Message-ID: <CA+M3ks4BsrRWMOHQ4rVLB1VZxQQVyLt8JyUTkyp5WH1m1D4PnA@mail.gmail.com>
Date:   Sun, 12 Mar 2017 14:18:47 +0100
From:   Benjamin Gaignard <benjamin.gaignard@...aro.org>
To:     Jonathan Cameron <jic23@...nel.org>, vilhelm.gray@...il.com
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-iio@...r.kernel.org, Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Fabrice Gasnier <fabrice.gasnier@...com>,
        Linaro Kernel Mailman List <linaro-kernel@...ts.linaro.org>,
        Benjamin Gaignard <benjamin.gaignard@...com>
Subject: Re: [PATCH v1 2/2] iio: stm32 trigger: Add counter device

2017-03-05 13:04 GMT+01:00 Jonathan Cameron <jic23@...nel.org>:
> On 01/03/17 14:45, Benjamin Gaignard wrote:
>> One of the features of STM32 trigger hardware block is a counter
>> that can counts up/down depending of the levels and edges of the
>> selected external pins.
>>
>> This patch allow to read/write the counter, get the direction and
>> set the preset value.
>> When counting up preset value is the limit of the counter.
>> When counting down the counter start from preset value down to 0.
>>
>> The hardware have multiple way to use inputs edges and levels to
>> performing counting, those different modes are exposed in:
>> /sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
>> and documented in Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>>
>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@...com>
> This is rapidly turning into a driver for soemthing other than a trigger,
> but I suppose that doesn't matter to much.  We may just want to
> move it at some stage...

Yes It could be put into counter directory.

>
> The primary issues in here are still around the ABI for counter-mode
> It's combining a load of generic concepts and forcing them all into
> one attribute.  That never generalises well so we need to break these
> up before moving futher with this one.

I'm adding William in this thread since he has wrote 104-quad-8 driver.
William may you help us to make this ABI more generic ?

>
> Few other bits inline.
>
> Jonathan
>> ---
>>  .../ABI/testing/sysfs-bus-iio-timer-stm32          |  40 ++++
>>  drivers/iio/trigger/stm32-timer-trigger.c          | 231 ++++++++++++++++++++-
>>  include/linux/mfd/stm32-timers.h                   |   2 +
>>  3 files changed, 267 insertions(+), 6 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32 b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> index 6534a60..17933ef 100644
>> --- a/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> +++ b/Documentation/ABI/testing/sysfs-bus-iio-timer-stm32
>> @@ -27,3 +27,43 @@ Description:
>>               Reading returns the current sampling frequency.
>>               Writing an value different of 0 set and start sampling.
>>               Writing 0 stop sampling.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/in_count_count_mode_available
>> +KernelVersion:       4.12
>> +Contact:     benjamin.gaignard@...com
>> +Description:
>> +             Reading returns the list of possible counting modes which are:
>> +             - "internal_clock": Counter is clocked by the internal clock rising edges.
> As we are describing this now as a hardware counter, perhaps this first one should be
> something like
> pseudo encoder, or simulated encoder to represent it's use as a way of providing encoder
> like counting when we don't have an encoder.

It is more a counter than an encoder here, I would like to keep "count
mode" or "count control" for this.

>
>> +             - "encoder_1" : Counter is clocked by the rising edges of external pin 2 and the counter
>> +                             direction depend of the level of external pin 1.
>> +             - "encoder_2" : Counter is clocked by the rising edges of external pin 1 and the counter
>> +                             direction depend of the level of external pin 2.
>> +             - "encoder_3" : Counter counts up/down on channels 1 & 2 edge depending on channel 1 & 2 level.
>> +                             Counter is clocked by the rising edges of external pins 1 & 2,
>> +                             the counter direction is depend of the levels of external pin 1 & 2.
> We absolutely need to figure out a generic name for these modes.  They are standard ways of handling an encoder
> so it should be possible to come up with something.

I can add them into a "quaduature mode" attribute:
- channel_A
- channel_B
- 2x_speed

For what I read it is generic way to describe encoder way of working.
http://www.dynapar.com/Technology/Encoder_Basics/Quadrature_Encoder/
An other mode could 4x_speed but it isn't supported by my hardware.

>
>> +             - "reset"     : Rising edges on pin 1 reinitializes the counter value to preset value.
>> +             - "gated"     : Counter counts when external pin level is high.
>> +                             Counter stops (but is not reset) as soon as external pin becomes low.
>> +             - "trigger"   : Counter starts at a rising edge of the external pin (but it is not reset).
> We still have the same issue here.  These are totally different concepts.
> To drive towards a generic interface we need to split this up.
>
> What clock are the last 3 using?  Not clear from the description currently.

