[PATCH] Platform: goldfish: goldfish_pipe.c: Add DMA support using managed version

From: Shraddha Barke
Date: Fri Feb 12 2016 - 02:23:49 EST


setup_access_params_addr has 2 goals-

-Initialize the access_params field so that it can be used to send and read
commands from the device in access_with_param
-Get a bus address for the allocated memory to transfer to the device.

Replace the combination of devm_kzalloc and _pa() with dmam_alloc_coherent.
Coherent mapping guarantees that the device and CPU are in sync.

Signed-off-by: Shraddha Barke <shraddha.6596@xxxxxxxxx>
---
drivers/platform/goldfish/goldfish_pipe.c | 18 ++++++++++--------
1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c
index e7a29e2..49f877d 100644
--- a/drivers/platform/goldfish/goldfish_pipe.c
+++ b/drivers/platform/goldfish/goldfish_pipe.c
@@ -57,6 +57,7 @@
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/goldfish.h>
+#include <linux/dma-mapping.h>

/*
* IMPORTANT: The following constants must match the ones used and defined
@@ -217,17 +218,18 @@ static int valid_batchbuffer_addr(struct goldfish_pipe_dev *dev,
static int setup_access_params_addr(struct platform_device *pdev,
struct goldfish_pipe_dev *dev)
{
- u64 paddr;
+ dma_addr_t dma_handle;
struct access_params *aps;

- aps = devm_kzalloc(&pdev->dev, sizeof(struct access_params), GFP_KERNEL);
- if (!aps)
- return -1;
+ aps = dmam_alloc_coherent(&pdev->dev, sizeof(struct access_params),
+ &dma_handle, GFP_KERNEL);
+ if (!aps) {
+ dev_err(&pdev->dev, "allocate buffer failed\n");
+ return -ENOMEM;
+ }

- /* FIXME */
- paddr = __pa(aps);
- writel((u32)(paddr >> 32), dev->base + PIPE_REG_PARAMS_ADDR_HIGH);
- writel((u32)paddr, dev->base + PIPE_REG_PARAMS_ADDR_LOW);
+ writel(upper_32_bits(dma_handle), dev->base + PIPE_REG_PARAMS_ADDR_HIGH);
+ writel(lower_32_bits(dma_handle), dev->base + PIPE_REG_PARAMS_ADDR_LOW);

if (valid_batchbuffer_addr(dev, aps)) {
dev->aps = aps;
--
2.1.4