Re: [PATCH v3 2/4] drivers: iio: ti_am335x_adc: add dma support

From: Peter Ujfalusi
Date: Wed Oct 05 2016 - 05:27:17 EST

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In reply to: Mugunthan V N: "[PATCH v3 2/4] drivers: iio: ti_am335x_adc: add dma support"
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On 10/05/16 12:04, Mugunthan V N wrote:
> This patch adds the required pieces to ti_am335x_adc driver for
> DMA support
>
> Signed-off-by: Mugunthan V N <mugunthanvnm@xxxxxx>
> ---
> drivers/iio/adc/ti_am335x_adc.c | 148 ++++++++++++++++++++++++++++++++++-
> include/linux/mfd/ti_am335x_tscadc.h | 7 ++
> 2 files changed, 152 insertions(+), 3 deletions(-)

Reviewed-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>

>
> diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c
> index c3cfacca..ad9dec3 100644
> --- a/drivers/iio/adc/ti_am335x_adc.c
> +++ b/drivers/iio/adc/ti_am335x_adc.c
> @@ -30,10 +30,28 @@
> #include <linux/iio/buffer.h>
> #include <linux/iio/kfifo_buf.h>
>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-mapping.h>
> +
> +#define DMA_BUFFER_SIZE SZ_2K
> +
> +struct tiadc_dma {
> + struct dma_slave_config conf;
> + struct dma_chan *chan;
> + dma_addr_t addr;
> + dma_cookie_t cookie;
> + u8 *buf;
> + int current_period;
> + int period_size;
> + u8 fifo_thresh;
> +};
> +
> struct tiadc_device {
> struct ti_tscadc_dev *mfd_tscadc;
> + struct tiadc_dma dma;
> struct mutex fifo1_lock; /* to protect fifo access */
> int channels;
> + int total_ch_enabled;
> u8 channel_line[8];
> u8 channel_step[8];
> int buffer_en_ch_steps;
> @@ -198,6 +216,67 @@ static irqreturn_t tiadc_worker_h(int irq, void *private)
> return IRQ_HANDLED;
> }
>
> +static void tiadc_dma_rx_complete(void *param)
> +{
> + struct iio_dev *indio_dev = param;
> + struct tiadc_device *adc_dev = iio_priv(indio_dev);
> + struct tiadc_dma *dma = &adc_dev->dma;
> + u8 *data;
> + int i;
> +
> + data = dma->buf + dma->current_period * dma->period_size;
> + dma->current_period = 1 - dma->current_period; /* swap the buffer ID */
> +
> + for (i = 0; i < dma->period_size; i += indio_dev->scan_bytes) {
> + iio_push_to_buffers(indio_dev, data);
> + data += indio_dev->scan_bytes;
> + }
> +}
> +
> +static int tiadc_start_dma(struct iio_dev *indio_dev)
> +{
> + struct tiadc_device *adc_dev = iio_priv(indio_dev);
> + struct tiadc_dma *dma = &adc_dev->dma;
> + struct dma_async_tx_descriptor *desc;
> +
> + dma->current_period = 0; /* We start to fill period 0 */
> + /*
> + * Make the fifo thresh as the multiple of total number of
> + * channels enabled, so make sure that cyclic DMA period
> + * length is also a multiple of total number of channels
> + * enabled. This ensures that no invalid data is reported
> + * to the stack via iio_push_to_buffers().
> + */
> + dma->fifo_thresh = rounddown(FIFO1_THRESHOLD + 1,
> + adc_dev->total_ch_enabled) - 1;
> + /* Make sure that period length is multiple of fifo thresh level */
> + dma->period_size = rounddown(DMA_BUFFER_SIZE / 2,
> + (dma->fifo_thresh + 1) * sizeof(u16));
