rockchip: i2c: fix >32 byte reads

The hw can read up to 32 bytes at a time. If we need
more than one chunk, we have to enter the plain RX mode.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

diff --git a/drivers/i2c/rk_i2c.c b/drivers/i2c/rk_i2c.c
index 8bc045a1a02b22482926b4ced8218c60dbb52761..68e66536e4e3af6ae759b461ee072b73ff9c4191 100644 (file)
--- a/drivers/i2c/rk_i2c.c
+++ b/drivers/i2c/rk_i2c.c
@@ -164,6 +164,7 @@ static int rk_i2c_read(struct rk_i2c *i2c, uchar chip, uint reg, uint r_len,
        uint rxdata;
        uint i, j;
        int err;
+       bool snd_chunk = false;
 
        debug("rk_i2c_read: chip = %d, reg = %d, r_len = %d, b_len = %d\n",
              chip, reg, r_len, b_len);
@@ -184,15 +185,26 @@ static int rk_i2c_read(struct rk_i2c *i2c, uchar chip, uint reg, uint r_len,
 
        while (bytes_remain_len) {
                if (bytes_remain_len > RK_I2C_FIFO_SIZE) {
-                       con = I2C_CON_EN | I2C_CON_MOD(I2C_MODE_TRX);
+                       con = I2C_CON_EN;
                        bytes_xferred = 32;
                } else {
-                       con = I2C_CON_EN | I2C_CON_MOD(I2C_MODE_TRX) |
-                               I2C_CON_LASTACK;
+                       /*
+                        * The hw can read up to 32 bytes at a time. If we need
+                        * more than one chunk, send an ACK after the last byte.
+                        */
+                       con = I2C_CON_EN | I2C_CON_LASTACK;
                        bytes_xferred = bytes_remain_len;
                }
                words_xferred = DIV_ROUND_UP(bytes_xferred, 4);
 
+               /*
+                * make sure we are in plain RX mode if we read a second chunk
+                */
+               if (snd_chunk)
+                       con |= I2C_CON_MOD(I2C_MODE_RX);
+               else
+                       con |= I2C_CON_MOD(I2C_MODE_TRX);
+
                writel(con, &regs->con);
                writel(bytes_xferred, &regs->mrxcnt);
                writel(I2C_MBRFIEN | I2C_NAKRCVIEN, &regs->ien);
@@ -227,6 +239,7 @@ static int rk_i2c_read(struct rk_i2c *i2c, uchar chip, uint reg, uint r_len,
                }
 
                bytes_remain_len -= bytes_xferred;
+               snd_chunk = true;
                debug("I2C Read bytes_remain_len %d\n", bytes_remain_len);
        }