On Wednesday 21 September 2016 09:41 PM, 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 | 160 ++++++++++++++++++++++++++++++++++- > include/linux/mfd/ti_am335x_tscadc.h | 7 ++ > 2 files changed, 164 insertions(+), 3 deletions(-) > > diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c > index c3cfacca..89d0b07 100644 > --- a/drivers/iio/adc/ti_am335x_adc.c > +++ b/drivers/iio/adc/ti_am335x_adc.c > @@ -30,10 +30,32 @@ > #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 { > + /* Filter function */ > + dma_filter_fn fn; > + /* Parameter to the filter function */ > + void *param; These will not be needed with newer APIs (see below) > + struct dma_slave_config conf; > + struct dma_chan *chan; > + dma_addr_t addr; > + dma_cookie_t cookie; > + u8 *buf; > + bool valid_buf_seg; > + int buf_offset; > + 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; > @@ -184,6 +206,7 @@ static irqreturn_t tiadc_worker_h(int irq, void *private) > u16 *data = adc_dev->data; > > fifo1count = tiadc_readl(adc_dev, REG_FIFO1CNT); > + > for (k = 0; k < fifo1count; k = k + i) { > for (i = 0; i < (indio_dev->scan_bytes)/2; i++) { > read = tiadc_readl(adc_dev, REG_FIFO1); > @@ -198,6 +221,68 @@ 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->valid_buf_seg ? dma->buf + dma->buf_offset : dma->buf; > + dma->valid_buf_seg = !dma->valid_buf_seg; > + > + for (i = 0; i < dma->buf_offset; 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->valid_buf_seg = false; > + dma->fifo_thresh = FIFO1_THRESHOLD; > + /* > + * Make the fifo thresh as the multiple of total number of > + * channels enabled, so make sure that 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 -= (dma->fifo_thresh + 1) % adc_dev->total_ch_enabled; Can we use rounddown(FIFO1_THRESHOLD + 1, adc_dev->total_ch_enabled)? > + dma->buf_offset = DMA_BUFFER_SIZE / 2; > + /* Make sure that period length is multiple of fifo thresh level */ > + dma->buf_offset -= dma->buf_offset % ((dma->fifo_thresh + 1) * > + sizeof(u16)); > + Can we use rounddown()? > + 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->buf_offset * 2, > + dma->buf_offset, 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 +303,30 @@ 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 enb = 0; > u8 bit; > + u32 irq_enable; > > 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 +334,18 @@ 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 +531,50 @@ static const struct iio_info tiadc_info = { > .driver_module = THIS_MODULE, > }; > > +static bool the_no_dma_filter_fn(struct dma_chan *chan, void *param) > +{ > + return false; > +} > + > +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; > + > + dma->fn = the_no_dma_filter_fn; > + > + /* 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_slave_channel_compat(mask, > + dma->fn, dma->param, > + adc_dev->mfd_tscadc->dev, > + "fifo1"); Please use dma_request_chan() API instead, this does not need dma_filter_fn and probe defer can be handled. > + if (!dma->chan) > + return -ENODEV; > + > + /* RX buffer */ > + dma->buf = dma_alloc_coherent(dma->chan->device->dev, DMA_BUFFER_SIZE, > + &dma->addr, GFP_KERNEL); > + if (!dma->buf) > + goto err; > + > + dev_dbg_ratelimited(adc_dev->mfd_tscadc->dev, "got dma channel\n"); Do we need _ratelimited? AFAICS, this print is called only once. > + > + 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 +657,14 @@ static int tiadc_probe(struct platform_device *pdev) > > platform_set_drvdata(pdev, indio_dev); > > + err = tiadc_request_dma(pdev, adc_dev); > + if (err && err != -ENODEV) > + 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 +676,11 @@ 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_release_channel(dma->chan); dma_free_coherent() for dma->buf? > 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..fb9dc99 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 0x038 > #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 > -- Regards Vignesh -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html