[PATCH 5/6] i2c: i2c-stm32f7: allow controller to be wakeup-source

[Alain Volmat]

Allow the i2c-stm32f7 controller to become a wakeup-source
of the system. In such case, when a slave is registered to the
I2C controller, receiving a I2C message targeting that registered
slave address wakes up the suspended system.

In order to be able to wake-up, the I2C controller DT node
must have the property wakeup-source defined and a slave
must be registered.

Signed-off-by: Alain Volmat <alain.volmat@xxxxxx>
---
 drivers/i2c/busses/i2c-stm32f7.c | 98 ++++++++++++++++++++++++++++++++++------
 1 file changed, 83 insertions(+), 15 deletions(-)

diff --git a/drivers/i2c/busses/i2c-stm32f7.c b/drivers/i2c/busses/i2c-stm32f7.c
index 5c3e8ac6ad92..844a22d64aa8 100644
--- a/drivers/i2c/busses/i2c-stm32f7.c
+++ b/drivers/i2c/busses/i2c-stm32f7.c
@@ -29,6 +29,7 @@
 #include <linux/platform_device.h>
 #include <linux/pinctrl/consumer.h>
 #include <linux/pm_runtime.h>
+#include <linux/pm_wakeirq.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
 #include <linux/slab.h>
@@ -49,6 +50,7 @@
 
 /* STM32F7 I2C control 1 */
 #define STM32F7_I2C_CR1_PECEN			BIT(23)
+#define STM32F7_I2C_CR1_WUPEN			BIT(18)
 #define STM32F7_I2C_CR1_SBC			BIT(16)
 #define STM32F7_I2C_CR1_RXDMAEN			BIT(15)
 #define STM32F7_I2C_CR1_TXDMAEN			BIT(14)
@@ -301,6 +303,7 @@ struct stm32f7_i2c_msg {
  * @dma: dma data
  * @use_dma: boolean to know if dma is used in the current transfer
  * @regmap: holds SYSCFG phandle for Fast Mode Plus bits
+ * @wakeup_src: boolean to know if the device is a wakeup source
  */
 struct stm32f7_i2c_dev {
 	struct i2c_adapter adap;
@@ -323,6 +326,7 @@ struct stm32f7_i2c_dev {
 	struct stm32_i2c_dma *dma;
 	bool use_dma;
 	struct regmap *regmap;
+	bool wakeup_src;
 };
 
 /*
@@ -1691,6 +1695,9 @@ static int stm32f7_i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr,
 	return ret;
 }
 
+static void stm32f7_i2c_enable_wakeup(struct stm32f7_i2c_dev *i2c_dev,
+				      bool enable);
+
 static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
 {
 	struct stm32f7_i2c_dev *i2c_dev = i2c_get_adapdata(slave->adapter);
@@ -1717,6 +1724,9 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
 	if (ret < 0)
 		return ret;
 
+	if (!stm32f7_i2c_is_slave_registered(i2c_dev))
+		stm32f7_i2c_enable_wakeup(i2c_dev, true);
+
 	if (id == 0) {
 		/* Configure Own Address 1 */
 		oar1 = readl_relaxed(i2c_dev->base + STM32F7_I2C_OAR1);
@@ -1758,6 +1768,9 @@ static int stm32f7_i2c_reg_slave(struct i2c_client *slave)
 
 	ret = 0;
 pm_free:
+	if (!stm32f7_i2c_is_slave_registered(i2c_dev))
+		stm32f7_i2c_enable_wakeup(i2c_dev, false);
+
 	pm_runtime_mark_last_busy(dev);
 	pm_runtime_put_autosuspend(dev);
 
@@ -1791,8 +1804,10 @@ static int stm32f7_i2c_unreg_slave(struct i2c_client *slave)
 
 	i2c_dev->slave[id] = NULL;
 
-	if (!(stm32f7_i2c_is_slave_registered(i2c_dev)))
+	if (!stm32f7_i2c_is_slave_registered(i2c_dev)) {
 		stm32f7_i2c_disable_irq(i2c_dev, STM32F7_I2C_ALL_IRQ_MASK);
+		stm32f7_i2c_enable_wakeup(i2c_dev, false);
+	}
 
 	pm_runtime_mark_last_busy(i2c_dev->dev);
 	pm_runtime_put_autosuspend(i2c_dev->dev);
@@ -1879,6 +1894,9 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 		return irq_error ? : -ENOENT;
 	}
 
+	i2c_dev->wakeup_src = of_property_read_bool(pdev->dev.of_node,
+						    "wakeup-source");
+
 	i2c_dev->clk = devm_clk_get(&pdev->dev, NULL);
 	if (IS_ERR(i2c_dev->clk)) {
 		dev_err(&pdev->dev, "Error: Missing controller clock\n");
@@ -1985,6 +2003,16 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 		goto clk_free;
 	}
 
