Re: [PATCH v2 1/7] iio: adc: stm32: add support for triggered buffer mode
From: Jonathan Cameron
Date: Sat Jan 28 2017 - 13:37:38 EST
On 26/01/17 14:28, Fabrice Gasnier wrote:
> STM32 ADC conversions can be launched using hardware triggers.
> It can be used to start conversion sequences (group of channels).
> Selected channels are select via sequence registers.
> Trigger source is selected via 'extsel' (external trigger mux).
> Trigger polarity is set to rising edge by default.
>
> Signed-off-by: Fabrice Gasnier <fabrice.gasnier@xxxxxx>
I thought about leaving this longer to see if anyone else wanted
to comment, but seeing as the changes are minor and the original
patches were about for over a week I'm happy to take these now.
If anyone was planning on taking a look, give me a shout and I'll
yank them back out for a bit.
Anyhow, I've pulled in the immutable branch from mfd to get the
prerequisites and applied this to my togreg branch - initially pushed
out as testing to see what the autobuilders make of them.
This series came together very nicely (and quickly *touch wood*)
Thanks,
Jonathan
> ---
> Changes in v2:
> based on Jonathan's comments:
> - remove all STM32F4_SQx[SHIFT/MASK], put the numbers directly in sq
> description array.
> - make data buffer part of stm32_adc structure (remove preenable and
> postdisable routines)
> - add comment on reading DR to clear OEC flag
> - use bitmap_weight()
> - fix error handling in stm32_adc_buffer_postenable()
> ---
> drivers/iio/adc/Kconfig | 2 +
> drivers/iio/adc/stm32-adc.c | 317 +++++++++++++++++++++++++++++++++++++++++---
> 2 files changed, 298 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 9c8b558..33341f4 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -446,6 +446,8 @@ config STM32_ADC_CORE
> depends on ARCH_STM32 || COMPILE_TEST
> depends on OF
> depends on REGULATOR
> + select IIO_BUFFER
> + select IIO_TRIGGERED_BUFFER
> help
> Select this option to enable the core driver for STMicroelectronics
> STM32 analog-to-digital converter (ADC).
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 5715e79..1e382b6 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -22,6 +22,10 @@
> #include <linux/clk.h>
> #include <linux/delay.h>
> #include <linux/iio/iio.h>
> +#include <linux/iio/buffer.h>
> +#include <linux/iio/trigger.h>
> +#include <linux/iio/trigger_consumer.h>
> +#include <linux/iio/triggered_buffer.h>
> #include <linux/interrupt.h>
> #include <linux/io.h>
> #include <linux/module.h>
> @@ -58,21 +62,37 @@
>
> /* STM32F4_ADC_CR2 - bit fields */
> #define STM32F4_SWSTART BIT(30)
> +#define STM32F4_EXTEN_SHIFT 28
> #define STM32F4_EXTEN_MASK GENMASK(29, 28)
> +#define STM32F4_EXTSEL_SHIFT 24
> +#define STM32F4_EXTSEL_MASK GENMASK(27, 24)
> #define STM32F4_EOCS BIT(10)
> #define STM32F4_ADON BIT(0)
>
> -/* STM32F4_ADC_SQR1 - bit fields */
> -#define STM32F4_L_SHIFT 20
> -#define STM32F4_L_MASK GENMASK(23, 20)
> -
> -/* STM32F4_ADC_SQR3 - bit fields */
> -#define STM32F4_SQ1_SHIFT 0
> -#define STM32F4_SQ1_MASK GENMASK(4, 0)
