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Subject[PATCH 03/13] i2c-designware: Allow mixed endianness accesses
Date
From: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>

Allows CPUs of a given endianness to access a dw controller of a different
endianness. Endianncess difference is detected at run time through the dw
component type register.

Signed-off-by: Jean-Hugues Deschenes <jean-hugues.deschenes@octasic.com>
Signed-off-by: Dirk Brandewie <dirk.brandewie@gmail.com>
---
drivers/i2c/busses/i2c-designware.c | 17 +++++++++++++++--
1 files changed, 15 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-designware.c b/drivers/i2c/busses/i2c-designware.c
index b2b2a19..f58f05d 100644
--- a/drivers/i2c/busses/i2c-designware.c
+++ b/drivers/i2c/busses/i2c-designware.c
@@ -37,6 +37,7 @@
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/slab.h>
+#include <linux/swab.h>

/*
* Registers offset
@@ -193,6 +194,7 @@ static char *abort_sources[] = {
* @status: i2c master status, one of STATUS_*
* @abort_source: copy of the TX_ABRT_SOURCE register
* @irq: interrupt number for the i2c master
+ * @swab: true if the instantiated IP is of different endianess
* @adapter: i2c subsystem adapter node
* @tx_fifo_depth: depth of the hardware tx fifo
* @rx_fifo_depth: depth of the hardware rx fifo
@@ -216,6 +218,7 @@ struct dw_i2c_dev {
unsigned int status;
u32 abort_source;
int irq;
+ int swab;
struct i2c_adapter adapter;
unsigned int tx_fifo_depth;
unsigned int rx_fifo_depth;
@@ -223,11 +226,19 @@ struct dw_i2c_dev {

static u32 dw_readl(struct dw_i2c_dev *dev, int offset)
{
- return readl(dev->base + offset);
+ u32 value = readl(dev->base + offset);
+
+ if (dev->swab)
+ return swab32(value);
+ else
+ return value;
}

static void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
{
+ if (dev->swab)
+ b = swab32(b);
+
writel(b, dev->base + offset);
}

@@ -760,7 +771,9 @@ static int __devinit dw_i2c_probe(struct platform_device *pdev)
}

reg = dw_readl(dev, DW_IC_COMP_TYPE);
- if (reg != 0x44570140) {
+ if (reg == ___constant_swab32(0x44570140))
+ dev->swab = 1;
+ else if (reg != 0x44570140) {
dev_err(&pdev->dev, "Unknown Synopsys component type: "
"0x%08x\n", reg);
r = -ENODEV;
--
1.7.3.4


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