From abbotti@mev.co.uk Tue Jun 1 13:22:20 2010 From: Ian Abbott Date: Wed, 19 May 2010 16:59:40 +0100 Subject: Staging: comedi: amplc_dio200: Protect counter subdevice with spinlock Cc: Greg Kroah-Hartman , Frank Mori Hess , Ian Abbott Message-ID: <1274284780-8902-1-git-send-email-abbotti@mev.co.uk> The internal state of an 82C54 counter timer chip will get messed up if several threads read, write, configure, or check the status of the chip simultaneously. Protect the register access sequences with a spin lock. Signed-off-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/amplc_dio200.c | 35 ++++++++++++++++++-------- 1 file changed, 25 insertions(+), 10 deletions(-) --- a/drivers/staging/comedi/drivers/amplc_dio200.c +++ b/drivers/staging/comedi/drivers/amplc_dio200.c @@ -460,6 +460,7 @@ struct dio200_subdev_8254 { int has_clk_gat_sce; unsigned clock_src[3]; /* Current clock sources */ unsigned gate_src[3]; /* Current gate sources */ + spinlock_t spinlock; }; struct dio200_subdev_intr { @@ -1042,8 +1043,11 @@ dio200_subdev_8254_read(struct comedi_de { struct dio200_subdev_8254 *subpriv = s->private; int chan = CR_CHAN(insn->chanspec); + unsigned long flags; + spin_lock_irqsave(&subpriv->spinlock, flags); data[0] = i8254_read(subpriv->iobase, 0, chan); + spin_unlock_irqrestore(&subpriv->spinlock, flags); return 1; } @@ -1057,8 +1061,11 @@ dio200_subdev_8254_write(struct comedi_d { struct dio200_subdev_8254 *subpriv = s->private; int chan = CR_CHAN(insn->chanspec); + unsigned long flags; + spin_lock_irqsave(&subpriv->spinlock, flags); i8254_write(subpriv->iobase, 0, chan, data[0]); + spin_unlock_irqrestore(&subpriv->spinlock, flags); return 1; } @@ -1151,14 +1158,16 @@ dio200_subdev_8254_config(struct comedi_ struct comedi_insn *insn, unsigned int *data) { struct dio200_subdev_8254 *subpriv = s->private; - int ret; + int ret = 0; int chan = CR_CHAN(insn->chanspec); + unsigned long flags; + spin_lock_irqsave(&subpriv->spinlock, flags); switch (data[0]) { case INSN_CONFIG_SET_COUNTER_MODE: ret = i8254_set_mode(subpriv->iobase, 0, chan, data[1]); if (ret < 0) - return -EINVAL; + ret = -EINVAL; break; case INSN_CONFIG_8254_READ_STATUS: data[1] = i8254_status(subpriv->iobase, 0, chan); @@ -1166,30 +1175,35 @@ dio200_subdev_8254_config(struct comedi_ case INSN_CONFIG_SET_GATE_SRC: ret = dio200_set_gate_src(subpriv, chan, data[2]); if (ret < 0) - return -EINVAL; + ret = -EINVAL; break; case INSN_CONFIG_GET_GATE_SRC: ret = dio200_get_gate_src(subpriv, chan); - if (ret < 0) - return -EINVAL; + if (ret < 0) { + ret = -EINVAL; + break; + } data[2] = ret; break; case INSN_CONFIG_SET_CLOCK_SRC: ret = dio200_set_clock_src(subpriv, chan, data[1]); if (ret < 0) - return -EINVAL; + ret = -EINVAL; break; case INSN_CONFIG_GET_CLOCK_SRC: ret = dio200_get_clock_src(subpriv, chan, &data[2]); - if (ret < 0) - return -EINVAL; + if (ret < 0) { + ret = -EINVAL; + break; + } data[1] = ret; break; default: - return -EINVAL; + ret = -EINVAL; break; } - return insn->n; + spin_unlock_irqrestore(&subpriv->spinlock, flags); + return ret < 0 ? ret : insn->n; } /* @@ -1222,6 +1236,7 @@ dio200_subdev_8254_init(struct comedi_de s->insn_write = dio200_subdev_8254_write; s->insn_config = dio200_subdev_8254_config; + spin_lock_init(&subpriv->spinlock); subpriv->iobase = offset + iobase; subpriv->has_clk_gat_sce = has_clk_gat_sce; if (has_clk_gat_sce) {