The clock is the internal clock (like for the first one) so I think I
can merge them into a single
attribute.

>
> Right now it represents the hardware of this one device, not generic concepts which is where
> we need to be.
>
>
>> +
>> +             Encoder modes are used to automatically handle the counting direction of the internal counter.
>> +             Those modes are typically used for high-accuracy rotor position sensing in electrical motors
>> +             or for digital potentiometers. From the two outputs of a quadrature encoder sensor the timer
>> +             extracts a clock on each and every active edge and adjusts the counting direction depending on
>> +             the relative phase-shift between the two incomings signals. The timer counter thus directly
>> +             holds the angular position of the motor.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/in_count0_count_mode
>> +KernelVersion:       4.12
>> +Contact:     benjamin.gaignard@...com
>> +Description:
>> +             Reading returns the current counting mode.
>> +
>> +What:                /sys/bus/iio/devices/iio:deviceX/in_count0_preset
>> +KernelVersion:       4.12
>> +Contact:     benjamin.gaignard@...com
>> +Description:
>> +             Reading returns the current preset value.
>> +             Writing set the preset value.
>> +             When counting up the counter start from 0 and fire an event when reach preset value.
>> +             When counting down the counter start from preset value and fire event when reach 0.
> This is generic, so as with the other attribute you just handled, please make some generic text
> to cover both this and that in the other counter driver and move it up to the generic docs.
>> diff --git a/drivers/iio/trigger/stm32-timer-trigger.c b/drivers/iio/trigger/stm32-timer-trigger.c
>> index 994b96d..9026265 100644
>> --- a/drivers/iio/trigger/stm32-timer-trigger.c
>> +++ b/drivers/iio/trigger/stm32-timer-trigger.c
>> @@ -15,6 +15,7 @@
>>  #include <linux/platform_device.h>
>>
>>  #define MAX_TRIGGERS 6
>> +#define MAX_VALIDS 5
>>
>>  /* List the triggers created by each timer */
>>  static const void *triggers_table[][MAX_TRIGGERS] = {
>> @@ -32,12 +33,29 @@
>>       { TIM12_TRGO, TIM12_CH1, TIM12_CH2,},
>>  };
>>
>> +/* List the triggers accepted by each timer */
>> +static const void *valids_table[][MAX_VALIDS] = {
>> +     { TIM5_TRGO, TIM2_TRGO, TIM3_TRGO, TIM4_TRGO,},
>> +     { TIM1_TRGO, TIM8_TRGO, TIM3_TRGO, TIM4_TRGO,},
>> +     { TIM1_TRGO, TIM2_TRGO, TIM5_TRGO, TIM4_TRGO,},
>> +     { TIM1_TRGO, TIM2_TRGO, TIM3_TRGO, TIM8_TRGO,},
>> +     { TIM2_TRGO, TIM3_TRGO, TIM4_TRGO, TIM8_TRGO,},
>> +     { }, /* timer 6 */
>> +     { }, /* timer 7 */
>> +     { TIM1_TRGO, TIM2_TRGO, TIM4_TRGO, TIM5_TRGO,},
>> +     { TIM2_TRGO, TIM3_TRGO,},
>> +     { }, /* timer 10 */
>> +     { }, /* timer 11 */
>> +     { TIM4_TRGO, TIM5_TRGO,},
>> +};
>> +
>>  struct stm32_timer_trigger {
>>       struct device *dev;
>>       struct regmap *regmap;
>>       struct clk *clk;
>>       u32 max_arr;
>>       const void *triggers;
>> +     const void *valids;
>>  };
>>
>>  static int stm32_timer_start(struct stm32_timer_trigger *priv,
>> @@ -180,8 +198,7 @@ static ssize_t stm32_tt_show_master_mode(struct device *dev,
>>                                        struct device_attribute *attr,
>>                                        char *buf)
>>  {
>> -     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> -     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
>>       u32 cr2;
>>
>>       regmap_read(priv->regmap, TIM_CR2, &cr2);
>> @@ -194,8 +211,7 @@ static ssize_t stm32_tt_store_master_mode(struct device *dev,
>>                                         struct device_attribute *attr,
>>                                         const char *buf, size_t len)
>>  {
>> -     struct iio_dev *indio_dev = dev_to_iio_dev(dev);
>> -     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     struct stm32_timer_trigger *priv = dev_get_drvdata(dev);
>>       int i;
>>
>>       for (i = 0; i < ARRAY_SIZE(master_mode_table); i++) {
>> @@ -275,6 +291,203 @@ static int stm32_setup_iio_triggers(struct stm32_timer_trigger *priv)
>>       return 0;
>>  }
>>
>> +static int stm32_trigger_read_raw(struct iio_dev *indio_dev,
>> +                               struct iio_chan_spec const *chan,
>> +                               int *val, int *val2, long mask)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> +     switch (mask) {
>> +     case IIO_CHAN_INFO_RAW:
>> +     {
>> +             u32 cnt;
>> +
>> +             regmap_read(priv->regmap, TIM_CNT, &cnt);
>> +             *val = cnt;
>> +
>> +             return IIO_VAL_INT;
>> +     }
>> +     }
>> +
>> +     return -EINVAL;
>> +}
>> +
>> +static int stm32_trigger_write_raw(struct iio_dev *indio_dev,
>> +                                struct iio_chan_spec const *chan,
>> +                                int val, int val2, long mask)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> +     switch (mask) {
>> +     case IIO_CHAN_INFO_RAW:
> Why the brackets?