> +
> + dma->conf.src_maxburst = dma->fifo_thresh + 1;
> + dmaengine_slave_config(dma->chan, &dma->conf);
> +
> + desc = dmaengine_prep_dma_cyclic(dma->chan, dma->addr,
> + dma->period_size * 2,
> + dma->period_size, DMA_DEV_TO_MEM,
> + DMA_PREP_INTERRUPT);
> + if (!desc)
> + return -EBUSY;
> +
> + desc->callback = tiadc_dma_rx_complete;
> + desc->callback_param = indio_dev;
> +
> + dma->cookie = dmaengine_submit(desc);
> +
> + dma_async_issue_pending(dma->chan);
> +
> + tiadc_writel(adc_dev, REG_FIFO1THR, dma->fifo_thresh);
> + tiadc_writel(adc_dev, REG_DMA1REQ, dma->fifo_thresh);
> + tiadc_writel(adc_dev, REG_DMAENABLE_SET, DMA_FIFO1);
> +
> + return 0;
> +}
> +
> static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
> {
> struct tiadc_device *adc_dev = iio_priv(indio_dev);
> @@ -218,20 +297,30 @@ static int tiadc_buffer_preenable(struct iio_dev *indio_dev)
> static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
> {
> struct tiadc_device *adc_dev = iio_priv(indio_dev);
> + struct tiadc_dma *dma = &adc_dev->dma;
> + unsigned int irq_enable;
> unsigned int enb = 0;
> u8 bit;
>
> tiadc_step_config(indio_dev);
> - for_each_set_bit(bit, indio_dev->active_scan_mask, adc_dev->channels)
> + for_each_set_bit(bit, indio_dev->active_scan_mask, adc_dev->channels) {
> enb |= (get_adc_step_bit(adc_dev, bit) << 1);
> + adc_dev->total_ch_enabled++;
> + }
> adc_dev->buffer_en_ch_steps = enb;
>
> + if (dma->chan)
> + tiadc_start_dma(indio_dev);
> +
> am335x_tsc_se_set_cache(adc_dev->mfd_tscadc, enb);
>
> tiadc_writel(adc_dev, REG_IRQSTATUS, IRQENB_FIFO1THRES
> | IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW);
> - tiadc_writel(adc_dev, REG_IRQENABLE, IRQENB_FIFO1THRES
> - | IRQENB_FIFO1OVRRUN);
> +
> + irq_enable = IRQENB_FIFO1OVRRUN;
> + if (!dma->chan)
> + irq_enable |= IRQENB_FIFO1THRES;
> + tiadc_writel(adc_dev, REG_IRQENABLE, irq_enable);
>
> return 0;
> }
> @@ -239,12 +328,18 @@ static int tiadc_buffer_postenable(struct iio_dev *indio_dev)
> static int tiadc_buffer_predisable(struct iio_dev *indio_dev)
> {
> struct tiadc_device *adc_dev = iio_priv(indio_dev);
> + struct tiadc_dma *dma = &adc_dev->dma;
> int fifo1count, i, read;
>
> tiadc_writel(adc_dev, REG_IRQCLR, (IRQENB_FIFO1THRES |
> IRQENB_FIFO1OVRRUN | IRQENB_FIFO1UNDRFLW));
> am335x_tsc_se_clr(adc_dev->mfd_tscadc, adc_dev->buffer_en_ch_steps);
> adc_dev->buffer_en_ch_steps = 0;
> + adc_dev->total_ch_enabled = 0;
> + if (dma->chan) {
> + tiadc_writel(adc_dev, REG_DMAENABLE_CLEAR, 0x2);
> + dmaengine_terminate_async(dma->chan);
> + }
>
> /* Flush FIFO of leftover data in the time it takes to disable adc */
> fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT);
> @@ -430,6 +525,41 @@ static const struct iio_info tiadc_info = {
> .driver_module = THIS_MODULE,
> };
>
> +static int tiadc_request_dma(struct platform_device *pdev,
> + struct tiadc_device *adc_dev)
> +{
> + struct tiadc_dma *dma = &adc_dev->dma;
> + dma_cap_mask_t mask;
> +
> + /* Default slave configuration parameters */
