rtc: rv8803: Always apply the I²C workaround

The I²C NACK issue of the RV-8803 may occur after any I²C START
condition, depending on the timings. Consequently, the workaround must
be applied for all the I²C transfers.

This commit abstracts the I²C transfer code into register access
functions. This avoids duplicating the I²C workaround everywhere. This
also avoids the duplication of the code handling the return value of
i2c_smbus_read_i2c_block_data(). Error messages are issued in case of
definitive register access failures (if the workaround fails). This
change also makes the I²C transfer return value checks consistent.

Signed-off-by: Benoît Thébaudeau <benoit@wsystem.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

diff --git a/drivers/rtc/rtc-rv8803.c b/drivers/rtc/rtc-rv8803.c
index aa1d6b6..09ab5cb 100644 (file)
--- a/drivers/rtc/rtc-rv8803.c
+++ b/drivers/rtc/rtc-rv8803.c
@@ -20,6 +20,8 @@
 #include <linux/module.h>
 #include <linux/rtc.h>
 
+#define RV8803_I2C_TRY_COUNT           4
+
 #define RV8803_SEC                     0x00
 #define RV8803_MIN                     0x01
 #define RV8803_HOUR                    0x02
@@ -57,19 +59,85 @@ struct rv8803_data {
        u8 ctrl;
 };
 
+static int rv8803_read_reg(const struct i2c_client *client, u8 reg)
+{
+       int try = RV8803_I2C_TRY_COUNT;
+       s32 ret;
+
+       /*
+        * There is a 61µs window during which the RTC does not acknowledge I2C
+        * transfers. In that case, ensure that there are multiple attempts.
+        */
+       do
+               ret = i2c_smbus_read_byte_data(client, reg);
+       while ((ret == -ENXIO || ret == -EIO) && --try);
+       if (ret < 0)
+               dev_err(&client->dev, "Unable to read register 0x%02x\n", reg);
+
+       return ret;
+}
+
+static int rv8803_read_regs(const struct i2c_client *client,
+                           u8 reg, u8 count, u8 *values)
+{
+       int try = RV8803_I2C_TRY_COUNT;
+       s32 ret;
+
+       do
+               ret = i2c_smbus_read_i2c_block_data(client, reg, count, values);
+       while ((ret == -ENXIO || ret == -EIO) && --try);
+       if (ret != count) {
+               dev_err(&client->dev,
+                       "Unable to read registers 0x%02x..0x%02x\n",
+                       reg, reg + count - 1);
+               return ret < 0 ? ret : -EIO;
+       }
+
+       return 0;
+}
+
+static int rv8803_write_reg(const struct i2c_client *client, u8 reg, u8 value)
+{
+       int try = RV8803_I2C_TRY_COUNT;
+       s32 ret;
+
+       do
+               ret = i2c_smbus_write_byte_data(client, reg, value);
+       while ((ret == -ENXIO || ret == -EIO) && --try);
+       if (ret)
+               dev_err(&client->dev, "Unable to write register 0x%02x\n", reg);
+
+       return ret;
+}
+
+static int rv8803_write_regs(const struct i2c_client *client,
+                            u8 reg, u8 count, const u8 *values)
+{
+       int try = RV8803_I2C_TRY_COUNT;
+       s32 ret;
+
+       do
+               ret = i2c_smbus_write_i2c_block_data(client, reg, count,
+                                                    values);
+       while ((ret == -ENXIO || ret == -EIO) && --try);
+       if (ret)
+               dev_err(&client->dev,
+                       "Unable to write registers 0x%02x..0x%02x\n",
+                       reg, reg + count - 1);
+
+       return ret;
+}
+
 static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
 {
        struct i2c_client *client = dev_id;
        struct rv8803_data *rv8803 = i2c_get_clientdata(client);
        unsigned long events = 0;
-       int flags, try = 0;
+       int flags;
 
        mutex_lock(&rv8803->flags_lock);
 
-       do {
-               flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
-               try++;
-       } while (((flags == -ENXIO) || (flags == -EIO)) && (try < 4));
+       flags = rv8803_read_reg(client, RV8803_FLAG);
        if (flags <= 0) {
                mutex_unlock(&rv8803->flags_lock);
                return IRQ_NONE;
@@ -101,9 +169,8 @@ static irqreturn_t rv8803_handle_irq(int irq, void *dev_id)
 
        if (events) {
                rtc_update_irq(rv8803->rtc, 1, events);
-               i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
-               i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
-                                         rv8803->ctrl);
+               rv8803_write_reg(client, RV8803_FLAG, flags);
+               rv8803_write_reg(rv8803->client, RV8803_CTRL, rv8803->ctrl);
        }
 
        mutex_unlock(&rv8803->flags_lock);
@@ -119,7 +186,7 @@ static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
        u8 *date = date1;
        int ret, flags;
 
