linux-kernel - [PATCH v2] i2c: cadence: Add shutdown handler

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Message-ID: <20250724051243.22051-1-ajay.neeli@amd.com>
Date: Thu, 24 Jul 2025 10:42:43 +0530
From: Ajay Neeli <ajay.neeli@....com>
To: <git@....com>, <andi.shyti@...nel.org>,
	<linux-arm-kernel@...ts.infradead.org>, <linux-i2c@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <michal.simek@....com>, <srinivas.goud@....com>,
	<radhey.shyam.pandey@....com>, Ajay Neeli <ajay.neeli@....com>
Subject: [PATCH v2] i2c: cadence: Add shutdown handler

Implement shutdown function for Cadence I2C driver to suspend the bus
during system "reboot" or "shutdown".

Interrupts are disabled in the handler to avoid spurious events when the
driver is in slave mode.

Signed-off-by: Ajay Neeli <ajay.neeli@....com>
---
Changes in V2:
Disable interrupts
---
 drivers/i2c/busses/i2c-cadence.c | 32 ++++++++++++++++++++++++++------
 1 file changed, 26 insertions(+), 6 deletions(-)

diff --git a/drivers/i2c/busses/i2c-cadence.c b/drivers/i2c/busses/i2c-cadence.c
index 8df63aa..e0a56df 100644
--- a/drivers/i2c/busses/i2c-cadence.c
+++ b/drivers/i2c/busses/i2c-cadence.c
@@ -192,6 +192,7 @@ enum cdns_i2c_slave_state {
  * @transfer_size:	The maximum number of bytes in one transfer
  * @atomic:		Mode of transfer
  * @err_status_atomic:	Error status in atomic mode
+ * @irq:		IRQ Number
  */
 struct cdns_i2c {
 	struct device		*dev;
@@ -224,6 +225,7 @@ struct cdns_i2c {
 	unsigned int transfer_size;
 	bool atomic;
 	int err_status_atomic;
+	int irq;
 };
 
 struct cdns_platform_data {
@@ -1495,7 +1497,7 @@ static int cdns_i2c_probe(struct platform_device *pdev)
 {
 	struct resource *r_mem;
 	struct cdns_i2c *id;
-	int ret, irq;
+	int ret;
 	const struct of_device_id *match;
 
 	id = devm_kzalloc(&pdev->dev, sizeof(*id), GFP_KERNEL);
@@ -1526,9 +1528,9 @@ static int cdns_i2c_probe(struct platform_device *pdev)
 	if (IS_ERR(id->membase))
 		return PTR_ERR(id->membase);
 
-	irq = platform_get_irq(pdev, 0);
-	if (irq < 0)
-		return irq;
+	id->irq = platform_get_irq(pdev, 0);
+	if (id->irq < 0)
+		return id->irq;
 
 	id->adap.owner = THIS_MODULE;
 	id->adap.dev.of_node = pdev->dev.of_node;
@@ -1590,10 +1592,10 @@ static int cdns_i2c_probe(struct platform_device *pdev)
 		goto err_clk_notifier_unregister;
 	}
 
-	ret = devm_request_irq(&pdev->dev, irq, cdns_i2c_isr, 0,
+	ret = devm_request_irq(&pdev->dev, id->irq, cdns_i2c_isr, 0,
 				 DRIVER_NAME, id);
 	if (ret) {
-		dev_err(&pdev->dev, "cannot get irq %d\n", irq);
+		dev_err(&pdev->dev, "cannot get irq %d\n", id->irq);
 		goto err_clk_notifier_unregister;
 	}
 	cdns_i2c_init(id);
@@ -1636,6 +1638,23 @@ static void cdns_i2c_remove(struct platform_device *pdev)
 	reset_control_assert(id->reset);
 }
 
+/**
+ * cdns_i2c_shutdown - Shutdown the i2c device
+ * @pdev:	Handle to the platform device structure
+ *
+ * This function handles shutdown sequence
+ */
+static void cdns_i2c_shutdown(struct platform_device *pdev)
+{
+	struct cdns_i2c *id = platform_get_drvdata(pdev);
+
+	/* Disable interrupts */
+	disable_irq(id->irq);
+
+	/* Initiate failure of client i2c transfers */
+	i2c_mark_adapter_suspended(&id->adap);
+}
+
 static struct platform_driver cdns_i2c_drv = {
 	.driver = {
 		.name  = DRIVER_NAME,
@@ -1644,6 +1663,7 @@ static void cdns_i2c_remove(struct platform_device *pdev)
 	},
 	.probe  = cdns_i2c_probe,
 	.remove = cdns_i2c_remove,
+	.shutdown = cdns_i2c_shutdown,
 };
 
 module_platform_driver(cdns_i2c_drv);
-- 
1.8.3.1