drivers/rtc/rtc-rx8581.c: add SMBus-only adapters support

Add support for SMBus-only adapters (e.g.  i2c-piix4).  The driver has
implemented only support for I2C adapters which implement the
I2C_FUNC_SMBUS_I2C_BLOCK functionality before.

With this patch it is possible to load and use the RTC driver with I2C and
SMBUS adapters like the rtc-ds1307 does.

Tested on AMD G Series Platform (i2c-piix4 adapter driver).

Signed-off-by: Andreas Werner <andreas.werner@men.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 68 insertions, 13 deletions

diff --git a/drivers/rtc/rtc-rx8581.c b/drivers/rtc/rtc-rx8581.c
index 00b0eb7fe166..de8d9c427782 100644
--- a/drivers/rtc/rtc-rx8581.c
+++ b/drivers/rtc/rtc-rx8581.c
@@ -52,8 +52,45 @@
 #define RX8581_CTRL_STOP        0x02 /* STOP bit */
 #define RX8581_CTRL_RESET       0x01 /* RESET bit */
 
+struct rx8581 {
+        struct i2c_client       *client;
+        struct rtc_device       *rtc;
+        s32 (*read_block_data)(const struct i2c_client *client, u8 command,
+                                u8 length, u8 *values);
+        s32 (*write_block_data)(const struct i2c_client *client, u8 command,
+                                u8 length, const u8 *values);
+};
+
 static struct i2c_driver rx8581_driver;
 
+static int rx8581_read_block_data(const struct i2c_client *client, u8 command,
+                                        u8 length, u8 *values)
+{
+        s32 i, data;
+
+        for (i = 0; i < length; i++) {
+                data = i2c_smbus_read_byte_data(client, command + i);
+                if (data < 0)
+                        return data;
+                values[i] = data;
+        }
+        return i;
+}
+
+static int rx8581_write_block_data(const struct i2c_client *client, u8 command,
+                                        u8 length, const u8 *values)
+{
+        s32 i, ret;
+
+        for (i = 0; i < length; i++) {
+                ret = i2c_smbus_write_byte_data(client, command + i,
+                                                values[i]);
+                if (ret < 0)
+                        return ret;
+        }
+        return length;
+}
+
 /*
  * In the routines that deal directly with the rx8581 hardware, we use
  * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
@@ -62,6 +99,7 @@ static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
         unsigned char date[7];
         int data, err;
+        struct rx8581 *rx8581 = i2c_get_clientdata(client);
 
         /* First we ensure that the "update flag" is not set, we read the
          * time and date then re-read the "update flag". If the update flag
@@ -80,14 +118,13 @@ static int rx8581_get_datetime(struct i2c_client *client, struct rtc_time *tm)
                         err = i2c_smbus_write_byte_data(client,
                                 RX8581_REG_FLAG, (data & ~RX8581_FLAG_UF));
                         if (err != 0) {
-                                dev_err(&client->dev, "Unable to write device "
-                                        "flags\n");
+                                dev_err(&client->dev, "Unable to write device flags\n");
                                 return -EIO;
                         }
                 }
 
                 /* Now read time and date */
-                err = i2c_smbus_read_i2c_block_data(client, RX8581_REG_SC,
+                err = rx8581->read_block_data(client, RX8581_REG_SC,
                         7, date);
                 if (err < 0) {
                         dev_err(&client->dev, "Unable to read date\n");
@@ -140,6 +177,7 @@ static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
         int data, err;
         unsigned char buf[7];
+        struct rx8581 *rx8581 = i2c_get_clientdata(client);
 
         dev_dbg(&client->dev, "%s: secs=%d, mins=%d, hours=%d, "
                 "mday=%d, mon=%d, year=%d, wday=%d\n",
@@ -176,7 +214,7 @@ static int rx8581_set_datetime(struct i2c_client *client, struct rtc_time *tm)
         }
 
         /* write register's data */
-        err = i2c_smbus_write_i2c_block_data(client, RX8581_REG_SC, 7, buf);
+        err = rx8581->write_block_data(client, RX8581_REG_SC, 7, buf);
         if (err < 0) {
                 dev_err(&client->dev, "Unable to write to date registers\n");
                 return -EIO;
@@ -231,22 +269,39 @@ static const struct rtc_class_ops rx8581_rtc_ops = {
 static int rx8581_probe(struct i2c_client *client,
                         const struct i2c_device_id *id)
 {
-        struct rtc_device *rtc;
+        struct rx8581     *rx8581;
 
         dev_dbg(&client->dev, "%s\n", __func__);
 
-        if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
-                return -ENODEV;
+        if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_BYTE_DATA)
+                && !i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK))
+                return -EIO;
 
-        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+        rx8581 = devm_kzalloc(&client->dev, sizeof(struct rx8581), GFP_KERNEL);
+        if (!rx8581)
+                return -ENOMEM;
 
-        rtc = devm_rtc_device_register(&client->dev, rx8581_driver.driver.name,
-                                        &rx8581_rtc_ops, THIS_MODULE);
+        i2c_set_clientdata(client, rx8581);
+        rx8581->client = client;
 
-        if (IS_ERR(rtc))
-                return PTR_ERR(rtc);
+        if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_I2C_BLOCK)) {
+                rx8581->read_block_data = i2c_smbus_read_i2c_block_data;
+                rx8581->write_block_data = i2c_smbus_write_i2c_block_data;
+        } else {
+                rx8581->read_block_data = rx8581_read_block_data;
+                rx8581->write_block_data = rx8581_write_block_data;
+        }
 
-        i2c_set_clientdata(client, rtc);
+        dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
+
+        rx8581->rtc = devm_rtc_device_register(&client->dev,
+                rx8581_driver.driver.name, &rx8581_rtc_ops, THIS_MODULE);
+
+        if (IS_ERR(rx8581->rtc)) {
+                dev_err(&client->dev,
+                        "unable to register the class device\n");
+                return PTR_ERR(rx8581->rtc);
+        }
 
         return 0;
 }