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drivers: iio: ti_am335x_adc: add dma support
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This patch adds the required pieces to ti_am335x_adc driver for
DMA support

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Reviewed-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
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Mugunthan V N authored and Jonathan Cameron committed Nov 5, 2016
1 parent c9329d8 commit f438b9d
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Showing 2 changed files with 152 additions and 3 deletions.
148 changes: 145 additions & 3 deletions drivers/iio/adc/ti_am335x_adc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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;
Expand Down Expand Up @@ -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);
Expand All @@ -218,33 +297,49 @@ 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;
}

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);
Expand Down Expand Up @@ -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)
{
Expand Down Expand Up @@ -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:
Expand All @@ -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);
Expand Down
7 changes: 7 additions & 0 deletions include/linux/mfd/ti_am335x_tscadc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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
Expand All @@ -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

Expand Down Expand Up @@ -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
Expand Down

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