diff options
author | Måns Rullgård <mans@mansr.com> | 2015-12-15 23:15:05 +0000 |
---|---|---|
committer | Wolfram Sang <wsa@the-dreams.de> | 2015-12-16 11:42:30 +0100 |
commit | a45af72a609b095820feab26c49286337301377e (patch) | |
tree | c347d0cd0b11d7f4b0872d02aefea64d5786c1bd /drivers/i2c/busses/i2c-xlr.c | |
parent | 75d31c2372e4a08319919b14bd160c48305373a1 (diff) | |
download | linux-a45af72a609b095820feab26c49286337301377e.tar.bz2 |
i2c: xlr: fix extra read/write at end of rx transfer
The BYTECNT register holds the transfer size minus one. Setting it to
the correct value removes the need for a dummy read/write at the end of
each transfer. As zero-length transfers are not supported, do not
advertise I2C_FUNC_SMBUS_QUICK.
In other words, this patch makes the driver transfer the number of bytes
requested unless this is zero, which is not supported by the hardware
and is thus refused.
Signed-off-by: Mans Rullgard <mans@mansr.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Diffstat (limited to 'drivers/i2c/busses/i2c-xlr.c')
-rw-r--r-- | drivers/i2c/busses/i2c-xlr.c | 50 |
1 files changed, 27 insertions, 23 deletions
diff --git a/drivers/i2c/busses/i2c-xlr.c b/drivers/i2c/busses/i2c-xlr.c index 10fb916fa8c7..2cfaba7c1f92 100644 --- a/drivers/i2c/busses/i2c-xlr.c +++ b/drivers/i2c/busses/i2c-xlr.c @@ -89,38 +89,43 @@ static int xlr_i2c_tx(struct xlr_i2c_private *priv, u16 len, unsigned long timeout, stoptime, checktime; u32 i2c_status; int pos, timedout; - u8 offset, byte; + u8 offset; + u32 xfer; + + if (!len) + return -EOPNOTSUPP; offset = buf[0]; xlr_i2c_wreg(priv->iobase, XLR_I2C_ADDR, offset); xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr); xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_ADDR | priv->cfg->cfg_extra); - xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1); timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT); stoptime = jiffies + timeout; timedout = 0; - pos = 1; -retry: + if (len == 1) { - xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, - XLR_I2C_STARTXFR_ND); + xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1); + xfer = XLR_I2C_STARTXFR_ND; + pos = 1; } else { - xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos]); - xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, - XLR_I2C_STARTXFR_WR); + xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 2); + xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[1]); + xfer = XLR_I2C_STARTXFR_WR; + pos = 2; } +retry: + /* retry can only happen on the first byte */ + xlr_i2c_wreg(priv->iobase, XLR_I2C_STARTXFR, xfer); + while (!timedout) { checktime = jiffies; i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS); - if (i2c_status & XLR_I2C_SDOEMPTY) { - pos++; - /* need to do a empty dataout after the last byte */ - byte = (pos < len) ? buf[pos] : 0; - xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, byte); + if ((i2c_status & XLR_I2C_SDOEMPTY) && pos < len) { + xlr_i2c_wreg(priv->iobase, XLR_I2C_DATAOUT, buf[pos++]); /* reset timeout on successful xmit */ stoptime = jiffies + timeout; @@ -149,11 +154,13 @@ static int xlr_i2c_rx(struct xlr_i2c_private *priv, u16 len, u8 *buf, u16 addr) u32 i2c_status; unsigned long timeout, stoptime, checktime; int nbytes, timedout; - u8 byte; + + if (!len) + return -EOPNOTSUPP; xlr_i2c_wreg(priv->iobase, XLR_I2C_CFG, XLR_I2C_CFG_NOADDR | priv->cfg->cfg_extra); - xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len); + xlr_i2c_wreg(priv->iobase, XLR_I2C_BYTECNT, len - 1); xlr_i2c_wreg(priv->iobase, XLR_I2C_DEVADDR, addr); timeout = msecs_to_jiffies(XLR_I2C_TIMEOUT); @@ -167,14 +174,11 @@ retry: checktime = jiffies; i2c_status = xlr_i2c_rdreg(priv->iobase, XLR_I2C_STATUS); if (i2c_status & XLR_I2C_RXRDY) { - if (nbytes > len) + if (nbytes >= len) return -EIO; /* should not happen */ - /* we need to do a dummy datain when nbytes == len */ - byte = xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN); - if (nbytes < len) - buf[nbytes] = byte; - nbytes++; + buf[nbytes++] = + xlr_i2c_rdreg(priv->iobase, XLR_I2C_DATAIN); /* reset timeout on successful read */ stoptime = jiffies + timeout; @@ -228,7 +232,7 @@ static int xlr_i2c_xfer(struct i2c_adapter *adap, static u32 xlr_func(struct i2c_adapter *adap) { /* Emulate SMBUS over I2C */ - return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C; + return (I2C_FUNC_SMBUS_EMUL & ~I2C_FUNC_SMBUS_QUICK) | I2C_FUNC_I2C; } static struct i2c_algorithm xlr_i2c_algo = { |