i2c: designware: Convert driver to using regmap API

Seeing the DW I2C driver is using flags-based accessors with two
conditional clauses it would be better to replace them with the regmap
API IO methods and to initialize the regmap object with read/write
callbacks specific to the controller registers map implementation. This
will be also handy for the drivers with non-standard registers mapping
(like an embedded into the Baikal-T1 System Controller DW I2C block, which
glue-driver is a part of this series).

As before the driver tries to detect the mapping setup at probe stage and
creates a regmap object accordingly, which will be used by the rest of the
code to correctly access the controller registers. In two places it was
appropriate to convert the hand-written read-modify-write and
read-poll-loop design patterns to the corresponding regmap API
ready-to-use methods.

Note the regmap IO methods return value is checked only at the probe
stage. The rest of the code won't do this because basically we have
MMIO-based regmap so non of the read/write methods can fail (this also
won't be needed for the Baikal-T1-specific I2C controller).

Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
[wsa: fix type of 'rx_valid' and remove outdated kdoc var description]
Signed-off-by: Wolfram Sang <wsa@kernel.org>

1 files changed, 41 insertions, 36 deletions

diff --git a/drivers/i2c/busses/i2c-designware-slave.c b/drivers/i2c/busses/i2c-designware-slave.c
index 576e7af4e94b..44974b53a626 100644
--- a/drivers/i2c/busses/i2c-designware-slave.c
+++ b/drivers/i2c/busses/i2c-designware-slave.c
@@ -14,18 +14,19 @@
 #include <linux/io.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
+#include <linux/regmap.h>
 
 #include "i2c-designware-core.h"
 
 static void i2c_dw_configure_fifo_slave(struct dw_i2c_dev *dev)
 {
 	/* Configure Tx/Rx FIFO threshold levels. */
-	dw_writel(dev, 0, DW_IC_TX_TL);
-	dw_writel(dev, 0, DW_IC_RX_TL);
+	regmap_write(dev->map, DW_IC_TX_TL, 0);
+	regmap_write(dev->map, DW_IC_RX_TL, 0);
 
 	/* Configure the I2C slave. */
-	dw_writel(dev, dev->slave_cfg, DW_IC_CON);
-	dw_writel(dev, DW_IC_INTR_SLAVE_MASK, DW_IC_INTR_MASK);
+	regmap_write(dev->map, DW_IC_CON, dev->slave_cfg);
+	regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_SLAVE_MASK);
 }
 
 /**
@@ -49,7 +50,7 @@ static int i2c_dw_init_slave(struct dw_i2c_dev *dev)
 
 	/* Write SDA hold time if supported */
 	if (dev->sda_hold_time)
-		dw_writel(dev, dev->sda_hold_time, DW_IC_SDA_HOLD);
+		regmap_write(dev->map, DW_IC_SDA_HOLD, dev->sda_hold_time);
 
 	i2c_dw_configure_fifo_slave(dev);
 	i2c_dw_release_lock(dev);
@@ -72,7 +73,7 @@ static int i2c_dw_reg_slave(struct i2c_client *slave)
 	 * the address to which the DW_apb_i2c responds.
 	 */
 	__i2c_dw_disable_nowait(dev);
-	dw_writel(dev, slave->addr, DW_IC_SAR);
+	regmap_write(dev->map, DW_IC_SAR, slave->addr);
 	dev->slave = slave;
 
 	__i2c_dw_enable(dev);
@@ -103,7 +104,7 @@ static int i2c_dw_unreg_slave(struct i2c_client *slave)
 
 static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 {
-	u32 stat;
+	u32 stat, dummy;
 
 	/*
 	 * The IC_INTR_STAT register just indicates "enabled" interrupts.
@@ -111,39 +112,39 @@ static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 	 * in the IC_RAW_INTR_STAT register.
 	 *
 	 * That is,
-	 *   stat = dw_readl(IC_INTR_STAT);
+	 *   stat = readl(IC_INTR_STAT);
 	 * equals to,
-	 *   stat = dw_readl(IC_RAW_INTR_STAT) & dw_readl(IC_INTR_MASK);
+	 *   stat = readl(IC_RAW_INTR_STAT) & readl(IC_INTR_MASK);
 	 *
 	 * The raw version might be useful for debugging purposes.
 	 */
-	stat = dw_readl(dev, DW_IC_INTR_STAT);
+	regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
 
 	/*
 	 * Do not use the IC_CLR_INTR register to clear interrupts, or
 	 * you'll miss some interrupts, triggered during the period from
-	 * dw_readl(IC_INTR_STAT) to dw_readl(IC_CLR_INTR).
+	 * readl(IC_INTR_STAT) to readl(IC_CLR_INTR).
 	 *
 	 * Instead, use the separately-prepared IC_CLR_* registers.
 	 */
 	if (stat & DW_IC_INTR_TX_ABRT)
-		dw_readl(dev, DW_IC_CLR_TX_ABRT);
+		regmap_read(dev->map, DW_IC_CLR_TX_ABRT, &dummy);
 	if (stat & DW_IC_INTR_RX_UNDER)
-		dw_readl(dev, DW_IC_CLR_RX_UNDER);
+		regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &dummy);
 	if (stat & DW_IC_INTR_RX_OVER)
-		dw_readl(dev, DW_IC_CLR_RX_OVER);
+		regmap_read(dev->map, DW_IC_CLR_RX_OVER, &dummy);
 	if (stat & DW_IC_INTR_TX_OVER)
-		dw_readl(dev, DW_IC_CLR_TX_OVER);
+		regmap_read(dev->map, DW_IC_CLR_TX_OVER, &dummy);
 	if (stat & DW_IC_INTR_RX_DONE)
-		dw_readl(dev, DW_IC_CLR_RX_DONE);
+		regmap_read(dev->map, DW_IC_CLR_RX_DONE, &dummy);
 	if (stat & DW_IC_INTR_ACTIVITY)
-		dw_readl(dev, DW_IC_CLR_ACTIVITY);
+		regmap_read(dev->map, DW_IC_CLR_ACTIVITY, &dummy);
 	if (stat & DW_IC_INTR_STOP_DET)
-		dw_readl(dev, DW_IC_CLR_STOP_DET);
+		regmap_read(dev->map, DW_IC_CLR_STOP_DET, &dummy);
 	if (stat & DW_IC_INTR_START_DET)
-		dw_readl(dev, DW_IC_CLR_START_DET);
+		regmap_read(dev->map, DW_IC_CLR_START_DET, &dummy);
 	if (stat & DW_IC_INTR_GEN_CALL)
-		dw_readl(dev, DW_IC_CLR_GEN_CALL);
+		regmap_read(dev->map, DW_IC_CLR_GEN_CALL, &dummy);
 
