[PATCH v3 2/6] pinctrl: sh-pfc: Implement pinconf power-source param for voltage switching

[Ben Hutchings <ben.hutchings@codethink.co.uk>]

The pfc in the R8A7790 (and probably others in the R-Car gen 2 family)
supports switching SDHI signals between 3.3V and 1.8V voltage, and the
SD driver should do that when selecting a higher-speed mode.

Add a flag for pins that support low voltage mode and SoC operations to
get and set it.  Implement the pinconf power-source parameter using these
operations.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
---
 .../bindings/pinctrl/renesas,pfc-pinctrl.txt       |  4 ++-
 drivers/pinctrl/sh-pfc/pinctrl.c                   | 34 ++++++++++++++++++++--
 drivers/pinctrl/sh-pfc/sh_pfc.h                    |  6 ++++
 3 files changed, 41 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/pinctrl/renesas,pfc-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/renesas,pfc-pinctrl.txt
index bfe72ec055e3..93651742f1c1 100644
--- a/Documentation/devicetree/bindings/pinctrl/renesas,pfc-pinctrl.txt
+++ b/Documentation/devicetree/bindings/pinctrl/renesas,pfc-pinctrl.txt
@@ -69,7 +69,9 @@ Pin Configuration Node Properties:
 
 The pin configuration parameters use the generic pinconf bindings defined in
 pinctrl-bindings.txt in this directory. The supported parameters are
-bias-disable, bias-pull-up and bias-pull-down.
+bias-disable, bias-pull-up, bias-pull-down and power-source. For pins that
+can operate with either 3.3V or 1.8V signals, the power-source value should
+be 0 for 3.3V or 1 for 1.8V.
 

 GPIO
diff --git a/drivers/pinctrl/sh-pfc/pinctrl.c b/drivers/pinctrl/sh-pfc/pinctrl.c
index 072e7c62cab7..fa4066d4bc61 100644
--- a/drivers/pinctrl/sh-pfc/pinctrl.c
+++ b/drivers/pinctrl/sh-pfc/pinctrl.c
@@ -465,6 +465,9 @@ static bool sh_pfc_pinconf_validate(struct sh_pfc *pfc, unsigned int _pin,
 	case PIN_CONFIG_BIAS_PULL_DOWN:
 		return pin->configs & SH_PFC_PIN_CFG_PULL_DOWN;
 
+	case PIN_CONFIG_POWER_SOURCE:
+		return pin->configs & SH_PFC_PIN_CFG_LOW_VOLTAGE;
+
 	default:
 		return false;
 	}
@@ -477,7 +480,6 @@ static int sh_pfc_pinconf_get(struct pinctrl_dev *pctldev, unsigned _pin,
 	struct sh_pfc *pfc = pmx->pfc;
 	enum pin_config_param param = pinconf_to_config_param(*config);
 	unsigned long flags;
-	unsigned int bias;
 
 	if (!sh_pfc_pinconf_validate(pfc, _pin, param))
 		return -ENOTSUPP;
@@ -485,7 +487,9 @@ static int sh_pfc_pinconf_get(struct pinctrl_dev *pctldev, unsigned _pin,
 	switch (param) {
 	case PIN_CONFIG_BIAS_DISABLE:
 	case PIN_CONFIG_BIAS_PULL_UP:
-	case PIN_CONFIG_BIAS_PULL_DOWN:
+	case PIN_CONFIG_BIAS_PULL_DOWN: {
+		unsigned int bias;
+
 		if (!pfc->info->ops || !pfc->info->ops->get_bias)
 			return -ENOTSUPP;
 
@@ -498,6 +502,16 @@ static int sh_pfc_pinconf_get(struct pinctrl_dev *pctldev, unsigned _pin,
 
 		*config = 0;
 		break;
+	}
+
+	case PIN_CONFIG_POWER_SOURCE:
+		if (!pfc->info->ops || !pfc->info->ops->get_low_voltage)
+			return -ENOTSUPP;
+
+		spin_lock_irqsave(&pfc->lock, flags);
+		*config = pfc->info->ops->get_low_voltage(pfc, _pin);
+		spin_unlock_irqrestore(&pfc->lock, flags);
+		break;
 
 	default:
 		return -ENOTSUPP;
@@ -534,6 +548,22 @@ static int sh_pfc_pinconf_set(struct pinctrl_dev *pctldev, unsigned _pin,
 
 			break;
 
+		case PIN_CONFIG_POWER_SOURCE: {
+			unsigned int arg =
+				pinconf_to_config_argument(configs[i]);
+
+			if (!pfc->info->ops || !pfc->info->ops->set_low_voltage)
+				return -ENOTSUPP;
+			if (arg > 1)
+				return -ENOTSUPP;
+
+			spin_lock_irqsave(&pfc->lock, flags);
+			pfc->info->ops->set_low_voltage(pfc, _pin, arg);
+			spin_unlock_irqrestore(&pfc->lock, flags);
+
+			break;
+		}
+
 		default:
 			return -ENOTSUPP;
 		}
diff --git a/drivers/pinctrl/sh-pfc/sh_pfc.h b/drivers/pinctrl/sh-pfc/sh_pfc.h
index c7508d5f6886..b95d60bf2f1b 100644
--- a/drivers/pinctrl/sh-pfc/sh_pfc.h
+++ b/drivers/pinctrl/sh-pfc/sh_pfc.h
@@ -13,6 +13,7 @@
 
 #include <linux/bug.h>
 #include <linux/stringify.h>
+#include <linux/pinctrl/pinconf-generic.h>
 
 enum {
 	PINMUX_TYPE_NONE,
@@ -26,8 +27,11 @@ enum {
 #define SH_PFC_PIN_CFG_OUTPUT		(1 << 1)
 #define SH_PFC_PIN_CFG_PULL_UP		(1 << 2)
 #define SH_PFC_PIN_CFG_PULL_DOWN	(1 << 3)
+#define SH_PFC_PIN_CFG_LOW_VOLTAGE	(1 << 4)
 #define SH_PFC_PIN_CFG_NO_GPIO		(1 << 31)
 
+struct sh_pfc;
+
 struct sh_pfc_pin {
 	u16 pin;
 	u16 enum_id;
@@ -121,6 +125,8 @@ struct sh_pfc_soc_operations {
 	unsigned int (*get_bias)(struct sh_pfc *pfc, unsigned int pin);
 	void (*set_bias)(struct sh_pfc *pfc, unsigned int pin,
 			 unsigned int bias);
+	bool (*get_low_voltage)(struct sh_pfc *pfc, unsigned int pin);
+	void (*set_low_voltage)(struct sh_pfc *pfc, unsigned int pin, bool low);
 };
 
 struct sh_pfc_soc_info {
-- 
2.1.4