> -
> +#define STM32_ADC_MAX_SQ 16 /* SQ1..SQ16 */
> #define STM32_ADC_TIMEOUT_US 100000
> #define STM32_ADC_TIMEOUT (msecs_to_jiffies(STM32_ADC_TIMEOUT_US / 1000))
>
> +/* External trigger enable */
> +enum stm32_adc_exten {
> + STM32_EXTEN_SWTRIG,
> + STM32_EXTEN_HWTRIG_RISING_EDGE,
> + STM32_EXTEN_HWTRIG_FALLING_EDGE,
> + STM32_EXTEN_HWTRIG_BOTH_EDGES,
> +};
> +
> +/**
> + * stm32_adc_regs - stm32 ADC misc registers & bitfield desc
> + * @reg: register offset
> + * @mask: bitfield mask
> + * @shift: left shift
> + */
> +struct stm32_adc_regs {
> + int reg;
> + int mask;
> + int shift;
> +};
> +
> /**
> * struct stm32_adc - private data of each ADC IIO instance
> * @common: reference to ADC block common data
> @@ -82,15 +102,19 @@
> * @clk: clock for this adc instance
> * @irq: interrupt for this adc instance
> * @lock: spinlock
> + * @bufi: data buffer index
> + * @num_conv: expected number of scan conversions
> */
> struct stm32_adc {
> struct stm32_adc_common *common;
> u32 offset;
> struct completion completion;
> - u16 *buffer;
> + u16 buffer[STM32_ADC_MAX_SQ];
> struct clk *clk;
> int irq;
> spinlock_t lock; /* interrupt lock */
> + unsigned int bufi;
> + unsigned int num_conv;
> };
>
> /**
> @@ -126,6 +150,33 @@ struct stm32_adc_chan_spec {
> };
>
> /**
> + * stm32f4_sq - describe regular sequence registers
> + * - L: sequence len (register & bit field)
> + * - SQ1..SQ16: sequence entries (register & bit field)
> + */
> +static const struct stm32_adc_regs stm32f4_sq[STM32_ADC_MAX_SQ + 1] = {
> + /* L: len bit field description to be kept as first element */
> + { STM32F4_ADC_SQR1, GENMASK(23, 20), 20 },
> + /* SQ1..SQ16 registers & bit fields (reg, mask, shift) */
> + { STM32F4_ADC_SQR3, GENMASK(4, 0), 0 },
> + { STM32F4_ADC_SQR3, GENMASK(9, 5), 5 },
> + { STM32F4_ADC_SQR3, GENMASK(14, 10), 10 },
> + { STM32F4_ADC_SQR3, GENMASK(19, 15), 15 },
> + { STM32F4_ADC_SQR3, GENMASK(24, 20), 20 },
> + { STM32F4_ADC_SQR3, GENMASK(29, 25), 25 },
> + { STM32F4_ADC_SQR2, GENMASK(4, 0), 0 },
> + { STM32F4_ADC_SQR2, GENMASK(9, 5), 5 },
> + { STM32F4_ADC_SQR2, GENMASK(14, 10), 10 },
> + { STM32F4_ADC_SQR2, GENMASK(19, 15), 15 },
> + { STM32F4_ADC_SQR2, GENMASK(24, 20), 20 },
> + { STM32F4_ADC_SQR2, GENMASK(29, 25), 25 },
> + { STM32F4_ADC_SQR1, GENMASK(4, 0), 0 },
> + { STM32F4_ADC_SQR1, GENMASK(9, 5), 5 },
> + { STM32F4_ADC_SQR1, GENMASK(14, 10), 10 },
> + { STM32F4_ADC_SQR1, GENMASK(19, 15), 15 },
> +};
> +
> +/**
> * STM32 ADC registers access routines
> * @adc: stm32 adc instance
> * @reg: reg offset in adc instance
> @@ -211,6 +262,104 @@ static void stm32_adc_stop_conv(struct stm32_adc *adc)
> }
>
> /**
> + * stm32_adc_conf_scan_seq() - Build regular channels scan sequence
> + * @indio_dev: IIO device
> + * @scan_mask: channels to be converted
> + *
> + * Conversion sequence :
> + * Configure ADC scan sequence based on selected channels in scan_mask.
> + * Add channels to SQR registers, from scan_mask LSB to MSB, then
> + * program sequence len.
