linux-kernel - [PATCH v3 3/4] mtd: phram: Allow probing via reserved-memory

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Message-ID: <20220412135302.1682890-4-vincent.whitchurch@axis.com>
Date:   Tue, 12 Apr 2022 15:53:01 +0200
From:   Vincent Whitchurch <vincent.whitchurch@...s.com>
To:     <vigneshr@...com>, <richard@....at>, <miquel.raynal@...tlin.com>,
        <joern@...ybastard.org>
CC:     <kernel@...s.com>,
        Vincent Whitchurch <vincent.whitchurch@...s.com>,
        <linux-mtd@...ts.infradead.org>, <devicetree@...r.kernel.org>,
        <robh+dt@...nel.org>, <krzk+dt@...nel.org>,
        <frowand.list@...il.com>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 3/4] mtd: phram: Allow probing via reserved-memory

Allow phram to be probed from the devicetree.  It expects to be in a
reserved-memory node as documented by the bindings.  This allows things
like partitioning to be specified via the devicetree.

Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>
---

Notes:
    v3:
    - Add missing semicolon after MODULE_DEVICE_TABLE causing build errors on some
      configs.

 drivers/mtd/devices/phram.c | 67 ++++++++++++++++++++++++++++++++++---
 drivers/of/platform.c       |  1 +
 2 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index d503821a3e60..506e9edf5c85 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -27,6 +27,9 @@
 #include <linux/slab.h>
 #include <linux/mtd/mtd.h>
 #include <asm/div64.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/of.h>
 
 struct phram_mtd_list {
 	struct mtd_info mtd;
@@ -89,8 +92,10 @@ static void unregister_devices(void)
 	}
 }
 
-static int register_device(char *name, phys_addr_t start, size_t len, uint32_t erasesize)
+static int register_device(struct platform_device *pdev, const char *name,
+			   phys_addr_t start, size_t len, uint32_t erasesize)
 {
+	struct device_node *np = pdev ? pdev->dev.of_node : NULL;
 	struct phram_mtd_list *new;
 	int ret = -ENOMEM;
 
@@ -119,13 +124,19 @@ static int register_device(char *name, phys_addr_t start, size_t len, uint32_t e
 	new->mtd.erasesize = erasesize;
 	new->mtd.writesize = 1;
 
+	mtd_set_of_node(&new->mtd, np);
+
 	ret = -EAGAIN;
 	if (mtd_device_register(&new->mtd, NULL, 0)) {
 		pr_err("Failed to register new device\n");
 		goto out2;
 	}
 
-	list_add_tail(&new->list, &phram_list);
+	if (pdev)
+		platform_set_drvdata(pdev, new);
+	else
+		list_add_tail(&new->list, &phram_list);
+
 	return 0;
 
 out2:
@@ -278,7 +289,7 @@ static int phram_setup(const char *val)
 		goto error;
 	}
 
-	ret = register_device(name, start, len, (uint32_t)erasesize);
+	ret = register_device(NULL, name, start, len, (uint32_t)erasesize);
 	if (ret)
 		goto error;
 
@@ -325,10 +336,54 @@ static int phram_param_call(const char *val, const struct kernel_param *kp)
 module_param_call(phram, phram_param_call, NULL, NULL, 0200);
 MODULE_PARM_DESC(phram, "Memory region to map. \"phram=<name>,<start>,<length>[,<erasesize>]\"");
 
+#ifdef CONFIG_OF
+static const struct of_device_id phram_of_match[] = {
+	{ .compatible = "phram" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, phram_of_match);
+#endif
+
+static int phram_probe(struct platform_device *pdev)
+{
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOMEM;
+
+	/* mtd_set_of_node() reads name from "label" */
+	return register_device(pdev, NULL, res->start, resource_size(res),
+			       PAGE_SIZE);
+}
+
+static int phram_remove(struct platform_device *pdev)
+{
+	struct phram_mtd_list *phram = platform_get_drvdata(pdev);
+
+	mtd_device_unregister(&phram->mtd);
+	iounmap(phram->mtd.priv);
+	kfree(phram);
+
+	return 0;
+}
+
+static struct platform_driver phram_driver = {
+	.probe		= phram_probe,
+	.remove		= phram_remove,
+	.driver		= {
+		.name		= "phram",
+		.of_match_table	= of_match_ptr(phram_of_match),
+	},
+};
 
 static int __init init_phram(void)
 {
-	int ret = 0;
+	int ret;
+
+	ret = platform_driver_register(&phram_driver);
+	if (ret)
+		return ret;
 
 #ifndef MODULE
 	if (phram_paramline[0])
@@ -336,12 +391,16 @@ static int __init init_phram(void)
 	phram_init_called = 1;
 #endif
 
+	if (ret)
+		platform_driver_unregister(&phram_driver);
+
 	return ret;
 }
 
 static void __exit cleanup_phram(void)
 {
 	unregister_devices();
+	platform_driver_unregister(&phram_driver);
 }
 
 module_init(init_phram);
diff --git a/drivers/of/platform.c b/drivers/of/platform.c
index a16b74f32aa9..55d62b82c650 100644
--- a/drivers/of/platform.c
+++ b/drivers/of/platform.c
@@ -509,6 +509,7 @@ EXPORT_SYMBOL_GPL(of_platform_default_populate);
 
 #ifndef CONFIG_PPC
 static const struct of_device_id reserved_mem_matches[] = {
+	{ .compatible = "phram" },
 	{ .compatible = "qcom,rmtfs-mem" },
 	{ .compatible = "qcom,cmd-db" },
 	{ .compatible = "qcom,smem" },
-- 
2.34.1