[PATCH 4/4] can: c_can: Add d_can suspend resume support

[anilkumar@ti.com (AnilKumar Ch)]

Adds suspend resume support to DCAN driver which enables
DCAN power down mode bit (PDR). Then DCAN will ack the local
power-down mode by setting PDA bit in STATUS register.

Also adds a status flag to know the status of DCAN module,
whether it is opened or not.

Signed-off-by: AnilKumar Ch <anilkumar@ti.com>
---
 drivers/net/can/c_can/c_can.c          |   78 ++++++++++++++++++++++++++++++++
 drivers/net/can/c_can/c_can.h          |    5 ++
 drivers/net/can/c_can/c_can_platform.c |   70 ++++++++++++++++++++++++++--
 3 files changed, 150 insertions(+), 3 deletions(-)

diff --git a/drivers/net/can/c_can/c_can.c b/drivers/net/can/c_can/c_can.c
index c175410..36d5db4 100644
--- a/drivers/net/can/c_can/c_can.c
+++ b/drivers/net/can/c_can/c_can.c
@@ -46,6 +46,9 @@
 #define IF_ENUM_REG_LEN		11
 #define C_CAN_IFACE(reg, iface)	(C_CAN_IF1_##reg + (iface) * IF_ENUM_REG_LEN)
 
+/* control extension register D_CAN specific */
+#define CONTROL_EX_PDR		BIT(8)
+
 /* control register */
 #define CONTROL_TEST		BIT(7)
 #define CONTROL_CCE		BIT(6)
@@ -65,6 +68,7 @@
 #define TEST_BASIC		BIT(2)
 
 /* status register */
+#define STATUS_PDA		BIT(10)
 #define STATUS_BOFF		BIT(7)
 #define STATUS_EWARN		BIT(6)
 #define STATUS_EPASS		BIT(5)
@@ -164,6 +168,9 @@
 /* minimum timeout for checking BUSY status */
 #define MIN_TIMEOUT_VALUE	6
 
+/* Wait for ~1 sec for INIT bit */
+#define INIT_WAIT_COUNT		1000
+
 /* napi related */
 #define C_CAN_NAPI_WEIGHT	C_CAN_MSG_OBJ_RX_NUM
 
@@ -1102,6 +1109,7 @@ static int c_can_open(struct net_device *dev)
 
 	netif_start_queue(dev);
 
+	priv->is_opened = true;
 	return 0;
 
 exit_irq_fail:
@@ -1126,6 +1134,7 @@ static int c_can_close(struct net_device *dev)
 	/* De-Initialize DCAN RAM */
 	c_can_reset_ram(priv, false);
 	c_can_pm_runtime_put_sync(priv);
+	priv->is_opened = false;
 
 	return 0;
 }
@@ -1154,6 +1163,75 @@ struct net_device *alloc_c_can_dev(void)
 }
 EXPORT_SYMBOL_GPL(alloc_c_can_dev);
 
+#ifdef CONFIG_PM
+int c_can_power_down(struct net_device *dev)
+{
+	unsigned long time_out;
+	struct c_can_priv *priv = netdev_priv(dev);
+
+	if (!priv->is_opened)
+		return 0;
+
+	/* set `PDR` value so the device goes to power down mode */
+	priv->write_reg(priv, C_CAN_CTRL_EX_REG,
+		priv->read_reg(priv, C_CAN_CTRL_EX_REG) | CONTROL_EX_PDR);
+
+	/* Wait for the PDA bit to get set */
+	time_out = jiffies + msecs_to_jiffies(INIT_WAIT_COUNT);
+	while (!(priv->read_reg(priv, C_CAN_STS_REG) & STATUS_PDA) &&
+				time_after(time_out, jiffies))
+		cpu_relax();
+
+	if (time_after(jiffies, time_out))
+		return -ETIMEDOUT;
+
+	c_can_stop(dev);
+
+	/* De-initialize DCAN RAM */
+	c_can_reset_ram(priv, false);
+	c_can_pm_runtime_put_sync(priv);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(c_can_power_down);
+
+int c_can_power_up(struct net_device *dev)
+{
+	unsigned long time_out;
+	struct c_can_priv *priv = netdev_priv(dev);
+
+	if (!priv->is_opened)
+		return 0;
+
+	c_can_pm_runtime_get_sync(priv);
+	/* Initialize DCAN RAM */
+	c_can_reset_ram(priv, true);
+
+	/* Clear PDR and INIT bits */
+	priv->write_reg(priv, C_CAN_CTRL_EX_REG,
+		priv->read_reg(priv, C_CAN_CTRL_EX_REG) & ~CONTROL_EX_PDR);
+	priv->write_reg(priv, C_CAN_CTRL_REG,
+		priv->read_reg(priv, C_CAN_CTRL_REG) & ~CONTROL_INIT);
+
+	/* Wait for the PDA bit to get clear */
+	time_out = jiffies + msecs_to_jiffies(INIT_WAIT_COUNT);
+	while ((priv->read_reg(priv, C_CAN_STS_REG) & STATUS_PDA) &&
+				time_after(time_out, jiffies))
+		cpu_relax();
+
+	if (time_after(jiffies, time_out))
+		return -ETIMEDOUT;
+
+	c_can_start(dev);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(c_can_power_up);
+#else
+#define c_can_power_down NULL
+#define c_can_power_up NULL
+#endif
+
 void free_c_can_dev(struct net_device *dev)
 {
 	free_candev(dev);
diff --git a/drivers/net/can/c_can/c_can.h b/drivers/net/can/c_can/c_can.h
index 5f6339c..e5dd7ef 100644
--- a/drivers/net/can/c_can/c_can.h
+++ b/drivers/net/can/c_can/c_can.h
@@ -24,6 +24,7 @@
 
