diff options
Diffstat (limited to 'drivers/iio')
| -rw-r--r-- | drivers/iio/adc/ti_am335x_adc.c | 148 |
1 files changed, 145 insertions, 3 deletions
diff --git a/drivers/iio/adc/ti_am335x_adc.c b/drivers/iio/adc/ti_am335x_adc.c index c3cfacca2541..ad9dec30bb30 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); |