I will simplify code with if (mask == IIO_CHAN_INFO_RAW)

>> +     {
>> +             regmap_write(priv->regmap, TIM_CNT, val);
>> +
>> +             return IIO_VAL_INT;
>> +     }
>> +     }
>> +
>> +     return -EINVAL;
>> +}
>> +
>> +static const struct iio_info stm32_trigger_info = {
>> +     .driver_module = THIS_MODULE,
>> +     .read_raw = stm32_trigger_read_raw,
>> +     .write_raw = stm32_trigger_write_raw
>> +};
>> +
>> +static const char *const stm32_count_modes[] = {
>> +     "internal_clock",
>> +     "encoder_1",
>> +     "encoder_2",
>> +     "encoder_3",
>> +     "reset",
>> +     "gated",
>> +     "trigger",
>
>> +};
>> +
>> +static int stm32_set_count_mode(struct iio_dev *indio_dev,
>> +                             const struct iio_chan_spec *chan,
>> +                             unsigned int mode)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> +     regmap_update_bits(priv->regmap, TIM_SMCR, TIM_SMCR_SMS, mode);
>> +
>> +     return 0;
>> +}
>> +
>> +static int stm32_get_count_mode(struct iio_dev *indio_dev,
>> +                             const struct iio_chan_spec *chan)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     u32 smcr;
>> +
>> +     regmap_read(priv->regmap, TIM_SMCR, &smcr);
>> +     smcr &= TIM_SMCR_SMS;
>> +
>> +     return smcr;
>> +}
>> +
>> +static const struct iio_enum stm32_count_mode_enum = {
>> +     .items = stm32_count_modes,
>> +     .num_items = ARRAY_SIZE(stm32_count_modes),
>> +     .set = stm32_set_count_mode,
>> +     .get = stm32_get_count_mode
>> +};
>> +
>> +static const char *const stm32_count_direction_states[] = {
>> +     "up",
>> +     "down"
>> +};
>> +
>> +static int stm32_set_count_direction(struct iio_dev *indio_dev,
>> +                                  const struct iio_chan_spec *chan,
>> +                                  unsigned int mode)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +
>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_DIR, mode);
>> +
>> +     return 0;
>> +}
>> +
>> +static int stm32_get_count_direction(struct iio_dev *indio_dev,
>> +                                  const struct iio_chan_spec *chan)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     u32 cr1;
>> +
>> +     regmap_read(priv->regmap, TIM_CR1, &cr1);
>> +
>> +     return (cr1 & TIM_CR1_DIR);
>> +}
>> +
>> +static const struct iio_enum stm32_count_direction_enum = {
>> +     .items = stm32_count_direction_states,
>> +     .num_items = ARRAY_SIZE(stm32_count_direction_states),
>> +     .set = stm32_set_count_direction,
>> +     .get = stm32_get_count_direction
>> +};
>> +
>> +static ssize_t stm32_count_get_preset(struct iio_dev *indio_dev,
>> +                                   uintptr_t private,
>> +                                   const struct iio_chan_spec *chan,
>> +                                   char *buf)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     u32 arr;
>> +
>> +     regmap_read(priv->regmap, TIM_ARR, &arr);
>> +
>> +     return snprintf(buf, PAGE_SIZE, "%u\n", arr);
>> +}
>> +
>> +static ssize_t stm32_count_set_preset(struct iio_dev *indio_dev,
>> +                                   uintptr_t private,
>> +                                   const struct iio_chan_spec *chan,
>> +                                   const char *buf, size_t len)
>> +{
>> +     struct stm32_timer_trigger *priv = iio_priv(indio_dev);
>> +     unsigned int preset;
>> +     int ret;
>> +
>> +     ret = kstrtouint(buf, 0, &preset);
>> +     if (ret)
>> +             return ret;
>> +
>> +     regmap_write(priv->regmap, TIM_ARR, preset);
>> +     regmap_update_bits(priv->regmap, TIM_CR1, TIM_CR1_ARPE, TIM_CR1_ARPE);
>> +
>> +     return len;
>> +}
>> +
>> +static const struct iio_chan_spec_ext_info stm32_trigger_count_info[] = {
>> +     {
>> +             .name = "preset",
