All the SHDIs can operate with either 3.3V or 1.8V signals, depending
on negotiation with the card.

Implement the {get,set}_low_voltage operations and set the low-voltage
capability flag for the associated pins.

Signed-off-by: Ben Hutchings <redacted>
---
 drivers/pinctrl/sh-pfc/core.c        |  2 +-
 drivers/pinctrl/sh-pfc/core.h        |  1 +
 drivers/pinctrl/sh-pfc/pfc-r8a7790.c | 67 ++++++++++++++++++++++++++++++++-
 3 files changed, 68 insertions(+), 2
deletions(-)

diff --git a/drivers/pinctrl/sh-pfc/core.c b/drivers/pinctrl/sh-pfc/core.c
index 7b2c9495c383..7d51f96afc9a 100644
--- a/drivers/pinctrl/sh-pfc/core.c
+++ b/drivers/pinctrl/sh-pfc/core.c

@@ -92,7 +92,7 @@ static int sh_pfc_map_resources(struct sh_pfc *pfc,
 	return 0;
 }

-static void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 reg)
+void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 reg)
 {
 	struct sh_pfc_window *window;
 	phys_addr_t address = reg;

diff --git a/drivers/pinctrl/sh-pfc/core.h b/drivers/pinctrl/sh-pfc/core.h
index 6dc8a6fc2746..af355629c5d2 100644
--- a/drivers/pinctrl/sh-pfc/core.h
+++ b/drivers/pinctrl/sh-pfc/core.h

@@ -57,6 +57,7 @@ int sh_pfc_unregister_gpiochip(struct sh_pfc *pfc);
 int sh_pfc_register_pinctrl(struct sh_pfc *pfc);
 int sh_pfc_unregister_pinctrl(struct sh_pfc *pfc);

+void __iomem *sh_pfc_phys_to_virt(struct sh_pfc *pfc, u32 address);
 u32 sh_pfc_read_raw_reg(void __iomem *mapped_reg, unsigned int reg_width);
 void sh_pfc_write_raw_reg(void __iomem *mapped_reg, unsigned int reg_width,

u32 data);

diff --git a/drivers/pinctrl/sh-pfc/pfc-r8a7790.c

b/drivers/pinctrl/sh-pfc/pfc-r8a7790.c index 22a5470889f5..38be7cbea4ca
100644

--- a/drivers/pinctrl/sh-pfc/pfc-r8a7790.c
+++ b/drivers/pinctrl/sh-pfc/pfc-r8a7790.c

@@ -1739,10 +1739,20 @@ static const u16 pinmux_data[] = {
 #define PIN_NUMBER(r, c) (((r) - 'A') * 31 + (c) + 200)
 #define PIN_A_NUMBER(r, c) PIN_NUMBER(ROW_GROUP_A(r), c)

+#define PIN_LOW_VOLTAGE(bank, _pin, _name, sfx)		\
+	[RCAR_GP_PIN(bank, _pin)].configs = SH_PFC_PIN_CFG_LOW_VOLTAGE
+
 static const struct sh_pfc_pin pinmux_pins[] = {
 	PINMUX_GPIO_GP_ALL(),

-	/* Pins not associated with a GPIO port */
+	/*
+	 * All pins assigned to GPIO bank 3 can be used for SD interfaces
+	 * in which case they support low voltage (1.8V) signalling.
+	 */
+	PORT_GP_32(3, PIN_LOW_VOLTAGE, unused),

+	/* Pins not associated with a GPIO port, placed after all the GPIOs */
+	[RCAR_GP_PIN(5, 31) + 1] =
 	SH_PFC_PIN_NAMED(ROW_GROUP_A('F'), 15, AF15),
 	SH_PFC_PIN_NAMED(ROW_GROUP_A('G'), 15, AG15),
 	SH_PFC_PIN_NAMED(ROW_GROUP_A('H'), 15, AH15),

@@ -4595,6 +4605,55 @@ static const char * const vin3_groups[] = {
 	"vin3_clk",
 };

+static bool sdhi_get_low_voltage(struct sh_pfc *pfc, unsigned int pin)
+{
+	void __iomem *mapped_reg;
+	u32 data, mask;
+
+	if (WARN(pin < RCAR_GP_PIN(3, 0) || pin > RCAR_GP_PIN(3, 31),
+		 "sdhi_get_low_voltage: invalid pin %#x", pin))
+		return 0;

+
+	return !(data & mask);
+}
+
+static void
+sdhi_set_low_voltage(struct sh_pfc *pfc, unsigned int pin, bool low)
+{
+	void __iomem *mapped_reg;
+	u32 data, mask;
+
+	if (WARN(pin < RCAR_GP_PIN(3, 0) || pin > RCAR_GP_PIN(3, 31),
+		 "sdhi_set_low_voltage: invalid pin %#x", pin))
+		return;
+
+	/* Map IOCTRL6 */
+	mapped_reg = sh_pfc_phys_to_virt(pfc, 0xe606008c);
+
+	/* Bits in IOCTRL6 are numbered in opposite order to pins */
+	mask = 0x80000000 >> (pin & 0x1f);
+
+	data = sh_pfc_read_raw_reg(mapped_reg, 32);
+
+	if (low)
+		data &= ~mask;
+	else
+		data |= mask;
+
+	sh_pfc_write_raw_reg(
+		sh_pfc_phys_to_virt(pfc, pfc->info->unlock_reg), 32,
+		~data);
+	sh_pfc_write_raw_reg(mapped_reg, 32, data);
+}
+
 static const struct sh_pfc_function pinmux_functions[] = {
 	SH_PFC_FUNCTION(audio_clk),
 	SH_PFC_FUNCTION(avb),

@@ -5586,8 +5645,14 @@ static const struct pinmux_cfg_reg

pinmux_config_regs[] = { { },
 };

+static const struct sh_pfc_soc_operations pinmux_ops = {
+	.get_low_voltage = sdhi_get_low_voltage,
+	.set_low_voltage = sdhi_set_low_voltage,
+};
+
 const struct sh_pfc_soc_info r8a7790_pinmux_info = {
 	.name = "r8a77900_pfc",
+	.ops = &pinmux_ops,
 	.unlock_reg = 0xe6060000, /* PMMR */

 	.function = { PINMUX_FUNCTION_BEGIN, PINMUX_FUNCTION_END },