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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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