mtd: rawnand: omap_elm: u-boot driver model support

Support u-boot driver model. We still retain
support legacy way of doing things if ELM_BASE
is defined in <asm/arch/hardware.h>

We could completely get rid of that if all
platforms defining ELM_BASE get rid of that definition
and enable CONFIG_SYS_NAND_SELF_INIT and are verified
to work.

Signed-off-by: Roger Quadros <rogerq@kernel.org>
Signed-off-by: Michael Trimarchi <michael@amarulasolutions.com>
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Link: https://lore.kernel.org/all/20221220102203.52398-9-rogerq@kernel.org
Link: https://lore.kernel.org/all/CABGWkvrvKiVA_yaDnHJcHEKwc+pEuLdz=i6HQEY0oJQvohCUsw@mail.gmail.com
diff --git a/drivers/mtd/nand/raw/omap_elm.c b/drivers/mtd/nand/raw/omap_elm.c
index 35c6dd1..56a2c39 100644
--- a/drivers/mtd/nand/raw/omap_elm.c
+++ b/drivers/mtd/nand/raw/omap_elm.c
@@ -15,9 +15,14 @@
 #include <common.h>
 #include <asm/io.h>
 #include <linux/errno.h>
-#include <linux/mtd/omap_elm.h>
 #include <asm/arch/hardware.h>
 
+#include <dm.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+
+#include "omap_elm.h"
+
 #define DRIVER_NAME		"omap-elm"
 #define ELM_DEFAULT_POLY (0)
 
@@ -180,6 +185,7 @@
 		;
 }
 
+#ifdef ELM_BASE
 /**
  * elm_init - Initialize ELM module
  *
@@ -190,4 +196,34 @@
 {
 	elm_cfg = (struct elm *)ELM_BASE;
 	elm_reset();
+}
+#endif
+
+#if CONFIG_IS_ENABLED(SYS_NAND_SELF_INIT)
+
+static int elm_probe(struct udevice *dev)
+{
+#ifndef ELM_BASE
+	struct resource res;
+
+	dev_read_resource(dev, 0, &res);
+	elm_cfg = devm_ioremap(dev, res.start, resource_size(&res));
+	elm_reset();
+#endif
+
+	return 0;
 }
+
+static const struct udevice_id elm_ids[] = {
+	{ .compatible = "ti,am3352-elm" },
+	{ .compatible = "ti,am64-elm" },
+	{ }
+};
+
+U_BOOT_DRIVER(gpmc_elm) = {
+	.name           = DRIVER_NAME,
+	.id             = UCLASS_MTD,
+	.of_match       = elm_ids,
+	.probe          = elm_probe,
+};
+#endif /* CONFIG_SYS_NAND_SELF_INIT */