>> +             .shared = IIO_SEPARATE,
>> +             .read = stm32_count_get_preset,
>> +             .write = stm32_count_set_preset
>> +     },
>> +     IIO_ENUM("count_direction", IIO_SEPARATE, &stm32_count_direction_enum),
>> +     IIO_ENUM_AVAILABLE("count_direction", &stm32_count_direction_enum),
>> +     IIO_ENUM("count_mode", IIO_SEPARATE, &stm32_count_mode_enum),
>> +     IIO_ENUM_AVAILABLE("count_mode", &stm32_count_mode_enum),
>> +     {}
>> +};
>> +
>> +static const struct iio_chan_spec stm32_trigger_channel = {
>> +     .type = IIO_COUNT,
>> +     .channel = 0,
>> +     .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>> +     .ext_info = stm32_trigger_count_info,
>> +     .indexed = 1
>> +};
>> +
>> +static struct stm32_timer_trigger *stm32_setup_iio_device(struct device *dev)
>> +{
>> +     struct iio_dev *indio_dev;
>> +     int ret;
>> +
>> +     indio_dev = devm_iio_device_alloc(dev,
>> +                                       sizeof(struct stm32_timer_trigger));
>> +     if (!indio_dev)
>> +             return NULL;
>> +
>> +     indio_dev->name = dev_name(dev);
>> +     indio_dev->dev.parent = dev;
>> +     indio_dev->info = &stm32_trigger_info;
>> +     indio_dev->num_channels = 1;
>> +     indio_dev->channels = &stm32_trigger_channel;
>> +     indio_dev->dev.of_node = dev->of_node;
>> +
>> +     ret = devm_iio_device_register(dev, indio_dev);
>> +     if (ret)
>> +             return NULL;
>> +
>> +     return iio_priv(indio_dev);
>> +}
>> +
>>  /**
>>   * is_stm32_timer_trigger
>>   * @trig: trigger to be checked
>> @@ -299,10 +512,15 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
>>       if (of_property_read_u32(dev->of_node, "reg", &index))
>>               return -EINVAL;
>>
>> -     if (index >= ARRAY_SIZE(triggers_table))
>> +     if (index >= ARRAY_SIZE(triggers_table) ||
>> +         index >= ARRAY_SIZE(valids_table))
>>               return -EINVAL;
>>
>> -     priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> +     /* Create an IIO device only if we have triggers to be validated */
>> +     if (*valids_table[index])
>> +             priv = stm32_setup_iio_device(dev);
>> +     else
>> +             priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>>
>>       if (!priv)
>>               return -ENOMEM;
>> @@ -312,6 +530,7 @@ static int stm32_timer_trigger_probe(struct platform_device *pdev)
>>       priv->clk = ddata->clk;
>>       priv->max_arr = ddata->max_arr;
>>       priv->triggers = triggers_table[index];
>> +     priv->valids = valids_table[index];
>>
>>       ret = stm32_setup_iio_triggers(priv);
>>       if (ret)
>> diff --git a/include/linux/mfd/stm32-timers.h b/include/linux/mfd/stm32-timers.h
>> index d030004..4a0abbc 100644
>> --- a/include/linux/mfd/stm32-timers.h
>> +++ b/include/linux/mfd/stm32-timers.h
>> @@ -21,6 +21,7 @@
>>  #define TIM_CCMR1    0x18    /* Capt/Comp 1 Mode Reg    */
>>  #define TIM_CCMR2    0x1C    /* Capt/Comp 2 Mode Reg    */
>>  #define TIM_CCER     0x20    /* Capt/Comp Enable Reg    */
>> +#define TIM_CNT              0x24    /* Counter                 */
>>  #define TIM_PSC              0x28    /* Prescaler               */
>>  #define TIM_ARR              0x2c    /* Auto-Reload Register    */
>>  #define TIM_CCR1     0x34    /* Capt/Comp Register 1    */
>> @@ -30,6 +31,7 @@
>>  #define TIM_BDTR     0x44    /* Break and Dead-Time Reg */
>>
>>  #define TIM_CR1_CEN  BIT(0)  /* Counter Enable          */
>> +#define TIM_CR1_DIR  BIT(4)  /* Counter Direction       */
>>  #define TIM_CR1_ARPE BIT(7)  /* Auto-reload Preload Ena */
>>  #define TIM_CR2_MMS  (BIT(4) | BIT(5) | BIT(6)) /* Master mode selection */
>>  #define TIM_SMCR_SMS (BIT(0) | BIT(1) | BIT(2)) /* Slave mode selection */
>>
>

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