mtd: bcm47xxsflash: use ioremap_cache() instead of KSEG0ADDR()

Using KSEG0ADDR makes code highly MIPS dependent and not portable.
Thanks to the fix a68f3768 ("MIPS: io.h: Define `ioremap_cache'") we can
use ioremap_cache which is generic and supported on MIPS as well now.

KSEG0ADDR was translating 0x1c000000 into 0x9c000000. With ioremap_cache
we use MIPS's __ioremap (and then remap_area_pages). This results in
different address (e.g. 0xc0080000) but it still should be cached as
expected and it was successfully tested with BCM47186B0.

Other than that drivers/bcma/driver_chipcommon_sflash.c nicely setups a
struct resource for access window, but we wren't using it. Use it now
and drop duplicated info.
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>

drivers/bcma/driver_chipcommon_sflash.c

@@ -146,7 +146,6 @@ int bcma_sflash_init(struct bcma_drv_cc *cc)
 		return -ENOTSUPP;
 	}
 
-	sflash->window = BCMA_SOC_FLASH2;
 	sflash->blocksize = e->blocksize;
 	sflash->numblocks = e->numblocks;
 	sflash->size = sflash->blocksize * sflash->numblocks;

drivers/mtd/devices/bcm47xxsflash.c

@@ -2,6 +2,7 @@
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/delay.h>
+#include <linux/ioport.h>
 #include <linux/mtd/mtd.h>
 #include <linux/platform_device.h>
 #include <linux/bcma/bcma.h>
@@ -109,8 +110,7 @@ static int bcm47xxsflash_read(struct mtd_info *mtd, loff_t from, size_t len,
 	if ((from + len) > mtd->size)
 		return -EINVAL;
 
-	memcpy_fromio(buf, (void __iomem *)KSEG0ADDR(b47s->window + from),
-		      len);
+	memcpy_fromio(buf, b47s->window + from, len);
 	*retlen = len;
 
 	return len;
@@ -275,15 +275,33 @@ static void bcm47xxsflash_bcma_cc_write(struct bcm47xxsflash *b47s, u16 offset,
 
 static int bcm47xxsflash_bcma_probe(struct platform_device *pdev)
 {
-	struct bcma_sflash *sflash = dev_get_platdata(&pdev->dev);
+	struct device *dev = &pdev->dev;
+	struct bcma_sflash *sflash = dev_get_platdata(dev);
 	struct bcm47xxsflash *b47s;
+	struct resource *res;
 	int err;
 
-	b47s = devm_kzalloc(&pdev->dev, sizeof(*b47s), GFP_KERNEL);
+	b47s = devm_kzalloc(dev, sizeof(*b47s), GFP_KERNEL);
 	if (!b47s)
 		return -ENOMEM;
 	sflash->priv = b47s;
 
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(dev, "invalid resource\n");
+		return -EINVAL;
+	}
+	if (!devm_request_mem_region(dev, res->start, resource_size(res),
+				     res->name)) {
+		dev_err(dev, "can't request region for resource %pR\n", res);
+		return -EBUSY;
+	}
+	b47s->window = ioremap_cache(res->start, resource_size(res));
+	if (!b47s->window) {
+		dev_err(dev, "ioremap failed for resource %pR\n", res);
+		return -ENOMEM;
+	}
+
 	b47s->bcma_cc = container_of(sflash, struct bcma_drv_cc, sflash);
 	b47s->cc_read = bcm47xxsflash_bcma_cc_read;
 	b47s->cc_write = bcm47xxsflash_bcma_cc_write;
@@ -297,7 +315,6 @@ static int bcm47xxsflash_bcma_probe(struct platform_device *pdev)
 		break;
 	}
 
-	b47s->window = sflash->window;
 	b47s->blocksize = sflash->blocksize;
 	b47s->numblocks = sflash->numblocks;
 	b47s->size = sflash->size;
@@ -306,6 +323,7 @@ static int bcm47xxsflash_bcma_probe(struct platform_device *pdev)
 	err = mtd_device_parse_register(&b47s->mtd, probes, NULL, NULL, 0);
 	if (err) {
 		pr_err("Failed to register MTD device: %d\n", err);
+		iounmap(b47s->window);
 		return err;
 	}
 
@@ -321,6 +339,7 @@ static int bcm47xxsflash_bcma_remove(struct platform_device *pdev)
 	struct bcm47xxsflash *b47s = sflash->priv;
 
 	mtd_device_unregister(&b47s->mtd);
+	iounmap(b47s->window);
 
 	return 0;
 }

drivers/mtd/devices/bcm47xxsflash.h

@@ -65,7 +65,8 @@ struct bcm47xxsflash {
 
 	enum bcm47xxsflash_type type;
 
-	u32 window;
+	void __iomem *window;
+
 	u32 blocksize;
 	u16 numblocks;
 	u32 size;

include/linux/bcma/bcma_driver_chipcommon.h

@@ -587,7 +587,6 @@ struct mtd_info;
 
 struct bcma_sflash {
 	bool present;
-	u32 window;
 	u32 blocksize;
 	u16 numblocks;
 	u32 size;