[PATCH v2 5/9] dmaengine: tegra: Support address width > 39 bits

Akhil R
2026-03-02T12:36:37Z

Tegra264 supports address width of 41 bits. Unlike older SoCs which use
a common high_addr register for upper address bits, Tegra264 has separate
src_high and dst_high registers to accommodate this wider address space.

Add an addr_bits property to the device data structure to specify the
number of address bits supported on each device and use that to program
the appropriate registers.

Update the sg_req struct to remove the high_addr field and use
dma_addr_t for src and dst to store the complete addresses. Extract
the high address bits only when programming the registers.

Signed-off-by: Akhil R <akhilrajeev@nvidia.com>
---
drivers/dma/tegra186-gpc-dma.c | 87 ++++++++++++++++++++++------------
1 file changed, 56 insertions(+), 31 deletions(-)

diff --git a/drivers/dma/tegra186-gpc-dma.c b/drivers/dma/tegra186-gpc-dma.c
index 09ba2755c06d..753e86d05a02 100644
--- a/drivers/dma/tegra186-gpc-dma.c
+++ b/drivers/dma/tegra186-gpc-dma.c
@@ -151,6 +151,7 @@ struct tegra_dma_channel;
*/
struct tegra_dma_chip_data {
bool hw_support_pause;
+ unsigned int addr_bits;
unsigned int nr_channels;
unsigned int channel_reg_size;
unsigned int max_dma_count;
@@ -166,6 +167,8 @@ struct tegra_dma_channel_regs {
u32 src;
u32 dst;
u32 high_addr;
+ u32 src_high;
+ u32 dst_high;
u32 mc_seq;
u32 mmio_seq;
u32 wcount;
@@ -186,10 +189,9 @@ struct tegra_dma_channel_regs {
*/
struct tegra_dma_sg_req {
unsigned int len;
+ dma_addr_t src;
+ dma_addr_t dst;
u32 csr;
- u32 src;
- u32 dst;
- u32 high_addr;
u32 mc_seq;
u32 mmio_seq;
u32 wcount;
@@ -273,6 +275,25 @@ static inline struct device *tdc2dev(struct tegra_dma_channel *tdc)
return tdc->vc.chan.device->dev;
}

+static void tegra_dma_program_addr(struct tegra_dma_channel *tdc,
+ struct tegra_dma_sg_req *sg_req)
+{
+ tdc_write(tdc, tdc->regs->src, lower_32_bits(sg_req->src));
+ tdc_write(tdc, tdc->regs->dst, lower_32_bits(sg_req->dst));
+
+ if (tdc->tdma->chip_data->addr_bits > 39) {
+ tdc_write(tdc, tdc->regs->src_high, upper_32_bits(sg_req->src));
+ tdc_write(tdc, tdc->regs->dst_high, upper_32_bits(sg_req->dst));
+ } else {
+ u32 src_high = FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR,
+ upper_32_bits(sg_req->src));
+ u32 dst_high = FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR,
+ upper_32_bits(sg_req->dst));
+
+ tdc_write(tdc, tdc->regs->high_addr, src_high | dst_high);
+ }
+}
+
static void tegra_dma_dump_chan_regs(struct tegra_dma_channel *tdc)
{
dev_dbg(tdc2dev(tdc), "DMA Channel %d name %s register dump:\n",
@@ -281,10 +302,20 @@ static void tegra_dma_dump_chan_regs(struct tegra_dma_channel *tdc)
tdc_read(tdc, tdc->regs->csr),
tdc_read(tdc, tdc->regs->status),
tdc_read(tdc, tdc->regs->csre));
- dev_dbg(tdc2dev(tdc), "SRC %x DST %x HI ADDR %x\n",
- tdc_read(tdc, tdc->regs->src),
- tdc_read(tdc, tdc->regs->dst),
- tdc_read(tdc, tdc->regs->high_addr));
+
+ if (tdc->tdma->chip_data->addr_bits > 39) {
+ dev_dbg(tdc2dev(tdc), "SRC %x SRC HI %x DST %x DST HI %x\n",
+ tdc_read(tdc, tdc->regs->src),
+ tdc_read(tdc, tdc->regs->src_high),
+ tdc_read(tdc, tdc->regs->dst),
+ tdc_read(tdc, tdc->regs->dst_high));
+ } else {
+ dev_dbg(tdc2dev(tdc), "SRC %x DST %x HI ADDR %x\n",
+ tdc_read(tdc, tdc->regs->src),
+ tdc_read(tdc, tdc->regs->dst),
+ tdc_read(tdc, tdc->regs->high_addr));
+ }
+
dev_dbg(tdc2dev(tdc), "MCSEQ %x IOSEQ %x WCNT %x XFER %x WSTA %x\n",
tdc_read(tdc, tdc->regs->mc_seq),
tdc_read(tdc, tdc->regs->mmio_seq),
@@ -487,9 +518,7 @@ static void tegra_dma_configure_next_sg(struct tegra_dma_channel *tdc)
sg_req = &dma_desc->sg_req[dma_desc->sg_idx];