> + */
> +static int stm32_adc_conf_scan_seq(struct iio_dev *indio_dev,
> + const unsigned long *scan_mask)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + const struct iio_chan_spec *chan;
> + u32 val, bit;
> + int i = 0;
> +
> + for_each_set_bit(bit, scan_mask, indio_dev->masklength) {
> + chan = indio_dev->channels + bit;
> + /*
> + * Assign one channel per SQ entry in regular
> + * sequence, starting with SQ1.
> + */
> + i++;
> + if (i > STM32_ADC_MAX_SQ)
> + return -EINVAL;
> +
> + dev_dbg(&indio_dev->dev, "%s chan %d to SQ%d\n",
> + __func__, chan->channel, i);
> +
> + val = stm32_adc_readl(adc, stm32f4_sq[i].reg);
> + val &= ~stm32f4_sq[i].mask;
> + val |= chan->channel << stm32f4_sq[i].shift;
> + stm32_adc_writel(adc, stm32f4_sq[i].reg, val);
> + }
> +
> + if (!i)
> + return -EINVAL;
> +
> + /* Sequence len */
> + val = stm32_adc_readl(adc, stm32f4_sq[0].reg);
> + val &= ~stm32f4_sq[0].mask;
> + val |= ((i - 1) << stm32f4_sq[0].shift);
> + stm32_adc_writel(adc, stm32f4_sq[0].reg, val);
> +
> + return 0;
> +}
> +
> +/**
> + * stm32_adc_get_trig_extsel() - Get external trigger selection
> + * @trig: trigger
> + *
> + * Returns trigger extsel value, if trig matches, -EINVAL otherwise.
> + */
> +static int stm32_adc_get_trig_extsel(struct iio_trigger *trig)
> +{
> + return -EINVAL;
> +}
> +
> +/**
> + * stm32_adc_set_trig() - Set a regular trigger
> + * @indio_dev: IIO device
> + * @trig: IIO trigger
> + *
> + * Set trigger source/polarity (e.g. SW, or HW with polarity) :
> + * - if HW trigger disabled (e.g. trig == NULL, conversion launched by sw)
> + * - if HW trigger enabled, set source & polarity
> + */
> +static int stm32_adc_set_trig(struct iio_dev *indio_dev,
> + struct iio_trigger *trig)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + u32 val, extsel = 0, exten = STM32_EXTEN_SWTRIG;
> + unsigned long flags;
> + int ret;
> +
> + if (trig) {
> + ret = stm32_adc_get_trig_extsel(trig);
> + if (ret < 0)
> + return ret;
> +
> + /* set trigger source and polarity (default to rising edge) */
> + extsel = ret;
> + exten = STM32_EXTEN_HWTRIG_RISING_EDGE;
> + }
> +
> + spin_lock_irqsave(&adc->lock, flags);
> + val = stm32_adc_readl(adc, STM32F4_ADC_CR2);
> + val &= ~(STM32F4_EXTEN_MASK | STM32F4_EXTSEL_MASK);
> + val |= exten << STM32F4_EXTEN_SHIFT;
> + val |= extsel << STM32F4_EXTSEL_SHIFT;
> + stm32_adc_writel(adc, STM32F4_ADC_CR2, val);
> + spin_unlock_irqrestore(&adc->lock, flags);
> +
> + return 0;
> +}
> +
> +/**
> * stm32_adc_single_conv() - Performs a single conversion
> * @indio_dev: IIO device
> * @chan: IIO channel
> @@ -228,21 +377,20 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
> struct stm32_adc *adc = iio_priv(indio_dev);
> long timeout;
> u32 val;
> - u16 result;
> int ret;
>
> reinit_completion(&adc->completion);
>
> - adc->buffer = &result;
> + adc->bufi = 0;
>
> - /* Program chan number in regular sequence */
> - val = stm32_adc_readl(adc, STM32F4_ADC_SQR3);
