linux-kernel - [PATCH] mtd: phram: Allow multiple phram devices on cmd line

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Date:	Tue, 21 Oct 2014 19:03:23 +0100 (BST)
From:	Rob Ward <robert.ward114@...glemail.com>
To:	joern@...ybastard.org, dwmw2@...radead.org,
	computersforpeace@...il.com
cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] mtd: phram: Allow multiple phram devices on cmd line

>From 9ddd010f1e2bf4fdfac5a7627c5de821a2dcd8f5 Mon Sep 17 00:00:00 2001
From: Rob Ward <robert.ward114@...glemail.com>
Date: Tue, 21 Oct 2014 17:46:53 +0100
Subject: [PATCH] mtd: phram: Allow multiple phram devices on cmd line

Allow the phram module the ability to create multiple phram mtd
devices via the kernel command line.

Currently the phram module only allows a single mtd device to be
created via the kernel command line. This is due to the phram
module having to store the values until it is initialised
later. This storage is done using a single char[] meaning when
the module_param_call is made the previous value is overidden.

This change modifies the phram system to use a char[][] allowing
multiple devices to be created.

The array currently allows up to 64 devices to be created via the
kernel command line.

If the array is full a message is printed to the console and the
module_param_call returns.

To test, in all cases an area of memory needs to be reserved via
the command line e.g. memmap=10M$114M

To test with phram build into the kernel on the command line add
the following:

phram.phram=alpha,114Mi,1Mi phram.phram=beta,115Mi,1Mi

To test phram built as a module insmod with the following arguments:

phram=gamma,114Mi,1Mi phram=delta,115Mi,1Mi

In both cases two mtd devices should be created.

Signed-off-by: Rob Ward <robert.ward114@...glemail.com>
---
 drivers/mtd/devices/phram.c | 41 ++++++++++++++++++++++++++++++++++++-----
 1 file changed, 36 insertions(+), 5 deletions(-)

diff --git a/drivers/mtd/devices/phram.c b/drivers/mtd/devices/phram.c
index effd9a4..bd409be 100644
--- a/drivers/mtd/devices/phram.c
+++ b/drivers/mtd/devices/phram.c
@@ -214,7 +214,7 @@ static int phram_init_called;
  * size.
  * Example: phram.phram=rootfs,0xa0000000,512Mi
  */
-static char phram_paramline[64 + 20 + 20];
+static char phram_paramline[64][64 + 20 + 20];
 #endif
 
 static int phram_setup(const char *val)
@@ -271,6 +271,9 @@ static int phram_param_call(const char *val, struct kernel_param *kp)
 #ifdef MODULE
 	return phram_setup(val);
 #else
+	int paramline_it = 0;
+	int arraysize = 0;
+
 	/*
 	 * If more parameters are later passed in via
 	 * /sys/module/phram/parameters/phram
@@ -290,9 +293,27 @@ static int phram_param_call(const char *val, struct kernel_param *kp)
 	 * phram_setup().
 	 */
 
-	if (strlen(val) >= sizeof(phram_paramline))
+	if (strlen(val) >= sizeof(phram_paramline[0]))
 		return -ENOSPC;
-	strcpy(phram_paramline, val);
+
+	arraysize = sizeof(phram_paramline)/sizeof(phram_paramline[0]);
+
+	/*
+	 * Check if any space is left in the array. If no space
+	 * is left then print warning and return 0
+	 */
+
+	if (phram_paramline[arraysize - 1][0]) {
+		pr_warn("exceeded limit via cmd_line - %s ignored", val);
+		return 0;
+	}
+
+	for (paramline_it = 0; paramline_it <= arraysize; paramline_it++) {
+		if (!phram_paramline[paramline_it][0]) {
+			strcpy(phram_paramline[paramline_it], val);
+			break;
+		}
+	}
 
 	return 0;
 #endif
@@ -307,8 +328,18 @@ static int __init init_phram(void)
 	int ret = 0;
 
 #ifndef MODULE
-	if (phram_paramline[0])
-		ret = phram_setup(phram_paramline);
+	int arraysize = 0;
+	int paramline_it = 0;
+
+	arraysize = sizeof(phram_paramline)/sizeof(phram_paramline[0]);
+
+	for (paramline_it = 0; paramline_it <= arraysize; paramline_it++) {
+		if (phram_paramline[paramline_it][0]) {
+			ret = phram_setup(phram_paramline[paramline_it]);
+			if (ret)
+				break;
+		}
+	}
 	phram_init_called = 1;
 #endif
 
-- 
2.0.2

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