 	return stat;
 }
@@ -155,14 +156,14 @@ static u32 i2c_dw_read_clear_intrbits_slave(struct dw_i2c_dev *dev)
 
 static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 {
-	u32 raw_stat, stat, enabled;
-	u8 val, slave_activity;
+	u32 raw_stat, stat, enabled, tmp;
+	u8 val = 0, slave_activity;
 
-	stat = dw_readl(dev, DW_IC_INTR_STAT);
-	enabled = dw_readl(dev, DW_IC_ENABLE);
-	raw_stat = dw_readl(dev, DW_IC_RAW_INTR_STAT);
-	slave_activity = ((dw_readl(dev, DW_IC_STATUS) &
-		DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
+	regmap_read(dev->map, DW_IC_INTR_STAT, &stat);
+	regmap_read(dev->map, DW_IC_ENABLE, &enabled);
+	regmap_read(dev->map, DW_IC_RAW_INTR_STAT, &raw_stat);
+	regmap_read(dev->map, DW_IC_STATUS, &tmp);
+	slave_activity = ((tmp & DW_IC_STATUS_SLAVE_ACTIVITY) >> 6);
 
 	if (!enabled || !(raw_stat & ~DW_IC_INTR_ACTIVITY) || !dev->slave)
 		return 0;
@@ -177,7 +178,8 @@ static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 	if (stat & DW_IC_INTR_RD_REQ) {
 		if (slave_activity) {
 			if (stat & DW_IC_INTR_RX_FULL) {
-				val = dw_readl(dev, DW_IC_DATA_CMD);
+				regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
+				val = tmp;
 
 				if (!i2c_slave_event(dev->slave,
 						     I2C_SLAVE_WRITE_RECEIVED,
@@ -185,24 +187,24 @@ static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 					dev_vdbg(dev->dev, "Byte %X acked!",
 						 val);
 				}
-				dw_readl(dev, DW_IC_CLR_RD_REQ);
+				regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
 				stat = i2c_dw_read_clear_intrbits_slave(dev);
 			} else {
-				dw_readl(dev, DW_IC_CLR_RD_REQ);
-				dw_readl(dev, DW_IC_CLR_RX_UNDER);
+				regmap_read(dev->map, DW_IC_CLR_RD_REQ, &tmp);
+				regmap_read(dev->map, DW_IC_CLR_RX_UNDER, &tmp);
 				stat = i2c_dw_read_clear_intrbits_slave(dev);
 			}
 			if (!i2c_slave_event(dev->slave,
 					     I2C_SLAVE_READ_REQUESTED,
 					     &val))
-				dw_writel(dev, val, DW_IC_DATA_CMD);
+				regmap_write(dev->map, DW_IC_DATA_CMD, val);
 		}
 	}
 
 	if (stat & DW_IC_INTR_RX_DONE) {
 		if (!i2c_slave_event(dev->slave, I2C_SLAVE_READ_PROCESSED,
 				     &val))
-			dw_readl(dev, DW_IC_CLR_RX_DONE);
+			regmap_read(dev->map, DW_IC_CLR_RX_DONE, &tmp);
 
 		i2c_slave_event(dev->slave, I2C_SLAVE_STOP, &val);
 		stat = i2c_dw_read_clear_intrbits_slave(dev);
@@ -210,7 +212,8 @@ static int i2c_dw_irq_handler_slave(struct dw_i2c_dev *dev)
 	}
 
 	if (stat & DW_IC_INTR_RX_FULL) {
-		val = dw_readl(dev, DW_IC_DATA_CMD);
+		regmap_read(dev->map, DW_IC_DATA_CMD, &tmp);
+		val = tmp;
 		if (!i2c_slave_event(dev->slave, I2C_SLAVE_WRITE_RECEIVED,
 				     &val))
 			dev_vdbg(dev->dev, "Byte %X acked!", val);
@@ -263,7 +266,7 @@ int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 	dev->disable = i2c_dw_disable;
 	dev->disable_int = i2c_dw_disable_int;
 
-	ret = i2c_dw_set_reg_access(dev);
+	ret = i2c_dw_init_regmap(dev);
 	if (ret)
 		return ret;
 
@@ -271,7 +274,9 @@ int i2c_dw_probe_slave(struct dw_i2c_dev *dev)
 	if (ret)
 		return ret;
 
-	i2c_dw_set_fifo_size(dev);
+	ret = i2c_dw_set_fifo_size(dev);
+	if (ret)
+		return ret;
 
 	ret = dev->init(dev);
 	if (ret)