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Subject[PATCH] dmaengine: at_hdmac: add device tree probe
Date
Add device tree probe support for atmel at_hdmac DMA driver.
Bindings are added to specify the number of channels that the implementation of
the controller actually has. They also allow to tell if the peripherals/DMA
transfer is supported by the IP.

Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
---
.../devicetree/bindings/dma/atmel-hdmac.txt | 23 +++++++++
drivers/dma/at_hdmac.c | 51 ++++++++++++++++----
2 files changed, 65 insertions(+), 9 deletions(-)
create mode 100644 Documentation/devicetree/bindings/dma/atmel-hdmac.txt

diff --git a/Documentation/devicetree/bindings/dma/atmel-hdmac.txt b/Documentation/devicetree/bindings/dma/atmel-hdmac.txt
new file mode 100644
index 0000000..0e48553
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/atmel-hdmac.txt
@@ -0,0 +1,23 @@
+* Atmel Direct Memory Access Controller
+
+Required properties:
+- compatible: Should be "atmel,<chip>-hdmac"
+- reg: Should contain DMA registers location and length
+- interrupts: Should contain DMA interrupt
+- atmel,hdmac-nr-channels: Should contain number of channels
+ available in the controller
+
+Optional properties:
+- atmel,hdmac-cap-memcpy: Chip can do memory to memory transfers
+- atmel,hdmac-cap-slave: Chip can do peripherals/memory transfers
+
+Examples:
+
+dma@ffffec00 {
+ compatible = "atmel,at91sam9g45-hdmac";
+ reg = <0xffffec00 0x200>;
+ interrupts = <21>;
+ atmel,hdmac-nr-channels = <8>;
+ atmel,hdmac-cap-memcpy;
+ atmel,hdmac-cap-slave;
+};
diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 8f1d2ee..4a0cefe 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -23,6 +23,8 @@
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/of_device.h>

#include "at_hdmac_regs.h"

@@ -1167,6 +1169,18 @@ static void atc_free_chan_resources(struct dma_chan *chan)

/*-- Module Management -----------------------------------------------*/

+#if defined(CONFIG_OF)
+static const struct of_device_id atmel_dma_dt_ids[] = {
+ { .compatible = "atmel,at91sam9rl-hdmac" },
+ { .compatible = "atmel,at91sam9g45-hdmac" },
+ { /* sentinel */ }
+};
+
+MODULE_DEVICE_TABLE(of, atmel_dma_dt_ids);
+#else
+#define atmel_dma_dt_ids NULL
+#endif
+
/**
* at_dma_off - disable DMA controller
* @atdma: the Atmel HDAMC device
@@ -1185,17 +1199,36 @@ static void at_dma_off(struct at_dma *atdma)

static int __init at_dma_probe(struct platform_device *pdev)
{
- struct at_dma_platform_data *pdata;
+ const struct of_device_id *of_id =
+ of_match_device(atmel_dma_dt_ids, &pdev->dev);
+ struct device_node *np = pdev->dev.of_node;
+ struct at_dma_platform_data *pdata = pdev->dev.platform_data;
struct resource *io;
struct at_dma *atdma;
size_t size;
int irq;
int err;
int i;
+ u32 nr_channels;
+ dma_cap_mask_t cap_mask = {};
+
+ /* get DMA Controller parameters */
+ if (of_id) {
+ if (of_property_read_u32(np, "atmel,hdmac-nr-channels",
+ &nr_channels))
+ return -EINVAL;
+ if (of_find_property(np, "atmel,hdmac-cap-memcpy", NULL))
+ dma_cap_set(DMA_MEMCPY, cap_mask);
+ if (of_find_property(np, "atmel,hdmac-cap-slave", NULL))
+ dma_cap_set(DMA_SLAVE, cap_mask);
+ } else if (pdata) {
+ nr_channels = pdata->nr_channels;
+ cap_mask = pdata->cap_mask;
+ } else {
+ return -EINVAL;
+ }

- /* get DMA Controller parameters from platform */
- pdata = pdev->dev.platform_data;
- if (!pdata || pdata->nr_channels > AT_DMA_MAX_NR_CHANNELS)
+ if (!nr_channels || nr_channels > AT_DMA_MAX_NR_CHANNELS)
return -EINVAL;

io = platform_get_resource(pdev, IORESOURCE_MEM, 0);
@@ -1207,14 +1240,13 @@ static int __init at_dma_probe(struct platform_device *pdev)
return irq;

size = sizeof(struct at_dma);
- size += pdata->nr_channels * sizeof(struct at_dma_chan);
+ size += nr_channels * sizeof(struct at_dma_chan);
atdma = kzalloc(size, GFP_KERNEL);
if (!atdma)
return -ENOMEM;

- /* discover transaction capabilites from the platform data */
- atdma->dma_common.cap_mask = pdata->cap_mask;
- atdma->all_chan_mask = (1 << pdata->nr_channels) - 1;
+ atdma->dma_common.cap_mask = cap_mask;
+ atdma->all_chan_mask = (1 << nr_channels) - 1;

size = io->end - io->start + 1;
if (!request_mem_region(io->start, size, pdev->dev.driver->name)) {
@@ -1260,7 +1292,7 @@ static int __init at_dma_probe(struct platform_device *pdev)

/* initialize channels related values */
INIT_LIST_HEAD(&atdma->dma_common.channels);
- for (i = 0; i < pdata->nr_channels; i++, atdma->dma_common.chancnt++) {
+ for (i = 0; i < nr_channels; i++, atdma->dma_common.chancnt++) {
struct at_dma_chan *atchan = &atdma->chan[i];

atchan->chan_common.device = &atdma->dma_common;
@@ -1406,6 +1438,7 @@ static struct platform_driver at_dma_driver = {
.driver = {
.name = "at_hdmac",
.pm = &at_dma_dev_pm_ops,
+ .of_match_table = atmel_dma_dt_ids,
},
};

--
1.7.4.1


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