[PATCH] rtc-rs5c372: change register reading method

According to the datasheet rs5c372 supports three different methods for
reading register values.  Change from method #1 to method #3, since method #3
is the only one that works on Thecus N2100 board with this RTC.

Signed-off-by: Riku Voipio <riku.voipio@movial.fi>
Cc: Alessandro Zummo <alessandro.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 44 insertions, 40 deletions

diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
index 9e1bb3a72f7a..e2c7698fdba3 100644
--- a/drivers/rtc/rtc-rs5c372.c
+++ b/drivers/rtc/rtc-rs5c372.c
@@ -13,7 +13,7 @@
 #include <linux/rtc.h>
 #include <linux/bcd.h>
 
-#define DRV_VERSION "0.2"
+#define DRV_VERSION "0.3"
 
 /* Addresses to scan */
 static unsigned short normal_i2c[] = { /* 0x32,*/ I2C_CLIENT_END };
@@ -39,6 +39,14 @@ static int rs5c372_attach(struct i2c_adapter *adapter);
 static int rs5c372_detach(struct i2c_client *client);
 static int rs5c372_probe(struct i2c_adapter *adapter, int address, int kind);
 
+struct rs5c372 {
+        u8 reg_addr;
+        u8 regs[17];
+        struct i2c_msg msg[1];
+        struct i2c_client client;
+        struct rtc_device *rtc;
+};
+
 static struct i2c_driver rs5c372_driver = {
         .driver         = {
                 .name   = "rs5c372",
@@ -49,18 +57,16 @@ static struct i2c_driver rs5c372_driver = {
 
 static int rs5c372_get_datetime(struct i2c_client *client, struct rtc_time *tm)
 {
-        unsigned char buf[7] = { RS5C372_REG_BASE };
 
-        /* this implements the 1st reading method, according
-         * to the datasheet. buf[0] is initialized with
-         * address ptr and transmission format register.
+        struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
+        u8 *buf = &(rs5c372->regs[1]);
+
+        /* this implements the 3rd reading method, according
+         * to the datasheet. rs5c372 defaults to internal
+         * address 0xF, so 0x0 is in regs[1]
          */
-        struct i2c_msg msgs[] = {
-                { client->addr, 0, 1, buf },
-                { client->addr, I2C_M_RD, 7, buf },
-        };
 
-        if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
+        if ((i2c_transfer(client->adapter, rs5c372->msg, 1)) != 1) {
                 dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
                 return -EIO;
         }
@@ -114,23 +120,14 @@ static int rs5c372_set_datetime(struct i2c_client *client, struct rtc_time *tm)
 
 static int rs5c372_get_trim(struct i2c_client *client, int *osc, int *trim)
 {
-        unsigned char buf = RS5C372_REG_TRIM;
-
-        struct i2c_msg msgs[] = {
-                { client->addr, 0, 1, &buf },
-                { client->addr, I2C_M_RD, 1, &buf },
-        };
-
-        if ((i2c_transfer(client->adapter, msgs, 2)) != 2) {
-                dev_err(&client->dev, "%s: read error\n", __FUNCTION__);
-                return -EIO;
-        }
+        struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
+        u8 tmp = rs5c372->regs[RS5C372_REG_TRIM + 1];
 
         if (osc)
-                *osc = (buf & RS5C372_TRIM_XSL) ? 32000 : 32768;
+                *osc = (tmp & RS5C372_TRIM_XSL) ? 32000 : 32768;
 
         if (trim) {
-                *trim = buf & RS5C372_TRIM_MASK;
+                *trim = tmp & RS5C372_TRIM_MASK;
                 dev_dbg(&client->dev, "%s: raw trim=%x\n", __FUNCTION__, *trim);
         }
 
@@ -201,7 +198,7 @@ static int rs5c372_probe(struct i2c_adapter *adapter, int address, int kind)
 {
         int err = 0;
         struct i2c_client *client;
-        struct rtc_device *rtc;
+        struct rs5c372 *rs5c372;
 
         dev_dbg(&adapter->dev, "%s\n", __FUNCTION__);
 
@@ -210,10 +207,11 @@ static int rs5c372_probe(struct i2c_adapter *adapter, int address, int kind)
                 goto exit;
         }
 
-        if (!(client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
+        if (!(rs5c372 = kzalloc(sizeof(struct rs5c372), GFP_KERNEL))) {
                 err = -ENOMEM;
                 goto exit;
         }
+        client = &rs5c372->client;
 
         /* I2C client */
         client->addr = address;
@@ -222,26 +220,33 @@ static int rs5c372_probe(struct i2c_adapter *adapter, int address, int kind)
 
         strlcpy(client->name, rs5c372_driver.driver.name, I2C_NAME_SIZE);
 
+        i2c_set_clientdata(client, rs5c372);
+
+        rs5c372->msg[0].addr = address;
+        rs5c372->msg[0].flags = I2C_M_RD;
+        rs5c372->msg[0].len = sizeof(rs5c372->regs);
+        rs5c372->msg[0].buf = rs5c372->regs;
+
         /* Inform the i2c layer */
         if ((err = i2c_attach_client(client)))
                 goto exit_kfree;
 
         dev_info(&client->dev, "chip found, driver version " DRV_VERSION "\n");
 
-        rtc = rtc_device_register(rs5c372_driver.driver.name, &client->dev,
-                                &rs5c372_rtc_ops, THIS_MODULE);
+        rs5c372->rtc = rtc_device_register(rs5c372_driver.driver.name,
+                                &client->dev, &rs5c372_rtc_ops, THIS_MODULE);
 
-        if (IS_ERR(rtc)) {
-                err = PTR_ERR(rtc);
+        if (IS_ERR(rs5c372->rtc)) {
+                err = PTR_ERR(rs5c372->rtc);
                 goto exit_detach;
         }
 
-        i2c_set_clientdata(client, rtc);
-
         err = device_create_file(&client->dev, &dev_attr_trim);
-        if (err) goto exit_devreg;
+        if (err)
+                goto exit_devreg;
         err = device_create_file(&client->dev, &dev_attr_osc);
-        if (err) goto exit_trim;
+        if (err)
+                goto exit_trim;
 
         return 0;
 
@@ -249,13 +254,13 @@ exit_trim:
         device_remove_file(&client->dev, &dev_attr_trim);
 
 exit_devreg:
-        rtc_device_unregister(rtc);
+        rtc_device_unregister(rs5c372->rtc);
 
 exit_detach:
         i2c_detach_client(client);
 
 exit_kfree:
-        kfree(client);
+        kfree(rs5c372);
 
 exit:
         return err;
@@ -264,16 +269,15 @@ exit:
 static int rs5c372_detach(struct i2c_client *client)
 {
         int err;
-        struct rtc_device *rtc = i2c_get_clientdata(client);
+        struct rs5c372 *rs5c372 = i2c_get_clientdata(client);
 
-        if (rtc)
-                rtc_device_unregister(rtc);
+        if (rs5c372->rtc)
+                rtc_device_unregister(rs5c372->rtc);
 
         if ((err = i2c_detach_client(client)))
                 return err;
 
-        kfree(client);
-
+        kfree(rs5c372);
         return 0;
 }