Message-ID: <20251216131442.8464-4-heikki.krogerus@linux.intel.com>
Date: Tue, 16 Dec 2025 14:14:38 +0100
From: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
To: Andi Shyti <andi.shyti@...nel.org>,
	Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc: Jan Dabros <jsd@...ihalf.com>,
	Raag Jadav <raag.jadav@...el.com>,
	linux-i2c@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v1 3/6] i2c: designware: Combine some of the common functions

The adapter can be registered just in the core instead of
separately in the master and slave drivers. The same applies
to the interrupt.

Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
---
 drivers/i2c/busses/i2c-designware-common.c | 108 +++++++++++++++++++--
 drivers/i2c/busses/i2c-designware-core.h   |  11 ++-
 drivers/i2c/busses/i2c-designware-master.c |  97 +++---------------
 drivers/i2c/busses/i2c-designware-slave.c  |  53 ++--------
 4 files changed, 126 insertions(+), 143 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index 5b1e8f74c4ac..1823e4b71004 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -131,7 +131,7 @@ static int dw_reg_write_word(void *context, unsigned int reg, unsigned int val)
  *
  * Return: 0 on success, or negative errno otherwise.
  */
-int i2c_dw_init_regmap(struct dw_i2c_dev *dev)
+static int i2c_dw_init_regmap(struct dw_i2c_dev *dev)
 {
 	struct regmap_config map_cfg = {
 		.reg_bits = 32,
@@ -457,7 +457,7 @@ u32 i2c_dw_scl_lcnt(struct dw_i2c_dev *dev, unsigned int reg, u32 ic_clk,
 	return DIV_ROUND_CLOSEST_ULL((u64)ic_clk * (tLOW + tf), MICRO) - 1 + offset;
 }
 
-int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)
+static int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)
 {
 	unsigned int reg;
 	int ret;
@@ -672,7 +672,7 @@ int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev)
 	return -EIO;
 }
 
-int i2c_dw_set_fifo_size(struct dw_i2c_dev *dev)
+static int i2c_dw_set_fifo_size(struct dw_i2c_dev *dev)
 {
 	u32 tx_fifo_depth, rx_fifo_depth;
 	unsigned int param;
@@ -741,19 +741,113 @@ void i2c_dw_disable(struct dw_i2c_dev *dev)
 }
 EXPORT_SYMBOL_GPL(i2c_dw_disable);
 
+static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
+{
+	struct dw_i2c_dev *dev = dev_id;
+
+	if (dev->mode == DW_IC_SLAVE)
+		return i2c_dw_isr_slave(dev);
+
+	return i2c_dw_isr_master(dev);
+}
+
+static const struct i2c_algorithm i2c_dw_algo = {
+	.xfer = i2c_dw_xfer,
+	.functionality = i2c_dw_func,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+	.reg_slave = i2c_dw_reg_slave,
+	.unreg_slave = i2c_dw_unreg_slave,
+#endif
+};
+
+static const struct i2c_adapter_quirks i2c_dw_quirks = {
+	.flags = I2C_AQ_NO_ZERO_LEN,
+};
+
 int i2c_dw_probe(struct dw_i2c_dev *dev)
 {
+	struct i2c_adapter *adap = &dev->adapter;
+	unsigned long irq_flags;
+	int ret;
+
 	device_set_node(&dev->adapter.dev, dev_fwnode(dev->dev));
 
