This is a note to let you know that I've just added the patch titled
sh: dma: Fix DMA channel offset calculation
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sh-dma-fix-dma-channel-offset-calculation.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 380452e650d23ba0ea533e6b4622e018ba77d5a3
Author: Artur Rojek <contact@xxxxxxxxxxxxxx>
Date: Sat May 27 18:44:50 2023 +0200
sh: dma: Fix DMA channel offset calculation
[ Upstream commit e82e47584847129a20b8c9f4a1dcde09374fb0e0 ]
Various SoCs of the SH3, SH4 and SH4A family, which use this driver,
feature a differing number of DMA channels, which can be distributed
between up to two DMAC modules. The existing implementation fails to
correctly accommodate for all those variations, resulting in wrong
channel offset calculations and leading to kernel panics.
Rewrite dma_base_addr() in order to properly calculate channel offsets
in a DMAC module. Fix dmaor_read_reg() and dmaor_write_reg(), so that
the correct DMAC module base is selected for the DMAOR register.
Fixes: 7f47c7189b3e8f19 ("sh: dma: More legacy cpu dma chainsawing.")
Signed-off-by: Artur Rojek <contact@xxxxxxxxxxxxxx>
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20230527164452.64797-2-contact@xxxxxxxxxxxxxx
Signed-off-by: John Paul Adrian Glaubitz <glaubitz@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/sh/drivers/dma/dma-sh.c b/arch/sh/drivers/dma/dma-sh.c
index afde2a7d3eb35..e0679d8a9b34b 100644
--- a/arch/sh/drivers/dma/dma-sh.c
+++ b/arch/sh/drivers/dma/dma-sh.c
@@ -21,6 +21,18 @@
#include <cpu/dma-register.h>
#include <cpu/dma.h>
+/*
+ * Some of the SoCs feature two DMAC modules. In such a case, the channels are
+ * distributed equally among them.
+ */
+#ifdef SH_DMAC_BASE1
+#define SH_DMAC_NR_MD_CH (CONFIG_NR_ONCHIP_DMA_CHANNELS / 2)
+#else
+#define SH_DMAC_NR_MD_CH CONFIG_NR_ONCHIP_DMA_CHANNELS
+#endif
+
+#define SH_DMAC_CH_SZ 0x10
+
/*
* Define the default configuration for dual address memory-memory transfer.
* The 0x400 value represents auto-request, external->external.
@@ -32,7 +44,7 @@ static unsigned long dma_find_base(unsigned int chan)
unsigned long base = SH_DMAC_BASE0;
#ifdef SH_DMAC_BASE1
- if (chan >= 6)
+ if (chan >= SH_DMAC_NR_MD_CH)
base = SH_DMAC_BASE1;
#endif
@@ -43,13 +55,13 @@ static unsigned long dma_base_addr(unsigned int chan)
{
unsigned long base = dma_find_base(chan);
- /* Normalize offset calculation */
- if (chan >= 9)
- chan -= 6;
- if (chan >= 4)
- base += 0x10;
+ chan = (chan % SH_DMAC_NR_MD_CH) * SH_DMAC_CH_SZ;
+
+ /* DMAOR is placed inside the channel register space. Step over it. */
+ if (chan >= DMAOR)
+ base += SH_DMAC_CH_SZ;
- return base + (chan * 0x10);
+ return base + chan;
}
#ifdef CONFIG_SH_DMA_IRQ_MULTI
@@ -253,12 +265,11 @@ static int sh_dmac_get_dma_residue(struct dma_channel *chan)
#define NR_DMAOR 1
#endif
-/*
- * DMAOR bases are broken out amongst channel groups. DMAOR0 manages
- * channels 0 - 5, DMAOR1 6 - 11 (optional).
- */
-#define dmaor_read_reg(n) __raw_readw(dma_find_base((n)*6))
-#define dmaor_write_reg(n, data) __raw_writew(data, dma_find_base(n)*6)
+#define dmaor_read_reg(n) __raw_readw(dma_find_base((n) * \
+ SH_DMAC_NR_MD_CH) + DMAOR)
+#define dmaor_write_reg(n, data) __raw_writew(data, \
+ dma_find_base((n) * \
+ SH_DMAC_NR_MD_CH) + DMAOR)
static inline int dmaor_reset(int no)
{