tdc_write(tdc, tdc->regs->wcount, sg_req->wcount);
- tdc_write(tdc, tdc->regs->src, sg_req->src);
- tdc_write(tdc, tdc->regs->dst, sg_req->dst);
- tdc_write(tdc, tdc->regs->high_addr, sg_req->high_addr);
+ tegra_dma_program_addr(tdc, sg_req);

/* Start DMA */
tdc_write(tdc, tdc->regs->csr,
@@ -517,11 +546,9 @@ static void tegra_dma_start(struct tegra_dma_channel *tdc)

sg_req = &dma_desc->sg_req[dma_desc->sg_idx];

+ tegra_dma_program_addr(tdc, sg_req);
tdc_write(tdc, tdc->regs->wcount, sg_req->wcount);
tdc_write(tdc, tdc->regs->csr, 0);
- tdc_write(tdc, tdc->regs->src, sg_req->src);
- tdc_write(tdc, tdc->regs->dst, sg_req->dst);
- tdc_write(tdc, tdc->regs->high_addr, sg_req->high_addr);
tdc_write(tdc, tdc->regs->fixed_pattern, sg_req->fixed_pattern);
tdc_write(tdc, tdc->regs->mmio_seq, sg_req->mmio_seq);
tdc_write(tdc, tdc->regs->mc_seq, sg_req->mc_seq);
@@ -826,7 +853,7 @@ static unsigned int get_burst_size(struct tegra_dma_channel *tdc,

static int get_transfer_param(struct tegra_dma_channel *tdc,
enum dma_transfer_direction direction,
- u32 *apb_addr,
+ dma_addr_t *apb_addr,
u32 *mmio_seq,
u32 *csr,
unsigned int *burst_size,
@@ -904,11 +931,9 @@ tegra_dma_prep_dma_memset(struct dma_chan *dc, dma_addr_t dest, int value,
dma_desc->bytes_req = len;
dma_desc->sg_count = 1;
sg_req = dma_desc->sg_req;
-
sg_req[0].src = 0;
sg_req[0].dst = dest;
- sg_req[0].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> 32));
+
sg_req[0].fixed_pattern = value;
/* Word count reg takes value as (N +1) words */
sg_req[0].wcount = ((len - 4) >> 2);
@@ -976,10 +1001,7 @@ tegra_dma_prep_dma_memcpy(struct dma_chan *dc, dma_addr_t dest,

