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SubjectRe: [PATCH v3] counter: 104-quad-8: Support Differential Encoder Cable Status
On Sun,  1 Mar 2020 17:07:19 -0500
William Breathitt Gray <vilhelm.gray@gmail.com> wrote:

> The ACCES 104-QUAD-8 series provides status information about the
> connection state of the differential encoder cable inputs. This patch
> implements support to expose such information from these devices.
>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
Looks good to me. Applied to the togreg branch of iio.git
and pushed out as testing for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> Changes in v3:
> - Split cable_status attribute into cable_fault and cable_fault_enable;
> both under each Signal so we can control each channel independently
> - Initialize to a default state of disabled for all channels
>
> .../ABI/testing/sysfs-bus-counter-104-quad-8 | 18 +++++
> drivers/counter/104-quad-8.c | 75 +++++++++++++++++++
> 2 files changed, 93 insertions(+)
>
> diff --git a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8 b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> index 3c905d3cf5d7..eac32180c40d 100644
> --- a/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> +++ b/Documentation/ABI/testing/sysfs-bus-counter-104-quad-8
> @@ -1,3 +1,21 @@
> +What: /sys/bus/counter/devices/counterX/signalY/cable_fault
> +KernelVersion: 5.7
> +Contact: linux-iio@vger.kernel.org
> +Description:
> + Read-only attribute that indicates whether a differential
> + encoder cable fault (not connected or loose wires) is detected
> + for the respective channel of Signal Y. Valid attribute values
> + are boolean. Detection must first be enabled via the
> + corresponding cable_fault_enable attribute.
> +
> +What: /sys/bus/counter/devices/counterX/signalY/cable_fault_enable
> +KernelVersion: 5.7
> +Contact: linux-iio@vger.kernel.org
> +Description:
> + Whether detection of differential encoder cable faults for the
> + respective channel of Signal Y is enabled. Valid attribute
> + values are boolean.
> +
> What: /sys/bus/counter/devices/counterX/signalY/filter_clock_prescaler
> KernelVersion: 5.7
> Contact: linux-iio@vger.kernel.org
> diff --git a/drivers/counter/104-quad-8.c b/drivers/counter/104-quad-8.c
> index 0cfc813ee2cb..9dab190c49b0 100644
> --- a/drivers/counter/104-quad-8.c
> +++ b/drivers/counter/104-quad-8.c
> @@ -31,6 +31,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
> /**
> * struct quad8_iio - IIO device private data structure
> * @counter: instance of the counter_device
> + * @fck_prescaler: array of filter clock prescaler configurations
> * @preset: array of preset values
> * @count_mode: array of count mode configurations
> * @quadrature_mode: array of quadrature mode configurations
> @@ -39,6 +40,7 @@ MODULE_PARM_DESC(base, "ACCES 104-QUAD-8 base addresses");
> * @preset_enable: array of set_to_preset_on_index attribute configurations
> * @synchronous_mode: array of index function synchronous mode configurations
> * @index_polarity: array of index function polarity configurations
> + * @cable_fault_enable: differential encoder cable status enable configurations
> * @base: base port address of the IIO device
> */
> struct quad8_iio {
> @@ -52,11 +54,13 @@ struct quad8_iio {
> unsigned int preset_enable[QUAD8_NUM_COUNTERS];
> unsigned int synchronous_mode[QUAD8_NUM_COUNTERS];
> unsigned int index_polarity[QUAD8_NUM_COUNTERS];
> + unsigned int cable_fault_enable;
> unsigned int base;
> };
>
> #define QUAD8_REG_CHAN_OP 0x11
> #define QUAD8_REG_INDEX_INPUT_LEVELS 0x16
> +#define QUAD8_DIFF_ENCODER_CABLE_STATUS 0x17
> /* Borrow Toggle flip-flop */
> #define QUAD8_FLAG_BT BIT(0)
> /* Carry Toggle flip-flop */
> @@ -1143,6 +1147,66 @@ static ssize_t quad8_count_preset_enable_write(struct counter_device *counter,
> return len;
> }
>
> +static ssize_t quad8_signal_cable_fault_read(struct counter_device *counter,
> + struct counter_signal *signal,
> + void *private, char *buf)
> +{
> + const struct quad8_iio *const priv = counter->priv;
> + const size_t channel_id = signal->id / 2;
> + const bool disabled = !(priv->cable_fault_enable & BIT(channel_id));
> + unsigned int status;
> + unsigned int fault;
> +
> + if (disabled)
> + return -EINVAL;
> +
> + /* Logic 0 = cable fault */
> + status = inb(priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
> +
> + /* Mask respective channel and invert logic */
> + fault = !(status & BIT(channel_id));
> +
> + return sprintf(buf, "%u\n", fault);
> +}
> +
> +static ssize_t quad8_signal_cable_fault_enable_read(
> + struct counter_device *counter, struct counter_signal *signal,
> + void *private, char *buf)
> +{
> + const struct quad8_iio *const priv = counter->priv;
> + const size_t channel_id = signal->id / 2;
> + const unsigned int enb = !!(priv->cable_fault_enable & BIT(channel_id));
> +
> + return sprintf(buf, "%u\n", enb);
> +}
> +
> +static ssize_t quad8_signal_cable_fault_enable_write(
> + struct counter_device *counter, struct counter_signal *signal,
> + void *private, const char *buf, size_t len)
> +{
> + struct quad8_iio *const priv = counter->priv;
> + const size_t channel_id = signal->id / 2;
> + bool enable;
> + int ret;
> + unsigned int cable_fault_enable;
> +
> + ret = kstrtobool(buf, &enable);
> + if (ret)
> + return ret;
> +
> + if (enable)
> + priv->cable_fault_enable |= BIT(channel_id);
> + else
> + priv->cable_fault_enable &= ~BIT(channel_id);
> +
> + /* Enable is active low in Differential Encoder Cable Status register */
> + cable_fault_enable = ~priv->cable_fault_enable;
> +
> + outb(cable_fault_enable, priv->base + QUAD8_DIFF_ENCODER_CABLE_STATUS);
> +
> + return len;
> +}
> +
> static ssize_t quad8_signal_fck_prescaler_read(struct counter_device *counter,
> struct counter_signal *signal, void *private, char *buf)
> {
> @@ -1180,6 +1244,15 @@ static ssize_t quad8_signal_fck_prescaler_write(struct counter_device *counter,
> }
>
> static const struct counter_signal_ext quad8_signal_ext[] = {
> + {
> + .name = "cable_fault",
> + .read = quad8_signal_cable_fault_read
> + },
> + {
> + .name = "cable_fault_enable",
> + .read = quad8_signal_cable_fault_enable_read,
> + .write = quad8_signal_cable_fault_enable_write
> + },
> {
> .name = "filter_clock_prescaler",
> .read = quad8_signal_fck_prescaler_read,
> @@ -1383,6 +1456,8 @@ static int quad8_probe(struct device *dev, unsigned int id)
> /* Disable index function; negative index polarity */
> outb(QUAD8_CTR_IDR, base_offset + 1);
> }
> + /* Disable Differential Encoder Cable Status for all channels */
> + outb(0xFF, base[id] + QUAD8_DIFF_ENCODER_CABLE_STATUS);
> /* Enable all counters */
> outb(QUAD8_CHAN_OP_ENABLE_COUNTERS, base[id] + QUAD8_REG_CHAN_OP);
>

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