscon: A phandle pointing to a syscon node representing the control module
 	  register space of the SoC.
 
 Optional properties:
 --------------------
+- "vdd-supply", "vbb-supply": to define two regulators for dra7xx
+- "cpu0-supply", "vbb-supply": to define two regulators for omap36xx
+
 For each opp entry in 'operating-points-v2' table:
 - opp-supported-hw: Two bitfields indicating:
 	1. Which revision of the SoC the OPP is supported by

drivers/cpufreq/ti-cpufreq.c

···
 struct ti_cpufreq_data;
 
 struct ti_cpufreq_soc_data {
+	const char * const *reg_names;
 	unsigned long (*efuse_xlate)(struct ti_cpufreq_data *opp_data,
 				     unsigned long efuse);
 	unsigned long efuse_fallback;
···
  *    seems to always read as 0).
  */
 
+static const char * const omap3_reg_names[] = {"cpu0", "vbb"};
+
 static struct ti_cpufreq_soc_data omap36xx_soc_data = {
+	.reg_names = omap3_reg_names,
 	.efuse_xlate = omap3_efuse_xlate,
 	.efuse_offset = OMAP3_CONTROL_DEVICE_STATUS - OMAP3_SYSCON_BASE,
 	.efuse_shift = 9,
···
 	const struct of_device_id *match;
 	struct opp_table *ti_opp_table;
 	struct ti_cpufreq_data *opp_data;
-	const char * const reg_names[] = {"vdd", "vbb"};
+	const char * const default_reg_names[] = {"vdd", "vbb"};
 	int ret;
 
 	match = dev_get_platdata(&pdev->dev);
···
 	opp_data->opp_table = ti_opp_table;
 
 	if (opp_data->soc_data->multi_regulator) {
+		const char * const *reg_names = default_reg_names;
+
+		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(reg_names));
+							 ARRAY_SIZE(default_reg_names));
 		if (IS_ERR(ti_opp_table)) {
 			dev_pm_opp_put_supported_hw(opp_data->opp_table);
 			ret =  PTR_ERR(ti_opp_table);