misc: Add devicetree SRAM driver

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

drivers/misc/Kconfig

@@ -9,4 +9,10 @@ config JTAG
 	depends on GENERIC_GPIO
 	help
 	  Controls JTAG chains connected to I/O pins
+
+config SRAM
+	bool "Generic SRAM driver"
+	help
+	  This driver adds support for memory mapped SRAM.
+
 endmenu

drivers/misc/Makefile

@@ -3,3 +3,4 @@
 #
 
 obj-$(CONFIG_JTAG)		+= jtag.o
+obj-$(CONFIG_SRAM)		+= sram.o

drivers/misc/sram.c

@@ -0,0 +1,75 @@
+/*
+ * drivers/misc/sram.c - generic memory mapped SRAM driver
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <common.h>
+#include <errno.h>
+#include <driver.h>
+#include <malloc.h>
+#include <init.h>
+
+struct sram {
+	struct resource *res;
+	char *name;
+	struct cdev cdev;
+};
+
+static struct file_operations memops = {
+	.read  = mem_read,
+	.write = mem_write,
+	.memmap = generic_memmap_rw,
+	.lseek = dev_lseek_default,
+};
+
+static int sram_probe(struct device_d *dev)
+{
+	struct sram *sram;
+	struct resource *res;
+	void __iomem *base;
+	int ret;
+
+	base = dev_request_mem_region(dev, 0);
+	if (!base)
+		return -EBUSY;
+
+	sram = xzalloc(sizeof(*sram));
+
+	sram->cdev.name = asprintf("sram%d",
+			cdev_find_free_index("sram"));
+
+	res = dev_get_resource(dev, 0);
+
+	sram->cdev.size = (unsigned long)resource_size(res);
+	sram->cdev.ops = &memops;
+	sram->cdev.dev = dev;
+
+	ret = devfs_create(&sram->cdev);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static __maybe_unused struct of_device_id sram_dt_ids[] = {
+	{
+		.compatible = "mmio-sram",
+	}, {
+	},
+};
+
+static struct driver_d sram_driver = {
+	.name = "mmio-sram",
+	.probe = sram_probe,
+	.of_compatible = sram_dt_ids,
+};
+device_platform_driver(sram_driver);