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From:   Vincent Whitchurch <vincent.whitchurch@axis.com>
To:     <vigneshr@ti.com>, <richard@nod.at>, <miquel.raynal@bootlin.com>,
        <joern@lazybastard.org>
CC:     <kernel@axis.com>,
        Vincent Whitchurch <vincent.whitchurch@axis.com>,
        <linux-mtd@lists.infradead.org>, <devicetree@vger.kernel.org>,
        <robh+dt@kernel.org>, <krzk+dt@kernel.org>,
        <frowand.list@gmail.com>, <linux-kernel@vger.kernel.org>
Subject: [PATCH v2 1/4] mtd: core: Check devicetree alias for index
Date:   Tue, 5 Apr 2022 15:03:47 +0200
Message-ID: <20220405130350.1640985-2-vincent.whitchurch@axis.com>
In-Reply-To: <20220405130350.1640985-1-vincent.whitchurch@axis.com>
References: <20220405130350.1640985-1-vincent.whitchurch@axis.com>
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Allow the MTD index to be specified via a devicetree alias, so that the
number does not just depend on probe order.  This is useful to allow
pseudo-devices like phram to be optionally used on systems, without
having this affect the numbering of the real hardware MTD devices.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@axis.com>
---
 drivers/mtd/mtdcore.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 7731796024e0..9eb0680db312 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -557,9 +557,10 @@ static int mtd_nvmem_add(struct mtd_info *mtd)
 
 int add_mtd_device(struct mtd_info *mtd)
 {
+	struct device_node *np = mtd_get_of_node(mtd);
 	struct mtd_info *master = mtd_get_master(mtd);
 	struct mtd_notifier *not;
-	int i, error;
+	int i, error, ofidx;
 
 	/*
 	 * May occur, for instance, on buggy drivers which call
@@ -598,7 +599,13 @@ int add_mtd_device(struct mtd_info *mtd)
 
 	mutex_lock(&mtd_table_mutex);
 
-	i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
+	ofidx = -1;
+	if (np)
+		ofidx = of_alias_get_id(np, "mtd");
+	if (ofidx >= 0)
+		i = idr_alloc(&mtd_idr, mtd, ofidx, ofidx + 1, GFP_KERNEL);
+	else
+		i = idr_alloc(&mtd_idr, mtd, 0, 0, GFP_KERNEL);
 	if (i < 0) {
 		error = i;
 		goto fail_locked;
-- 
2.34.1