rtc: sd3078: drop needless struct sd3078

The memory pointed to by the ::rtc member is managed via devres, and
no code in this driver uses it past _probe().

We can drop it from the structure and just use a local temporary
variable, reducing runtime memory consumption by a few bytes.

Since this now means that the structure has just one member only left,
there  is no need anymore to allocate data for it and pass that around
via the various callbacks, just to extract that one member.

Instead, we can just pass that one member and avoid the extra memory
allocation for the containing struct, reducing runtime memory
consumption.

Signed-off-by: André Draszik <andre.draszik@linaro.org>
Link: https://lore.kernel.org/r/20250304-rtc-cleanups-v2-14-d4689a71668c@linaro.org
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

Author: andred

drivers/rtc/rtc-sd3078.c

@@ -36,11 +36,6 @@
  */
 #define WRITE_PROTECT_EN	0
 
-struct sd3078 {
-	struct rtc_device	*rtc;
-	struct regmap		*regmap;
-};
-
 /*
  * In order to prevent arbitrary modification of the time register,
  * when modification of the register,
@@ -49,14 +44,11 @@ struct sd3078 {
  * 2. set WRITE2 bit
  * 3. set WRITE3 bit
  */
-static void sd3078_enable_reg_write(struct sd3078 *sd3078)
+static void sd3078_enable_reg_write(struct regmap *regmap)
 {
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
-			   KEY_WRITE1, KEY_WRITE1);
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
-			   KEY_WRITE2, KEY_WRITE2);
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
-			   KEY_WRITE3, KEY_WRITE3);
+	regmap_update_bits(regmap, SD3078_REG_CTRL2, KEY_WRITE1, KEY_WRITE1);
+	regmap_update_bits(regmap, SD3078_REG_CTRL1, KEY_WRITE2, KEY_WRITE2);
+	regmap_update_bits(regmap, SD3078_REG_CTRL1, KEY_WRITE3, KEY_WRITE3);
 }
 
 #if WRITE_PROTECT_EN
@@ -69,14 +61,11 @@ static void sd3078_enable_reg_write(struct sd3078 *sd3078)
  * 2. clear WRITE3 bit
  * 3. clear WRITE1 bit
  */
-static void sd3078_disable_reg_write(struct sd3078 *sd3078)
+static void sd3078_disable_reg_write(struct regmap *regmap)
 {
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
-			   KEY_WRITE2, 0);
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL1,
-			   KEY_WRITE3, 0);
-	regmap_update_bits(sd3078->regmap, SD3078_REG_CTRL2,
-			   KEY_WRITE1, 0);
+	regmap_update_bits(regmap, SD3078_REG_CTRL1, KEY_WRITE2, 0);
+	regmap_update_bits(regmap, SD3078_REG_CTRL1, KEY_WRITE3, 0);
+	regmap_update_bits(regmap, SD3078_REG_CTRL2, KEY_WRITE1, 0);
 }
 #endif
 
@@ -85,11 +74,10 @@ static int sd3078_rtc_read_time(struct device *dev, struct rtc_time *tm)
 	unsigned char hour;
 	unsigned char rtc_data[NUM_TIME_REGS] = {0};
 	struct i2c_client *client = to_i2c_client(dev);
-	struct sd3078 *sd3078 = i2c_get_clientdata(client);
+	struct regmap *regmap = i2c_get_clientdata(client);
 	int ret;
 
-	ret = regmap_bulk_read(sd3078->regmap, SD3078_REG_SC, rtc_data,
-			       NUM_TIME_REGS);
+	ret = regmap_bulk_read(regmap, SD3078_REG_SC, rtc_data, NUM_TIME_REGS);
 	if (ret < 0) {
 		dev_err(dev, "reading from RTC failed with err:%d\n", ret);
 		return ret;
@@ -123,7 +111,7 @@ static int sd3078_rtc_set_time(struct device *dev, struct rtc_time *tm)
 {
 	unsigned char rtc_data[NUM_TIME_REGS];
 	struct i2c_client *client = to_i2c_client(dev);
-	struct sd3078 *sd3078 = i2c_get_clientdata(client);
+	struct regmap *regmap = i2c_get_clientdata(client);
 	int ret;
 
 	rtc_data[SD3078_REG_SC] = bin2bcd(tm->tm_sec);
@@ -135,18 +123,18 @@ static int sd3078_rtc_set_time(struct device *dev, struct rtc_time *tm)
 	rtc_data[SD3078_REG_YR] = bin2bcd(tm->tm_year - 100);
 
 #if WRITE_PROTECT_EN
-	sd3078_enable_reg_write(sd3078);
+	sd3078_enable_reg_write(regmap);
 #endif
 
-	ret = regmap_bulk_write(sd3078->regmap, SD3078_REG_SC, rtc_data,
+	ret = regmap_bulk_write(regmap, SD3078_REG_SC, rtc_data,
 				NUM_TIME_REGS);
 	if (ret < 0) {
 		dev_err(dev, "writing to RTC failed with err:%d\n", ret);
 		return ret;
 	}
 
 #if WRITE_PROTECT_EN
-	sd3078_disable_reg_write(sd3078);
+	sd3078_disable_reg_write(regmap);
 #endif
 
 	return 0;
@@ -166,36 +154,33 @@ static const struct regmap_config regmap_config = {
 static int sd3078_probe(struct i2c_client *client)
 {
 	int ret;
-	struct sd3078 *sd3078;
+	struct regmap *regmap;
+	struct rtc_device *rtc;
 
 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
 		return -ENODEV;
 
-	sd3078 = devm_kzalloc(&client->dev, sizeof(*sd3078), GFP_KERNEL);
-	if (!sd3078)
-		return -ENOMEM;
-
-	sd3078->regmap = devm_regmap_init_i2c(client, &regmap_config);
-	if (IS_ERR(sd3078->regmap)) {
+	regmap = devm_regmap_init_i2c(client, &regmap_config);
+	if (IS_ERR(regmap)) {
 		dev_err(&client->dev, "regmap allocation failed\n");
-		return PTR_ERR(sd3078->regmap);
+		return PTR_ERR(regmap);
 	}
 
-	i2c_set_clientdata(client, sd3078);
+	i2c_set_clientdata(client, regmap);
 
-	sd3078->rtc = devm_rtc_allocate_device(&client->dev);
-	if (IS_ERR(sd3078->rtc))
-		return PTR_ERR(sd3078->rtc);
+	rtc = devm_rtc_allocate_device(&client->dev);
+	if (IS_ERR(rtc))
+		return PTR_ERR(rtc);
 
-	sd3078->rtc->ops = &sd3078_rtc_ops;
-	sd3078->rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
-	sd3078->rtc->range_max = RTC_TIMESTAMP_END_2099;
+	rtc->ops = &sd3078_rtc_ops;
+	rtc->range_min = RTC_TIMESTAMP_BEGIN_2000;
+	rtc->range_max = RTC_TIMESTAMP_END_2099;
 
-	ret = devm_rtc_register_device(sd3078->rtc);
+	ret = devm_rtc_register_device(rtc);
 	if (ret)
 		return ret;
 
-	sd3078_enable_reg_write(sd3078);
+	sd3078_enable_reg_write(regmap);
 
 	return 0;
 }