-       flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
+       flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
        if (flags < 0)
                return flags;
 
@@ -128,16 +195,14 @@ static int rv8803_get_time(struct device *dev, struct rtc_time *tm)
                return -EINVAL;
        }
 
-       ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
-                                           7, date);
-       if (ret != 7)
-               return ret < 0 ? ret : -EIO;
+       ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date);
+       if (ret)
+               return ret;
 
        if ((date1[RV8803_SEC] & 0x7f) == bin2bcd(59)) {
-               ret = i2c_smbus_read_i2c_block_data(rv8803->client, RV8803_SEC,
-                                                   7, date2);
-               if (ret != 7)
-                       return ret < 0 ? ret : -EIO;
+               ret = rv8803_read_regs(rv8803->client, RV8803_SEC, 7, date2);
+               if (ret)
+                       return ret;
 
                if ((date2[RV8803_SEC] & 0x7f) != bin2bcd(59))
                        date = date2;
@@ -171,21 +236,20 @@ static int rv8803_set_time(struct device *dev, struct rtc_time *tm)
        date[RV8803_MONTH] = bin2bcd(tm->tm_mon + 1);
        date[RV8803_YEAR]  = bin2bcd(tm->tm_year - 100);
 
-       ret = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_SEC,
-                                            7, date);
-       if (ret < 0)
+       ret = rv8803_write_regs(rv8803->client, RV8803_SEC, 7, date);
+       if (ret)
                return ret;
 
        mutex_lock(&rv8803->flags_lock);
 
-       flags = i2c_smbus_read_byte_data(rv8803->client, RV8803_FLAG);
+       flags = rv8803_read_reg(rv8803->client, RV8803_FLAG);
        if (flags < 0) {
                mutex_unlock(&rv8803->flags_lock);
                return flags;
        }
 
-       ret = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG,
-                                       flags & ~RV8803_FLAG_V2F);
+       ret = rv8803_write_reg(rv8803->client, RV8803_FLAG,
+                              flags & ~RV8803_FLAG_V2F);
 
        mutex_unlock(&rv8803->flags_lock);
 
@@ -199,12 +263,11 @@ static int rv8803_get_alarm(struct device *dev, struct rtc_wkalrm *alrm)
        u8 alarmvals[3];
        int flags, ret;
 
-       ret = i2c_smbus_read_i2c_block_data(client, RV8803_ALARM_MIN,
-                                           3, alarmvals);
-       if (ret != 3)
-               return ret < 0 ? ret : -EIO;
+       ret = rv8803_read_regs(client, RV8803_ALARM_MIN, 3, alarmvals);
+       if (ret)
+               return ret;
 
-       flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+       flags = rv8803_read_reg(client, RV8803_FLAG);
        if (flags < 0)
                return flags;
 
@@ -237,10 +300,10 @@ static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
        mutex_lock(&rv8803->flags_lock);
 
-       ret = i2c_smbus_read_i2c_block_data(client, RV8803_FLAG, 2, ctrl);
-       if (ret != 2) {
+       ret = rv8803_read_regs(client, RV8803_FLAG, 2, ctrl);
+       if (ret) {
                mutex_unlock(&rv8803->flags_lock);
-               return ret < 0 ? ret : -EIO;
+               return ret;
        }
 
        alarmvals[0] = bin2bcd(alrm->time.tm_min);
@@ -249,8 +312,8 @@ static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
 
        if (rv8803->ctrl & (RV8803_CTRL_AIE | RV8803_CTRL_UIE)) {
                rv8803->ctrl &= ~(RV8803_CTRL_AIE | RV8803_CTRL_UIE);
-               err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
-                                               rv8803->ctrl);
+               err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
+                                      rv8803->ctrl);
                if (err) {
                        mutex_unlock(&rv8803->flags_lock);
                        return err;
@@ -258,13 +321,12 @@ static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
        }
 
        ctrl[1] &= ~RV8803_FLAG_AF;
-       err = i2c_smbus_write_byte_data(rv8803->client, RV8803_FLAG, ctrl[1]);
+       err = rv8803_write_reg(rv8803->client, RV8803_FLAG, ctrl[1]);
        mutex_unlock(&rv8803->flags_lock);
        if (err)
                return err;
 
-       err = i2c_smbus_write_i2c_block_data(rv8803->client, RV8803_ALARM_MIN,
-                                            3, alarmvals);
+       err = rv8803_write_regs(rv8803->client, RV8803_ALARM_MIN, 3, alarmvals);
        if (err)
                return err;
 
@@ -274,8 +336,8 @@ static int rv8803_set_alarm(struct device *dev, struct rtc_wkalrm *alrm)
                if (rv8803->rtc->aie_timer.enabled)
                        rv8803->ctrl |= RV8803_CTRL_AIE;
 
