[PATCH v4] dmaengine: tegra-apb: proper default init of channel slave_id

From: Shardar Shariff Md
Date: Sat Apr 23 2016 - 05:36:25 EST


Initialize default channel slave_id(req_sel) to invalid id
(i.e max supported slave id + 1) to avoid overwriting of slave_id
during tegra_dma_slave_config() with client data if slave_id
is not initialized through DT

Signed-off-by: Shardar Shariff Md <smohammed@xxxxxxxxxx>

---
Changes from v1:
- Instead of initializing the slave id to -1 define macros for
max slave id and invalid slave id and do the checks accordingly.

Changes from v2:
- Check slave id boundary before dma channel is allocated to
avoid channel leakage.
- Calculate the max slave id from the CSR slave id(req sel)
mask bits.

Changes from v3:
- Remove *MAX_SLAVD_ID macro and instead use *REQ_SEL_MASK
- During tegra_dma_slave_config() check for slave_id boundary
condition
---
drivers/dma/tegra20-apb-dma.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index 3871f29..01e316f 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -54,6 +54,7 @@
#define TEGRA_APBDMA_CSR_ONCE BIT(27)
#define TEGRA_APBDMA_CSR_FLOW BIT(21)
#define TEGRA_APBDMA_CSR_REQ_SEL_SHIFT 16
+#define TEGRA_APBDMA_CSR_REQ_SEL_MASK 0x1F
#define TEGRA_APBDMA_CSR_WCOUNT_MASK 0xFFFC

/* STATUS register */
@@ -114,6 +115,8 @@
/* Channel base address offset from APBDMA base address */
#define TEGRA_APBDMA_CHANNEL_BASE_ADD_OFFSET 0x1000

+#define TEGRA_APBDMA_SLAVE_ID_INVALID (TEGRA_APBDMA_CSR_REQ_SEL_MASK + 1)
+
struct tegra_dma;

/*
@@ -353,8 +356,11 @@ static int tegra_dma_slave_config(struct dma_chan *dc,
}

memcpy(&tdc->dma_sconfig, sconfig, sizeof(*sconfig));
- if (!tdc->slave_id)
+ if (tdc->slave_id == TEGRA_APBDMA_SLAVE_ID_INVALID) {
+ if (sconfig->slave_id > TEGRA_APBDMA_CSR_REQ_SEL_MASK)
+ return -EINVAL;
tdc->slave_id = sconfig->slave_id;
+ }
tdc->config_init = true;
return 0;
}
@@ -1236,7 +1242,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
}
pm_runtime_put(tdma->dev);

- tdc->slave_id = 0;
+ tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;
}

static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
@@ -1246,6 +1252,11 @@ static struct dma_chan *tegra_dma_of_xlate(struct of_phandle_args *dma_spec,
struct dma_chan *chan;
struct tegra_dma_channel *tdc;

+ if (dma_spec->args[0] > TEGRA_APBDMA_CSR_REQ_SEL_MASK) {
+ dev_err(tdma->dev, "Invalid slave id: %d\n", dma_spec->args[0]);
+ return NULL;
+ }
+
chan = dma_get_any_slave_channel(&tdma->dma_dev);
if (!chan)
return NULL;
@@ -1389,6 +1400,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
&tdma->dma_dev.channels);
tdc->tdma = tdma;
tdc->id = i;
+ tdc->slave_id = TEGRA_APBDMA_SLAVE_ID_INVALID;

tasklet_init(&tdc->tasklet, tegra_dma_tasklet,
(unsigned long)tdc);
--
1.8.1.5