mmc: atmel-mci: fix burst/chunk size modification
The use of DMA slave config operation requires that the burst size
(aka chunk size) is specified through this interface.
Modify atmel-mci slave driver to use this specification on its side.
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
diff --git a/drivers/mmc/host/atmel-mci-regs.h b/drivers/mmc/host/atmel-mci-regs.h
index 787aba1..ab56f7d 100644
--- a/drivers/mmc/host/atmel-mci-regs.h
+++ b/drivers/mmc/host/atmel-mci-regs.h
@@ -140,4 +140,18 @@
#define atmci_writel(port,reg,value) \
__raw_writel((value), (port)->regs + reg)
+/*
+ * Fix sconfig's burst size according to atmel MCI. We need to convert them as:
+ * 1 -> 0, 4 -> 1, 8 -> 2, 16 -> 3.
+ *
+ * This can be done by finding most significant bit set.
+ */
+static inline unsigned int atmci_convert_chksize(unsigned int maxburst)
+{
+ if (maxburst > 1)
+ return fls(maxburst) - 2;
+ else
+ return 0;
+}
+
#endif /* __DRIVERS_MMC_ATMEL_MCI_H__ */