hwmon: (ads2828) Convert to use regmap

Simplify code and reduce code size by using regmap to access i2c registers.

Reviewed-and-Tested-by: Robert Rosengren <[e-mail]>
Signed-off-by: Guenter Roeck <[e-mail]>

drivers/hwmon/Kconfig

···
 config SENSORS_ADS7828
 	tristate "Texas Instruments ADS7828 and compatibles"
 	depends on I2C
+	select REGMAP_I2C
 	help
 	  If you say yes here you get support for Texas Instruments ADS7828 and
 	  ADS7830 8-channel A/D converters. ADS7828 resolution is 12-bit, while

drivers/hwmon/ads7828.c

···
 #include <linux/hwmon-sysfs.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
-#include <linux/jiffies.h>
 #include <linux/module.h>
-#include <linux/mutex.h>
 #include <linux/platform_data/ads7828.h>
+#include <linux/regmap.h>
 #include <linux/slab.h>
 
 /* The ADS7828 registers */
-#define ADS7828_NCH		8	/* 8 channels supported */
 #define ADS7828_CMD_SD_SE	0x80	/* Single ended inputs */
 #define ADS7828_CMD_PD1		0x04	/* Internal vref OFF && A/D ON */
 #define ADS7828_CMD_PD3		0x0C	/* Internal vref ON && A/D ON */
···
 
 /* Client specific data */
 struct ads7828_data {
-	struct i2c_client *client;
-	struct mutex update_lock;	/* Mutex protecting updates */
-	unsigned long last_updated;	/* Last updated time (in jiffies) */
-	u16 adc_input[ADS7828_NCH];	/* ADS7828_NCH samples */
-	bool valid;			/* Validity flag */
+	struct regmap *regmap;
 	bool diff_input;		/* Differential input */
 	bool ext_vref;			/* External voltage reference */
 	unsigned int vref_mv;		/* voltage reference value */
 	u8 cmd_byte;			/* Command byte without channel bits */
 	unsigned int lsb_resol;		/* Resolution of the ADC sample LSB */
-	s32 (*read_channel)(const struct i2c_client *client, u8 command);
 };
 
 /* Command byte C2,C1,C0 - see datasheet */
···
 	return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4);
 }
 
-/* Update data for the device (all 8 channels) */
-static struct ads7828_data *ads7828_update_device(struct device *dev)
-{
-	struct ads7828_data *data = dev_get_drvdata(dev);
-	struct i2c_client *client = data->client;
-
-	mutex_lock(&data->update_lock);
-
-	if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
-			|| !data->valid) {
-		unsigned int ch;
-		dev_dbg(&client->dev, "Starting ads7828 update\n");
-
-		for (ch = 0; ch < ADS7828_NCH; ch++) {
-			u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch);
-			data->adc_input[ch] = data->read_channel(client, cmd);
-		}
-		data->last_updated = jiffies;
-		data->valid = true;
-	}
-
-	mutex_unlock(&data->update_lock);
-
-	return data;
-}
-
 /* sysfs callback function */
 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da,
 			       char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
-	struct ads7828_data *data = ads7828_update_device(dev);
-	unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] *
-					       data->lsb_resol, 1000);
+	struct ads7828_data *data = dev_get_drvdata(dev);
+	u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index);
+	unsigned int regval;
+	int err;
 
-	return sprintf(buf, "%d\n", value);
+	err = regmap_read(data->regmap, cmd, &regval);
+	if (err < 0)
+		return err;
+
+	return sprintf(buf, "%d\n",
+		       DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000));
 }
 
 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0);
···
 };
 
 ATTRIBUTE_GROUPS(ads7828);
+
+static const struct regmap_config ads2828_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 16,
+};
+
+static const struct regmap_config ads2830_regmap_config = {
+	.reg_bits = 8,
+	.val_bits = 8,
+};
 
 static int ads7828_probe(struct i2c_client *client,
 			 const struct i2c_device_id *id)
···
 	/* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */
 	if (id->driver_data == ads7828) {
 		data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096);
-		data->read_channel = i2c_smbus_read_word_swapped;
+		data->regmap = devm_regmap_init_i2c(client,
+						    &ads2828_regmap_config);
 	} else {
 		data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256);
-		data->read_channel = i2c_smbus_read_byte_data;
+		data->regmap = devm_regmap_init_i2c(client,
+						    &ads2830_regmap_config);
 	}
 
 	data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3;
 	if (!data->diff_input)
 		data->cmd_byte |= ADS7828_CMD_SD_SE;
-
-	data->client = client;
-	mutex_init(&data->update_lock);
 
 	hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name,
 							   data,