linux-kernel - [PATCH v2] memory: jz4780_nemc: Only request IO memory the driver will use

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Date:   Tue, 28 Jul 2020 17:26:29 +0200
From:   Paul Cercueil <paul@...pouillou.net>
To:     Krzysztof Kozlowski <krzk@...nel.org>
Cc:     od@...c.me, linux-kernel@...r.kernel.org,
        Paul Cercueil <paul@...pouillou.net>,
        "H . Nikolaus Schaller" <hns@...delico.com>
Subject: [PATCH v2] 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.

Tested-by: H. Nikolaus Schaller <hns@...delico.com>
Signed-off-by: Paul Cercueil <paul@...pouillou.net>
---

Notes:
    v2: Only ioremap() the registers we will use

 drivers/memory/jz4780-nemc.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/drivers/memory/jz4780-nemc.c b/drivers/memory/jz4780-nemc.c
index b232ed279fc3..3ec5cb0fce1e 100644
--- a/drivers/memory/jz4780-nemc.c
+++ b/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);
-- 
2.27.0