[PATCH v2 11/12] i2c: designware: Use provided regmap instead of reg resource

[Serge Semin]

This is a preparation patch before adding a glue platform driver for the
Baikal-T1 I2C controller. Since the i2c controller registers are indirectly
accessed by means of the Baikal-T1 System Controller registers we need to
have a way to disable the default registers mapping setup procedure and
make the DW I2C core/platform code to use a provided by a glue driver
regmap.

Signed-off-by: Serge Semin <sergey.se...@baikalelectronics.ru>
Cc: Alexey Malahov <alexey.mala...@baikalelectronics.ru>
Cc: Thomas Bogendoerfer <tsbog...@alpha.franken.de>
Cc: Paul Burton <paulbur...@kernel.org>
Cc: Ralf Baechle <r...@linux-mips.org>
Cc: Rob Herring <robh...@kernel.org>
Cc: Frank Rowand <frowand.l...@gmail.com>
Cc: linux-m...@vger.kernel.org
Cc: devicet...@vger.kernel.org
---
 drivers/i2c/busses/i2c-designware-common.c  |  7 +++++++
 drivers/i2c/busses/i2c-designware-platdrv.c | 14 ++++++++++----
 2 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-common.c 
b/drivers/i2c/busses/i2c-designware-common.c
index 35c5ad7e274e..141ea0651a8f 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -133,6 +133,13 @@ int i2c_dw_init_regmap(struct dw_i2c_dev *dev)
        u32 reg;
        int ret;
 
+       /*
+        * Skip detecting the registers map configuration if the regmap has
+        * already been provided by a higher code.
+        */
+       if (dev->map)
+               return 0;
+
        ret = i2c_dw_acquire_lock(dev);
        if (ret)
                return ret;
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c 
b/drivers/i2c/busses/i2c-designware-platdrv.c
index f577e2a92a4f..9d131a64ea81 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -212,10 +212,16 @@ int i2c_dw_plat_setup(struct dw_i2c_dev *dev)
        if (dev->irq < 0)
                return dev->irq;
 
-       mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-       dev->base = devm_ioremap_resource(&pdev->dev, mem);
-       if (IS_ERR(dev->base))
-               return PTR_ERR(dev->base);
+       /*
+        * Don't try to get the controller registers MMIO space if regmap has
+        * been provided by a higher level code.
+        */
+       if (!dev->map) {
+               mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+               dev->base = devm_ioremap_resource(&pdev->dev, mem);
+               if (IS_ERR(dev->base))
+                       return PTR_ERR(dev->base);
+       }
 
        dev->rst = devm_reset_control_get_optional_exclusive(&pdev->dev, NULL);
        if (IS_ERR(dev->rst))
-- 
2.25.1