+	ret = i2c_dw_init_regmap(dev);
+	if (ret)
+		return ret;
+
+	ret = i2c_dw_set_sda_hold(dev);
+	if (ret)
+		return ret;
+
+	ret = i2c_dw_set_fifo_size(dev);
+	if (ret)
+		return ret;
+
 	switch (dev->mode) {
 	case DW_IC_SLAVE:
-		return i2c_dw_probe_slave(dev);
+		ret = i2c_dw_probe_slave(dev);
+		break;
 	case DW_IC_MASTER:
-		return i2c_dw_probe_master(dev);
+		ret = i2c_dw_probe_master(dev);
+		break;
 	default:
-		dev_err(dev->dev, "Wrong operation mode: %d\n", dev->mode);
-		return -EINVAL;
+		ret = -EINVAL;
+		break;
 	}
+	if (ret)
+		return ret;
+
+	ret = dev->init(dev);
+	if (ret)
+		return ret;
+
+	if (!adap->name[0])
+		strscpy(adap->name, "Synopsys DesignWare I2C adapter");
+
+	adap->retries = 3;
+	adap->algo = &i2c_dw_algo;
+	adap->quirks = &i2c_dw_quirks;
+	adap->dev.parent = dev->dev;
+	i2c_set_adapdata(adap, dev);
+
+	/*
+	 * REVISIT: The mode check may not be necessary.
+	 * For now keeping the flags as they were originally.
+	 */
+	if (dev->mode == DW_IC_SLAVE)
+		irq_flags = IRQF_SHARED;
+	else if (dev->flags & ACCESS_NO_IRQ_SUSPEND)
+		irq_flags = IRQF_NO_SUSPEND;
+	else
+		irq_flags = IRQF_SHARED | IRQF_COND_SUSPEND;
+
+	ret = i2c_dw_acquire_lock(dev);
+	if (ret)
+		return ret;
+
+	__i2c_dw_write_intr_mask(dev, 0);
+	i2c_dw_release_lock(dev);
+
+	if (!(dev->flags & ACCESS_POLLING)) {
+		ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr,
+				       irq_flags, dev_name(dev->dev), dev);
+		if (ret)
+			return ret;
+	}
+
+	/*
+	 * Increment PM usage count during adapter registration in order to
+	 * avoid possible spurious runtime suspend when adapter device is
+	 * registered to the device core and immediate resume in case bus has
+	 * registered I2C slaves that do I2C transfers in their probe.
+	 */
+	ACQUIRE(pm_runtime_noresume, pm)(dev->dev);
+	ret = ACQUIRE_ERR(pm_runtime_noresume, &pm);
+	if (ret)
+		return ret;
+
+	return i2c_add_numbered_adapter(adap);
 }
 EXPORT_SYMBOL_GPL(i2c_dw_probe);
 
diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 2a7decc24931..0f58c4b50377 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -13,6 +13,7 @@
 #include <linux/completion.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
+#include <linux/irqreturn.h>
 #include <linux/pm.h>
 #include <linux/regmap.h>
 #include <linux/types.h>
@@ -333,20 +334,18 @@ struct i2c_dw_semaphore_callbacks {
 	int	(*probe)(struct dw_i2c_dev *dev);
 };
 
-int i2c_dw_init_regmap(struct dw_i2c_dev *dev);
 u32 i2c_dw_scl_hcnt(struct dw_i2c_dev *dev, unsigned int reg, u32 ic_clk,
 		    u32 tSYMBOL, u32 tf, int offset);
 u32 i2c_dw_scl_lcnt(struct dw_i2c_dev *dev, unsigned int reg, u32 ic_clk,
 		    u32 tLOW, u32 tf, int offset);
-int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev);
 u32 i2c_dw_clk_rate(struct dw_i2c_dev *dev);
 int i2c_dw_prepare_clk(struct dw_i2c_dev *dev, bool prepare);
 int i2c_dw_acquire_lock(struct dw_i2c_dev *dev);
 void i2c_dw_release_lock(struct dw_i2c_dev *dev);
 int i2c_dw_wait_bus_not_busy(struct dw_i2c_dev *dev);
 int i2c_dw_handle_tx_abort(struct dw_i2c_dev *dev);
-int i2c_dw_set_fifo_size(struct dw_i2c_dev *dev);
 u32 i2c_dw_func(struct i2c_adapter *adap);
+irqreturn_t i2c_dw_isr_master(struct dw_i2c_dev *dev);
 
 extern const struct dev_pm_ops i2c_dw_dev_pm_ops;
 
@@ -386,12 +385,18 @@ void i2c_dw_disable(struct dw_i2c_dev *dev);
 extern void i2c_dw_configure_master(struct dw_i2c_dev *dev);
 extern int i2c_dw_probe_master(struct dw_i2c_dev *dev);
 
+int i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num);
+
 #if IS_ENABLED(CONFIG_I2C_SLAVE)
 extern void i2c_dw_configure_slave(struct dw_i2c_dev *dev);
 extern int i2c_dw_probe_slave(struct dw_i2c_dev *dev);
+irqreturn_t i2c_dw_isr_slave(struct dw_i2c_dev *dev);
+int i2c_dw_reg_slave(struct i2c_client *client);
+int i2c_dw_unreg_slave(struct i2c_client *client);
 #else
 static inline void i2c_dw_configure_slave(struct dw_i2c_dev *dev) { }
 static inline int i2c_dw_probe_slave(struct dw_i2c_dev *dev) { return -EINVAL; }
+static inline irqreturn_t i2c_dw_isr_slave(struct dw_i2c_dev *dev) { return IRQ_NONE; }
 #endif
 
 static inline void i2c_dw_configure(struct dw_i2c_dev *dev)
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 15b3a46f0132..91540a4520a3 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -191,10 +191,6 @@ static int i2c_dw_set_timings_master(struct dw_i2c_dev *dev)
 			dev->hs_hcnt, dev->hs_lcnt);
 	}
 
