[PATCH v2 6/6] dmaengine: jz4780: Support bidirectional I/O on one channel

Paul Cercueil
2021-12-06T17:44:00Z

For some devices with only half-duplex capabilities, it doesn't make
much sense to use one DMA channel per direction, as both channels will
never be active at the same time.

Add support for bidirectional I/O on DMA channels. The client drivers
can then request a "tx-rx" DMA channel which will be used for both
directions.

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
drivers/dma/dma-jz4780.c | 48 ++++++++++++++++++++++++++--------------
1 file changed, 32 insertions(+), 16 deletions(-)

diff --git a/drivers/dma/dma-jz4780.c b/drivers/dma/dma-jz4780.c
index c8c4bbd57d14..fc513eb2b289 100644
--- a/drivers/dma/dma-jz4780.c
+++ b/drivers/dma/dma-jz4780.c
@@ -122,6 +122,7 @@ struct jz4780_dma_desc {
dma_addr_t desc_phys;
unsigned int count;
enum dma_transaction_type type;
+ u32 transfer_type;
u32 status;
};

@@ -130,7 +131,7 @@ struct jz4780_dma_chan {
unsigned int id;
struct dma_pool *desc_pool;

- u32 transfer_type;
+ u32 transfer_type_tx, transfer_type_rx;
u32 transfer_shift;
struct dma_slave_config config;

@@ -157,7 +158,7 @@ struct jz4780_dma_dev {
};

struct jz4780_dma_filter_data {
- u32 transfer_type;
+ u32 transfer_type_tx, transfer_type_rx;
int channel;
};

@@ -226,9 +227,10 @@ static inline void jz4780_dma_chan_disable(struct jz4780_dma_dev *jzdma,
jz4780_dma_ctrl_writel(jzdma, JZ_DMA_REG_DCKEC, BIT(chn));
}

-static struct jz4780_dma_desc *jz4780_dma_desc_alloc(
- struct jz4780_dma_chan *jzchan, unsigned int count,
- enum dma_transaction_type type)
+static struct jz4780_dma_desc *
+jz4780_dma_desc_alloc(struct jz4780_dma_chan *jzchan, unsigned int count,
+ enum dma_transaction_type type,
+ enum dma_transfer_direction direction)
{
struct jz4780_dma_desc *desc;

@@ -248,6 +250,12 @@ static struct jz4780_dma_desc *jz4780_dma_desc_alloc(

desc->count = count;
desc->type = type;
+
+ if (direction == DMA_DEV_TO_MEM)
+ desc->transfer_type = jzchan->transfer_type_rx;
+ else
+ desc->transfer_type = jzchan->transfer_type_tx;
+
return desc;
}

@@ -361,7 +369,7 @@ static struct dma_async_tx_descriptor *jz4780_dma_prep_slave_sg(
unsigned int i;
int err;

- desc = jz4780_dma_desc_alloc(jzchan, sg_len, DMA_SLAVE);
+ desc = jz4780_dma_desc_alloc(jzchan, sg_len, DMA_SLAVE, direction);
if (!desc)
return NULL;

@@ -410,7 +418,7 @@ static struct dma_async_tx_descriptor *jz4780_dma_prep_dma_cyclic(

periods = buf_len / period_len;

- desc = jz4780_dma_desc_alloc(jzchan, periods, DMA_CYCLIC);
+ desc = jz4780_dma_desc_alloc(jzchan, periods, DMA_CYCLIC, direction);
if (!desc)
return NULL;

@@ -455,14 +463,14 @@ static struct dma_async_tx_descriptor *jz4780_dma_prep_dma_memcpy(
struct jz4780_dma_desc *desc;
u32 tsz;

- desc = jz4780_dma_desc_alloc(jzchan, 1, DMA_MEMCPY);
+ desc = jz4780_dma_desc_alloc(jzchan, 1, DMA_MEMCPY, 0);
if (!desc)
return NULL;

tsz = jz4780_dma_transfer_size(jzchan, dest | src | len,
&jzchan->transfer_shift);

- jzchan->transfer_type = JZ_DMA_DRT_AUTO;
+ desc->transfer_type = JZ_DMA_DRT_AUTO;

desc->desc[0].dsa = src;
desc->desc[0].dta = dest;
@@ -528,7 +536,7 @@ static void jz4780_dma_begin(struct jz4780_dma_chan *jzchan)

/* Set transfer type. */
jz4780_dma_chn_writel(jzdma, jzchan->id, JZ_DMA_REG_DRT,
- jzchan->transfer_type);
+ jzchan->desc->transfer_type);

/*
* Set the transfer count. This is redundant for a descriptor-driven
@@ -788,7 +796,8 @@ static bool jz4780_dma_filter_fn(struct dma_chan *chan, void *param)
return false;
}

- jzchan->transfer_type = data->transfer_type;
+ jzchan->transfer_type_tx = data->transfer_type_tx;
+ jzchan->transfer_type_rx = data->transfer_type_rx;

return true;
}
@@ -800,11 +809,17 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
dma_cap_mask_t mask = jzdma->dma_device.cap_mask;
struct jz4780_dma_filter_data data;

- if (dma_spec->args_count != 2)
+ if (dma_spec->args_count == 2) {
+ data.transfer_type_tx = dma_spec->args[0];
+ data.transfer_type_rx = dma_spec->args[0];
+ data.channel = dma_spec->args[1];
+ } else if (dma_spec->args_count == 3) {
+ data.transfer_type_tx = dma_spec->args[0];
+ data.transfer_type_rx = dma_spec->args[1];
+ data.channel = dma_spec->args[2];
+ } else {
return NULL;
-
- data.transfer_type = dma_spec->args[0];
- data.channel = dma_spec->args[1];
+ }

if (data.channel > -1) {
if (data.channel >= jzdma->soc_data->nb_channels) {
@@ -822,7 +837,8 @@ static struct dma_chan *jz4780_of_dma_xlate(struct of_phandle_args *dma_spec,
return NULL;
}

- jzdma->chan[data.channel].transfer_type = data.transfer_type;
+ jzdma->chan[data.channel].transfer_type_tx = data.transfer_type_tx;
+ jzdma->chan[data.channel].transfer_type_rx = data.transfer_type_rx;

return dma_get_slave_channel(
&jzdma->chan[data.channel].vchan.chan);
--
2.33.0