pinctrl: stm32: add suspend/resume management

During power sequence, GPIO hardware registers could be lost if the power
supply is switched off. Each device using pinctrl API is in charge of
managing pins during suspend/resume sequences. But for pins used as gpio or
irq stm32 pinctrl driver has to save the hardware configuration.
Signed-off-by: Alexandre Torgue <alexandre.torgue@st.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/stm32/pinctrl-stm32.c

@@ -44,6 +44,18 @@
 #define STM32_GPIO_AFRL		0x20
 #define STM32_GPIO_AFRH		0x24
 
+/* custom bitfield to backup pin status */
+#define STM32_GPIO_BKP_MODE_SHIFT	0
+#define STM32_GPIO_BKP_MODE_MASK	GENMASK(1, 0)
+#define STM32_GPIO_BKP_ALT_SHIFT	2
+#define STM32_GPIO_BKP_ALT_MASK		GENMASK(5, 2)
+#define STM32_GPIO_BKP_SPEED_SHIFT	6
+#define STM32_GPIO_BKP_SPEED_MASK	GENMASK(7, 6)
+#define STM32_GPIO_BKP_PUPD_SHIFT	8
+#define STM32_GPIO_BKP_PUPD_MASK	GENMASK(9, 8)
+#define STM32_GPIO_BKP_TYPE		10
+#define STM32_GPIO_BKP_VAL		11
+
 #define STM32_GPIO_PINS_PER_BANK 16
 #define STM32_GPIO_IRQ_LINE	 16
 
@@ -79,6 +91,7 @@ struct stm32_gpio_bank {
 	struct irq_domain *domain;
 	u32 bank_nr;
 	u32 bank_ioport_nr;
+	u32 pin_backup[STM32_GPIO_PINS_PER_BANK];
 };
 
 struct stm32_pinctrl {
@@ -133,11 +146,50 @@ static inline u32 stm32_gpio_get_alt(u32 function)
 	return 0;
 }
 
+static void stm32_gpio_backup_value(struct stm32_gpio_bank *bank,
+				    u32 offset, u32 value)
+{
+	bank->pin_backup[offset] &= ~BIT(STM32_GPIO_BKP_VAL);
+	bank->pin_backup[offset] |= value << STM32_GPIO_BKP_VAL;
+}
+
+static void stm32_gpio_backup_mode(struct stm32_gpio_bank *bank, u32 offset,
+				   u32 mode, u32 alt)
+{
+	bank->pin_backup[offset] &= ~(STM32_GPIO_BKP_MODE_MASK |
+				      STM32_GPIO_BKP_ALT_MASK);
+	bank->pin_backup[offset] |= mode << STM32_GPIO_BKP_MODE_SHIFT;
+	bank->pin_backup[offset] |= alt << STM32_GPIO_BKP_ALT_SHIFT;
+}
+
+static void stm32_gpio_backup_driving(struct stm32_gpio_bank *bank, u32 offset,
+				      u32 drive)
+{
+	bank->pin_backup[offset] &= ~BIT(STM32_GPIO_BKP_TYPE);
+	bank->pin_backup[offset] |= drive << STM32_GPIO_BKP_TYPE;
+}
+
+static void stm32_gpio_backup_speed(struct stm32_gpio_bank *bank, u32 offset,
+				    u32 speed)
+{
+	bank->pin_backup[offset] &= ~STM32_GPIO_BKP_SPEED_MASK;
+	bank->pin_backup[offset] |= speed << STM32_GPIO_BKP_SPEED_SHIFT;
+}
+
+static void stm32_gpio_backup_bias(struct stm32_gpio_bank *bank, u32 offset,
+				   u32 bias)
+{
+	bank->pin_backup[offset] &= ~STM32_GPIO_BKP_PUPD_MASK;
+	bank->pin_backup[offset] |= bias << STM32_GPIO_BKP_PUPD_SHIFT;
+}
+
 /* GPIO functions */
 
 static inline void __stm32_gpio_set(struct stm32_gpio_bank *bank,
 	unsigned offset, int value)
 {
+	stm32_gpio_backup_value(bank, offset, value);
+
 	if (!value)
 		offset += STM32_GPIO_PINS_PER_BANK;
 
@@ -620,6 +672,8 @@ static int stm32_pmx_set_mode(struct stm32_gpio_bank *bank,
 	if (pctl->hwlock)
 		hwspin_unlock(pctl->hwlock);
 
+	stm32_gpio_backup_mode(bank, pin, mode, alt);
+
 unlock:
 	spin_unlock_irqrestore(&bank->lock, flags);
 	clk_disable(bank->clk);
@@ -732,6 +786,8 @@ static int stm32_pconf_set_driving(struct stm32_gpio_bank *bank,
 	if (pctl->hwlock)
 		hwspin_unlock(pctl->hwlock);
 