-               err = i2c_smbus_write_byte_data(rv8803->client, RV8803_CTRL,
-                                               rv8803->ctrl);
+               err = rv8803_write_reg(rv8803->client, RV8803_CTRL,
+                                      rv8803->ctrl);
                if (err)
                        return err;
        }
@@ -304,21 +366,20 @@ static int rv8803_alarm_irq_enable(struct device *dev, unsigned int enabled)
        }
 
        mutex_lock(&rv8803->flags_lock);
-       flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+       flags = rv8803_read_reg(client, RV8803_FLAG);
        if (flags < 0) {
                mutex_unlock(&rv8803->flags_lock);
                return flags;
        }
        flags &= ~(RV8803_FLAG_AF | RV8803_FLAG_UF);
-       err = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
+       err = rv8803_write_reg(client, RV8803_FLAG, flags);
        mutex_unlock(&rv8803->flags_lock);
        if (err)
                return err;
 
        if (ctrl != rv8803->ctrl) {
                rv8803->ctrl = ctrl;
-               err = i2c_smbus_write_byte_data(client, RV8803_CTRL,
-                                               rv8803->ctrl);
+               err = rv8803_write_reg(client, RV8803_CTRL, rv8803->ctrl);
                if (err)
                        return err;
        }
@@ -334,7 +395,7 @@ static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 
        switch (cmd) {
        case RTC_VL_READ:
-               flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+               flags = rv8803_read_reg(client, RV8803_FLAG);
                if (flags < 0)
                        return flags;
 
@@ -353,16 +414,16 @@ static int rv8803_ioctl(struct device *dev, unsigned int cmd, unsigned long arg)
 
        case RTC_VL_CLR:
                mutex_lock(&rv8803->flags_lock);
-               flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
+               flags = rv8803_read_reg(client, RV8803_FLAG);
                if (flags < 0) {
                        mutex_unlock(&rv8803->flags_lock);
                        return flags;
                }
 
                flags &= ~(RV8803_FLAG_V1F | RV8803_FLAG_V2F);
-               ret = i2c_smbus_write_byte_data(client, RV8803_FLAG, flags);
+               ret = rv8803_write_reg(client, RV8803_FLAG, flags);
                mutex_unlock(&rv8803->flags_lock);
-               if (ret < 0)
+               if (ret)
                        return ret;
 
                return 0;
@@ -380,8 +441,8 @@ static ssize_t rv8803_nvram_write(struct file *filp, struct kobject *kobj,
        struct i2c_client *client = to_i2c_client(dev);
        int ret;
 
-       ret = i2c_smbus_write_byte_data(client, RV8803_RAM, buf[0]);
-       if (ret < 0)
+       ret = rv8803_write_reg(client, RV8803_RAM, buf[0]);
+       if (ret)
                return ret;
 
        return 1;
@@ -395,7 +456,7 @@ static ssize_t rv8803_nvram_read(struct file *filp, struct kobject *kobj,
        struct i2c_client *client = to_i2c_client(dev);
        int ret;
 
-       ret = i2c_smbus_read_byte_data(client, RV8803_RAM);
+       ret = rv8803_read_reg(client, RV8803_RAM);
        if (ret < 0)
                return ret;
 
@@ -425,7 +486,7 @@ static int rv8803_probe(struct i2c_client *client,
 {
        struct i2c_adapter *adapter = to_i2c_adapter(client->dev.parent);
        struct rv8803_data *rv8803;
-       int err, flags, try = 0;
+       int err, flags;
 
        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA |
                                     I2C_FUNC_SMBUS_I2C_BLOCK)) {
@@ -442,16 +503,7 @@ static int rv8803_probe(struct i2c_client *client,
        rv8803->client = client;
        i2c_set_clientdata(client, rv8803);
 
-       /*
-        * There is a 60µs window where the RTC may not reply on the i2c bus in
-        * that case, the transfer is not ACKed. In that case, ensure there are
-        * multiple attempts.
-        */
-       do {
-               flags = i2c_smbus_read_byte_data(client, RV8803_FLAG);
-               try++;
-       } while (((flags == -ENXIO) || (flags == -EIO)) && (try < 4));
-
+       flags = rv8803_read_reg(client, RV8803_FLAG);
        if (flags < 0)
                return flags;
 
@@ -486,12 +538,7 @@ static int rv8803_probe(struct i2c_client *client,
                return PTR_ERR(rv8803->rtc);
        }
 
-       try = 0;
-       do {
-               err = i2c_smbus_write_byte_data(rv8803->client, RV8803_EXT,
-                                               RV8803_EXT_WADA);
-               try++;
-       } while (((err == -ENXIO) || (flags == -EIO)) && (try < 4));
+       err = rv8803_write_reg(rv8803->client, RV8803_EXT, RV8803_EXT_WADA);
        if (err)
                return err;