> - val &= ~STM32F4_SQ1_MASK;
> - val |= chan->channel << STM32F4_SQ1_SHIFT;
> - stm32_adc_writel(adc, STM32F4_ADC_SQR3, val);
> + /* Program chan number in regular sequence (SQ1) */
> + val = stm32_adc_readl(adc, stm32f4_sq[1].reg);
> + val &= ~stm32f4_sq[1].mask;
> + val |= chan->channel << stm32f4_sq[1].shift;
> + stm32_adc_writel(adc, stm32f4_sq[1].reg, val);
>
> /* Set regular sequence len (0 for 1 conversion) */
> - stm32_adc_clr_bits(adc, STM32F4_ADC_SQR1, STM32F4_L_MASK);
> + stm32_adc_clr_bits(adc, stm32f4_sq[0].reg, stm32f4_sq[0].mask);
>
> /* Trigger detection disabled (conversion can be launched in SW) */
> stm32_adc_clr_bits(adc, STM32F4_ADC_CR2, STM32F4_EXTEN_MASK);
> @@ -258,7 +406,7 @@ static int stm32_adc_single_conv(struct iio_dev *indio_dev,
> } else if (timeout < 0) {
> ret = timeout;
> } else {
> - *res = result;
> + *res = adc->buffer[0];
> ret = IIO_VAL_INT;
> }
>
> @@ -301,17 +449,56 @@ static int stm32_adc_read_raw(struct iio_dev *indio_dev,
> static irqreturn_t stm32_adc_isr(int irq, void *data)
> {
> struct stm32_adc *adc = data;
> + struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> u32 status = stm32_adc_readl(adc, STM32F4_ADC_SR);
>
> if (status & STM32F4_EOC) {
> - *adc->buffer = stm32_adc_readw(adc, STM32F4_ADC_DR);
> - complete(&adc->completion);
> + /* Reading DR also clears EOC status flag */
> + adc->buffer[adc->bufi] = stm32_adc_readw(adc, STM32F4_ADC_DR);
> + if (iio_buffer_enabled(indio_dev)) {
> + adc->bufi++;
> + if (adc->bufi >= adc->num_conv) {
> + stm32_adc_conv_irq_disable(adc);
> + iio_trigger_poll(indio_dev->trig);
> + }
> + } else {
> + complete(&adc->completion);
> + }
> return IRQ_HANDLED;
> }
>
> return IRQ_NONE;
> }
>
> +/**
> + * stm32_adc_validate_trigger() - validate trigger for stm32 adc
> + * @indio_dev: IIO device
> + * @trig: new trigger
> + *
> + * Returns: 0 if trig matches one of the triggers registered by stm32 adc
> + * driver, -EINVAL otherwise.
> + */
> +static int stm32_adc_validate_trigger(struct iio_dev *indio_dev,
> + struct iio_trigger *trig)
> +{
> + return stm32_adc_get_trig_extsel(trig) < 0 ? -EINVAL : 0;
> +}
> +
> +static int stm32_adc_update_scan_mode(struct iio_dev *indio_dev,
> + const unsigned long *scan_mask)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + int ret;
> +
> + adc->num_conv = bitmap_weight(scan_mask, indio_dev->masklength);
> +
> + ret = stm32_adc_conf_scan_seq(indio_dev, scan_mask);
> + if (ret)
> + return ret;
> +
> + return 0;
> +}
> +
> static int stm32_adc_of_xlate(struct iio_dev *indio_dev,
> const struct of_phandle_args *iiospec)
> {
> @@ -350,11 +537,86 @@ static int stm32_adc_debugfs_reg_access(struct iio_dev *indio_dev,
>
> static const struct iio_info stm32_adc_iio_info = {
> .read_raw = stm32_adc_read_raw,
> + .validate_trigger = stm32_adc_validate_trigger,
> + .update_scan_mode = stm32_adc_update_scan_mode,
> .debugfs_reg_access = stm32_adc_debugfs_reg_access,