+	if (i2c_dev->wakeup_src) {
+		device_set_wakeup_capable(i2c_dev->dev, true);
+
+		ret = dev_pm_set_wake_irq(i2c_dev->dev, irq_event);
+		if (ret) {
+			dev_err(i2c_dev->dev, "Failed to set wake up irq\n");
+			goto clr_wakeup_capable;
+		}
+	}
+
 	platform_set_drvdata(pdev, i2c_dev);
 
 	pm_runtime_set_autosuspend_delay(i2c_dev->dev,
@@ -2014,6 +2042,13 @@ static int stm32f7_i2c_probe(struct platform_device *pdev)
 	pm_runtime_set_suspended(i2c_dev->dev);
 	pm_runtime_dont_use_autosuspend(i2c_dev->dev);
 
+	if (i2c_dev->wakeup_src)
+		dev_pm_clear_wake_irq(i2c_dev->dev);
+
+clr_wakeup_capable:
+	if (i2c_dev->wakeup_src)
+		device_set_wakeup_capable(i2c_dev->dev, false);
+
 	if (i2c_dev->dma) {
 		stm32_i2c_dma_free(i2c_dev->dma);
 		i2c_dev->dma = NULL;
@@ -2032,6 +2067,15 @@ static int stm32f7_i2c_remove(struct platform_device *pdev)
 	i2c_del_adapter(&i2c_dev->adap);
 	pm_runtime_get_sync(i2c_dev->dev);
 
+	if (i2c_dev->wakeup_src) {
+		dev_pm_clear_wake_irq(i2c_dev->dev);
+		/*
+		 * enforce that wakeup is disabled and that the device
+		 * is marked as non wakeup capable
+		 */
+		device_init_wakeup(i2c_dev->dev, false);
+	}
+
 	pm_runtime_put_noidle(i2c_dev->dev);
 	pm_runtime_disable(i2c_dev->dev);
 	pm_runtime_set_suspended(i2c_dev->dev);
@@ -2127,20 +2171,41 @@ stm32f7_i2c_regs_restore(struct stm32f7_i2c_dev *i2c_dev)
 	return ret;
 }
 
+static void stm32f7_i2c_enable_wakeup(struct stm32f7_i2c_dev *i2c_dev,
+				      bool enable)
+{
+	void __iomem *base = i2c_dev->base;
+	u32 mask = STM32F7_I2C_CR1_WUPEN;
+
+	if (!i2c_dev->wakeup_src)
+		return;
+
+	if (enable) {
+		device_set_wakeup_enable(i2c_dev->dev, true);
+		stm32f7_i2c_set_bits(base + STM32F7_I2C_CR1, mask);
+	} else {
+		device_set_wakeup_enable(i2c_dev->dev, false);
+		stm32f7_i2c_clr_bits(base + STM32F7_I2C_CR1, mask);
+	}
+}
+
 static int __maybe_unused stm32f7_i2c_suspend(struct device *dev)
 {
 	struct stm32f7_i2c_dev *i2c_dev = dev_get_drvdata(dev);
 	int ret;
 
 	i2c_mark_adapter_suspended(&i2c_dev->adap);
-	ret = stm32f7_i2c_regs_backup(i2c_dev);
-	if (ret < 0) {
-		i2c_mark_adapter_resumed(&i2c_dev->adap);
-		return ret;
-	}
 
-	pinctrl_pm_select_sleep_state(dev);
-	pm_runtime_force_suspend(dev);
+	if (!device_may_wakeup(dev) && !dev->power.wakeup_path) {
+		ret = stm32f7_i2c_regs_backup(i2c_dev);
+		if (ret < 0) {
+			i2c_mark_adapter_resumed(&i2c_dev->adap);
+			return ret;
+		}
+
+		pinctrl_pm_select_sleep_state(dev);
+		pm_runtime_force_suspend(dev);
+	}
 
 	return 0;
 }
@@ -2150,14 +2215,17 @@ static int __maybe_unused stm32f7_i2c_resume(struct device *dev)
 	struct stm32f7_i2c_dev *i2c_dev = dev_get_drvdata(dev);
 	int ret;
 
-	ret = pm_runtime_force_resume(dev);
-	if (ret < 0)
-		return ret;
-	pinctrl_pm_select_default_state(dev);
+	if (!device_may_wakeup(dev) && !dev->power.wakeup_path) {
+		ret = pm_runtime_force_resume(dev);
+		if (ret < 0)
+			return ret;
+		pinctrl_pm_select_default_state(dev);
+
+		ret = stm32f7_i2c_regs_restore(i2c_dev);
+		if (ret < 0)
+			return ret;
+	}
 
-	ret = stm32f7_i2c_regs_restore(i2c_dev);
-	if (ret < 0)
-		return ret;
 	i2c_mark_adapter_resumed(&i2c_dev->adap);
 
 	return 0;
-- 
2.7.4