> + dma->conf.direction = DMA_DEV_TO_MEM;
> + dma->conf.src_addr_width = DMA_SLAVE_BUSWIDTH_2_BYTES;
> + dma->conf.src_addr = adc_dev->mfd_tscadc->tscadc_phys_base + REG_FIFO1;
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_CYCLIC, mask);
> +
> + /* Get a channel for RX */
> + dma->chan = dma_request_chan(adc_dev->mfd_tscadc->dev, "fifo1");
> + if (IS_ERR(dma->chan)) {
> + int ret = PTR_ERR(dma->chan);
> +
> + dma->chan = NULL;
> + return ret;
> + }
> +
> + /* RX buffer */
> + dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
> + &dma->addr, GFP_KERNEL);
> + if (!dma->buf)
> + goto err;
> +
> + return 0;
> +err:
> + dma_release_channel(dma->chan);
> + return -ENOMEM;
> +}
> +
> static int tiadc_parse_dt(struct platform_device *pdev,
> struct tiadc_device *adc_dev)
> {
> @@ -512,8 +642,14 @@ static int tiadc_probe(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, indio_dev);
>
> + err = tiadc_request_dma(pdev, adc_dev);
> + if (err && err == -EPROBE_DEFER)
> + goto err_dma;
> +
> return 0;
>
> +err_dma:
> + iio_device_unregister(indio_dev);
> err_buffer_unregister:
> tiadc_iio_buffered_hardware_remove(indio_dev);
> err_free_channels:
> @@ -525,8 +661,14 @@ static int tiadc_remove(struct platform_device *pdev)
> {
> struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> struct tiadc_device *adc_dev = iio_priv(indio_dev);
> + struct tiadc_dma *dma = &adc_dev->dma;
> u32 step_en;
>
> + if (dma->chan) {
> + dma_free_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE,
> + dma->buf, dma->addr);
> + dma_release_channel(dma->chan);
> + }
> iio_device_unregister(indio_dev);
> tiadc_iio_buffered_hardware_remove(indio_dev);
> tiadc_channels_remove(indio_dev);
> diff --git a/include/linux/mfd/ti_am335x_tscadc.h b/include/linux/mfd/ti_am335x_tscadc.h
> index e45a208..b9a53e0 100644
> --- a/include/linux/mfd/ti_am335x_tscadc.h
> +++ b/include/linux/mfd/ti_am335x_tscadc.h
> @@ -23,6 +23,8 @@
> #define REG_IRQENABLE 0x02C
> #define REG_IRQCLR 0x030
> #define REG_IRQWAKEUP 0x034
> +#define REG_DMAENABLE_SET 0x038
> +#define REG_DMAENABLE_CLEAR 0x03c
> #define REG_CTRL 0x040
> #define REG_ADCFSM 0x044
> #define REG_CLKDIV 0x04C
> @@ -36,6 +38,7 @@
> #define REG_FIFO0THR 0xE8
> #define REG_FIFO1CNT 0xF0
> #define REG_FIFO1THR 0xF4
> +#define REG_DMA1REQ 0xF8
> #define REG_FIFO0 0x100
> #define REG_FIFO1 0x200
>
> @@ -126,6 +129,10 @@
> #define FIFOREAD_DATA_MASK (0xfff << 0)
> #define FIFOREAD_CHNLID_MASK (0xf << 16)
>
> +/* DMA ENABLE/CLEAR Register */
> +#define DMA_FIFO0 BIT(0)
> +#define DMA_FIFO1 BIT(1)
> +
> /* Sequencer Status */
> #define SEQ_STATUS BIT(5)
> #define CHARGE_STEP 0x11
>

--
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Next message: Johannes Weiner: "Re: BUG_ON() in workingset_node_shadows_dec() triggers"
Previous message: Johannes Weiner: "Re: BUG_ON() in workingset_node_shadows_dec() triggers"
In reply to: Mugunthan V N: "[PATCH v3 2/4] drivers: iio: ti_am335x_adc: add dma support"
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