 enum reg {
 	C_CAN_CTRL_REG = 0,
+	C_CAN_CTRL_EX_REG,
 	C_CAN_STS_REG,
 	C_CAN_ERR_CNT_REG,
 	C_CAN_BTR_REG,
@@ -104,6 +105,7 @@ static const u16 reg_map_c_can[] = {
 
 static const u16 reg_map_d_can[] = {
 	[C_CAN_CTRL_REG]	= 0x00,
+	[C_CAN_CTRL_EX_REG]	= 0x02,
 	[C_CAN_STS_REG]		= 0x04,
 	[C_CAN_ERR_CNT_REG]	= 0x08,
 	[C_CAN_BTR_REG]		= 0x0C,
@@ -166,6 +168,7 @@ struct c_can_priv {
 	unsigned int tx_echo;
 	void *priv;		/* for board-specific data */
 	u16 irqstatus;
+	bool is_opened;
 	unsigned int instance;
 	void (*ram_init) (unsigned int instance, bool enable);
 };
@@ -174,5 +177,7 @@ struct net_device *alloc_c_can_dev(void);
 void free_c_can_dev(struct net_device *dev);
 int register_c_can_dev(struct net_device *dev);
 void unregister_c_can_dev(struct net_device *dev);
+int c_can_power_up(struct net_device *dev);
+int c_can_power_down(struct net_device *dev);
 
 #endif /* C_CAN_H */
diff --git a/drivers/net/can/c_can/c_can_platform.c b/drivers/net/can/c_can/c_can_platform.c
index c6963b2..65ec232 100644
--- a/drivers/net/can/c_can/c_can_platform.c
+++ b/drivers/net/can/c_can/c_can_platform.c
@@ -255,15 +255,79 @@ static int __devexit c_can_plat_remove(struct platform_device *pdev)
 	return 0;
 }
 
+#ifdef CONFIG_PM
+static int c_can_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	int ret;
+	struct net_device *ndev = platform_get_drvdata(pdev);
+	struct c_can_priv *priv = netdev_priv(ndev);
+	const struct platform_device_id *id = platform_get_device_id(pdev);
+
+	if (id->driver_data != BOSCH_D_CAN) {
+		dev_warn(&pdev->dev, "Not supported\n");
+		return 0;
+	}
+
+	if (netif_running(ndev)) {
+		netif_stop_queue(ndev);
+		netif_device_detach(ndev);
+	}
+
+	ret = c_can_power_down(ndev);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enter power down mode\n");
+		return ret;
+	}
+
+	priv->can.state = CAN_STATE_SLEEPING;
+
+	return 0;
+}
+
+static int c_can_resume(struct platform_device *pdev)
+{
+	int ret;
+
+	struct net_device *ndev = platform_get_drvdata(pdev);
+	struct c_can_priv *priv = netdev_priv(ndev);
+	const struct platform_device_id *id = platform_get_device_id(pdev);
+
+	if (id->driver_data != BOSCH_D_CAN) {
+		dev_warn(&pdev->dev, "Not supported\n");
+		return 0;
+	}
+
+	ret = c_can_power_up(ndev);
+	if (ret) {
+		dev_err(&pdev->dev, "Still in power down mode\n");
+		return ret;
+	}
+
+	priv->can.state = CAN_STATE_ERROR_ACTIVE;
+
+	if (netif_running(ndev)) {
+		netif_device_attach(ndev);
+		netif_start_queue(ndev);
+	}
+
+	return 0;
+}
+#else
+#define c_can_suspend NULL
+#define c_can_resume NULL
+#endif
+
 static struct platform_driver c_can_plat_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
 		.owner = THIS_MODULE,
 		.of_match_table = of_match_ptr(c_can_of_table),
 	},
-	.probe = c_can_plat_probe,
-	.remove = __devexit_p(c_can_plat_remove),
-	.id_table = c_can_id_table,
+	.probe		= c_can_plat_probe,
+	.remove		= __devexit_p(c_can_plat_remove),
+	.suspend	= c_can_suspend,
+	.resume		= c_can_resume,
+	.id_table	= c_can_id_table,
 };
 
 module_platform_driver(c_can_plat_driver);
-- 
1.7.9.5