-	ret = i2c_dw_set_sda_hold(dev);
-	if (ret)
-		return ret;
-
 	dev_dbg(dev->dev, "Bus speed: %s\n", i2c_freq_mode_string(t->bus_freq_hz));
 	return 0;
 }
@@ -353,9 +349,8 @@ static int i2c_dw_status(struct dw_i2c_dev *dev)
  * Initiate and continue master read/write transaction with polling
  * based transfer routine afterward write messages into the Tx buffer.
  */
-static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs, int num_msgs)
+static int amd_i2c_dw_xfer_quirk(struct dw_i2c_dev *dev, struct i2c_msg *msgs, int num_msgs)
 {
-	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
 	int msg_wrt_idx, msg_itr_lmt, buf_len, data_idx;
 	int cmd = 0, status;
 	u8 *tx_buf;
@@ -752,9 +747,8 @@ static void i2c_dw_process_transfer(struct dw_i2c_dev *dev, unsigned int stat)
  * Interrupt service routine. This gets called whenever an I2C master interrupt
  * occurs.
  */
-static irqreturn_t i2c_dw_isr(int this_irq, void *dev_id)
+irqreturn_t i2c_dw_isr_master(struct dw_i2c_dev *dev)
 {
-	struct dw_i2c_dev *dev = dev_id;
 	unsigned int stat, enabled;
 
 	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
@@ -815,9 +809,8 @@ static int i2c_dw_wait_transfer(struct dw_i2c_dev *dev)
  * Prepare controller for a transaction and call i2c_dw_xfer_msg.
  */
 static int
-i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
+i2c_dw_xfer_common(struct dw_i2c_dev *dev, struct i2c_msg msgs[], int num)
 {
-	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
 	int ret;
 
 	dev_dbg(dev->dev, "%s: msgs: %d\n", __func__, num);
@@ -908,19 +901,15 @@ i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[], int num)
 	return ret;
 }
 
-static const struct i2c_algorithm i2c_dw_algo = {
-	.xfer = i2c_dw_xfer,
-	.functionality = i2c_dw_func,
-};
+int i2c_dw_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	struct dw_i2c_dev *dev = i2c_get_adapdata(adap);
 
-static const struct i2c_algorithm amd_i2c_dw_algo = {
-	.xfer = amd_i2c_dw_xfer_quirk,
-	.functionality = i2c_dw_func,
-};
+	if ((dev->flags & MODEL_MASK) == MODEL_AMD_NAVI_GPU)
+		return amd_i2c_dw_xfer_quirk(dev, msgs, num);
 
-static const struct i2c_adapter_quirks i2c_dw_quirks = {
-	.flags = I2C_AQ_NO_ZERO_LEN,
-};
+	return i2c_dw_xfer_common(dev, msgs, num);
+}
 
 void i2c_dw_configure_master(struct dw_i2c_dev *dev)
 {
@@ -1005,8 +994,6 @@ static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 
 int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 {
-	struct i2c_adapter *adap = &dev->adapter;
-	unsigned long irq_flags;
 	unsigned int ic_con;
 	int ret;
 
@@ -1014,18 +1001,10 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 
 	dev->init = i2c_dw_init_master;
 
-	ret = i2c_dw_init_regmap(dev);
-	if (ret)
-		return ret;
-
 	ret = i2c_dw_set_timings_master(dev);
 	if (ret)
 		return ret;
 
-	ret = i2c_dw_set_fifo_size(dev);
-	if (ret)
-		return ret;
-
 	/* Lock the bus for accessing DW_IC_CON */
 	ret = i2c_dw_acquire_lock(dev);
 	if (ret)
@@ -1045,61 +1024,7 @@ int i2c_dw_probe_master(struct dw_i2c_dev *dev)
 	if (ic_con & DW_IC_CON_BUS_CLEAR_CTRL)
 		dev->master_cfg |= DW_IC_CON_BUS_CLEAR_CTRL;
 
