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Subject[PATCH AUTOSEL 5.2 09/12] dmaengine: rcar-dmac: Fix DMACHCLR handling if iommu is mapped
Date
From: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

[ Upstream commit cf24aac38698bfa1d021afd3883df3c4c65143a4 ]

The commit 20c169aceb45 ("dmaengine: rcar-dmac: clear pertinence
number of channels") forgets to clear the last channel by
DMACHCLR in rcar_dmac_init() (and doesn't need to clear the first
channel) if iommu is mapped to the device. So, this patch fixes it
by using "channels_mask" bitfield.

Note that the hardware and driver don't support more than 32 bits
in DMACHCLR register anyway, so this patch should reject more than
32 channels in rcar_dmac_parse_of().

Fixes: 20c169aceb459575 ("dmaengine: rcar-dmac: clear pertinence number of channels")
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/1567424643-26629-1-git-send-email-yoshihiro.shimoda.uh@renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/dma/sh/rcar-dmac.c | 28 +++++++++++++++++++---------
1 file changed, 19 insertions(+), 9 deletions(-)

diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 54de669c38b84..f1d89bdebddab 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -192,6 +192,7 @@ struct rcar_dmac_chan {
* @iomem: remapped I/O memory base
* @n_channels: number of available channels
* @channels: array of DMAC channels
+ * @channels_mask: bitfield of which DMA channels are managed by this driver
* @modules: bitmask of client modules in use
*/
struct rcar_dmac {
@@ -202,6 +203,7 @@ struct rcar_dmac {

unsigned int n_channels;
struct rcar_dmac_chan *channels;
+ unsigned int channels_mask;

DECLARE_BITMAP(modules, 256);
};
@@ -438,7 +440,7 @@ static int rcar_dmac_init(struct rcar_dmac *dmac)
u16 dmaor;

/* Clear all channels and enable the DMAC globally. */
- rcar_dmac_write(dmac, RCAR_DMACHCLR, GENMASK(dmac->n_channels - 1, 0));
+ rcar_dmac_write(dmac, RCAR_DMACHCLR, dmac->channels_mask);
rcar_dmac_write(dmac, RCAR_DMAOR,
RCAR_DMAOR_PRI_FIXED | RCAR_DMAOR_DME);

@@ -814,6 +816,9 @@ static void rcar_dmac_stop_all_chan(struct rcar_dmac *dmac)
for (i = 0; i < dmac->n_channels; ++i) {
struct rcar_dmac_chan *chan = &dmac->channels[i];

+ if (!(dmac->channels_mask & BIT(i)))
+ continue;
+
/* Stop and reinitialize the channel. */
spin_lock_irq(&chan->lock);
rcar_dmac_chan_halt(chan);
@@ -1776,6 +1781,8 @@ static int rcar_dmac_chan_probe(struct rcar_dmac *dmac,
return 0;
}

+#define RCAR_DMAC_MAX_CHANNELS 32
+
static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
{
struct device_node *np = dev->of_node;
@@ -1787,12 +1794,16 @@ static int rcar_dmac_parse_of(struct device *dev, struct rcar_dmac *dmac)
return ret;
}

- if (dmac->n_channels <= 0 || dmac->n_channels >= 100) {
+ /* The hardware and driver don't support more than 32 bits in CHCLR */
+ if (dmac->n_channels <= 0 ||
+ dmac->n_channels >= RCAR_DMAC_MAX_CHANNELS) {
dev_err(dev, "invalid number of channels %u\n",
dmac->n_channels);
return -EINVAL;
}

+ dmac->channels_mask = GENMASK(dmac->n_channels - 1, 0);
+
return 0;
}

@@ -1802,7 +1813,6 @@ static int rcar_dmac_probe(struct platform_device *pdev)
DMA_SLAVE_BUSWIDTH_2_BYTES | DMA_SLAVE_BUSWIDTH_4_BYTES |
DMA_SLAVE_BUSWIDTH_8_BYTES | DMA_SLAVE_BUSWIDTH_16_BYTES |
DMA_SLAVE_BUSWIDTH_32_BYTES | DMA_SLAVE_BUSWIDTH_64_BYTES;
- unsigned int channels_offset = 0;
struct dma_device *engine;
struct rcar_dmac *dmac;
struct resource *mem;
@@ -1831,10 +1841,8 @@ static int rcar_dmac_probe(struct platform_device *pdev)
* level we can't disable it selectively, so ignore channel 0 for now if
* the device is part of an IOMMU group.
*/
- if (device_iommu_mapped(&pdev->dev)) {
- dmac->n_channels--;
- channels_offset = 1;
- }
+ if (device_iommu_mapped(&pdev->dev))
+ dmac->channels_mask &= ~BIT(0);

dmac->channels = devm_kcalloc(&pdev->dev, dmac->n_channels,
sizeof(*dmac->channels), GFP_KERNEL);
@@ -1892,8 +1900,10 @@ static int rcar_dmac_probe(struct platform_device *pdev)
INIT_LIST_HEAD(&engine->channels);

for (i = 0; i < dmac->n_channels; ++i) {
- ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i],
- i + channels_offset);
+ if (!(dmac->channels_mask & BIT(i)))
+ continue;
+
+ ret = rcar_dmac_chan_probe(dmac, &dmac->channels[i], i);
if (ret < 0)
goto error;
}
--
2.20.1
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