> .of_xlate = stm32_adc_of_xlate,
> .driver_module = THIS_MODULE,
> };
>
> +static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + int ret;
> +
> + ret = stm32_adc_set_trig(indio_dev, indio_dev->trig);
> + if (ret) {
> + dev_err(&indio_dev->dev, "Can't set trigger\n");
> + return ret;
> + }
> +
> + ret = iio_triggered_buffer_postenable(indio_dev);
> + if (ret < 0)
> + goto err_clr_trig;
> +
> + /* Reset adc buffer index */
> + adc->bufi = 0;
> +
> + stm32_adc_conv_irq_enable(adc);
> + stm32_adc_start_conv(adc);
> +
> + return 0;
> +
> +err_clr_trig:
> + stm32_adc_set_trig(indio_dev, NULL);
> +
> + return ret;
> +}
> +
> +static int stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
> +{
> + struct stm32_adc *adc = iio_priv(indio_dev);
> + int ret;
> +
> + stm32_adc_stop_conv(adc);
> + stm32_adc_conv_irq_disable(adc);
> +
> + ret = iio_triggered_buffer_predisable(indio_dev);
> + if (ret < 0)
> + dev_err(&indio_dev->dev, "predisable failed\n");
> +
> + if (stm32_adc_set_trig(indio_dev, NULL))
> + dev_err(&indio_dev->dev, "Can't clear trigger\n");
> +
> + return ret;
> +}
> +
> +static const struct iio_buffer_setup_ops stm32_adc_buffer_setup_ops = {
> + .postenable = &stm32_adc_buffer_postenable,
> + .predisable = &stm32_adc_buffer_predisable,
> +};
> +
> +static irqreturn_t stm32_adc_trigger_handler(int irq, void *p)
> +{
> + struct iio_poll_func *pf = p;
> + struct iio_dev *indio_dev = pf->indio_dev;
> + struct stm32_adc *adc = iio_priv(indio_dev);
> +
> + dev_dbg(&indio_dev->dev, "%s bufi=%d\n", __func__, adc->bufi);
> +
> + /* reset buffer index */
> + adc->bufi = 0;
> + iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
> + pf->timestamp);
> +
> + iio_trigger_notify_done(indio_dev->trig);
> +
> + /* re-enable eoc irq */
> + stm32_adc_conv_irq_enable(adc);
> +
> + return IRQ_HANDLED;
> +}
> +
> static void stm32_adc_chan_init_one(struct iio_dev *indio_dev,
> struct iio_chan_spec *chan,
> const struct stm32_adc_chan_spec *channel,
> @@ -471,14 +733,26 @@ static int stm32_adc_probe(struct platform_device *pdev)
> if (ret < 0)
> goto err_clk_disable;
>
> + ret = iio_triggered_buffer_setup(indio_dev,
> + &iio_pollfunc_store_time,
> + &stm32_adc_trigger_handler,
> + &stm32_adc_buffer_setup_ops);
> + if (ret) {
> + dev_err(&pdev->dev, "buffer setup failed\n");
> + goto err_clk_disable;
> + }
> +
> ret = iio_device_register(indio_dev);
> if (ret) {
> dev_err(&pdev->dev, "iio dev register failed\n");
> - goto err_clk_disable;
> + goto err_buffer_cleanup;
> }
>
> return 0;
>
> +err_buffer_cleanup:
> + iio_triggered_buffer_cleanup(indio_dev);
> +
> err_clk_disable:
> clk_disable_unprepare(adc->clk);
>
> @@ -491,6 +765,7 @@ static int stm32_adc_remove(struct platform_device *pdev)
> struct iio_dev *indio_dev = iio_priv_to_dev(adc);
>
> iio_device_unregister(indio_dev);
> + iio_triggered_buffer_cleanup(indio_dev);
> clk_disable_unprepare(adc->clk);
>
> return 0;
>