i2c: octeon: Improve error status checking

Introduce a function that checks for valid status codes depending
on the phase of a transmit or receive. Also add all existing status
codes and improve error handling for various states.

The Octeon TWSI has an "assert acknowledge" bit (TWSI_CTL_AAK) that
is required to be set in master receive mode until the last byte is
requested. The state check needs to consider if this bit was set.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-octeon.c b/drivers/i2c/busses/i2c-octeon.c
index 4275007..471d06e 100644 (file)
--- a/drivers/i2c/busses/i2c-octeon.c
+++ b/drivers/i2c/busses/i2c-octeon.c
@@ -55,13 +55,35 @@
 #define TWSI_CTL_IFLG          0x08    /* HW event, SW writes 0 to ACK */
 #define TWSI_CTL_AAK           0x04    /* Assert ACK */
 
-/* Some status values */
+/* Status values */
+#define STAT_ERROR             0x00
 #define STAT_START             0x08
-#define STAT_RSTART            0x10
+#define STAT_REP_START         0x10
 #define STAT_TXADDR_ACK                0x18
+#define STAT_TXADDR_NAK                0x20
 #define STAT_TXDATA_ACK                0x28
+#define STAT_TXDATA_NAK                0x30
+#define STAT_LOST_ARB_38       0x38
 #define STAT_RXADDR_ACK                0x40
+#define STAT_RXADDR_NAK                0x48
 #define STAT_RXDATA_ACK                0x50
+#define STAT_RXDATA_NAK                0x58
+#define STAT_SLAVE_60          0x60
+#define STAT_LOST_ARB_68       0x68
+#define STAT_SLAVE_70          0x70
+#define STAT_LOST_ARB_78       0x78
+#define STAT_SLAVE_80          0x80
+#define STAT_SLAVE_88          0x88
+#define STAT_GENDATA_ACK       0x90
+#define STAT_GENDATA_NAK       0x98
+#define STAT_SLAVE_A0          0xA0
+#define STAT_SLAVE_A8          0xA8
+#define STAT_LOST_ARB_B0       0xB0
+#define STAT_SLAVE_LOST                0xB8
+#define STAT_SLAVE_NAK         0xC0
+#define STAT_SLAVE_ACK         0xC8
+#define STAT_AD2W_ACK          0xD0
+#define STAT_AD2W_NAK          0xD8
 #define STAT_IDLE              0xF8
 
 /* TWSI_INT values */
@@ -225,6 +247,67 @@ static int octeon_i2c_wait(struct octeon_i2c *i2c)
        return 0;
 }
 
+static int octeon_i2c_check_status(struct octeon_i2c *i2c, int final_read)
+{
+       u8 stat = octeon_i2c_stat_read(i2c);
+
+       switch (stat) {
+       /* Everything is fine */
+       case STAT_IDLE:
+       case STAT_AD2W_ACK:
+       case STAT_RXADDR_ACK:
+       case STAT_TXADDR_ACK:
+       case STAT_TXDATA_ACK:
+               return 0;
+
+       /* ACK allowed on pre-terminal bytes only */
+       case STAT_RXDATA_ACK:
+               if (!final_read)
+                       return 0;
+               return -EIO;
+
+       /* NAK allowed on terminal byte only */
+       case STAT_RXDATA_NAK:
+               if (final_read)
+                       return 0;
+               return -EIO;
+
+       /* Arbitration lost */
+       case STAT_LOST_ARB_38:
+       case STAT_LOST_ARB_68:
+       case STAT_LOST_ARB_78:
+       case STAT_LOST_ARB_B0:
+               return -EAGAIN;
+
+       /* Being addressed as slave, should back off & listen */
+       case STAT_SLAVE_60:
+       case STAT_SLAVE_70:
+       case STAT_GENDATA_ACK:
+       case STAT_GENDATA_NAK:
+               return -EOPNOTSUPP;
+
+       /* Core busy as slave */
+       case STAT_SLAVE_80:
+       case STAT_SLAVE_88:
+       case STAT_SLAVE_A0:
+       case STAT_SLAVE_A8:
+       case STAT_SLAVE_LOST:
+       case STAT_SLAVE_NAK:
+       case STAT_SLAVE_ACK:
+               return -EOPNOTSUPP;
+
+       case STAT_TXDATA_NAK:
+               return -EIO;
+       case STAT_TXADDR_NAK:
+       case STAT_RXADDR_NAK:
+       case STAT_AD2W_NAK:
+               return -ENXIO;
+       default:
+               dev_err(i2c->dev, "unhandled state: %d\n", stat);
+               return -EIO;
+       }
+}
+
 /* calculate and set clock divisors */
 static void octeon_i2c_set_clock(struct octeon_i2c *i2c)
 {
@@ -318,7 +401,7 @@ static int octeon_i2c_start(struct octeon_i2c *i2c)
        }
 
        data = octeon_i2c_stat_read(i2c);
-       if ((data != STAT_START) && (data != STAT_RSTART)) {
+       if ((data != STAT_START) && (data != STAT_REP_START)) {
                dev_err(i2c->dev, "%s: bad status (0x%x)\n", __func__, data);
                return -EIO;
        }
@@ -347,7 +430,6 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
                            const u8 *data, int length)
 {
        int i, result;
-       u8 tmp;
 
        result = octeon_i2c_start(i2c);
        if (result)
@@ -361,14 +443,9 @@ static int octeon_i2c_write(struct octeon_i2c *i2c, int target,
                return result;
 
        for (i = 0; i < length; i++) {
-               tmp = octeon_i2c_stat_read(i2c);
-
-               if ((tmp != STAT_TXADDR_ACK) && (tmp != STAT_TXDATA_ACK)) {
-                       dev_err(i2c->dev,
-                               "%s: bad status before write (0x%x)\n",
-                               __func__, tmp);
-                       return -EIO;
-               }
+               result = octeon_i2c_check_status(i2c, false);
+               if (result)
+                       return result;
 
                octeon_i2c_data_write(i2c, data[i]);
                octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
@@ -397,7 +474,7 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
                           u8 *data, u16 *rlength, bool recv_len)
 {
        int i, result, length = *rlength;
-       u8 tmp;
+       bool final_read = false;
 
        if (length < 1)
                return -EINVAL;
@@ -413,19 +490,21 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
        if (result)
                return result;
 
+       /* address OK ? */
+       result = octeon_i2c_check_status(i2c, false);
+       if (result)
+               return result;
+
        for (i = 0; i < length; i++) {
-               tmp = octeon_i2c_stat_read(i2c);
-               if ((tmp != STAT_RXDATA_ACK) && (tmp != STAT_RXADDR_ACK)) {
-                       dev_err(i2c->dev,
-                               "%s: bad status before read (0x%x)\n",
-                               __func__, tmp);
-                       return -EIO;
-               }
+               /* for the last byte TWSI_CTL_AAK must not be set */
+               if (i + 1 == length)
+                       final_read = true;
 
-               if (i + 1 < length)
-                       octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_AAK);
-               else
+               /* clear iflg to allow next event */
+               if (final_read)
                        octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB);
+               else
+                       octeon_i2c_ctl_write(i2c, TWSI_CTL_ENAB | TWSI_CTL_AAK);
 
                result = octeon_i2c_wait(i2c);
                if (result)
@@ -441,6 +520,10 @@ static int octeon_i2c_read(struct octeon_i2c *i2c, int target,
                        }
                        length += data[i];
                }
+
+               result = octeon_i2c_check_status(i2c, final_read);
+               if (result)
+                       return result;
        }
        *rlength = length;
        return 0;