sg_req[0].src = src;
sg_req[0].dst = dest;
- sg_req[0].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (src >> 32));
- sg_req[0].high_addr |=
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (dest >> 32));
+
/* Word count reg takes value as (N +1) words */
sg_req[0].wcount = ((len - 4) >> 2);
sg_req[0].csr = csr;
@@ -999,7 +1021,8 @@ tegra_dma_prep_slave_sg(struct dma_chan *dc, struct scatterlist *sgl,
struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
unsigned int max_dma_count = tdc->tdma->chip_data->max_dma_count;
enum dma_slave_buswidth slave_bw = DMA_SLAVE_BUSWIDTH_UNDEFINED;
- u32 csr, mc_seq, apb_ptr = 0, mmio_seq = 0;
+ u32 csr, mc_seq, mmio_seq = 0;
+ dma_addr_t apb_ptr = 0;
struct tegra_dma_sg_req *sg_req;
struct tegra_dma_desc *dma_desc;
struct scatterlist *sg;
@@ -1087,13 +1110,9 @@ tegra_dma_prep_slave_sg(struct dma_chan *dc, struct scatterlist *sgl,
if (direction == DMA_MEM_TO_DEV) {
sg_req[i].src = mem;
sg_req[i].dst = apb_ptr;
- sg_req[i].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (mem >> 32));
} else if (direction == DMA_DEV_TO_MEM) {
sg_req[i].src = apb_ptr;
sg_req[i].dst = mem;
- sg_req[i].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (mem >> 32));
}

/*
@@ -1117,7 +1136,8 @@ tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_l
unsigned long flags)
{
enum dma_slave_buswidth slave_bw = DMA_SLAVE_BUSWIDTH_UNDEFINED;
- u32 csr, mc_seq, apb_ptr = 0, mmio_seq = 0, burst_size;
+ u32 csr, mc_seq, mmio_seq = 0, burst_size;
+ dma_addr_t apb_ptr = 0;
unsigned int max_dma_count, len, period_count, i;
struct tegra_dma_channel *tdc = to_tegra_dma_chan(dc);
struct tegra_dma_desc *dma_desc;
@@ -1209,13 +1229,9 @@ tegra_dma_prep_dma_cyclic(struct dma_chan *dc, dma_addr_t buf_addr, size_t buf_l
if (direction == DMA_MEM_TO_DEV) {
sg_req[i].src = mem;
sg_req[i].dst = apb_ptr;
- sg_req[i].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_SRC_PTR, (mem >> 32));
} else if (direction == DMA_DEV_TO_MEM) {
sg_req[i].src = apb_ptr;
sg_req[i].dst = mem;
- sg_req[i].high_addr =
- FIELD_PREP(TEGRA_GPCDMA_HIGH_ADDR_DST_PTR, (mem >> 32));
}
/*
* Word count register takes input in words. Writing a value
@@ -1314,6 +1330,7 @@ static const struct tegra_dma_channel_regs tegra186_reg_offsets = {

static const struct tegra_dma_chip_data tegra186_dma_chip_data = {
.nr_channels = 32,
+ .addr_bits = 39,
.channel_reg_size = SZ_64K,
.max_dma_count = SZ_1G,
.hw_support_pause = false,
@@ -1323,6 +1340,7 @@ static const struct tegra_dma_chip_data tegra186_dma_chip_data = {

static const struct tegra_dma_chip_data tegra194_dma_chip_data = {
.nr_channels = 32,
+ .addr_bits = 39,
.channel_reg_size = SZ_64K,
.max_dma_count = SZ_1G,
.hw_support_pause = true,
@@ -1332,6 +1350,7 @@ static const struct tegra_dma_chip_data tegra194_dma_chip_data = {

static const struct tegra_dma_chip_data tegra234_dma_chip_data = {
.nr_channels = 32,
+ .addr_bits = 39,
.channel_reg_size = SZ_64K,
.max_dma_count = SZ_1G,
.hw_support_pause = true,
@@ -1443,6 +1462,12 @@ static int tegra_dma_probe(struct platform_device *pdev)
tdc->stream_id = stream_id;
}

+ ret = dma_set_mask_and_coherent(&pdev->dev, DMA_BIT_MASK(cdata->addr_bits));
+ if (ret) {
+ dev_err(&pdev->dev, "Failed to set DMA mask: %d\n", ret);
+ return ret;
+ }
+
dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
dma_cap_set(DMA_MEMCPY, tdma->dma_dev.cap_mask);
--
2.50.1