Re: [PATCH 2/4] dmaengine: Add STM32 DMA driver

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Hi Cedric,

On 10/08/2015 05:20 PM, M'boumba Cedric Madianga wrote:
This patch adds support for the STM32 DMA controller.

Signed-off-by: M'boumba Cedric Madianga <cedric.madianga@xxxxxxxxx>
---
  drivers/dma/Kconfig     |   12 +
  drivers/dma/Makefile    |    1 +
  drivers/dma/stm32-dma.c | 1193 +++++++++++++++++++++++++++++++++++++++++++++++
  3 files changed, 1206 insertions(+)
  create mode 100644 drivers/dma/stm32-dma.c

diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
index 5c931d4..4c6b37b 100644
--- a/drivers/dma/Kconfig
+++ b/drivers/dma/Kconfig
@@ -431,6 +431,18 @@ config STE_DMA40
  	help
  	  Support for ST-Ericsson DMA40 controller

+config STM32_DMA
+	tristate "STMicroelectronics STM32 dma support"
s/dma/DMA/ ?

diff --git a/drivers/dma/stm32-dma.c b/drivers/dma/stm32-dma.c
new file mode 100644
index 0000000..9814ca5
--- /dev/null
+++ b/drivers/dma/stm32-dma.c
@@ -0,0 +1,1193 @@

+#define STM32_DMA_LISR			0x0000 /* DMA Low Int Status Reg */
+#define STM32_DMA_HISR			0x0004 /* DMA High Int Status Reg */
+#define STM32_DMA_LIFCR			0x0008 /* DMA Low Int Flag Clear Reg */
+#define STM32_DMA_HIFCR			0x000C /* DMA High Int Flag Clear Reg */
We usually use lower case for numerical values.

+static int stm32_dma_set_xfer_param(struct stm32_dma_chan *chan,
+				    enum dma_transfer_direction direction,
+				    enum dma_slave_buswidth *buswidth)
+{
+	enum dma_slave_buswidth src_addr_width, dst_addr_width;
+	u32 src_bus_width, dst_bus_width, src_burst_size, dst_burst_size;
+	u32 src_maxburst, dst_maxburst;
+	dma_addr_t src_addr, dst_addr;
+
+	src_addr_width = chan->dma_sconfig.src_addr_width;
+	dst_addr_width = chan->dma_sconfig.dst_addr_width;
+	src_maxburst = chan->dma_sconfig.src_maxburst;
+	dst_maxburst = chan->dma_sconfig.dst_maxburst;
+	src_addr = chan->dma_sconfig.src_addr;
+	dst_addr = chan->dma_sconfig.dst_addr;
+
+	switch (direction) {
+	case DMA_MEM_TO_DEV:
+		dst_bus_width = stm32_get_dma_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return -EINVAL;
dst_bus_width is a u32, so cannot be negative.
Also, you should propagate de error returned by stm32_get_dma_width().

The comment also applies below:
+		dst_burst_size = stm32_get_dma_burst(chan, dst_maxburst);
+		if (dst_burst_size < 0)
+			return -EINVAL;
+		if (!src_addr_width)
+			src_addr_width = dst_addr_width;
+		src_bus_width = stm32_get_dma_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return -EINVAL;
+		src_burst_size = stm32_get_dma_burst(chan, src_maxburst);
+		if (src_burst_size < 0)
+			return -EINVAL;
+
+		chan->chan_reg.dma_scr |= (chan->chan_reg.dma_scr &
+			~(STM32_DMA_SCR_DIR_MASK | STM32_DMA_SCR_PSIZE_MASK |
+			STM32_DMA_SCR_MSIZE_MASK | STM32_DMA_SCR_PBURST_MASK |
+			STM32_DMA_SCR_MBURST_MASK)) |
+			STM32_DMA_SCR_DIR(STM32_DMA_MEM_TO_DEV) |
+			STM32_DMA_SCR_PSIZE(dst_bus_width) |
+			STM32_DMA_SCR_MSIZE(src_bus_width) |
+			STM32_DMA_SCR_PBURST(dst_burst_size) |
+			STM32_DMA_SCR_MBURST(src_burst_size);
+
+		chan->chan_reg.dma_spar = chan->dma_sconfig.dst_addr;
+		*buswidth = dst_addr_width;
+		return 0;
+
+	case DMA_DEV_TO_MEM:
+		src_bus_width = stm32_get_dma_width(chan, src_addr_width);
+		if (src_bus_width < 0)
+			return -EINVAL;
+		src_burst_size = stm32_get_dma_burst(chan, src_maxburst);
+		if (src_burst_size < 0)
+			return -EINVAL;
+		if (!dst_addr_width)
+			dst_addr_width = src_addr_width;
+		dst_bus_width = stm32_get_dma_width(chan, dst_addr_width);
+		if (dst_bus_width < 0)
+			return -EINVAL;
+		dst_burst_size = stm32_get_dma_burst(chan, dst_maxburst);
+		if (dst_burst_size < 0)
+			return -EINVAL;
+
+		chan->chan_reg.dma_scr |= (chan->chan_reg.dma_scr &
+			~(STM32_DMA_SCR_DIR_MASK | STM32_DMA_SCR_PSIZE_MASK |
+			STM32_DMA_SCR_MSIZE_MASK | STM32_DMA_SCR_PBURST_MASK |
+			STM32_DMA_SCR_MBURST_MASK)) |
+			STM32_DMA_SCR_DIR(STM32_DMA_DEV_TO_MEM) |
+			STM32_DMA_SCR_PSIZE(src_bus_width) |
+			STM32_DMA_SCR_MSIZE(dst_bus_width) |
+			STM32_DMA_SCR_PBURST(src_burst_size) |
+			STM32_DMA_SCR_MBURST(dst_burst_size);
+		chan->chan_reg.dma_spar = chan->dma_sconfig.src_addr;
+		*buswidth = chan->dma_sconfig.src_addr_width;
+		return 0;
+
+	default:
+		dev_err(chan2dev(chan), "Dma direction is not supported\n");
+		return -EINVAL;
+	}
+
+	return -EINVAL;
+}

Thanks,
Maxime
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