-	ret = dev->init(dev);
-	if (ret)
-		return ret;
-
-	if (!adap->name[0])
-		scnprintf(adap->name, sizeof(adap->name),
-			  "Synopsys DesignWare I2C adapter");
-	adap->retries = 3;
-	if ((dev->flags & MODEL_MASK) == MODEL_AMD_NAVI_GPU)
-		adap->algo = &amd_i2c_dw_algo;
-	else
-		adap->algo = &i2c_dw_algo;
-	adap->quirks = &i2c_dw_quirks;
-	adap->dev.parent = dev->dev;
-	i2c_set_adapdata(adap, dev);
-
-	if (dev->flags & ACCESS_NO_IRQ_SUSPEND) {
-		irq_flags = IRQF_NO_SUSPEND;
-	} else {
-		irq_flags = IRQF_SHARED | IRQF_COND_SUSPEND;
-	}
-
-	ret = i2c_dw_acquire_lock(dev);
-	if (ret)
-		return ret;
-
-	__i2c_dw_write_intr_mask(dev, 0);
-	i2c_dw_release_lock(dev);
-
-	if (!(dev->flags & ACCESS_POLLING)) {
-		ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr,
-				       irq_flags, dev_name(dev->dev), dev);
-		if (ret)
-			return dev_err_probe(dev->dev, ret,
-					     "failure requesting irq %i: %d\n",
-					     dev->irq, ret);
-	}
-
-	ret = i2c_dw_init_recovery_info(dev);
-	if (ret)
-		return ret;
-
-	/*
-	 * Increment PM usage count during adapter registration in order to
-	 * avoid possible spurious runtime suspend when adapter device is
-	 * registered to the device core and immediate resume in case bus has
-	 * registered I2C slaves that do I2C transfers in their probe.
-	 */
-	pm_runtime_get_noresume(dev->dev);
-	ret = i2c_add_numbered_adapter(adap);
-	if (ret)
-		dev_err(dev->dev, "failure adding adapter: %d\n", ret);
-	pm_runtime_put_noidle(dev->dev);
-
-	return ret;
+	return i2c_dw_init_recovery_info(dev);
 }
 
 MODULE_DESCRIPTION("Synopsys DesignWare I2C bus master adapter");
diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index 1995be79544d..c0baf53e97d8 100644
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -63,7 +63,7 @@ static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
 	return 0;
 }
 
-static int i2c_dw_reg_slave(struct i2c_client *slave)
+int i2c_dw_reg_slave(struct i2c_client *slave)
 {
 	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
 
@@ -88,7 +88,7 @@ static int i2c_dw_reg_slave(struct i2c_client *slave)
 	return 0;
 }
 
-static int i2c_dw_unreg_slave(struct i2c_client *slave)
+int i2c_dw_unreg_slave(struct i2c_client *slave)
 {
 	struct dw_i2c_dev *dev = i2c_get_adapdata(slave->adapter);
 
@@ -152,9 +152,8 @@ static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
  * Interrupt service routine. This gets called whenever an I2C slave interrupt
  * occurs.
  */
-static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
+irqreturn_t i2c_dw_isr_slave(struct dw_i2c_dev *dev)
 {
-	struct dw_i2c_dev *dev = dev_id;
 	unsigned int raw_stat, stat, enabled, tmp;
 	u8 val = 0, slave_activity;
 
@@ -217,12 +216,6 @@ static irqreturn_t i2c_dw_isr_slave(int this_irq, void *dev_id)
 	return IRQ_HANDLED;
 }
 
-static const struct i2c_algorithm i2c_dw_algo = {
-	.functionality = i2c_dw_func,
-	.reg_slave = i2c_dw_reg_slave,
-	.unreg_slave = i2c_dw_unreg_slave,
-};
-
 void i2c_dw_configure_slave(struct dw_i2c_dev *dev)
 {
 	dev->functionality = I2C_FUNC_SLAVE;
@@ -236,46 +229,12 @@ EXPORT_SYMBOL_GPL(i2c_dw_configure_slave);
 
 int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 {
-	struct i2c_adapter *adap = &dev->adapter;
-	int ret;
+	if (dev->flags & ACCESS_POLLING)
+		return -EOPNOTSUPP;
 
 	dev->init = i2c_dw_init_slave;
 
-	ret = i2c_dw_init_regmap(dev);
-	if (ret)
-		return ret;
-
-	ret = i2c_dw_set_sda_hold(dev);
-	if (ret)
-		return ret;
-
-	ret = i2c_dw_set_fifo_size(dev);
-	if (ret)
-		return ret;
-
-	ret = dev->init(dev);
-	if (ret)
-		return ret;
-
-	snprintf(adap->name, sizeof(adap->name),
-		 "Synopsys DesignWare I2C Slave adapter");
-	adap->retries = 3;
-	adap->algo = &i2c_dw_algo;
-	adap->dev.parent = dev->dev;
-	i2c_set_adapdata(adap, dev);
-
-	ret = devm_request_irq(dev->dev, dev->irq, i2c_dw_isr_slave,
-			       IRQF_SHARED, dev_name(dev->dev), dev);
-	if (ret)
-		return dev_err_probe(dev->dev, ret,
-				     "failure requesting IRQ %i: %d\n",
-				     dev->irq, ret);
-
-	ret = i2c_add_numbered_adapter(adap);
-	if (ret)
-		dev_err(dev->dev, "failure adding adapter: %d\n", ret);
-
-	return ret;
+	return 0;
 }
 
 MODULE_AUTHOR("Luis Oliveira <lolivei@...opsys.com>");
-- 
2.50.1

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