+	stm32_gpio_backup_driving(bank, offset, drive);
+
 unlock:
 	spin_unlock_irqrestore(&bank->lock, flags);
 	clk_disable(bank->clk);
@@ -784,6 +840,8 @@ static int stm32_pconf_set_speed(struct stm32_gpio_bank *bank,
 	if (pctl->hwlock)
 		hwspin_unlock(pctl->hwlock);
 
+	stm32_gpio_backup_speed(bank, offset, speed);
+
 unlock:
 	spin_unlock_irqrestore(&bank->lock, flags);
 	clk_disable(bank->clk);
@@ -836,6 +894,8 @@ static int stm32_pconf_set_bias(struct stm32_gpio_bank *bank,
 	if (pctl->hwlock)
 		hwspin_unlock(pctl->hwlock);
 
+	stm32_gpio_backup_bias(bank, offset, bias);
+
 unlock:
 	spin_unlock_irqrestore(&bank->lock, flags);
 	clk_disable(bank->clk);
@@ -1369,3 +1429,75 @@ int stm32_pctl_probe(struct platform_device *pdev)
 
 	return 0;
 }
+
+static int __maybe_unused stm32_pinctrl_restore_gpio_regs(
+					struct stm32_pinctrl *pctl, u32 pin)
+{
+	const struct pin_desc *desc = pin_desc_get(pctl->pctl_dev, pin);
+	u32 val, alt, mode, offset = stm32_gpio_pin(pin);
+	struct pinctrl_gpio_range *range;
+	struct stm32_gpio_bank *bank;
+	bool pin_is_irq;
+	int ret;
+
+	range = pinctrl_find_gpio_range_from_pin(pctl->pctl_dev, pin);
+	if (!range)
+		return 0;
+
+	pin_is_irq = gpiochip_line_is_irq(range->gc, offset);
+
+	if (!desc || (!pin_is_irq && !desc->gpio_owner))
+		return 0;
+
+	bank = gpiochip_get_data(range->gc);
+
+	alt = bank->pin_backup[offset] & STM32_GPIO_BKP_ALT_MASK;
+	alt >>= STM32_GPIO_BKP_ALT_SHIFT;
+	mode = bank->pin_backup[offset] & STM32_GPIO_BKP_MODE_MASK;
+	mode >>= STM32_GPIO_BKP_MODE_SHIFT;
+
+	ret = stm32_pmx_set_mode(bank, offset, mode, alt);
+	if (ret)
+		return ret;
+
+	if (mode == 1) {
+		val = bank->pin_backup[offset] & BIT(STM32_GPIO_BKP_VAL);
+		val = val >> STM32_GPIO_BKP_VAL;
+		__stm32_gpio_set(bank, offset, val);
+	}
+
+	val = bank->pin_backup[offset] & BIT(STM32_GPIO_BKP_TYPE);
+	val >>= STM32_GPIO_BKP_TYPE;
+	ret = stm32_pconf_set_driving(bank, offset, val);
+	if (ret)
+		return ret;
+
+	val = bank->pin_backup[offset] & STM32_GPIO_BKP_SPEED_MASK;
+	val >>= STM32_GPIO_BKP_SPEED_SHIFT;
+	ret = stm32_pconf_set_speed(bank, offset, val);
+	if (ret)
+		return ret;
+
+	val = bank->pin_backup[offset] & STM32_GPIO_BKP_PUPD_MASK;
+	val >>= STM32_GPIO_BKP_PUPD_SHIFT;
+	ret = stm32_pconf_set_bias(bank, offset, val);
+	if (ret)
+		return ret;
+
+	if (pin_is_irq)
+		regmap_field_write(pctl->irqmux[offset], bank->bank_ioport_nr);
+
+	return 0;
+}
+
+int __maybe_unused stm32_pinctrl_resume(struct device *dev)
+{
+	struct stm32_pinctrl *pctl = dev_get_drvdata(dev);
+	struct stm32_pinctrl_group *g = pctl->groups;
+	int i;
+
+	for (i = g->pin; i < g->pin + pctl->ngroups; i++)
+		stm32_pinctrl_restore_gpio_regs(pctl, i);
+
+	return 0;
+}

drivers/pinctrl/stm32/pinctrl-stm32.h

@@ -65,5 +65,7 @@ struct stm32_gpio_bank;
 int stm32_pctl_probe(struct platform_device *pdev);
 void stm32_pmx_get_mode(struct stm32_gpio_bank *bank,
 			int pin, u32 *mode, u32 *alt);
+int stm32_pinctrl_resume(struct device *dev);
+
 #endif /* __PINCTRL_STM32_H */