rtc-pcf85063: simplify code and use appropriate types

linux_kernel_modules/rtc-pcf85063/rtc-pcf85063.c

@@ -47,11 +47,19 @@
 #define PCF85063_REG_MO			0x09
 #define PCF85063_REG_YR			0x0A
 
-/* Lookup for square-wave clkout frequencies */
-#define NUM_FREQUENCIES			8
-static const int clkout_freq_table[NUM_FREQUENCIES][2] = {
-	{32768, 0}, {16384, 1}, {8192, 2}, {4096, 3},
-	{2048, 4}, {1024, 5}, {1, 6}, {0, 7}
+/*
+ * The output frequency at index N is generated by writing N the Control_2.COF
+ * register field.
+ */
+static const u16 clkout_freq_table[] = {
+	32768,
+	16384,
+	 8192,
+	 4096,
+	 2048,
+	 1024,
+	    1,
+	    0
 };
 
 static struct i2c_driver pcf85063_driver;
@@ -66,46 +74,47 @@ static struct i2c_driver pcf85063_driver;
  */
 static DEFINE_MUTEX(pcf85063_rtc_mutex);
 
-static int pcf85063_get_clkout_freq(struct device *dev, s32 *freq)
+static int pcf85063_get_clkout_freq(struct device *dev, u16 *freq)
 {
 	struct i2c_client *client = to_i2c_client(dev);
-	int i;
+	s32 ctrl2_reg_read;
 
 	mutex_lock(&pcf85063_rtc_mutex);
-	*freq = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL2);
+	ctrl2_reg_read = i2c_smbus_read_byte_data(client, PCF85063_REG_CTRL2);
 	mutex_unlock(&pcf85063_rtc_mutex);
 
-	if (*freq < 0) {
+	if (ctrl2_reg_read < 0) {
 		dev_err(&client->dev, "Failed to read PCF85063_REG_CTRL2\n");
 		return -EIO;
 	}
 
-	*freq &= CLKOUT_FREQ_MASK;
-
-	for(i = 0; i < NUM_FREQUENCIES && clkout_freq_table[i][1] != *freq; i++)
-		;
-	if (i == NUM_FREQUENCIES)
-		return -EINVAL;
-	*freq = clkout_freq_table[i][0];
+	*freq = clkout_freq_table[(((u8)ctrl2_reg_read) & CLKOUT_FREQ_MASK)];
 
 	return 0;
 }
 
-static int pcf85063_set_clkout_freq(struct device *dev, int freq)
+static int pcf85063_set_clkout_freq(struct device *dev, u16 freq)
 {
 	struct i2c_client *client = to_i2c_client(dev);
-	int i, ret;
-
-	for(i = 0; i < NUM_FREQUENCIES && clkout_freq_table[i][0] != freq; i++)
-		;
-	if (i == NUM_FREQUENCIES)
-		return -EINVAL;
+	size_t i;
+	int ret;
+	u8 freq_code;
 
-	freq = clkout_freq_table[i][1];
-	freq &= CLKOUT_FREQ_MASK;
+	for (i = 0; i < ARRAY_SIZE(clkout_freq_table); i++) {
+		if (clkout_freq_table[i] == freq)
+			goto found;
+	}
+	return -EINVAL;
 
+found:
+	freq_code = (i & CLKOUT_FREQ_MASK);
 	mutex_lock(&pcf85063_rtc_mutex);
-	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL2, (u8) freq);
+	/*
+	 * NOTE: The write below zeros the MI, HMI and TF fields of register
+	 * control_2, but the driver doesn't make use of those fields, so this
+	 * is acceptable.
+	 */
+	ret = i2c_smbus_write_byte_data(client, PCF85063_REG_CTRL2, freq_code);
 	mutex_unlock(&pcf85063_rtc_mutex);
 
 	if (ret) {
@@ -268,22 +277,23 @@ static ssize_t pcf85063_sysfs_show_clkout_freq(struct device *dev,
 					       char *buf)
 {
 	int err;
-	s32 freq;
+	u16 freq;
 
 	err = pcf85063_get_clkout_freq(dev, &freq);
 	if (err)
 		return err;
 
-	return sprintf(buf, "%d\n", (int) freq);
+	return sprintf(buf, "%u\n", freq);
 }
 
 static ssize_t pcf85063_sysfs_store_clkout_freq(struct device *dev,
 						struct device_attribute *attr,
 						const char *buf, size_t count)
 {
-	int freq, err;
+	int err;
+	u16 freq;
 
-	if (sscanf(buf, "%i", &freq) != 1)
+	if (kstrtou16(buf, 10, &freq))
 		return -EINVAL;
 
 	err = pcf85063_set_clkout_freq(dev, freq);