From 27c4d23cb070fd83f5705aabfad8d277fed9e022 Mon Sep 17 00:00:00 2001 From: H Hartley Sweeten Date: Thu, 24 Jul 2014 10:14:26 -0700 Subject: [PATCH] staging: comedi: ni_tio: fix ni_tio_insn_read() The comedi core expects the (*insn_read) operations to read insn->n values and return the number of values read. Fix this function to work line the core expects. For aesthetics, factor out the code that reads the SM_Save_Reg. Signed-off-by: H Hartley Sweeten Reviewed-by: Ian Abbott Signed-off-by: Greg Kroah-Hartman --- drivers/staging/comedi/drivers/ni_tio.c | 80 +++++++++++++++---------- 1 file changed, 47 insertions(+), 33 deletions(-) diff --git a/drivers/staging/comedi/drivers/ni_tio.c b/drivers/staging/comedi/drivers/ni_tio.c index 694bd5142cc5..da6602392fb3 100644 --- a/drivers/staging/comedi/drivers/ni_tio.c +++ b/drivers/staging/comedi/drivers/ni_tio.c @@ -1512,6 +1512,38 @@ int ni_tio_insn_config(struct comedi_device *dev, } EXPORT_SYMBOL_GPL(ni_tio_insn_config); +static unsigned int ni_tio_read_sw_save_reg(struct comedi_device *dev, + struct comedi_subdevice *s) +{ + struct ni_gpct *counter = s->private; + unsigned cidx = counter->counter_index; + unsigned int first_read; + unsigned int second_read; + unsigned int correct_read; + + ni_tio_set_bits(counter, NITIO_CMD_REG(cidx), Gi_Save_Trace_Bit, 0); + ni_tio_set_bits(counter, NITIO_CMD_REG(cidx), + Gi_Save_Trace_Bit, Gi_Save_Trace_Bit); + + /* + * The count doesn't get latched until the next clock edge, so it is + * possible the count may change (once) while we are reading. Since + * the read of the SW_Save_Reg isn't atomic (apparently even when it's + * a 32 bit register according to 660x docs), we need to read twice + * and make sure the reading hasn't changed. If it has, a third read + * will be correct since the count value will definitely have latched + * by then. + */ + first_read = read_register(counter, NITIO_SW_SAVE_REG(cidx)); + second_read = read_register(counter, NITIO_SW_SAVE_REG(cidx)); + if (first_read != second_read) + correct_read = read_register(counter, NITIO_SW_SAVE_REG(cidx)); + else + correct_read = first_read; + + return correct_read; +} + int ni_tio_insn_read(struct comedi_device *dev, struct comedi_subdevice *s, struct comedi_insn *insn, @@ -1519,42 +1551,24 @@ int ni_tio_insn_read(struct comedi_device *dev, { struct ni_gpct *counter = s->private; struct ni_gpct_device *counter_dev = counter->counter_dev; - const unsigned channel = CR_CHAN(insn->chanspec); + unsigned int channel = CR_CHAN(insn->chanspec); unsigned cidx = counter->counter_index; - unsigned first_read; - unsigned second_read; - unsigned correct_read; + int i; - if (insn->n < 1) - return 0; - switch (channel) { - case 0: - ni_tio_set_bits(counter, NITIO_CMD_REG(cidx), - Gi_Save_Trace_Bit, 0); - ni_tio_set_bits(counter, NITIO_CMD_REG(cidx), - Gi_Save_Trace_Bit, Gi_Save_Trace_Bit); - /* The count doesn't get latched until the next clock edge, so it is possible the count - may change (once) while we are reading. Since the read of the SW_Save_Reg isn't - atomic (apparently even when it's a 32 bit register according to 660x docs), - we need to read twice and make sure the reading hasn't changed. If it has, - a third read will be correct since the count value will definitely have latched by then. */ - first_read = read_register(counter, NITIO_SW_SAVE_REG(cidx)); - second_read = read_register(counter, NITIO_SW_SAVE_REG(cidx)); - if (first_read != second_read) - correct_read = - read_register(counter, NITIO_SW_SAVE_REG(cidx)); - else - correct_read = first_read; - data[0] = correct_read; - return 0; - case 1: - data[0] = counter_dev->regs[NITIO_LOADA_REG(cidx)]; - break; - case 2: - data[0] = counter_dev->regs[NITIO_LOADB_REG(cidx)]; - break; + for (i = 0; i < insn->n; i++) { + switch (channel) { + case 0: + data[i] = ni_tio_read_sw_save_reg(dev, s); + break; + case 1: + data[i] = counter_dev->regs[NITIO_LOADA_REG(cidx)]; + break; + case 2: + data[i] = counter_dev->regs[NITIO_LOADB_REG(cidx)]; + break; + } } - return 0; + return insn->n; } EXPORT_SYMBOL_GPL(ni_tio_insn_read); -- 2.30.2