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authorRussell King <rmk+kernel@arm.linux.org.uk>2011-01-11 19:35:53 +0000
committerRussell King <rmk+kernel@arm.linux.org.uk>2011-02-04 13:25:49 +0000
commitc8ebae37034c0ead62eb4df8ef88e999ddb8d5cf (patch)
treec9925f03a9c627d7408ef483d7920e25a927e633 /include/linux
parent51d4375dd72f352594f1a4f1d7598bf9a75b8dfe (diff)
ARM: mmci: add dmaengine-based DMA support
Based on a patch from Linus Walleij. Add dmaengine based support for DMA to the MMCI driver, using the Primecell DMA engine interface. The changes over Linus' driver are: - rename txsize_threshold to dmasize_threshold, as this reflects the purpose more. - use 'mmci_dma_' as the function prefix rather than 'dma_mmci_'. - clean up requesting of dma channels. - don't release a single channel twice when it's shared between tx and rx. - get rid of 'dma_enable' bool - instead check whether the channel is NULL. - detect incomplete DMA at the end of a transfer. Some DMA controllers (eg, PL08x) are unable to be configured for scatter DMA and also listen to all four DMA request signals [BREQ,SREQ,LBREQ,LSREQ] from the MMCI. They can do one or other but not both. As MMCI uses LBREQ/LSREQ for the final burst/words, PL08x does not transfer the last few words. - map and unmap DMA buffers using the DMA engine struct device, not the MMCI struct device - the DMA engine is doing the DMA transfer, not us. - avoid double-unmapping of the DMA buffers on MMCI data errors. - don't check for negative values from the dmaengine tx submission function - Dan says this must never fail. - use new dmaengine helper functions rather than using the ugly function pointers directly. - allow DMA code to be fully optimized away using dma_inprogress() which is defined to constant 0 if DMA engine support is disabled. - request maximum segment size from the DMA engine struct device and set this appropriately. - removed checking of buffer alignment - the DMA engine should deal with its own restrictions on buffer alignment, not the individual DMA engine users. - removed setting DMAREQCTL - this confuses some DMA controllers as it causes LBREQ to be asserted for the last seven transfers, rather than six SREQ and one LSREQ. - removed burst setting - the DMA controller should not burst past the transfer size required to complete the DMA operation. Tested-by: Linus Walleij <linus.walleij@linaro.org> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'include/linux')
-rw-r--r--include/linux/amba/mmci.h17
1 files changed, 17 insertions, 0 deletions
diff --git a/include/linux/amba/mmci.h b/include/linux/amba/mmci.h
index f4ee9acc9721..f60227088b7b 100644
--- a/include/linux/amba/mmci.h
+++ b/include/linux/amba/mmci.h
@@ -6,6 +6,9 @@
#include <linux/mmc/host.h>
+/* Just some dummy forwarding */
+struct dma_chan;
+
/**
* struct mmci_platform_data - platform configuration for the MMCI
* (also known as PL180) block.
@@ -27,6 +30,17 @@
* @cd_invert: true if the gpio_cd pin value is active low
* @capabilities: the capabilities of the block as implemented in
* this platform, signify anything MMC_CAP_* from mmc/host.h
+ * @dma_filter: function used to select an apropriate RX and TX
+ * DMA channel to be used for DMA, if and only if you're deploying the
+ * generic DMA engine
+ * @dma_rx_param: parameter passed to the DMA allocation
+ * filter in order to select an apropriate RX channel. If
+ * there is a bidirectional RX+TX channel, then just specify
+ * this and leave dma_tx_param set to NULL
+ * @dma_tx_param: parameter passed to the DMA allocation
+ * filter in order to select an apropriate TX channel. If this
+ * is NULL the driver will attempt to use the RX channel as a
+ * bidirectional channel
*/
struct mmci_platform_data {
unsigned int f_max;
@@ -38,6 +52,9 @@ struct mmci_platform_data {
int gpio_cd;
bool cd_invert;
unsigned long capabilities;
+ bool (*dma_filter)(struct dma_chan *chan, void *filter_param);
+ void *dma_rx_param;
+ void *dma_tx_param;
};
#endif