[PATCH v3 2/4] drivers: iio: ti_am335x_adc: add dma support
Mugunthan V N
mugunthanvnm at ti.com
Wed Oct 5 02:04:41 PDT 2016
This patch adds the required pieces to ti_am335x_adc driver for
DMA support
Signed-off-by: Mugunthan V N <mugunthanvnm at ti.com>
---
drivers/iio/adc/ti_am335x_adc.c | 148 ++++++++++++++++++++++++++++++++++-
include/linux/mfd/ti_am335x_tscadc.h | 7 ++
2 files changed, 152 insertions(+), 3 deletions(-)
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
--
2.10.0.372.g6fe1b14
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