i2c: designware: Add support for 16bit register access

The STM SPEAr platform can only access the i2c controller register
via 16bit read/write functions. This patch adds support to
automatically detect this 16bit access mode.

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>

diff --git a/drivers/i2c/busses/i2c-designware-core.c b/drivers/i2c/busses/i2c-designware-core.c
index df8799241009e85ca045fb149f3e108986a5a09c..1e48bec80edfb08a0628cc816004c1955075fc42 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-core.c
+++ b/drivers/i2c/busses/i2c-designware-core.c
@@ -164,9 +164,15 @@ static char *abort_sources[] = {
 
 u32 dw_readl(struct dw_i2c_dev *dev, int offset)
 {
-       u32 value = readl(dev->base + offset);
+       u32 value;
 
-       if (dev->swab)
+       if (dev->accessor_flags & ACCESS_16BIT)
+               value = readw(dev->base + offset) |
+                       (readw(dev->base + offset + 2) << 16);
+       else
+               value = readl(dev->base + offset);
+
+       if (dev->accessor_flags & ACCESS_SWAP)
                return swab32(value);
        else
                return value;
@@ -174,10 +180,15 @@ u32 dw_readl(struct dw_i2c_dev *dev, int offset)
 
 void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset)
 {
-       if (dev->swab)
+       if (dev->accessor_flags & ACCESS_SWAP)
                b = swab32(b);
 
-       writel(b, dev->base + offset);
+       if (dev->accessor_flags & ACCESS_16BIT) {
+               writew((u16)b, dev->base + offset);
+               writew((u16)(b >> 16), dev->base + offset + 2);
+       } else {
+               writel(b, dev->base + offset);
+       }
 }
 
 static u32
@@ -251,14 +262,14 @@ int i2c_dw_init(struct dw_i2c_dev *dev)
 
        input_clock_khz = dev->get_clk_rate_khz(dev);
 
-       /* Configure register endianess access */
        reg = dw_readl(dev, DW_IC_COMP_TYPE);
        if (reg == ___constant_swab32(DW_IC_COMP_TYPE_VALUE)) {
-               dev->swab = 1;
-               reg = DW_IC_COMP_TYPE_VALUE;
-       }
-
-       if (reg != DW_IC_COMP_TYPE_VALUE) {
+               /* Configure register endianess access */
+               dev->accessor_flags |= ACCESS_SWAP;
+       } else if (reg == (DW_IC_COMP_TYPE_VALUE & 0x0000ffff)) {
+               /* Configure register access mode 16bit */
+               dev->accessor_flags |= ACCESS_16BIT;
+       } else if (reg != DW_IC_COMP_TYPE_VALUE) {
                dev_err(dev->dev, "Unknown Synopsys component type: "
                        "0x%08x\n", reg);
                return -ENODEV;

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 02d1a2ddd853bed03ecbffa6b13b839c46f72038..9c1840ee09c7a4fde94a468a5ff339bdb42ae2ac 100644 (file)
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -82,7 +82,7 @@ struct dw_i2c_dev {
        unsigned int            status;
        u32                     abort_source;
        int                     irq;
-       int                     swab;
+       u32                     accessor_flags;
        struct i2c_adapter      adapter;
        u32                     functionality;
        u32                     master_cfg;
@@ -90,6 +90,9 @@ struct dw_i2c_dev {
        unsigned int            rx_fifo_depth;
 };
 
+#define ACCESS_SWAP            0x00000001
+#define ACCESS_16BIT           0x00000002
+
 extern u32 dw_readl(struct dw_i2c_dev *dev, int offset);
 extern void dw_writel(struct dw_i2c_dev *dev, u32 b, int offset);
 extern int i2c_dw_init(struct dw_i2c_dev *dev);