memory: jz4780_nemc: Only request IO memory the driver will use

The driver only uses the registers up to offset 0x54. Since the EFUSE
registers are in the middle of the NEMC registers, we only request
the registers we will use for now - that way the EFUSE driver can
probe too.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Tested-by: H. Nikolaus Schaller <hns@goldelico.com>
Link: https://lore.kernel.org/r/20200728152629.28878-1-paul@crapouillou.netSigned-off-by: Krzysztof Kozlowski <krzk@kernel.org>

drivers/memory/jz4780-nemc.c

@@ -8,6 +8,7 @@
 
 #include <linux/clk.h>
 #include <linux/init.h>
+#include <linux/io.h>
 #include <linux/math64.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
@@ -22,6 +23,8 @@
 #define NEMC_SMCRn(n)		(0x14 + (((n) - 1) * 4))
 #define NEMC_NFCSR		0x50
 
+#define NEMC_REG_LEN		0x54
+
 #define NEMC_SMCR_SMT		BIT(0)
 #define NEMC_SMCR_BW_SHIFT	6
 #define NEMC_SMCR_BW_MASK	(0x3 << NEMC_SMCR_BW_SHIFT)
@@ -288,7 +291,19 @@ static int jz4780_nemc_probe(struct platform_device *pdev)
 	nemc->dev = dev;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
-	nemc->base = devm_ioremap_resource(dev, res);
+
+	/*
+	 * The driver currently only uses the registers up to offset
+	 * NEMC_REG_LEN. Since the EFUSE registers are in the middle of the
+	 * NEMC registers, we only request the registers we will use for now;
+	 * that way the EFUSE driver can probe too.
+	 */
+	if (!devm_request_mem_region(dev, res->start, NEMC_REG_LEN, dev_name(dev))) {
+		dev_err(dev, "unable to request I/O memory region\n");
+		return -EBUSY;
+	}
+
+	nemc->base = devm_ioremap(dev, res->start, NEMC_REG_LEN);
 	if (IS_ERR(nemc->base)) {
 		dev_err(dev, "failed to get I/O memory\n");
 		return PTR_ERR(nemc->base);