iMX28: Add PINMUX control

Taken from Linux kernel with minor modifications:

commit bf985969e27b507f734435a99df8bf745a3dbb2b
Author: Shawn Guo <shawn.guo@freescale.com>
Date:   Mon Dec 20 22:57:43 2010 +0800

    ARM: mxs: Add iomux support

Signed-off-by: Marek Vasut <marek.vasut@gmail.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Wolfgang Denk <wd@denx.de>
Cc: Detlev Zundel <dzu@denx.de>
diff --git a/arch/arm/cpu/arm926ejs/mx28/iomux.c b/arch/arm/cpu/arm926ejs/mx28/iomux.c
new file mode 100644
index 0000000..9ea411f
--- /dev/null
+++ b/arch/arm/cpu/arm926ejs/mx28/iomux.c
@@ -0,0 +1,109 @@
+/*
+ * Copyright 2004-2006,2010 Freescale Semiconductor, Inc. All Rights Reserved.
+ * Copyright (C) 2008 by Sascha Hauer <kernel@pengutronix.de>
+ * Copyright (C) 2009 by Jan Weitzel Phytec Messtechnik GmbH,
+ *                       <armlinux@phytec.de>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
+ * MA 02110-1301, USA.
+ */
+
+#include <common.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+#include <asm/arch/clock.h>
+#include <asm/arch/iomux.h>
+#include <asm/arch/imx-regs.h>
+
+#if	defined(CONFIG_MX23)
+#define	DRIVE_OFFSET	0x200
+#define	PULL_OFFSET	0x400
+#elif	defined(CONFIG_MX28)
+#define	DRIVE_OFFSET	0x300
+#define	PULL_OFFSET	0x600
+#else
+#error "Please select CONFIG_MX23 or CONFIG_MX28"
+#endif
+
+/*
+ * configures a single pad in the iomuxer
+ */
+int mxs_iomux_setup_pad(iomux_cfg_t pad)
+{
+	u32 reg, ofs, bp, bm;
+	void *iomux_base = (void *)MXS_PINCTRL_BASE;
+	struct mx28_register *mxs_reg;
+
+	/* muxsel */
+	ofs = 0x100;
+	ofs += PAD_BANK(pad) * 0x20 + PAD_PIN(pad) / 16 * 0x10;
+	bp = PAD_PIN(pad) % 16 * 2;
+	bm = 0x3 << bp;
+	reg = readl(iomux_base + ofs);
+	reg &= ~bm;
+	reg |= PAD_MUXSEL(pad) << bp;
+	writel(reg, iomux_base + ofs);
+
+	/* drive */
+	ofs = DRIVE_OFFSET;
+	ofs += PAD_BANK(pad) * 0x40 + PAD_PIN(pad) / 8 * 0x10;
+	/* mA */
+	if (PAD_MA_VALID(pad)) {
+		bp = PAD_PIN(pad) % 8 * 4;
+		bm = 0x3 << bp;
+		reg = readl(iomux_base + ofs);
+		reg &= ~bm;
+		reg |= PAD_MA(pad) << bp;
+		writel(reg, iomux_base + ofs);
+	}
+	/* vol */
+	if (PAD_VOL_VALID(pad)) {
+		bp = PAD_PIN(pad) % 8 * 4 + 2;
+		mxs_reg = (struct mx28_register *)(iomux_base + ofs);
+		if (PAD_VOL(pad))
+			writel(1 << bp, &mxs_reg->reg_set);
+		else
+			writel(1 << bp, &mxs_reg->reg_clr);
+	}
+
+	/* pull */
+	if (PAD_PULL_VALID(pad)) {
+		ofs = PULL_OFFSET;
+		ofs += PAD_BANK(pad) * 0x10;
+		bp = PAD_PIN(pad);
+		mxs_reg = (struct mx28_register *)(iomux_base + ofs);
+		if (PAD_PULL(pad))
+			writel(1 << bp, &mxs_reg->reg_set);
+		else
+			writel(1 << bp, &mxs_reg->reg_clr);
+	}
+
+	return 0;
+}
+
+int mxs_iomux_setup_multiple_pads(const iomux_cfg_t *pad_list, unsigned count)
+{
+	const iomux_cfg_t *p = pad_list;
+	int i;
+	int ret;
+
+	for (i = 0; i < count; i++) {
+		ret = mxs_iomux_setup_pad(*p);
+		if (ret)
+			return ret;
+		p++;
+	}
+
+	return 0;
+}